draft-ietf-forces-netlink-03.txt   draft-ietf-forces-netlink-04.txt 
ForCES Working Group Jamal Hadi Salim ForCES Working Group Jamal Hadi Salim
Internet Draft Znyx Networks Internet Draft Znyx Networks
Hormuzd Khosravi Expiration: June 2003 Hormuzd Khosravi
Intel Intel
Andi Kleen Andi Kleen
Suse Suse
Alexey Kuznetsov Alexey Kuznetsov
INR/Swsoft INR/Swsoft
June 2002 December 2002
Netlink as an IP Services Protocol Netlink as an IP Services Protocol
draft-ietf-forces-netlink-03.txt draft-ietf-forces-netlink-04.txt
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. Internet-Drafts are working all provisions of Section 10 of RFC2026. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas, documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute and its working groups. Note that other groups may also distribute
working documents as Internet-Drafts. working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as ``work in progress.'' material or to cite them other than as ``work in progress.''
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
Conventions used in this document Abstract
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in [RFC-2119].
1. Abstract
This document describes Linux Netlink, which is used in Linux both This document describes Linux Netlink, which is used in Linux both
as an intra-kernel messaging system as well as between kernel and as an intra-kernel messaging system as well as between kernel and
user space. This document is intended as informational in the
jhs_hk_ak_ank draft-forces-Netlink-03.txt context of prior art for the ForCES IETF working group. The focus
of this
user space. This document is intended as informational in the con-
text of prior art for the ForCES IETF working group. The focus of
this
document is to describe Netlink from a perspective of a protocol document is to describe Netlink from a perspective of a protocol
between a Forwarding Engine Component (FEC) and a Control Plane between a Forwarding Engine Component (FEC) and a Control Plane
Component (CPC), the two components that define an IP service. Component (CPC), the two components that define an IP service.
The document ignores the ability of Netlink as a intra-kernel mes- The document ignores the ability of Netlink as a intra-kernel
saging system, as an inter-process communication scheme (IPC), or messaging system, as an inter-process communication scheme (IPC), or
J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
as a configuration tool for other non-networking or non-IP network as a configuration tool for other non-networking or non-IP network
services (such as decnet, etc.). services (such as decnet, etc.).
2. Introduction Table of Contents
1. Introduction ................................................. 2
1.1. Definitions ............................................ 3
1.1.1. Control Plane Components (CPCs)................... 3
1.1.2. Forwarding Engine Components (FECs)............... 4
1.1.2.1. Linux IP Forwarding Engine Model............ 4
1.1.3. IP Services ...................................... 5
2. Netlink Architecture ......................................... 7
2.1. Netlink Logical Model .................................. 8
2.2. Message Format.......................................... 9
2.3. Protocol Model.......................................... 9
2.3.1. Service Addressing................................ 10
2.3.2. Netlink Message Header............................ 10
2.3.2.1. Mechanisms for Creating Protocols........... 12
2.3.2.2. The ACK Netlink Message..................... 12
2.3.3. FE System Services' Templates..................... 13
2.3.3.1. Network Interface Service Module............. 13
2.3.3.2. IP Address Service Module................... 15
3. Currently Defined Netlink IP Services......................... 16
3.1. IP Service NETLINK_ROUTE................................ 16
3.1.1. Network Route Service Module...................... 17
3.1.2. Neighbour Setup Service Module.................... 19
3.1.3. Traffic Control Service........................... 21
3.2. IP Service NETLINK_FIREWALL............................. 23
3.3. IP Service NETLINK_ARPD................................. 27
4. References.................................................... 27
4.1. Normative References.................................... 27
4.2. Informative References.................................. 28
5. Security Considerations....................................... 28
6. Acknowledgements.............................................. 29
7. Author's Address............................................. 29
8. Appendix 1: Sample Service Hierachy .......................... 30
9. Appendix 2: Sample Protocol for the Foo IP Service............ 31
9.1. Interacting with Other IP services...................... 31
10. Appendix 3: Examples......................................... 32
1. Introduction
The concept of IP Service control-forwarding separation was first The concept of IP Service control-forwarding separation was first
introduced in the early 1980s by the BSD 4.4 routing sockets introduced in the early 1980s by the BSD 4.4 routing sockets
[Stevens]. The focus at that time was a simple IP(v4) forwarding [9]. The focus at that time was a simple IP(v4) forwarding
service and how the CPC, either via a command line configuration service and how the CPC, either via a command line configuration
J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
tool or a dynamic route daemon, could control forwarding tables for tool or a dynamic route daemon, could control forwarding tables for
that IPv4 forwarding service. that IPv4 forwarding service.
The IP world has evolved considerably since those days. Linux The IP world has evolved considerably since those days. Linux
Netlink, when observed from a service provisioning and management Netlink, when observed from a service provisioning and management
point of view, takes routing sockets one step further by breaking point of view, takes routing sockets one step further by breaking
the barrier of focus around IPv4 forwarding. Since the Linux 2.1 the barrier of focus around IPv4 forwarding. Since the Linux 2.1
kernel, Netlink has been providing the IP service abstraction to a kernel, Netlink has been providing the IP service abstraction to a
few services other than the classical RFC 1812 IPv4 forwarding. few services other than the classical RFC 1812 IPv4 forwarding.
The motivation for this document is not to list every possible ser- The motivation for this document is not to list every possible
vice for which Netlink is applied. In fact, we leave out a lot of service for which Netlink is applied. In fact, we leave out a lot
services (multicast routing, tunnelling, policy routing, etc.). of services (multicast routing, tunnelling, policy routing, etc).
Neither is this document intended to be a tutorial on Netlink. The Neither is this document intended to be a tutorial on Netlink. The
idea is to explain the overall Netlink view with a special focus on idea is to explain the overall Netlink view with a special focus on
the mandatory building blocks within the ForCES charter (i.e., IPv4 the mandatory building blocks within the ForCES charter (i.e., IPv4
and QoS). This document also serves to capture prior art to many and QoS). This document also serves to capture prior art to many
mechanisms that are useful within the context of ForCES. The text mechanisms that are useful within the context of ForCES. The text
is limited to a subset of what is available in kernel 2.4.6, the is limited to a subset of what is available in kernel 2.4.6, the
newest kernel when this document was first written. It is also newest kernel when this document was first written. It is also
limited to IPv4 functionality. limited to IPv4 functionality.
We first give some concept definitions and then describe how We first give some concept definitions and then describe how
Netlink fits in. Netlink fits in.
jhs_hk_ak_ank draft-forces-Netlink-03.txt 1.1. Definitions
2.1. Definitions
A Control Plane (CP) is an execution environment that may have sev- A Control Plane (CP) is an execution environment that may have
eral sub-components, which we refer to as CPCs. Each CPC provides several sub-components, which we refer to as CPCs. Each CPC
control for a different IP service being executed by a Forwarding provides control for a different IP service being executed by a
Engine (FE) component. This relationship means that there might be Forwarding Engine (FE) component. This relationship means that
several CPCs on a physical CP, if it is controlling several IP ser- there might be several CPCs on a physical CP, if it is controlling
vices. In essence, the cohesion between a CP component and an FE several IP services. In essence, the cohesion between a CP
component is the service abstraction. component and an FE component is the service abstraction.
2.1.1. Control Plane Components (CPCs) 1.1.1. Control Plane Components (CPCs)
Control Plane Components encompass signalling protocols, with Control Plane Components encompass signalling protocols, with
diversity ranging from dynamic routing protocols, such as OSPF diversity ranging from dynamic routing protocols, such as OSPF
[RFC2328], to tag distribution protocols, such as CR-LDP [RFC3036]. [5], to tag distribution protocols, such as CR-LDP [7].
Classical management protocols and activities also fall under this Classical management protocols and activities also fall under this
category. These include SNMP [RFC1157], COPS [RFC2748], and pro- category. These include SNMP [6], COPS [4], and proprietary
prietary CLI/GUI configuration mechanisms. CLI/GUI configuration mechanisms.
The purpose of the control plane is to provide an execution
The purpose of the control plane is to provide an execution envi- environment for the above-mentioned activities with the ultimate
ronment for the above-mentioned activities with the ultimate goal goal being to configure and manage the second Network Element (NE)
being to configure and manage the second Network Element (NE) com- component: the FE. The result of the configuration defines the way
ponent: the FE. The result of the configuration defines the way
that packets traversing the FE are treated. that packets traversing the FE are treated.
2.1.2. Forwarding Engine Components (FECs) J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
The FE is the entity of the NE that incoming packets (from the net- 1.1.2. Forwarding Engine Components (FECs)
work into the NE) first encounter.
The FE is the entity of the NE that incoming packets (from the
network into the NE) first encounter.
The FE's service-specific component massages the packet to provide The FE's service-specific component massages the packet to provide
it with a treatment to achieve an IP service, as defined by the it with a treatment to achieve an IP service, as defined by the
Control Plane Components for that IP service. Different services Control Plane Components for that IP service. Different services
will utilize different FECs. Service modules may be chained to will utilize different FECs. Service modules may be chained to
achieve a more complex service (refer to the Linux FE model, achieve a more complex service (refer to the Linux FE model,
described later). When built for providing a specific service, the described later). When built for providing a specific service, the
FE service component will adhere to a forwarding model. FE service component will adhere to a forwarding model.
jhs_hk_ak_ank draft-forces-Netlink-03.txt 1.1.2.1. Linux IP Forwarding Engine Model
2.1.2.1. Linux IP Forwarding Engine Model
____ +---------------+ ____ +---------------+
+->-| FW |---> | TCP, UDP, ... | +->-| FW |---> | TCP, UDP, ... |
| +----+ +---------------+ | +----+ +---------------+
| | | |
^ v ^ v
| _|_ | _|_
+----<----+ | FW | +----<----+ | FW |
| +----+ | +----+
^ | ^ |
skipping to change at page 4, line 32 skipping to change at page 4, line 45
|_____ | |_____ |
Ingress ^ Y Ingress ^ Y
device ____ +-------+ +|---|--+ ____ +--------+ Egress device ____ +-------+ +|---|--+ ____ +--------+ Egress
->----->| FW |-->|Ingress|-->---->| Forw- |->| FW |->| Egress | device ->----->| FW |-->|Ingress|-->---->| Forw- |->| FW |->| Egress | device
+----+ | TC | | ard | +----+ | TC |--> +----+ | TC | | ard | +----+ | TC |-->
+-------+ +-------+ +--------+ +-------+ +-------+ +--------+
The figure above shows the Linux FE model per device. The only The figure above shows the Linux FE model per device. The only
mandatory part of the datapath is the Forwarding module, which is mandatory part of the datapath is the Forwarding module, which is
RFC 1812 conformant. The different Firewall (FW), Ingress Traffic RFC 1812 conformant. The different Firewall (FW), Ingress Traffic
Control, and Egress Traffic Control building blocks are not manda- Control, and Egress Traffic Control building blocks are not
tory in the datapath and may even be used to bypass the RFC 1812 mandatory in the datapath and may even be used to bypass the RFC
module. These modules are shown as simple blocks in the datapath 1812 module. These modules are shown as simple blocks in the
but, in fact, could be multiple cascaded, independent submodules datapath but, in fact, could be multiple cascaded, independent
within the indicated blocks. More information can be found at
[Netfilter] and [Diffserv].
Packets arriving at the ingress device first pass through a fire- J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
wall module. Packets may be dropped, munged, etc., by the firewall
module. The incoming packet, depending on set policy, may then be submodules within the indicated blocks. More information can be
passed via an Ingress Traffic Control module. Metering and polic- found at [10] and [11].
ing activities are contained within the Ingress TC module. Packets
may be dropped, depending on metering results and policing poli- Packets arriving at the ingress device first pass through a
cies, at this module. Next, the packet is subjected to the only firewall module. Packets may be dropped, munged, etc., by the
non-optional module, the RFC 1812-conformant Forwarding module. firewall module. The incoming packet, depending on set policy,
may then be passed via an Ingress Traffic Control module.
Metering and policing activities are contained within the
Ingress TC module. Packets may be dropped, depending on
metering results and policing policies, at this module.
Next, the packet is subjected to the only non-optional module,
the RFC 1812-conformant Forwarding module.
The packet may be dropped if it is nonconformant (to the many RFCs The packet may be dropped if it is nonconformant (to the many RFCs
complementing 1812 and 1122). This module is a juncture point at complementing 1812 and 1122). This module is a juncture point at
which packets destined to the forwarding NE may be sent up to the which packets destined to the forwarding NE may be sent up to the
host stack. host stack.
Packets that are not for the NE may further traverse a policy rout- Packets that are not for the NE may further traverse a policy
ing submodule (within the forwarding module), if so provisioned. routing submodule (within the forwarding module), if so
provisioned.
jhs_hk_ak_ank draft-forces-Netlink-03.txt
Another firewall module is walked next. The firewall module can Another firewall module is walked next. The firewall module can
drop or munge/transform packets, depending on the configured sub- drop or munge/transform packets, depending on the configured
modules encountered and their policies. If all goes well, the sub-modules encountered and their policies. If all goes well,
Egress TC module is accessed next. the Egress TC module is accessed next.
The Egress TC may drop packets for policing, scheduling, congestion The Egress TC may drop packets for policing, scheduling, congestion
control, or rate control reasons. Egress queues exist at this control, or rate control reasons. Egress queues exist at this
point and any of the drops or delays may happen before or after the point and any of the drops or delays may happen before or after the
packet is queued. All is dependent on configured module algorithms packet is queued. All is dependent on configured module algorithms
and policies. and policies.
2.1.3. IP Services 1.1.3. IP Services
An IP service is the treatment of an IP packet within the NE. This An IP service is the treatment of an IP packet within the NE. This
treatment is provided by a combination of both the CPC and the FEC. treatment is provided by a combination of both the CPC and the FEC.
The time span of the service is from the moment when the packet The time span of the service is from the moment when the packet
arrives at the NE to the moment that it departs. In essence, an IP arrives at the NE to the moment that it departs. In essence, an IP
service in this context is a Per-Hop Behavior. CP components run- service in this context is a Per-Hop Behavior. CP components
ning on NEs define the end-to-end path control for a service by running on NEs define the end-to-end path control for a service by
running control/signaling protocol/management-applications. These running control/signaling protocol/management-applications. These
distributed CPCs unify the end-to-end view of the IP service. As distributed CPCs unify the end-to-end view of the IP service. As
noted above, these CP components then define the behavior of the FE noted above, these CP components then define the behavior of the FE
(and therefore the NE) for a described packet. (and therefore the NE) for a described packet.
A simple example of an IP service is the classical IPv4 Forwarding. A simple example of an IP service is the classical IPv4 Forwarding.
In this case, control components, such as routing protocols (OSPF, In this case, control components, such as routing protocols (OSPF,
RIP, etc.) and proprietary CLI/GUI configurations, modify the FE's
forwarding tables in order to offer the simple service of forward-
ing packets to the next hop. Traditionally, NEs offering this sim-
ple service are known as routers. In the diagram below, we show a
simple FE<->CP setup to provide an example of the classical IPv4
service with an extension to do some basic QoS egress scheduling
and illustrate how the setup fits in this described model.
jhs_hk_ak_ank draft-forces-Netlink-03.txt J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
RIP, etc.) and proprietary CLI/GUI configurations, modify the FE's
forwarding tables in order to offer the simple service of
forwarding packets to the next hop. Traditionally, NEs offering
this simple service are known as routers. In the diagram below,
we show a simple FE<->CP setup to provide an example of the
classical IPv4 service with an extension to do some basic QoS
egress scheduling and illustrate how the setup fits in this
described model.
Control Plane (CP) Control Plane (CP)
.------------------------------------ .------------------------------------
| /^^^^^^\ /^^^^^^\ | | /^^^^^^\ /^^^^^^\ |
| | | | COPS |-\ | | | | | COPS |-\ |
| | ospfd | | PEP | \ | | | ospfd | | PEP | \ |
| \ / \_____/ | | | \ / \_____/ | |
/------\_____/ | / | /------\_____/ | / |
| | | | / | | | | | / |
| |_________\__________|____|_________| | |_________\__________|____|_________|
| | | | | | | |
****************************************** ******************************************
Forwarding ************* Netlink layer ************ Forwarding ************* Netlink layer ************
Engine (FE) ***************************************** Engine (FE) *****************************************
.-------------|-----------|----------|---|------------- .-------------|-----------|----------|---|-------------
| IPv4 forwading | | | | IPv4 forwarding | | |
| FE Service / / | | FE Service / / |
| Component / / | | Component / / |
| ---------------/---------------/--------- | | ---------------/---------------/--------- |
| | | / | | | | | / | |
packet | | --------|-- ----|----- | packet packet | | --------|-- ----|----- | packet
in | | | IPv4 | | Egress | | out in | | | IPv4 | | Egress | | out
-->--->|------>|---->|Forwading |----->| QoS |--->| ---->|-> -->--->|------>|---->|Forwading |----->| QoS |--->| ---->|->
| | | | | Scheduler| | | | | | | | Scheduler| | |
| | ----------- ---------- | | | | ----------- ---------- | |
| | | | | | | |
| --------------------------------------- | | --------------------------------------- |
| | | |
------------------------------------------------------- -------------------------------------------------------
The above diagram illustrates ospfd, an OSPF protocol control dae- The above diagram illustrates ospfd, an OSPF protocol control
mon, and a COPS Policy Enforcement Point (PEP) as distinct CPCs. daemon, and a COPS Policy Enforcement Point (PEP) as distinct CPCs.
The IPv4 FE component includes the IPv4 Forwarding service module The IPv4 FE component includes the IPv4 Forwarding service module
as well as the Egress Scheduling service module. Another service as well as the Egress Scheduling service module. Another service
might add a policy forwarder between the IPv4 forwarder and the QoS might add a policy forwarder between the IPv4 forwarder and the QoS
egress scheduler. A simpler classical service would have consti- egress scheduler. A simpler classical service would have
tuted only the IPv4 forwarder. constituted only the IPv4 forwarder.
Over the years, it has become important to add aditional services Over the years, it has become important to add aditional services
to routers to meet emerging requirements. More complex services to routers to meet emerging requirements. More complex services
extending classical forwarding have been added and standardized. extending classical forwarding have been added and standardized.
J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
These newer services might go beyond the layer 3 contents of the These newer services might go beyond the layer 3 contents of the
packet header. However, the name "router," although a misnomer, is packet header. However, the name "router," although a misnomer, is
still used to describe these NEs. Services (which may look beyond still used to describe these NEs. Services (which may look beyond
the classical L3 service headers) include firewalling, QoS in Diff- the classical L3 service headers) include firewalling, QoS in
serv and RSVP, NAT, policy based routing, etc. Newer control pro- Diffserv and RSVP, NAT, policy based routing, etc. Newer control
tocols or management activities are introduced with these new ser- protocols or management activities are introduced with these new
vices. services.
jhs_hk_ak_ank draft-forces-Netlink-03.txt
One extreme definition of a IP service is something for which a One extreme definition of a IP service is something for which a
service provider would be able to charge. service provider would be able to charge.
3. Netlink Architecture 2. Netlink Architecture
Control of IP service components is defined by using templates. Control of IP service components is defined by using templates.
The FEC and CPC participate to deliver the IP service by communi- The FEC and CPC participate to deliver the IP service by
cating using these templates. The FEC might continously get communicating using these templates. The FEC might continously get
updates from the Control Plane Component on how to operate the ser- updates from the Control Plane Component on how to operate the
vice (e.g., for v4 forwarding or for route additions or deletions). service (e.g., for v4 forwarding or for route additions or
deletions).
The interaction between the FEC and the CPC, in the Netlink con- The interaction between the FEC and the CPC, in the Netlink
text, defines a protocol. Netlink provides mechanisms for the CPC context, defines a protocol. Netlink provides mechanisms for the
(residing in user space) and the FEC (residing in kernel space) to CPC (residing in user space) and the FEC (residing in kernel space)
have their own protocol definition--kernel space and user space to have their own protocol definition--kernel space and user space
just mean different protection domains. Therefore, a wire protocol just mean different protection domains. Therefore, a wire protocol
is needed to communicate. The wire protocol is normally provided is needed to communicate. The wire protocol is normally provided
by some privileged service that is able to copy between multiple by some privileged service that is able to copy between multiple
protection domains. We will refer to this service as the Netlink protection domains. We will refer to this service as the Netlink
service. The Netlink service can also be encapsulated in a differ- service. The Netlink service can also be encapsulated in a
ent transport layer, if the CPC executes on a different node than different transport layer, if the CPC executes on a different node
the FEC. The FEC and CPC, using Netlink mechanisms, may choose to than the FEC. The FEC and CPC, using Netlink mechanisms, may
define a reliable protocol between each other. By default, how- choose to define a reliable protocol between each other. By
ever, Netlink provides an unreliable communication. default, however, Netlink provides an unreliable communication.
Note that the FEC and CPC can both live in the same memory protec- Note that the FEC and CPC can both live in the same memory
tion domain and use the connect() system call to create a path to protection domain and use the connect() system call to create a
the peer and talk to each other. We will not discuss this mecha- path to the peer and talk to each other. We will not discuss this
nism further other than to say that it is available. Throughout mechanism further other than to say that it is available.
this document, we will refer interchangebly to the FEC to mean ker- Throughout this document, we will refer interchangebly to the FEC
nel space and the CPC to mean user space. This denomination is not to mean kernel space and the CPC to mean user space. This
meant, however, to restrict the two components to these protection denomination is not meant, however, to restrict the two components
domains or to the same compute node. to these protection domains or to the same compute node.
Note: Netlink allows participation in IP services by both service Note: Netlink allows participation in IP services by both service
components. components.
3.1. Netlink Logical Model J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
In the diagram below we show a simple FEC<->CPC logical relation-
ship. We use the IPv4 forwarding FEC (NETLINK_ROUTE, which is
jhs_hk_ak_ank draft-forces-Netlink-03.txt 2.1. Netlink Logical Model
discussed further below) as an example. In the diagram below we show a simple FEC<->CPC logical
relationship. We use the IPv4 forwarding FEC (NETLINK_ROUTE,
which is discussed further below) as an example.
Control Plane (CP) Control Plane (CP)
.------------------------------------ .------------------------------------
| /^^^^^\ /^^^^^\ | | /^^^^^\ /^^^^^\ |
| | | / CPC-2 \ | | | | / CPC-2 \ |
| | CPC-1 | | COPS | | | | CPC-1 | | COPS | |
| | ospfd | | PEP | | | | ospfd | | PEP | |
| / _____/ | | | / \____ _/ |
| _____/ | | | \____/ | |
| | | | | | | |
****************************************| ****************************************|
************* BROADCAST WIRE ************ ************* BROADCAST WIRE ************
FE---------- *****************************************. FE---------- *****************************************.
| IPv4 forwading | | | | | IPv4 forwarding | | | |
| FEC | | | | | FEC | | | |
| --------------/ ----|-----------|-------- | | --------------/ ----|-----------|-------- |
| | / | | | | | | / | | | |
| | .-------. .-------. .------. | | | | .-------. .-------. .------. | |
| | |Ingress| | IPv4 | |Egress| | | | | |Ingress| | IPv4 | |Egress| | |
| | |police | |Forward| | QoS | | | | | |police | |Forward| | QoS | | |
| | |_______| |_______| |Sched | | | | | |_______| |_______| |Sched | | |
| | ------ | | | | ------ | |
| --------------------------------------- | | --------------------------------------- |
| | | |
----------------------------------------------------- -----------------------------------------------------
Netlink logically models FECs and CPCs in the form of nodes inter- Netlink logically models FECs and CPCs in the form of nodes
connected to each other via a broadcast wire. interconnected to each other via a broadcast wire.
The wire is specific to a service. The example above shows the The wire is specific to a service. The example above shows the
broadcast wire belonging to the extended IPv4 forwarding service. broadcast wire belonging to the extended IPv4 forwarding service.
Nodes (CPCs or FECs as illustrated above) connect to the wire and Nodes (CPCs or FECs as illustrated above) connect to the wire and
register to receive specific messages. CPCs may connect to multi- register to receive specific messages. CPCs may connect to
ple wires if it helps them to control the service better. All multiple wires if it helps them to control the service better. All
nodes (CPCs and FECs) dump packets on the broadcast wire. Packets nodes (CPCs and FECs) dump packets on the broadcast wire. Packets
can be discarded by the wire if they are malformed or not specifi- can be discarded by the wire if they are malformed or not
cally formatted for the wire. Dropped packets are not seen by any specifically formatted for the wire. Dropped packets are not seen
of the nodes. The Netlink service MAY signal an error to the by any of the nodes. The Netlink service may signal an error to
sender if it detects a malformatted Netlink packet. the sender if it detects a malformatted Netlink packet.
Packets sent on the wire can be broadcast, multicast, or unicast. J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
FECs or CPCs register for specific messages of interest for pro-
cessing or just monitoring purposes.
jhs_hk_ak_ank draft-forces-Netlink-03.txt Packets sent on the wire can be broadcast, multicast, or unicast.
FECs or CPCs register for specific messages of interest for
processing or just monitoring purposes.
Appendices 1 and 2 have a high level overview of this interaction. Appendices 1 and 2 have a high level overview of this interaction.
3.2. Message Format 2.2. Message Format
There are three levels to a Netlink message: The general Netlink There are three levels to a Netlink message: The general Netlink
message header, the IP service specific template, and the IP ser- message header, the IP service specific template, and the IP
vice specific data. service specific data.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Netlink message header | | Netlink message header |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| IP Service Template | | IP Service Template |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| IP Service specific data in TLVs | | IP Service specific data in TLVs |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Netlink message is used to communicate between the FEC and CPC The Netlink message is used to communicate between the FEC and CPC
for parametrization of the FECs, asynchoronous event notification for parametrization of the FECs, asynchoronous event notification
of FEC events to the CPCs, and statistics querying/gathering (typi- of FEC events to the CPCs, and statistics querying/gathering
cally by a CPC). (typically by a CPC).
The Netlink message header is generic for all services, whereas the The Netlink message header is generic for all services, whereas the
IP Service Template header is specific to a service. Each IP Ser- IP Service Template header is specific to a service. Each IP
vice then carries parametrization data (CPC->FEC direction) or Service then carries parametrization data (CPC->FEC direction) or
response (FEC->CPC direction). These parametrizations are in TLV response (FEC->CPC direction). These parametrizations are in TLV
(Type-Length-Value) format and are unique to the service. (Type-Length-Value) format and are unique to the service.
3.3. Protocol Model The different parts of the netlink message are discussed in the
following sections.
This section expands on how Netlink provides the mechanism for ser- 2.3. Protocol Model
vice-oriented FEC and CPC interaction.
jhs_hk_ak_ank draft-forces-Netlink-03.txt This section expands on how Netlink provides the mechanism for
service-oriented FEC and CPC interaction.
3.3.1. Service Addressing J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
2.3.1. Service Addressing
Access is provided by first connecting to the service on the FE. Access is provided by first connecting to the service on the FE.
The connection is achieved by making a socket() system call to the The connection is achieved by making a socket() system call to the
PF_NETLINK domain. Each FEC is identified by a protocol number. PF_NETLINK domain. Each FEC is identified by a protocol number.
One may open either SOCK_RAW or SOCK_DGRAM type sockets, although One may open either SOCK_RAW or SOCK_DGRAM type sockets, although
Netlink does not distinguish between the two. The socket connec- Netlink does not distinguish between the two. The socket
tion provides the basis for the FE<->CP addressing. connection provides the basis for the FE<->CP addressing.
Connecting to a service is followed (at any point during the life Connecting to a service is followed (at any point during the life
of the connection) by either issuing a service-specific command of the connection) by either issuing a service-specific command
(from the CPC to the FEC, mostly for configuration purposes), issu- (from the CPC to the FEC, mostly for configuration purposes),
ing a statistics-collection command, or subscribing/unsubscribing issuing a statistics-collection command, or
to service events. Closing the socket terminates the transaction. subscribing/unsubscribing to service events. Closing the socket
terminates the transaction.
Refer to Appendices 1 and 2 for examples. Refer to Appendices 1 and 2 for examples.
3.3.2. Netlink Message Header 2.3.2. Netlink Message Header
Netlink messages consist of a byte stream with one or multiple Netlink messages consist of a byte stream with one or multiple
Netlink headers and an associated payload. If the payload is too Netlink headers and an associated payload. If the payload is too
big to fit into a single message it, can be split over multiple big to fit into a single message it, can be split over multiple
Netlink messages, collectively called a multipart message. For Netlink messages, collectively called a multipart message. For
multipart messages, the first and all following headers have the multipart messages, the first and all following headers have the
NLM_F_MULTI Netlink header flag set, except for the last header NLM_F_MULTI Netlink header flag set, except for the last header
which has the Netlink header type NLMSG_DONE. which has the Netlink header type NLMSG_DONE.
The Netlink message header is shown below. The Netlink message header is shown below.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Flags | | Type | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number | | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Process ID (PID) | | Process ID (PID) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields in the header are: The fields in the header are:
jhs_hk_ak_ank draft-forces-Netlink-03.txt J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
Length: 32 bits Length: 32 bits
The length of the message in bytes, including the header. The length of the message in bytes, including the header.
Type: 16 bits Type: 16 bits
This field describes the message content. This field describes the message content.
It can be one of the standard message types: It can be one of the standard message types:
NLMSG_NOOP Message is ignored. NLMSG_NOOP Message is ignored.
NLMSG_ERROR The message signals an error and the payload NLMSG_ERROR The message signals an error and the payload
contains a nlmsgerr structure. This can be looked contains a nlmsgerr structure. This can be looked
skipping to change at page 12, line 5 skipping to change at page 12, line 5
service in the FE for a longer time. service in the FE for a longer time.
Convenience macros for flag bits: Convenience macros for flag bits:
NLM_F_DUMP This is NLM_F_ROOT or'ed with NLM_F_MATCH NLM_F_DUMP This is NLM_F_ROOT or'ed with NLM_F_MATCH
Additional flag bits for NEW requests Additional flag bits for NEW requests
NLM_F_REPLACE Replace existing matching config object with NLM_F_REPLACE Replace existing matching config object with
this request. this request.
NLM_F_EXCL Don't replace the config object if it already NLM_F_EXCL Don't replace the config object if it already
jhs_hk_ak_ank draft-forces-Netlink-03.txt J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
exists. exists.
NLM_F_CREATE Create config object if it doesn't already NLM_F_CREATE Create config object if it doesn't already
exist. exist.
NLM_F_APPEND Add to the end of the object list. NLM_F_APPEND Add to the end of the object list.
For those familiar with BSDish use of such operations in route For those familiar with BSDish use of such operations in route
sockets, the equivalent translations are: sockets, the equivalent translations are:
- BSD ADD operation equates to NLM_F_CREATE or-ed - BSD ADD operation equates to NLM_F_CREATE or-ed
skipping to change at page 12, line 30 skipping to change at page 12, line 30
NLM_F_CREATE NLM_F_CREATE
Sequence Number: 32 bits Sequence Number: 32 bits
The sequence number of the message. The sequence number of the message.
Process ID (PID): 32 bits Process ID (PID): 32 bits
The PID of the process sending the message. The PID is used by the The PID of the process sending the message. The PID is used by the
kernel to multiplex to the correct sockets. A PID of zero is used kernel to multiplex to the correct sockets. A PID of zero is used
when sending messages to user space from the kernel. when sending messages to user space from the kernel.
3.3.2.1. Mechanisms for Creating Protocols 2.3.2.1. Mechanisms for Creating Protocols
One could create a reliable protocol between an FEC and a CPC by One could create a reliable protocol between an FEC and a CPC by
using the combination of sequence numbers, ACKs, and retransmit using the combination of sequence numbers, ACKs, and retransmit
timers. Both sequence numbers and ACKs are provided by Netlink; timers. Both sequence numbers and ACKs are provided by Netlink;
timers are provided by Linux. timers are provided by Linux.
One could create a heartbeat protocol between the FEC and CPC by One could create a heartbeat protocol between the FEC and CPC by
using the ECHO flags and the NLMSG_NOOP message. using the ECHO flags and the NLMSG_NOOP message.
3.3.2.2. The ACK Netlink Message 2.3.2.2. The ACK Netlink Message
This message is actually used to denote both an ACK and a NACK. This message is actually used to denote both an ACK and a NACK.
Typically, the direction is from FEC to CPC (in response to an ACK Typically, the direction is from FEC to CPC (in response to an ACK
request message). However, the CPC should be able to send ACKs request message). However, the CPC should be able to send ACKs
back to FEC when requested. The semantics for this are IP service- back to FEC when requested. The semantics for this are IP
specific. service specific.
jhs_hk_ak_ank draft-forces-Netlink-03.txt J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Netlink message header | | Netlink message header |
| type = NLMSG_ERROR | | type = NLMSG_ERROR |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error code | | Error code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OLD Netlink message header | | OLD Netlink message header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Error code: integer (typically 32 bits) Error code: integer (typically 32 bits)
skipping to change at page 13, line 33 skipping to change at page 13, line 32
message header, which can be used to compare against (sent sequence message header, which can be used to compare against (sent sequence
numbers, etc). numbers, etc).
A non-zero error code message is equivalent to a Negative ACK A non-zero error code message is equivalent to a Negative ACK
(NACK). In such a situation, the Netlink data that was sent down (NACK). In such a situation, the Netlink data that was sent down
to the kernel is returned appended to the original Netlink message to the kernel is returned appended to the original Netlink message
header. An error code printable via the perror() is also set (not header. An error code printable via the perror() is also set (not
in the message header, rather in the executing environment state in the message header, rather in the executing environment state
variable). variable).
3.3.3. FE System Services' Templates 2.3.3. FE System Services' Templates
These are services that are offered by the system for general use These are services that are offered by the system for general use
by other services. They include the ability to configure, gather by other services. They include the ability to configure, gather
statistics and listen to changes in shared resources. IP address statistics and listen to changes in shared resources. IP address
management, link events, etc. fit here. We create this section for management, link events, etc. fit here. We create this section for
these services for logical separation, despite the fact that they these services for logical separation, despite the fact that they
are accessed via the NETLINK_ROUTE FEC. The reason that they exist are accessed via the NETLINK_ROUTE FEC. The reason that they exist
within NETLINK_ROUTE is due to historical cruft: the BSD 4.4 Route within NETLINK_ROUTE is due to historical cruft: the BSD 4.4 Route
Sockets implemented them as part of the IPv4 forwarding sockets. Sockets implemented them as part of the IPv4 forwarding sockets.
3.3.3.1. 2.3.3.1. Network Interface Service Module
Network Interface Service Module
jhs_hk_ak_ank draft-forces-Netlink-03.txt J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
This service provides the ability to create, remove, or get infor- This service provides the ability to create, remove, or get
mation about a specific network interface. The network interface information about a specific network interface. The network
can be either physical or virtual and is network protocol indepen- interface can be either physical or virtual and is network protocol
dent (e.g., an x.25 interface can be defined via this message). independent (e.g., an x.25 interface can be defined via this
The Interface service message template is shown below. message). The Interface service message template is shown below.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Family | Reserved | Device Type | | Family | Reserved | Device Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Interface Index | | Interface Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Device Flags | | Device Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Change Mask | | Change Mask |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
jhs_hk_ak_ank draft-forces-Netlink-03.txt
Family: 8 bits Family: 8 bits
This is always set to AF_UNSPEC. This is always set to AF_UNSPEC.
Device Type: 16 bits Device Type: 16 bits
This defines the type of the link. The link could be Ethernet, a This defines the type of the link. The link could be Ethernet, a
tunnel, etc. We are interested only in IPv4, although the link type tunnel, etc. We are interested only in IPv4, although the link type
is L3 protocol-independent. is L3 protocol-independent.
Interface Index: 32 bits Interface Index: 32 bits
Uniquely identifies interface. Uniquely identifies interface.
skipping to change at page 15, line 37 skipping to change at page 15, line 5
IFF_PROMISC Interface is in promiscuous mode. IFF_PROMISC Interface is in promiscuous mode.
IFF_NOTRAILERS Avoid use of trailers. IFF_NOTRAILERS Avoid use of trailers.
IFF_ALLMULTI Receive all multicast packets. IFF_ALLMULTI Receive all multicast packets.
IFF_MASTER Master of a load balancing bundle. IFF_MASTER Master of a load balancing bundle.
IFF_SLAVE Slave of a load balancing bundle. IFF_SLAVE Slave of a load balancing bundle.
IFF_MULTICAST Supports multicast IFF_MULTICAST Supports multicast
IFF_PORTSEL Is able to select media type via ifmap. IFF_PORTSEL Is able to select media type via ifmap.
IFF_AUTOMEDIA Auto media selection active. IFF_AUTOMEDIA Auto media selection active.
IFF_DYNAMIC Interface was dynamically created. IFF_DYNAMIC Interface was dynamically created.
J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
Change Mask: 32 bits Change Mask: 32 bits
Reserved for future use. Must be set to 0xFFFFFFFF. Reserved for future use. Must be set to 0xFFFFFFFF.
Applicable attributes: Applicable attributes:
Attribute Description Attribute Description
........................................................... ..........................................................
IFLA_UNSPEC Unspecified. IFLA_UNSPEC Unspecified.
IFLA_ADDRESS Hardware address interface L2 address. IFLA_ADDRESS Hardware address interface L2 address.
IFLA_BROADCAST Hardware address L2 broadcast IFLA_BROADCAST Hardware address L2 broadcast
address. address.
IFLA_IFNAME ASCII string device name. IFLA_IFNAME ASCII string device name.
IFLA_MTU MTU of the device. IFLA_MTU MTU of the device.
IFLA_LINK ifindex of link to which this device IFLA_LINK ifindex of link to which this device
is bound. is bound.
IFLA_QDISC ASCII string defining egress root IFLA_QDISC ASCII string defining egress root
queueing discipline. queueing discipline.
IFLA_STATS Interface statistics. IFLA_STATS Interface statistics.
jhs_hk_ak_ank draft-forces-Netlink-03.txt
Netlink message types specific to this service: Netlink message types specific to this service:
RTM_NEWLINK, RTM_DELLINK, and RTM_GETLINK RTM_NEWLINK, RTM_DELLINK, and RTM_GETLINK
3.3.3.2. IP Address Service Module 2.3.3.2. IP Address Service Module
This service provides the ability to add, remove, or receive information This service provides the ability to add, remove, or receive information
about an IP address associated with an interface. The address provi- about an IP address associated with an interface. The address
sioning service message template is shown below. provisioning service message template is shown below.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Family | Length | Flags | Scope | | Family | Length | Flags | Scope |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Interface Index | | Interface Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Family: 8 bits Family: 8 bits
Address Family: AF_INET for IPv4; and AF_INET6 for IPV4. Address Family: AF_INET for IPv4; and AF_INET6 for IPV6.
Length: 8 bits Length: 8 bits
The length of the address mask. The length of the address mask.
Flags: 8 bits Flags: 8 bits
IFA_F_SECONDARY For secondary address (alias interface). IFA_F_SECONDARY For secondary address (alias interface).
J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
IFA_F_PERMANENT For a permanent address set by the user. IFA_F_PERMANENT For a permanent address set by the user.
When this is not set, it means the address When this is not set, it means the address
was dynamically created (e.g., by stateless was dynamically created (e.g., by stateless
autoconfiguration). autoconfiguration).
IFA_F_DEPRECATED Defines deprecated (IPV4) address. IFA_F_DEPRECATED Defines deprecated (IPV4) address.
IFA_F_TENTATIVE Defines tentative (IPV4) address (duplicate IFA_F_TENTATIVE Defines tentative (IPV4) address (duplicate
address detection is still in progress). address detection is still in progress).
Scope: 8 bits Scope: 8 bits
The address scope in which the address stays valid. The address scope in which the address stays valid.
SCOPE_UNIVERSE: Global scope. SCOPE_UNIVERSE: Global scope.
SCOPE_SITE (IPv6 only): Only valid within this site. SCOPE_SITE (IPv6 only): Only valid within this site.
SCOPE_LINK: Valid only on this device. SCOPE_LINK: Valid only on this device.
SCOPE_HOST: Valid only on this host. SCOPE_HOST: Valid only on this host.
Applicable attributes: Applicable attributes:
jhs_hk_ak_ank draft-forces-Netlink-03.txt
Attribute Description Attribute Description
......................................................... .........................................................
IFA_UNSPEC Unspecified. IFA_UNSPEC Unspecified.
IFA_ADDRESS Raw protocol address of interface. IFA_ADDRESS Raw protocol address of interface.
IFA_LOCAL Raw protocol local address. IFA_LOCAL Raw protocol local address.
IFA_LABEL ASCII string name of the interface. IFA_LABEL ASCII string name of the interface.
IFA_BROADCAST Raw protocol broadcast address. IFA_BROADCAST Raw protocol broadcast address.
IFA_ANYCAST Raw protocol anycast address. IFA_ANYCAST Raw protocol anycast address.
IFA_CACHEINFO Cache address information. IFA_CACHEINFO Cache address information.
Netlink messages specific to this service: RTM_NEWADDR, Netlink messages specific to this service: RTM_NEWADDR,
RTM_DELADDR, and RTM_GETADDR. RTM_DELADDR, and RTM_GETADDR.
4. Currently Defined Netlink IP Services 3. Currently Defined Netlink IP Services
Although there are many other IP services defined that are using Although there are many other IP services defined that are using
Netlink, as mentioned earlier, we will talk only about a handful of Netlink, as mentioned earlier, we will talk only about a handful of
those integrated into kernel version 2.4.6. These are: those integrated into kernel version 2.4.6. These are:
NETLINK_ROUTE, NETLINK_FIREWALL, and NETLINK_ARPD. NETLINK_ROUTE, NETLINK_FIREWALL, and NETLINK_ARPD.
4.1. IP Service NETLINK_ROUTE 3.1. IP Service NETLINK_ROUTE
This service allows CPCs to modify the IPv4 routing table in the This service allows CPCs to modify the IPv4 routing table in the
Forwarding Engine. It can also be used by CPCs to receive routing Forwarding Engine. It can also be used by CPCs to receive routing
updates, as well as to collect statistics. updates, as well as to collect statistics.
4.1.1. Network Route Service Module J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
3.1.1. Network Route Service Module
This service provides the ability to create, remove or receive This service provides the ability to create, remove or receive
information about a network route. The service message template is information about a network route. The service message template is
shown below. shown below.
jhs_hk_ak_ank draft-forces-Netlink-03.txt
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Family | Src length | Dest length | TOS | | Family | Src length | Dest length | TOS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Table ID | Protocol | Scope | Type | | Table ID | Protocol | Scope | Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Family: 8 bits Family: 8 bits
Address Family: AF_INET for IPv4; and AF_INET6 for IPV4. Address Family: AF_INET for IPv4; and AF_INET6 for IPV6.
Src length: 8 bits Src length: 8 bits
Prefix length of source IP address. Prefix length of source IP address.
Dest length: 8 bits Dest length: 8 bits
Prefix length of destination IP address. Prefix length of destination IP address.
TOS: 8 bits TOS: 8 bits
The 8-bit TOS (should be deprecated to make room for DSCP). The 8-bit TOS (should be deprecated to make room for DSCP).
jhs_hk_ak_ank draft-forces-Netlink-03.txt
Table ID: 8 bits Table ID: 8 bits
Table identifier. Up to 255 route tables are supported. Table identifier. Up to 255 route tables are supported.
RT_TABLE_UNSPEC An unspecified routing table. RT_TABLE_UNSPEC An unspecified routing table.
RT_TABLE_DEFAULT The default table. RT_TABLE_DEFAULT The default table.
RT_TABLE_MAIN The main table. RT_TABLE_MAIN The main table.
RT_TABLE_LOCAL The local table. RT_TABLE_LOCAL The local table.
The user may assign arbitary values between The user may assign arbitary values between
RT_TABLE_UNSPEC(0) and RT_TABLE_DEFAULT(253). RT_TABLE_UNSPEC(0) and RT_TABLE_DEFAULT(253).
skipping to change at page 19, line 29 skipping to change at page 18, line 4
Protocol Route origin. Protocol Route origin.
.............................................. ..............................................
RTPROT_UNSPEC Unknown. RTPROT_UNSPEC Unknown.
RTPROT_REDIRECT By an ICMP redirect. RTPROT_REDIRECT By an ICMP redirect.
RTPROT_KERNEL By the kernel. RTPROT_KERNEL By the kernel.
RTPROT_BOOT During bootup. RTPROT_BOOT During bootup.
RTPROT_STATIC By the administrator. RTPROT_STATIC By the administrator.
Values larger than RTPROT_STATIC(4) are not interpreted by the Values larger than RTPROT_STATIC(4) are not interpreted by the
kernel, they are just for user information. They may be used to kernel, they are just for user information. They may be used to
J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
tag the source of a routing information or to distingush between tag the source of a routing information or to distingush between
multiple routing daemons. See <linux/rtnetlink.h> for the multiple routing daemons. See <linux/rtnetlink.h> for the
routing daemon identifiers that are already assigned. routing daemon identifiers that are already assigned.
Scope: 8 bits Scope: 8 bits
Route scope (valid distance to destination). Route scope (valid distance to destination).
RT_SCOPE_UNIVERSE Global route. RT_SCOPE_UNIVERSE Global route.
RT_SCOPE_SITE Interior route in the RT_SCOPE_SITE Interior route in the
local autonomous system. local autonomous system.
RT_SCOPE_LINK Route on this link. RT_SCOPE_LINK Route on this link.
skipping to change at page 20, line 4 skipping to change at page 18, line 32
Type: 8 bits Type: 8 bits
The type of route. The type of route.
Route type Description Route type Description
---------------------------------------------------- ----------------------------------------------------
RTN_UNSPEC Unknown route. RTN_UNSPEC Unknown route.
RTN_UNICAST A gateway or direct route. RTN_UNICAST A gateway or direct route.
RTN_LOCAL A local interface route. RTN_LOCAL A local interface route.
RTN_BROADCAST A local broadcast route RTN_BROADCAST A local broadcast route
jhs_hk_ak_ank draft-forces-Netlink-03.txt
(sent as a broadcast). (sent as a broadcast).
RTN_ANYCAST An anycast route. RTN_ANYCAST An anycast route.
RTN_MULTICAST A multicast route. RTN_MULTICAST A multicast route.
RTN_BLACKHOLE A silent packet dropping route. RTN_BLACKHOLE A silent packet dropping route.
RTN_UNREACHABLE An unreachable destination. RTN_UNREACHABLE An unreachable destination.
Packets dropped and host Packets dropped and host
unreachable ICMPs are sent to the unreachable ICMPs are sent to the
originator. originator.
RTN_PROHIBIT A packet rejection route. Packets RTN_PROHIBIT A packet rejection route. Packets
are dropped and communication are dropped and communication
skipping to change at page 20, line 30 skipping to change at page 19, line 5
continue routing lookup in another continue routing lookup in another
table. Under normal routing, table. Under normal routing,
packets are dropped and net packets are dropped and net
unreachable ICMPs are sent to the unreachable ICMPs are sent to the
originator. originator.
RTN_NAT A network address translation RTN_NAT A network address translation
rule. rule.
RTN_XRESOLVE Refer to an external resolver (not RTN_XRESOLVE Refer to an external resolver (not
implemented). implemented).
J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
Flags: 32 bits Flags: 32 bits
Further qualify the route. Further qualify the route.
RTM_F_NOTIFY If the route changes, notify the RTM_F_NOTIFY If the route changes, notify the
user. user.
RTM_F_CLONED Route is cloned from another route. RTM_F_CLONED Route is cloned from another route.
RTM_F_EQUALIZE Allow randomization of next hop RTM_F_EQUALIZE Allow randomization of next hop
path in multi-path routing path in multi-path routing
(currently not implemented). (currently not implemented).
Attributes applicable to this service: Attributes applicable to this service:
skipping to change at page 21, line 4 skipping to change at page 19, line 30
RTA_DST Protocol address for route RTA_DST Protocol address for route
destination address. destination address.
RTA_SRC Protocol address for route source RTA_SRC Protocol address for route source
address. address.
RTA_IIF Input interface index. RTA_IIF Input interface index.
RTA_OIF Output interface index. RTA_OIF Output interface index.
RTA_GATEWAY Protocol address for the gateway of RTA_GATEWAY Protocol address for the gateway of
the route the route
RTA_PRIORITY Priority of route. RTA_PRIORITY Priority of route.
RTA_PREFSRC Preferred source address in cases RTA_PREFSRC Preferred source address in cases
jhs_hk_ak_ank draft-forces-Netlink-03.txt
where more than one source address where more than one source address
could be used. could be used.
RTA_METRICS Route metrics attributed to route RTA_METRICS Route metrics attributed to route
and associated protocols (e.g., and associated protocols (e.g.,
RTT, initial TCP window, etc.). RTT, initial TCP window, etc.).
RTA_MULTIPATH Multipath route next hop's RTA_MULTIPATH Multipath route next hop's
attributes. attributes.
RTA_PROTOINFO Firewall based policy routing RTA_PROTOINFO Firewall based policy routing
attribute. attribute.
RTA_FLOW Route realm. RTA_FLOW Route realm.
RTA_CACHEINFO Cached route information. RTA_CACHEINFO Cached route information.
Additional Netlink message types applicable to this service: Additional Netlink message types applicable to this service:
RTM_NEWROUTE, RTM_DELROUTE, and RTM_GETROUTE RTM_NEWROUTE, RTM_DELROUTE, and RTM_GETROUTE
4.1.2. Neighbour Setup Service Module 3.1.2. Neighbour Setup Service Module
This service provides the ability to add, remove, or receive infor- This service provides the ability to add, remove, or receive
mation about a neighbour table entry (e.g., an ARP entry or an IPv4 information about a neighbour table entry (e.g., an ARP entry or
neighbour solicitation, etc.). The service message template is an IPv4 neighbour solicitation, etc.). The service message
shown below. template is shown below.
J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Family | Reserved1 | Reserved2 | | Family | Reserved1 | Reserved2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Interface Index | | Interface Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| State | Flags | Type | | State | Flags | Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
jhs_hk_ak_ank draft-forces-Netlink-03.txt
Family: 8 bits Family: 8 bits
Address Family: AF_INET for IPv4; and AF_INET6 for IPV4. Address Family: AF_INET for IPv4; and AF_INET6 for IPV6.
Interface Index: 32 bits Interface Index: 32 bits
The unique interface index. The unique interface index.
State: 16 bits State: 16 bits
A bitmask of the following states: A bitmask of the following states:
NUD_INCOMPLETE Still attempting to resolve. NUD_INCOMPLETE Still attempting to resolve.
NUD_REACHABLE A confirmed working cache entry NUD_REACHABLE A confirmed working cache entry
NUD_STALE an expired cache entry. NUD_STALE an expired cache entry.
NUD_DELAY Neighbour no longer reachable. NUD_DELAY Neighbour no longer reachable.
skipping to change at page 22, line 45 skipping to change at page 21, line 5
NDA_UNSPEC Unknown type. NDA_UNSPEC Unknown type.
NDA_DST A neighbour cache network. NDA_DST A neighbour cache network.
layer destination address layer destination address
NDA_LLADDR A neighbour cache link layer NDA_LLADDR A neighbour cache link layer
address. address.
NDA_CACHEINFO Cache statistics. NDA_CACHEINFO Cache statistics.
Additional Netlink message types applicable to this service: Additional Netlink message types applicable to this service:
RTM_NEWNEIGH, RTM_DELNEIGH, and RTM_GETNEIGH. RTM_NEWNEIGH, RTM_DELNEIGH, and RTM_GETNEIGH.
4.1.3. Traffic Control Service J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
3.1.3. Traffic Control Service
This service provides the ability to provision, query or listen to This service provides the ability to provision, query or listen to
events under the auspicies of traffic control. These include events under the auspicies of traffic control. These include
queueing disciplines, (schedulers and queue treatment queueing disciplines, (schedulers and queue treatment
jhs_hk_ak_ank draft-forces-Netlink-03.txt
algorithms--e.g., priority-based scheduler or the RED algorithm) algorithms--e.g., priority-based scheduler or the RED algorithm)
and classifiers. Linux Traffic Control Service is very flexible and classifiers. Linux Traffic Control Service is very flexible
and allows for hierachical cascading of the different blocks for and allows for hierachical cascading of the different blocks for
traffic resource sharing. traffic resource sharing.
++ ++ +-----+ +-------+ ++ ++ .++ ++ ++ +-----+ +-------+ ++ ++ .++
|| . || +------+ | |-->| Qdisc |-->|| || || || . || +------+ | |-->| Qdisc |-->|| || ||
|| ||---->|Filter|--->|Class| +-------+ ||-+ || || || ||---->|Filter|--->|Class| +-------+ ||-+ || ||
|| || | +------+ | +---------------+| | || || || || | +------+ | +---------------+| | || ||
|| . || | +----------------------+ | || .|| || . || | +----------------------+ | || .||
skipping to change at page 23, line 35 skipping to change at page 21, line 40
|| | Parent Queuing discipline | .|| || | Parent Queuing discipline | .||
|| . +------------------------------------------------+ .|| || . +------------------------------------------------+ .||
|| . . .. . . .. . . . .. .. .. . .. || || . . .. . . .. . . . .. .. .. . .. ||
|+--------------------------------------------------------+| |+--------------------------------------------------------+|
| Parent Queuing discipline | | Parent Queuing discipline |
| (attached to egress device) | | (attached to egress device) |
+----------------------------------------------------------+ +----------------------------------------------------------+
The above diagram shows an example of the Egress TC block. We try The above diagram shows an example of the Egress TC block. We try
to be very brief here. For more information, please refer to to be very brief here. For more information, please refer to
[Diffserv]. A packet first goes through a filter that is used to [11]. A packet first goes through a filter that is used to
identify a class to which the packet may belong. A class is essen- identify a class to which the packet may belong. A class is
tially a terminal queueing discipline and has a queue associated essentially a terminal queueing discipline and has a queue
with it. The queue may be subject to a simple algorithm, like associated with it. The queue may be subject to a simple
FIFO, or a more complex one, like RED or a token bucket. The out- algorithm, like FIFO, or a more complex one, like RED or a token
ermost queueing discipline, which is refered to as the parent is bucket. The outermost queueing discipline, which is refered to as
typically associated with a scheduler. Within this scheduler hier- the parent is typically associated with a scheduler. Within this
archy, however, may be other scheduling algorithms, making the scheduler hierarchy, however, may be other scheduling algorithms,
Linux Egress TC very flexible. making the Linux Egress TC very flexible.
J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
The service message template that makes this possible is shown The service message template that makes this possible is shown
below. This template is used in both the ingress and the egress below. This template is used in both the ingress and the egress
queueing disciplines (refer to the egress traffic control model in queueing disciplines (refer to the egress traffic control model
the FE model section). Each of the specific components of the in the FE model section). Each of the specific components of the
model has unique attributes that describe it best. The common model has unique attributes that describe it best. The common
attributes are described below. attributes are described below.
jhs_hk_ak_ank draft-forces-Netlink-03.txt
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Family | Reserved1 | Reserved2 | | Family | Reserved1 | Reserved2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Interface Index | | Interface Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Qdisc handle | | Qdisc handle |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Parent Qdisc | | Parent Qdisc |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TCM Info | | TCM Info |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Family: 8 bits Family: 8 bits
Address Family: AF_INET for IPv4; and AF_INET6 for IPV4. Address Family: AF_INET for IPv4; and AF_INET6 for IPV6.
Interface Index: 32 bits Interface Index: 32 bits
The unique interface index. The unique interface index.
Qdisc handle: 32 bits Qdisc handle: 32 bits
Unique identifier for instance of queueing discipline. Typically, Unique identifier for instance of queueing discipline. Typically,
this is split into major:minor of 16 bits each. The major number this is split into major:minor of 16 bits each. The major number
would also be the major number of the parent of this instance. would also be the major number of the parent of this instance.
Parent Qdisc: 32 bits Parent Qdisc: 32 bits
Used in hierarchical layering of queueing disciplines. If this Used in hierarchical layering of queueing disciplines. If this
value and the Qdisc handle are the same and equal to TC_H_ROOT, value and the Qdisc handle are the same and equal to TC_H_ROOT,
then the defined qdisc is the top most layer known as the root then the defined qdisc is the top most layer known as the root
qdisc. qdisc.
jhs_hk_ak_ank draft-forces-Netlink-03.txt
TCM Info: 32 bits TCM Info: 32 bits
Set by the FE to 1 typically, except when the Qdisc instance is in Set by the FE to 1 typically, except when the Qdisc instance is in
use, in which case it is set to imply a reference count. From the use, in which case it is set to imply a reference count. From the
CPC towards the direction of the FEC, this is typically set to 0 CPC towards the direction of the FEC, this is typically set to 0
except when used in the context of filters. In that case, this except when used in the context of filters. In that case, this
32-bit field is split into a 16-bit priority field and 16-bit 32-bit field is split into a 16-bit priority field and 16-bit
protocol field. The protocol is defined in kernel source protocol field. The protocol is defined in kernel source
<include/linux/if_ether.h>, however, the most commonly used one <include/linux/if_ether.h>, however, the most commonly used one
is ETH_P_IP (the IP protocol). is ETH_P_IP (the IP protocol).
J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
The priority is used for conflict resolution when filters The priority is used for conflict resolution when filters
intersect in their expressions. intersect in their expressions.
Generic attributes applicable to this service: Generic attributes applicable to this service:
Attribute Description Attribute Description
------------------------------------ ------------------------------------
TCA_KIND Canonical name of FE component. TCA_KIND Canonical name of FE component.
TCA_STATS Generic usage statistics of FEC TCA_STATS Generic usage statistics of FEC
TCA_RATE rate estimator being attached to TCA_RATE rate estimator being attached to
FEC. Takes snapshots of stats to FEC. Takes snapshots of stats to
compute rate. compute rate.
TCA_XSTATS Specific statistics of FEC. TCA_XSTATS Specific statistics of FEC.
TCA_OPTIONS Nested FEC-specific attributes. TCA_OPTIONS Nested FEC-specific attributes.
skipping to change at page 25, line 36 skipping to change at page 23, line 25
TCA_RATE rate estimator being attached to TCA_RATE rate estimator being attached to
FEC. Takes snapshots of stats to FEC. Takes snapshots of stats to
compute rate. compute rate.
TCA_XSTATS Specific statistics of FEC. TCA_XSTATS Specific statistics of FEC.
TCA_OPTIONS Nested FEC-specific attributes. TCA_OPTIONS Nested FEC-specific attributes.
Appendix 3 has an example of configuring an FE component for a FIFO Appendix 3 has an example of configuring an FE component for a FIFO
Qdisc. Qdisc.
Additional Netlink message types applicable to this service: Additional Netlink message types applicable to this service:
RTM_NEWQDISC, RTM_DELQDISC, RTM_GETQDISC, RTM_NEWTCLASS, RTM_DELT- RTM_NEWQDISC, RTM_DELQDISC, RTM_GETQDISC, RTM_NEWTCLASS,
CLASS, RTM_GETTCLASS, RTM_NEWTFILTER, RTM_DELTFILTER, and RTM_GET- RTM_DELTCLASS, RTM_GETTCLASS, RTM_NEWTFILTER, RTM_DELTFILTER, and
TFILTER. RTM_GETTFILTER.
4.2. IP Service NETLINK_FIREWALL 3.2. IP Service NETLINK_FIREWALL
This service allows CPCs to receive, manipulate, and re-inject This service allows CPCs to receive, manipulate, and re-inject
packets via the IPv4 firewall service modules in the FE. A fire- packets via the IPv4 firewall service modules in the FE. A fire-
wall rule is first inserted to activate packet redirection. The wall rule is first inserted to activate packet redirection. The
CPC informs the FEC whether it would like to receive just the meta- CPC informs the FEC whether it would like to receive just the meta-
data on the packet or the actual data and, if the metadata is data on the packet or the actual data and, if the metadata is
desired, what is the maximum data length to be redirected. The desired, what is the maximum data length to be redirected. The
redirected packets are still stored in the FEC, waiting a verdict redirected packets are still stored in the FEC, waiting a verdict
jhs_hk_ak_ank draft-forces-Netlink-03.txt
from the CPC. The verdict could constitute a simple accept or drop from the CPC. The verdict could constitute a simple accept or drop
decision of the packet, in which case the verdict is imposed on the decision of the packet, in which case the verdict is imposed on the
packet still sitting on the FEC. The verdict may also include a packet still sitting on the FEC. The verdict may also include a
modified packet to be sent on as a replacement. modified packet to be sent on as a replacement.
Two types of messages exist that can be sent from CPC to FEC. Two types of messages exist that can be sent from CPC to FEC.
These are: Mode messages and Verdict messages. Mode messages are These are: Mode messages and Verdict messages. Mode messages are
sent immediately to the FEC to describe what the CPC would like to sent immediately to the FEC to describe what the CPC would like to
receive. Verdict messages are sent to the FEC after a decision has receive. Verdict messages are sent to the FEC after a decision has
been made on the fate of a received packet. The formats are been made on the fate of a received packet. The formats are
described below. described below.
J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
The mode message is described first. The mode message is described first.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mode | Reserved1 | Reserved2 | | Mode | Reserved1 | Reserved2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Range | | Range |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Mode: 8 bits Mode: 8 bits
Control information on the packet to be sent to the CPC. The Control information on the packet to be sent to the CPC. The
different types are: different types are:
IPQ_COPY_META Copy only packet metadata to CPC. IPQ_COPY_META Copy only packet metadata to CPC.
IPQ_COPY_PACKET Copy packet metadata and packet payloads IPQ_COPY_PACKET Copy packet metadata and packet payloads
to CPC. to CPC.
Range: 32 bits Range: 32 bits
If IPQ_COPY_PACKET, this defines the maximum length to copy. If IPQ_COPY_PACKET, this defines the maximum length to copy.
jhs_hk_ak_ank draft-forces-Netlink-03.txt J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
A packet and associated metadata received from user space looks A packet and associated metadata received from user space looks
as follows. as follows.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Packet ID | | Packet ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mark | | Mark |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| timestamp_m | | timestamp_m |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| timestamp_u | | timestamp_u |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| hook | | hook |
skipping to change at page 28, line 5 skipping to change at page 26, line 5
timestamp_m: 32 bits timestamp_m: 32 bits
Packet arrival time (seconds) Packet arrival time (seconds)
timestamp_u: 32 bits timestamp_u: 32 bits
Packet arrival time (useconds in addition to the seconds in Packet arrival time (useconds in addition to the seconds in
timestamp_m) timestamp_m)
hook: 32 bits hook: 32 bits
jhs_hk_ak_ank draft-forces-Netlink-03.txt J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
The firewall module from which the packet was picked. The firewall module from which the packet was picked.
indev_name: 128 bits indev_name: 128 bits
ASCII name of incoming interface. ASCII name of incoming interface.
outdev_name: 128 bits outdev_name: 128 bits
ASCII name of outgoing interface. ASCII name of outgoing interface.
hw_protocol: 16 bits hw_protocol: 16 bits
skipping to change at page 28, line 37 skipping to change at page 26, line 37
data_len: 32 bits data_len: 32 bits
Length of packet data. Length of packet data.
Payload: size defined by data_len Payload: size defined by data_len
The payload of the packet received. The payload of the packet received.
The Verdict message format is as follows The Verdict message format is as follows
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value | | Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Packet ID | | Packet ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Length | | Data Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload . . . | | Payload . . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Value: 32 bits Value: 32 bits
This is the verdict to be imposed on the packet still sitting This is the verdict to be imposed on the packet still sitting
in the FEC. Verdicts could be: in the FEC. Verdicts could be:
NF_ACCEPT Accept the packet and let it continue its NF_ACCEPT Accept the packet and let it continue its
traversal. traversal.
NF_DROP Drop the packet. NF_DROP Drop the packet.
jhs_hk_ak_ank draft-forces-Netlink-03.txt J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
Packet ID: 32 bits Packet ID: 32 bits
The packet identifier as passed to the CPC by the FEC. The packet identifier as passed to the CPC by the FEC.
Data Length: 32 bits Data Length: 32 bits
The data length of the modified packet (in bytes). If you dont The data length of the modified packet (in bytes). If you dont
modify the packet just set it to 0. modify the packet just set it to 0.
Payload: Payload:
Size as defined by the Data Length field. Size as defined by the Data Length field.
4.3. IP Service NETLINK_ARPD 3.3. IP Service NETLINK_ARPD
This service is used by CPCs for managing the neighbor table in the This service is used by CPCs for managing the neighbor table in the
FE. The message format used between the FEC and CPC is described FE. The message format used between the FEC and CPC is described
in the section on the Neighbour Setup Service Module. in the section on the Neighbour Setup Service Module.
The CPC service is expected to participate in neighbor solicitation The CPC service is expected to participate in neighbor solicitation
protocol(s). protocol(s).
A neighbor message of type RTM_NEWNEIGH is sent towards the CPC by A neighbor message of type RTM_NEWNEIGH is sent towards the CPC by
the FE to inform the CPC of changes that might have happened on the FE to inform the CPC of changes that might have happened on
that neighbour's entry (e.g., a neighbor being perceived as that neighbour's entry (e.g., a neighbor being perceived as
unreachable). unreachable).
RTM_GETNEIGH is used to solicit the CPC for information on a spe- RTM_GETNEIGH is used to solicit the CPC for information on a
cific neighbor. specific neighbor.
5. Security Considerations
Netlink lives in a trusted environment of a single host separated
by kernel and user space. Linux capabilities ensure that only
someone with CAP_NET_ADMIN capability (typically, the root user) is
allowed to open sockets.
6. References 4. References
jhs_hk_ak_ank draft-forces-Netlink-03.txt 4.1. Normative References
[RFC1633] R. Braden, D. Clark, and S. Shenker, "Integrated [1] R. Braden, D. Clark, and S. Shenker, "Integrated
Services in the Internet Architecture: an Overview", RFC 1633, Services in the Internet Architecture: an Overview", RFC 1633,
ISI, MIT, and PARC, June 1994. ISI, MIT, and PARC, June 1994.
[RFC1812] F. Baker, "Requirements for IP Version 4 [2] F. Baker, "Requirements for IP Version 4
Routers", RFC 1812, June 1995. Routers", RFC 1812, June 1995.
[RFC2475] M. Carlson, W. Weiss, S. Blake, Z. Wang, D. J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
[3] M. Carlson, W. Weiss, S. Blake, Z. Wang, D.
Black, and E. Davies, "An Architecture for Differentiated Black, and E. Davies, "An Architecture for Differentiated
Services", RFC 2475, December 1998. Services", RFC 2475, December 1998.
[RFC2748] J. Boyle, R. Cohen, D. Durham, S. Herzog, R. [4] J. Boyle, R. Cohen, D. Durham, S. Herzog, R.
Rajan, A. Sastry, "The COPS (Common Open Policy Service) Pro- Rajan, A. Sastry, "The COPS (Common Open Policy Service)
tocol", RFC 2748, January 2000. Protocol", RFC 2748, January 2000.
[RFC2328] J. Moy, "OSPF Version 2", RFC 2328, April 1998. [5] J. Moy, "OSPF Version 2", RFC 2328, April 1998.
[RFC1157] J.D. Case, M. Fedor, M.L. Schoffstall, C. Davin, [6] J.D. Case, M. Fedor, M.L. Schoffstall, C. Davin,
"Simple Network Management Protocol (SNMP)", RFC 1157, May "Simple Network Management Protocol (SNMP)", RFC 1157, May
1990. 1990.
[RFC3036] L. Andersson, P. Doolan, N. Feldman, A. Fredette, [7] L. Andersson, P. Doolan, N. Feldman, A. Fredette,
B. Thomas "LDP Specification", RFC 3036, January 2001. B. Thomas "LDP Specification", RFC 3036, January 2001.
[Stevens] G.R Wright, W. Richard Stevens. "TCP/IP Illus- [8] Y. Bernet, S. Blake, D. Grossman, A. Smith,
"An Informal Management Model for DiffServ Routers",
RFC 3290, May 2002.
4.2. Informative References
[9] G.R Wright, W. Richard Stevens. "TCP/IP Illus-
trated Volume 2, Chapter 20", June 1995 trated Volume 2, Chapter 20", June 1995
[Netfilter] http://netfilter.samba.org [10] http://www.netfilter.org
[Diffserv] http://diffserv.sourceforge.net [11] http://diffserv.sourceforge.net
7. Acknowledgements 5. Security Considerations
1) Andi Kleen, for man pages on netlink and rtnetlink. Netlink lives in a trusted environment of a single host separated
by kernel and user space. Linux capabilities ensure that only
someone with CAP_NET_ADMIN capability (typically, the root user) is
allowed to open sockets.
2) Alexey Kuznetsov is credited for extending Netlink to the IP ser- J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
vice delivery model. The original Netlink character device was
jhs_hk_ak_ank draft-forces-Netlink-03.txt 6. Acknowledgements
1) Andi Kleen, for man pages on netlink and rtnetlink.
2) Alexey Kuznetsov is credited for extending Netlink to the IP
service delivery model. The original Netlink character device was
written by Alan Cox. written by Alan Cox.
3) Jeremy Ethridge for taking the role of someone who did not under- 3) Jeremy Ethridge for taking the role of someone who did not
stand Netlink and reviewing the document to make sure that it made understand Netlink and reviewing the document to make sure that it
sense. made sense.
8. Author's Address: 7. Author's Address:
Jamal Hadi Salim Jamal Hadi Salim
Znyx Networks Znyx Networks
Ottawa, Ontario Ottawa, Ontario
Canada Canada
hadi@znyx.com hadi@znyx.com
Hormuzd M Khosravi Hormuzd M Khosravi
Intel Intel
2111 N.E. 25th Avenue JF3-206 2111 N.E. 25th Avenue JF3-206
Hillsboro OR 97124-5961 Hillsboro OR 97124-5961
USA USA
1 503 264 0334 1 503 264 0334
hormuzd.m.khosravi@intel.com hormuzd.m.khosravi@intel.com
Andi Kleen Andi Kleen
SuSE SuSE
Stahlgruberring 28 Stahlgruberring 28
81829 Muenchen 81829 Muenchen
Germany Germany
ak@suse.de
Alexey Kuznetsov Alexey Kuznetsov
INR/Swsoft INR/Swsoft
Moscow Moscow
Russia Russia
kuznet@ms2.inr.ac.ru
9. Appendix 1: Sample Service Hierachy J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
8. Appendix 1: Sample Service Hierachy
In the diagram below we show a simple IP service, foo, and the In the diagram below we show a simple IP service, foo, and the
interaction it has between CP and FE components for the service interaction it has between CP and FE components for the service
(labels 1-3). (labels 1-3).
The diagram is also used to demonstrate CP<->FE addressing. In The diagram is also used to demonstrate CP<->FE addressing. In
this section, we illustrate only the addressing semantics. In this section, we illustrate only the addressing semantics. In
Apendix 2, the diagram is referenced again to define the protocol Apendix 2, the diagram is referenced again to define the protocol
interaction between service foo's CPC and FEC (labels 4-10). interaction between service foo's CPC and FEC (labels 4-10).
jhs_hk_ak_ank draft-forces-Netlink-03.txt
CP CP
[--------------------------------------------------------. [--------------------------------------------------------.
| .-----. | | .-----. |
| | . -------. | | | . -------. |
| | CLI | / | | | CLI | / \ |
| | | | CP protocol | | | | | CP protocol | |
| /->> -. | component | <-. | | /->> -. | component | <-. |
| __ _/ | | For | | | | __ _/ | | For | | |
| | | IP service | ^ | | | | IP service | ^ |
| Y | foo | | | | Y | foo | | |
| | ___________/ ^ | | | ___________/ ^ |
| Y 1,4,6,8,9 / ^ 2,5,10 | 3,7 | | Y 1,4,6,8,9 / ^ 2,5,10 | 3,7 |
--------------- Y------------/---|----------|----------- --------------- Y------------/---|----------|-----------
| ^ | ^ | ^ | ^
**|***********|****|**********|********** **|***********|****|**********|**********
************* Netlink layer ************ ************* Netlink layer ************
skipping to change at page 32, line 39 skipping to change at page 31, line 4
| |FE component/module|/ | | |FE component/module|/ |
| | for IP Service | | | | for IP Service | |
--->---|------>---| foo |----->-----|------>-- --->---|------>---| foo |----->-----|------>--
| ------------------- | | ------------------- |
| | | |
| | | |
------------------------------------------ ------------------------------------------
The control plane protocol for IP service foo does the following to The control plane protocol for IP service foo does the following to
connect to its FE counterpart. The steps below are also numbered connect to its FE counterpart. The steps below are also numbered
J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
above in the diagram. above in the diagram.
1) Connect to the IP service foo through a socket connect. A typical 1) Connect to the IP service foo through a socket connect. A typical
connection would be via a call to: socket(AF_NETLINK, SOCK_RAW, connection would be via a call to: socket(AF_NETLINK, SOCK_RAW,
NETLINK_FOO). NETLINK_FOO).
2) Bind to listen to specific asynchronous events for service foo. 2) Bind to listen to specific asynchronous events for service foo.
3) Bind to listen to specific asynchronous FE events. 3) Bind to listen to specific asynchronous FE events.
jhs_hk_ak_ank draft-forces-Netlink-03.txt 9. Appendix 2: Sample Protocol for the Foo IP Service
10. Appendix 2: Sample Protocol for the Foo IP Service
Our example IP service foo is used again to demonstrate how one can Our example IP service foo is used again to demonstrate how one can
deploy a simple IP service control using Netlink. deploy a simple IP service control using Netlink.
These steps are continued from Appendix 1 (hence the numbering). These steps are continued from Appendix 1 (hence the numbering).
4) Query for current config of FE component. 4) Query for current config of FE component.
5) Receive response to (4) via channel on (3). 5) Receive response to (4) via channel on (3).
6) Query for current state of IP service foo. 6) Query for current state of IP service foo.
7) Receive response to (6) via channel on (2). 7) Receive response to (6) via channel on (2).
9) Register the protocol-specific packets you would like the FE to 9) Register the protocol-specific packets you would like the FE to
forward to you. forward to you.
10) Send service-specific foo commands and receive responses for them, 10) Send service-specific foo commands and receive responses for them,
if needed. if needed.
10.1. Interacting with Other IP services 9.1. Interacting with Other IP services
The diagram in Appendix 1 shows another control component configur- The diagram in Appendix 1 shows another control component
ing the same service. In this case, it is a proprietary Command configuring the same service. In this case, it is a proprietary
Line Interface. The CLI may or may not be using the Netlink proto- Command Line Interface. The CLI may or may not be using the
col to communicate to the foo component. If the CLI issues com- Netlink protocol to communicate to the foo component. If the CLI
mands that will affect the policy of the FEC for service foo then, issues commands that will affect the policy of the FEC for service
then the foo CPC is notified. It could then make algorithmic deci- foo then, then the foo CPC is notified. It could then make
sions based on this input. For example, if an FE allowed another algorithmic decisions based on this input. For example, if an FE
service to delete policies installed by a different service and a allowed another service to delete policies installed by a different
policy that foo installed was deleted by service bar, there might service and a policy that foo installed was deleted by service bar,
be a need to propagate this to all the peers of service foo. there might be a need to propagate this to all the peers of service
foo.
11. Appendix 3: Examples J. Hadi Salim et al draft-ietf-forces-netlink-04.txt
In this example, we show a simple configuration Netlink message 10. Appendix 3: Examples
sent from a TC CPC to an egress TC FIFO queue. This queue algo-
rithm is based on packet counting and drops packets when the limit
exceeds 100 packets. We assume that the queue is in a hierachical
setup with a parent 100:0 and a classid of 100:1 and that it is to
be installed on a device with an ifindex of 4.
jhs_hk_ak_ank draft-forces-Netlink-03.txt In this example, we show a simple configuration Netlink message
sent from a TC CPC to an egress TC FIFO queue. This queue
algorithm is based on packet counting and drops packets when the
limit exceeds 100 packets. We assume that the queue is in a
hierachical setup with a parent 100:0 and a classid of 100:1 and
that it is to be installed on a device with an ifindex of 4.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length (52) | | Length (52) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (RTM_NEWQDISC) | Flags (NLM_F_EXCL | | | Type (RTM_NEWQDISC) | Flags (NLM_F_EXCL | |
| |NLM_F_CREATE | NLM_F_REQUEST)| | |NLM_F_CREATE | NLM_F_REQUEST)|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number(arbitrary number) | | Sequence Number(arbitrary number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Process ID (0) | | Process ID (0) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 End of changes. 

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