draft-ietf-6man-segment-routing-header-11.txt   draft-ietf-6man-segment-routing-header-12.txt 
Network Working Group S. Previdi Network Working Group S. Previdi
Internet-Draft Individual Internet-Draft Individual
Intended status: Standards Track C. Filsfils, Ed. Intended status: Standards Track C. Filsfils, Ed.
Expires: September 29, 2018 Cisco Systems, Inc. Expires: October 21, 2018 Cisco Systems, Inc.
J. Leddy J. Leddy
Comcast Comcast
S. Matsushima S. Matsushima
Softbank Softbank
D. Voyer, Ed. D. Voyer, Ed.
Bell Canada Bell Canada
March 28, 2018 April 19, 2018
IPv6 Segment Routing Header (SRH) IPv6 Segment Routing Header (SRH)
draft-ietf-6man-segment-routing-header-11 draft-ietf-6man-segment-routing-header-12
Abstract Abstract
Segment Routing (SR) allows a node to steer a packet through a Segment Routing (SR) allows a node to steer a packet through a
controlled set of instructions, called segments, by prepending an SR controlled set of instructions, called segments, by prepending an SR
header to the packet. A segment can represent any instruction, header to the packet. A segment can represent any instruction,
topological or service-based. SR allows to enforce a flow through topological or service-based. SR allows a node to steer a flow
any path (topological, or application/service based) while through any path (topological, or application/service based) while
maintaining per-flow state only at the ingress node to the SR domain. maintaining per-flow state only at the ingress node to the SR domain.
Segment Routing can be applied to the IPv6 data plane with the Segment Routing can be applied to the IPv6 data plane with the
addition of a new type of Routing Extension Header. This draft addition of a new type of Routing Extension Header. This document
describes the Segment Routing Extension Header Type and how it is describes the Segment Routing Extension Header Type and how it is
used by SR capable nodes. used by SR capable nodes.
Requirements Language Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
Status of This Memo Status of This Memo
skipping to change at page 2, line 7 skipping to change at page 2, line 7
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This Internet-Draft will expire on September 29, 2018. This Internet-Draft will expire on October 21, 2018.
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Table of Contents Table of Contents
1. Segment Routing Documents . . . . . . . . . . . . . . . . . . 3 1. Segment Routing Documents . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Data Planes supporting Segment Routing . . . . . . . . . 4 2.1. Data Planes supporting Segment Routing . . . . . . . . . 4
2.2. SRv6 Segment . . . . . . . . . . . . . . . . . . . . . . 4 2.2. SRv6 Segment . . . . . . . . . . . . . . . . . . . . . . 4
2.3. Segment Routing (SR) Domain . . . . . . . . . . . . . . . 5 2.3. Segment Routing (SR) Domain . . . . . . . . . . . . . . . 5
2.3.1. SR Domain in a Service Provider Network . . . . . . . 6 3. Segment Routing Extension Header (SRH) . . . . . . . . . . . 5
2.3.2. SR Domain in a Overlay Network . . . . . . . . . . . 7 3.1. SRH TLVs . . . . . . . . . . . . . . . . . . . . . . . . 7
3. Segment Routing Extension Header (SRH) . . . . . . . . . . . 8 3.1.1. Padding TLVs . . . . . . . . . . . . . . . . . . . . 8
3.1. SRH TLVs . . . . . . . . . . . . . . . . . . . . . . . . 10 3.1.2. HMAC TLV . . . . . . . . . . . . . . . . . . . . . . 10
3.1.1. Ingress Node TLV . . . . . . . . . . . . . . . . . . 11 3.2. SRH Processing . . . . . . . . . . . . . . . . . . . . . 11
3.1.2. Egress Node TLV . . . . . . . . . . . . . . . . . . . 12 4. SRH Functions . . . . . . . . . . . . . . . . . . . . . . . . 11
3.1.3. Opaque Container TLV . . . . . . . . . . . . . . . . 13 4.1. Endpoint Function (End) . . . . . . . . . . . . . . . . . 11
3.1.4. Padding TLV . . . . . . . . . . . . . . . . . . . . . 13 4.2. End.X: Endpoint with Layer-3 cross-connect . . . . . . . 12
3.1.5. HMAC TLV . . . . . . . . . . . . . . . . . . . . . . 14 5. SR Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1.6. NSH Carrier TLV . . . . . . . . . . . . . . . . . . . 15 5.1. Source SR Node . . . . . . . . . . . . . . . . . . . . . 13
3.2. SRH and RFC8200 behavior . . . . . . . . . . . . . . . . 15 5.2. Transit Node . . . . . . . . . . . . . . . . . . . . . . 14
4. SRH Functions . . . . . . . . . . . . . . . . . . . . . . . . 16 5.3. SR Segment Endpoint Node . . . . . . . . . . . . . . . . 14
4.1. Endpoint Function (End) . . . . . . . . . . . . . . . . . 16 5.4. Load Balancing and ECMP . . . . . . . . . . . . . . . . . 14
4.2. End.X: Endpoint with Layer-3 cross-connect . . . . . . . 17 6. Security Considerations . . . . . . . . . . . . . . . . . . . 15
5. SR Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . 18 6.1. Threat model . . . . . . . . . . . . . . . . . . . . . . 15
5.1. Source SR Node . . . . . . . . . . . . . . . . . . . . . 18 6.1.1. Source routing threats . . . . . . . . . . . . . . . 15
5.2. Transit Node . . . . . . . . . . . . . . . . . . . . . . 19 6.1.2. Applicability of RFC 5095 to SRH . . . . . . . . . . 16
5.3. SR Segment Endpoint Node . . . . . . . . . . . . . . . . 20 6.1.3. Service stealing threat . . . . . . . . . . . . . . . 17
6. Security Considerations . . . . . . . . . . . . . . . . . . . 20 6.1.4. Topology disclosure . . . . . . . . . . . . . . . . . 17
6.1. Threat model . . . . . . . . . . . . . . . . . . . . . . 21 6.1.5. ICMP Generation . . . . . . . . . . . . . . . . . . . 17
6.1.1. Source routing threats . . . . . . . . . . . . . . . 21 6.2. Security fields in SRH . . . . . . . . . . . . . . . . . 18
6.1.2. Applicability of RFC 5095 to SRH . . . . . . . . . . 21 6.2.1. Selecting a hash algorithm . . . . . . . . . . . . . 19
6.1.3. Service stealing threat . . . . . . . . . . . . . . . 22 6.2.2. Performance impact of HMAC . . . . . . . . . . . . . 19
6.1.4. Topology disclosure . . . . . . . . . . . . . . . . . 22 6.2.3. Pre-shared key management . . . . . . . . . . . . . . 20
6.1.5. ICMP Generation . . . . . . . . . . . . . . . . . . . 22 6.3. Deployment Models . . . . . . . . . . . . . . . . . . . . 20
6.2. Security fields in SRH . . . . . . . . . . . . . . . . . 23 6.3.1. Nodes within the SR domain . . . . . . . . . . . . . 20
6.2.1. Selecting a hash algorithm . . . . . . . . . . . . . 24 6.3.2. Nodes outside of the SR domain . . . . . . . . . . . 21
6.2.2. Performance impact of HMAC . . . . . . . . . . . . . 24 6.3.3. SR path exposure . . . . . . . . . . . . . . . . . . 21
6.2.3. Pre-shared key management . . . . . . . . . . . . . . 25 6.3.4. Impact of BCP-38 . . . . . . . . . . . . . . . . . . 22
6.3. Deployment Models . . . . . . . . . . . . . . . . . . . . 26 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22
6.3.1. Nodes within the SR domain . . . . . . . . . . . . . 26 7.1. Segment Routing Header Flags Register . . . . . . . . . . 22
6.3.2. Nodes outside of the SR domain . . . . . . . . . . . 26 7.2. Segment Routing Header TLVs Register . . . . . . . . . . 23
6.3.3. SR path exposure . . . . . . . . . . . . . . . . . . 27 8. Implementation Status . . . . . . . . . . . . . . . . . . . . 23
6.3.4. Impact of BCP-38 . . . . . . . . . . . . . . . . . . 27 8.1. Linux . . . . . . . . . . . . . . . . . . . . . . . . . . 23
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27 8.2. Cisco Systems . . . . . . . . . . . . . . . . . . . . . . 23
7.1. Segment Routing Header TLVs Register . . . . . . . . . . 28 8.3. FD.io . . . . . . . . . . . . . . . . . . . . . . . . . . 24
8. Implementation Status . . . . . . . . . . . . . . . . . . . . 28 8.4. Barefoot . . . . . . . . . . . . . . . . . . . . . . . . 24
8.1. Linux . . . . . . . . . . . . . . . . . . . . . . . . . . 28 8.5. Juniper . . . . . . . . . . . . . . . . . . . . . . . . . 24
8.2. Cisco Systems . . . . . . . . . . . . . . . . . . . . . . 28 9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 24
8.3. FD.io . . . . . . . . . . . . . . . . . . . . . . . . . . 29 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 24
8.4. Barefoot . . . . . . . . . . . . . . . . . . . . . . . . 29 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 25
8.5. Juniper . . . . . . . . . . . . . . . . . . . . . . . . . 29 11.1. Normative References . . . . . . . . . . . . . . . . . . 25
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 29 11.2. Informative References . . . . . . . . . . . . . . . . . 26
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 30 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 28
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 30
11.1. Normative References . . . . . . . . . . . . . . . . . . 30
11.2. Informative References . . . . . . . . . . . . . . . . . 31
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33
1. Segment Routing Documents 1. Segment Routing Documents
Segment Routing terminology is defined in Segment Routing terminology is defined in
[I-D.ietf-spring-segment-routing]. [I-D.ietf-spring-segment-routing].
The network programming paradigm The network programming paradigm
[I-D.filsfils-spring-srv6-network-programming] defines additional [I-D.filsfils-spring-srv6-network-programming] defines additional
functions associated to an SRv6 SID. functions associated to a Segment Routing for IPv6 (SRv6) Segment ID
(SID).
Segment Routing use cases are described in [RFC7855] and Segment Routing use cases are described in [RFC7855] and [RFC8354].
[I-D.ietf-spring-ipv6-use-cases].
Segment Routing protocol extensions are defined in Segment Routing protocol extensions are defined in
[I-D.ietf-isis-segment-routing-extensions], and [I-D.ietf-isis-segment-routing-extensions], and
[I-D.ietf-ospf-ospfv3-segment-routing-extensions]. [I-D.ietf-ospf-ospfv3-segment-routing-extensions].
2. Introduction 2. Introduction
Segment Routing (SR), defined in [I-D.ietf-spring-segment-routing], Segment Routing (SR), defined in [I-D.ietf-spring-segment-routing],
allows a node to steer a packet through a controlled set of allows a node to steer a packet through a controlled set of
instructions, called segments, by prepending an SR header to the instructions, called segments, by prepending an SR header to the
packet. A segment can represent any instruction, topological or packet. A segment can represent any instruction, topological or
service-based. SR allows to enforce a flow through any path service-based. SR allows a node to steer a flow through any path
(topological or service/application based) while maintaining per-flow (topological or service/application based) while maintaining per-flow
state only at the ingress node to the SR domain. Segments can be state only at the ingress node to the SR domain. Segments can be
derived from different components: IGP, BGP, Services, Contexts, derived from different components: IGP, BGP, Services, Contexts,
Locators, etc. The list of segment forming the path is called the Locators, etc. The list of segment forming the path is called the
Segment List and is encoded in the packet header. Segment List and is encoded in the packet header.
SR allows the use of strict and loose source based routing paradigms SR allows the use of strict and loose source based routing paradigms
without requiring any additional signaling protocols in the without requiring any additional signaling protocols in the
infrastructure hence delivering an excellent scalability property. infrastructure hence delivering an excellent scalability property.
The source based routing model described in The source based routing model described in
[I-D.ietf-spring-segment-routing] is inherited from the ones proposed [I-D.ietf-spring-segment-routing] inherits from the ones proposed by
by [RFC1940] and [RFC8200]. The source based routing model offers [RFC1940] and [RFC8200]. The source based routing model offers the
the support for explicit routing capability. support for explicit routing capability.
2.1. Data Planes supporting Segment Routing 2.1. Data Planes supporting Segment Routing
Segment Routing (SR), can be instantiated over MPLS Segment Routing (SR), can be instantiated over MPLS
([I-D.ietf-spring-segment-routing-mpls]) and IPv6. This document (SRMPLS)([I-D.ietf-spring-segment-routing-mpls]) and IPv6 (SRv6).
defines its instantiation over the IPv6 data-plane based on the use- This document defines its instantiation over the IPv6 data-plane
cases defined in [I-D.ietf-spring-ipv6-use-cases]. based on the use-cases defined in [RFC8354].
This document defines a new type of Routing Header (originally This document defines a new type of Routing Header (originally
defined in [RFC8200]) called the Segment Routing Header (SRH) in defined in [RFC8200]) called the Segment Routing Header (SRH) in
order to convey the Segment List in the packet header as defined in order to convey the Segment List in the packet header as defined in
[I-D.ietf-spring-segment-routing]. Mechanisms through which segment [I-D.ietf-spring-segment-routing]. Mechanisms through which segments
are known and advertised are outside the scope of this document. are known and advertised are outside the scope of this document.
2.2. SRv6 Segment 2.2. SRv6 Segment
An SRv6 Segment is a 128-bit value. "SRv6 SID" or simply "SID" are An SRv6 Segment is a 128-bit value. "SRv6 SID" or simply "SID" are
often used as a shorter reference for "SRv6 Segment". often used as a shorter reference for "SRv6 Segment".
An SRv6-capable node N maintains a "My Local SID Table". This table An SRv6-capable node N maintains a "My Local SID Table". This table
contains all the local SRv6 segments explicitly instantiated at node contains all the local SRv6 segments explicitly instantiated at node
N. N is the parent node for these SID's. N. N is the parent node for these SIDs.
A local SID of N could be an IPv6 address of a local interface of N A local SID of N could be an IPv6 address of a local interface of N
but it does not have to. Most often, a local SID is not an address but it does not have to be. Most often, a local SID is not an
of a local interface of N. The My Local SID Table is thus not address of a local interface of N. The My Local SID Table is thus
populated by default with all the addresses of a node. not populated by default with all the addresses of a node.
An illustration is provided in
[I-D.filsfils-spring-srv6-network-programming].
Every SRv6 local SID instantiated has a specific instruction bounded Every SRv6 local SID instantiated has a specific instruction bounded
to it. to it.
This information is stored in the "My Local SID Table". The "My This information is stored in the My Local SID Table. The My Local
Local SID Table" has three main purposes: SID Table has three main purposes:
o Define which local SID's are explicitly instantiated. o Define which local SIDs are explicitly instantiated.
o Specify which instruction is bound to each of the instantiated o Specify which instruction is bound to each of the instantiated
SID's. SIDs.
o Store the parameters associated to such instruction (i.e. OIF, o Store the parameters associated to such instruction (i.e. OIF,
NextHop,...). NextHop,...).
A Segment ID (SID) in the destination address of an IPv6 header, is
routed through an IPv6 network as an IPv6 address. SIDs, or the
prefix(es) covering SIDs in the My Local SID Table, and their
reachability may be distributed by means outside the scope of this
document. For example, [RFC5308] or [RFC5340] may be used to
advertise a prefix covering the My Local SID Table.
A node may receive a packet with an SRv6 SID in the DA without an A node may receive a packet with an SRv6 SID in the DA without an
SRH. In such case the packet should still be processed by the SRH. In such case the packet should still be processed by the
Segment Routing engine. Segment Routing engine.
2.3. Segment Routing (SR) Domain 2.3. Segment Routing (SR) Domain
We define the concept of the Segment Routing Domain (SR Domain) as The Segment Routing Domain (SR Domain) is defined as the set of nodes
the set of nodes participating into the source based routing model. participating in the source based routing model. These nodes may be
These nodes may be connected to the same physical infrastructure connected to the same physical infrastructure (e.g.: a Service
(e.g.: a Service Provider's network) as well as nodes remotely Provider's network).
connected to each other (e.g.: an enterprise VPN or an overlay).
A non-exhaustive list of examples of SR Domains is:
o The network of an operator, service provider, content provider,
enterprise including nodes, links and Autonomous Systems.
o A set of nodes connected as an overlay over one or more transit
providers. The overlay nodes exchange SR-enabled traffic with
segments belonging solely to the overlay routers (the SR domain).
None of the segments in the SR-enabled packets exchanged by the
overlay belong to the transit networks
The source based routing model through its instantiation of the
Segment Routing Header (SRH) defined in this document equally applies
to all the above examples.
It is assumed in this document that the SRH is added to the packet by The SRH is added to the packet by its source, consistent with the
its source, consistently with the source routing model defined in source routing model defined in [RFC8200]. For example:
[RFC8200]. For example:
o At the node originating the packet (host, server). o At the node originating the packet (host, server).
o At the ingress node of an SR domain where the ingress node o At the ingress node of an SR domain where the ingress node
receives an IPv6 packet and encapsulates it into an outer IPv6 receives a packet and encapsulates it in an outer IPv6 header
header followed by a Segment Routing header. followed by a Segment Routing header.
2.3.1. SR Domain in a Service Provider Network
The following figure illustrates an SR domain consisting of an
operator's network infrastructure.
(-------------------------- Operator 1 -----------------------)
( )
( (-----AS 1-----) (-------AS 2-------) (----AS 3-------) )
( ( ) ( ) ( ) )
A1--(--(--11---13--14-)--(-21---22---23--24-)--(-31---32---34--)--)--Z1
( ( /|\ /|\ /| ) ( |\ /|\ /|\ /| ) ( |\ /|\ /| \ ) )
A2--(--(/ | \/ | \/ | ) ( | \/ | \/ | \/ | ) ( | \/ | \/ | \)--)--Z2
( ( | /\ | /\ | ) ( | /\ | /\ | /\ | ) ( | /\ | /\ | ) )
( ( |/ \|/ \| ) ( |/ \|/ \|/ \| ) ( |/ \|/ \| ) )
A3--(--(--15---17--18-)--(-25---26---27--28-)--(-35---36---38--)--)--Z3
( ( ) ( ) ( ) )
( (--------------) (------------------) (---------------) )
( )
(-------------------------------------------------------------)
Figure 1: Service Provider SR Domain
Figure 1 describes an operator network including several ASes and
delivering connectivity between endpoints. In this scenario, Segment
Routing is used within the operator networks and across the ASes
boundaries (all being under the control of the same operator). In
this case segment routing can be used in order to address use cases
such as end-to-end traffic engineering, fast re-route, egress peer
engineering, data-center traffic engineering as described in
[RFC7855], [I-D.ietf-spring-ipv6-use-cases] and
[I-D.ietf-spring-resiliency-use-cases].
Typically, an IPv6 packet received at ingress (i.e.: from outside the
SR domain), is classified according to network operator policies and
such classification results into an outer header with an SRH applied
to the incoming packet. The SRH contains the list of segment
representing the path the packet must take inside the SR domain.
Thus, the SA of the packet is the ingress node, the DA (due to SRH
procedures described in Section 5) is set as the first segment of the
path and the last segment of the path is the egress node of the SR
domain.
The path may include intra-AS as well as inter-AS segments. It has
to be noted that all nodes within the SR domain are under control of
the same administration. When the packet reaches the egress point of
the SR domain, the outer header and its SRH are removed so that the
destination of the packet is unaware of the SR domain the packet has
traversed.
The outer header with the SRH is no different from any other
tunneling encapsulation mechanism and allows a network operator to
implement traffic engineering mechanisms so to efficiently steer
traffic across his infrastructure.
2.3.2. SR Domain in a Overlay Network
The following figure illustrates an SR domain consisting of an
overlay network over multiple operator's networks.
(--Operator 1---) (-----Operator 2-----) (--Operator 3---)
( ) ( ) ( )
A1--(--11---13--14--)--(--21---22---23--24--)--(-31---32---34--)--C1
( /|\ /|\ /| ) ( |\ /|\ /|\ /| ) ( |\ /|\ /| \ )
A2--(/ | \/ | \/ | ) ( | \/ | \/ | \/ | ) ( | \/ | \/ | \)--C2
( | /\ | /\ | ) ( | /\ | /\ | /\ | ) ( | /\ | /\ | )
( |/ \|/ \| ) ( |/ \|/ \|/ \| ) ( |/ \|/ \| )
A3--(--15---17--18--)--(--25---26---27--28--)--(-35---36---38--)--C3
( ) ( | | | ) ( )
(---------------) (--|----|---------|--) (---------------)
| | |
B1 B2 B3
Figure 2: Overlay SR Domain
Figure 2 describes an overlay consisting of nodes connected to three
different network operators and forming a single overlay network
where Segment routing packets are exchanged.
The overlay consists of nodes A1, A2, A3, B1, B2, B3, C1, C2 and C3.
These nodes are connected to their respective network operator and
form an overlay network.
Each node may originate packets with an SRH which contains, in the
segment list of the SRH or in the DA, segments identifying other
overlay nodes. This implies that packets with an SRH may traverse
operator's networks but, obviously, these SRHs cannot contain an
address/segment of the transit operators 1, 2 and 3. The SRH
originated by the overlay can only contain address/segment under the
administration of the overlay (e.g. address/segments supported by A1,
A2, A3, B1, B2, B3, C1,C2 or C3).
In this model, the operator network nodes are transit nodes and, as
specified in [RFC8200], MUST NOT inspect the routing extension header
since they are not the DA of the packet.
It is a common practice in operators networks to filter out, at
ingress, any packet whose DA is the address of an internal node and
it is also possible that an operator would filter out any packet
destined to an internal address and having an extension header in it.
This common practice does not impact the SR-enabled traffic between
the overlay nodes as the intermediate transit networks never see a
destination address belonging to their infrastructure. These SR-
enabled overlay packets will thus never be filtered by the transit
operators.
In all cases, transit packets (i.e.: packets whose DA is outside the
domain of the operator's network) will be forwarded accordingly
without introducing any security concern in the operator's network.
This is similar to tunneled packets.
3. Segment Routing Extension Header (SRH) 3. Segment Routing Extension Header (SRH)
A new type of the Routing Header (originally defined in [RFC8200]) is A new type of the Routing Header (originally defined in [RFC8200]) is
defined: the Segment Routing Header (SRH) which has a new Routing defined: the Segment Routing Header (SRH) which has a new Routing
Type, (suggested value 4) to be assigned by IANA. Type, (suggested value 4) to be assigned by IANA.
The Segment Routing Header (SRH) is defined as follows: The Segment Routing Header (SRH) is defined as follows:
0 1 2 3 0 1 2 3
skipping to change at page 9, line 35 skipping to change at page 6, line 35
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// // // //
// Optional Type Length Value objects (variable) // // Optional Type Length Value objects (variable) //
// // // //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where: where:
o Next Header: 8-bit selector. Identifies the type of header o Next Header: Defined in [RFC8200]
immediately following the SRH.
o Hdr Ext Len: 8-bit unsigned integer, is the length of the SRH o Hdr Ext Len: Defined in [RFC8200]
header in 8-octet units, not including the first 8 octets.
o Routing Type: TBD, to be assigned by IANA (suggested value: 4). o Routing Type: TBD, to be assigned by IANA (suggested value: 4).
o Segments Left. Defined in [RFC8200], it contains the index, in o Segments Left: Defined in [RFC8200]. See Section 3.2 for detailed
the Segment List, of the next segment to inspect. Segments Left usage during SRH processing.
is decremented at each segment.
o Last Entry: contains the index, in the Segment List, of the last o Last Entry: contains the index (zero based), in the Segment List,
element of the Segment List. of the last element of the Segment List.
o Flags: 8 bits of flags. Following flags are defined: o Flags: 8 bits of flags. Following flags are defined:
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|U|P|O|A|H| U | | U |H| U |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
U: Unused and for future use. SHOULD be unset on transmission U: Unused and for future use. SHOULD be 0 on transmission and
and MUST be ignored on receipt. MUST be ignored on receipt.
P-flag: Protected flag. Set when the packet has been rerouted
through FRR mechanism by an SR endpoint node.
O-flag: OAM flag. When set, it indicates that this packet is
an operations and management (OAM) packet.
A-flag: Alert flag. If present, it means important Type Length
Value (TLV) objects are present. See Section 3.1 for details
on TLVs objects.
H-flag: HMAC flag. If set, the HMAC TLV is present and is H-flag: HMAC flag. If set, the HMAC TLV is present and is
encoded as the last TLV of the SRH. In other words, the last encoded as the last TLV of the SRH. In other words, the last
36 octets of the SRH represent the HMAC information. See 36 octets of the SRH represent the HMAC information. See
Section 3.1.5 for details on the HMAC TLV. Section 3.1.2 for details on the HMAC TLV.
o Tag: tag a packet as part of a class or group of packets, e.g., o Tag: tag a packet as part of a class or group of packets, e.g.,
packets sharing the same set of properties. packets sharing the same set of properties. When tag is not used
at source it SHOULD be set to zero on transmission. When tag is
not used during SRH Processing it MUST be ignored. The allocation
and use of tag is outside the scope of this document.
o Segment List[n]: 128 bit IPv6 addresses representing the nth o Segment List[n]: 128 bit IPv6 addresses representing the nth
segment in the Segment List. The Segment List is encoded starting segment in the Segment List. The Segment List is encoded starting
from the last segment of the path. I.e., the first element of the from the last segment of the path. I.e., the first element of the
segment list (Segment List [0]) contains the last segment of the segment list (Segment List [0]) contains the last segment of the
path, the second element contains the penultimate segment of the path, the second element contains the penultimate segment of the
path and so on. path and so on.
o Type Length Value (TLV) are described in Section 3.1. o Type Length Value (TLV) are described in Section 3.1.
3.1. SRH TLVs 3.1. SRH TLVs
This section defines TLVs of the Segment Routing Header. This section defines TLVs of the Segment Routing Header.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-----------------------
| Type | Length | Variable length data
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-----------------------
Type: An 8 bit value. Unrecognized Types MUST be ignored on receipt.
Length: The length of the Variable length data. It is RECOMMENDED
that the total length of new TLVs be multiple of 8 bytes to avoid the
use of Padding TLVs.
Variable length data: Length bytes of data that is specific to the
Type.
Type Length Value (TLV) contain optional information that may be used Type Length Value (TLV) contain optional information that may be used
by the node identified in the DA of the packet. It has to be noted by the node identified in the DA of the packet. The information
that the information carried in the TLVs is not intended to be used carried in the TLVs is not intended to be used by the routing layer.
by the routing layer. Typically, TLVs carry information that is Typically, TLVs carry information that is consumed by other
consumed by other components (e.g.: OAM) than the routing function. components (e.g.: OAM) than the routing function.
Each TLV has its own length, format and semantic. The code-point Each TLV has its own length, format and semantic. The code-point
allocated (by IANA) to each TLV defines both the format and the allocated (by IANA) to each TLV Type defines both the format and the
semantic of the information carried in the TLV. Multiple TLVs may be semantic of the information carried in the TLV. Multiple TLVs may be
encoded in the same SRH. encoded in the same SRH.
The "Length" field of the TLV is primarily used to skip the TLV while TLVs may change en route at each segment. To identify when a TLV
inspecting the SRH in case the node doesn't support or recognize the type may change en route the most significant bit of the Type has the
TLV codepoint. The "Length" defines the TLV length in octets and not following significance:
including the "Type" and "Length" fields.
The following TLVs are defined in this document: 0: TLV data does not change en route
Ingress Node TLV 1: TLV data does change en route
Egress Node TLV Identifying which TLVs change en route, without having to understand
the Type, is required for Authentication Header Integrity Check Value
(ICV) computation. Any TLV that changes en route is considered
mutable for the purpose of ICV computation, the Type Length and
Variable Length Data is ignored for the purpose of ICV Computation as
defined in [RFC4302].
Opaque TLV The "Length" field of the TLV is used to skip the TLV while
inspecting the SRH in case the node doesn't support or recognize the
Type. The "Length" defines the TLV length in octets, not including
the "Type" and "Length" fields.
The following TLVs are defined in this document:
Padding TLV Padding TLV
HMAC TLV HMAC TLV
NSH Carrier TLV
Additional TLVs may be defined in the future. Additional TLVs may be defined in the future.
3.1.1. Ingress Node TLV 3.1.1. Padding TLVs
The Ingress Node TLV is optional and identifies the node this packet
traversed when entered the SR domain. The Ingress Node TLV has
following format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | RESERVED | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Ingress Node (16 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: to be assigned by IANA (suggested value 1).
o Length: 18.
o RESERVED: 8 bits. SHOULD be unset on transmission and MUST be
ignored on receipt.
o Flags: 8 bits. No flags are defined in this document. SHOULD be
set to 0 on transmission and MUST be ignored on receipt.
o Ingress Node: 128 bits. Defines the node where the packet is
expected to enter the SR domain. In the encapsulation case
described in Section 2.3.1, this information corresponds to the SA
of the encapsulating header.
3.1.2. Egress Node TLV
The Egress Node TLV is optional and identifies the node this packet
is expected to traverse when exiting the SR domain. The Egress Node
TLV has following format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | RESERVED | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Egress Node (16 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: to be assigned by IANA (suggested value 2).
o Length: 18.
o RESERVED: 8 bits. SHOULD be unset on transmission and MUST be
ignored on receipt.
o Flags: 8 bits. No flags are defined in this document. SHOULD be
set to 0 on transmission and MUST be ignored on receipt.
o Egress Node: 128 bits. Defines the node where the packet is There are two types of padding TLVs, pad0 and padN, the following
expected to exit the SR domain. In the encapsulation case applies to both:
described in Section 2.3.1, this information corresponds to the
last segment of the SRH in the encapsulating header.
3.1.3. Opaque Container TLV Padding TLVs are optional and more than one Padding TLV MUST NOT
appear in the SRH.
The Opaque Container TLV is optional and has the following format: The Padding TLVs are used to align the SRH total length on the 8
octet boundary.
0 1 2 3 When present, a single Pad0 or PadN TLV MUST appear as the last
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 TLV before the HMAC TLV (if HMAC TLV is present).
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | RESERVED | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Opaque Container (16 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where: When present, a PadN TLV MUST have a length from 0 to 5 in order
to align the SRH total length on a 8-octet boundary.
o Type: to be assigned by IANA (suggested value 3). Padding TLVs are ignored by a node processing the SRH TLV, even if
more than one is present.
o Length: 18. Padding TLVs are ignored during ICV calculation.
o RESERVED: 8 bits. SHOULD be unset on transmission and MUST be 3.1.1.1. PAD0
ignored on receipt.
o Flags: 8 bits. No flags are defined in this document. SHOULD be 0 1 2 3 4 5 6 7
set to 0 on transmission and MUST be ignored on receipt. +-+-+-+-+-+-+-+-+
| Type |
+-+-+-+-+-+-+-+-+
o Opaque Container: 128 bits of opaque data not relevant for the Type: to be assigned by IANA (Suggested value 128)
routing layer. Typically, this information is consumed by a non-
routing component of the node receiving the packet (i.e.: the node
in the DA).
3.1.4. Padding TLV A single Pad0 TLV MUST be used when a single byte of padding is
required. If more than one byte of padding is required a Pad0 TLV
MUST NOT be used, the PadN TLV MUST be used.
The Padding TLV is optional and with the purpose of aligning the SRH 3.1.1.2. PADN
on a 8 octet boundary. The Padding TLV has the following format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Padding (variable) | | Type | Length | Padding (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Padding (variable) // // Padding (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where: Type: to be assigned by IANA (suggested value 129).
o Type: to be assigned by IANA (suggested value 4).
o Length: 0 to 7 Length: 0 to 5
o Padding: from 0 to 7 octets of padding. Padding bits have no Padding: Length octets of padding. Padding bits have no
semantic. They SHOULD be set to 0 on transmission and MUST be semantics. They SHOULD be set to 0 on transmission and MUST be
ignored on receipt. ignored on receipt.
The following applies to the Padding TLV: The PadN TLV MUST be used when more than one byte of padding is
required.
o Padding TLV is optional and MAY only appear once in the SRH.
o The Padding TLV is used in order to align the SRH total length on
the 8 octet boundary.
o When present, the Padding TLV MUST appear as the last TLV before
the HMAC TLV (if HMAC TLV is present).
o When present, the Padding TLV MUST have a length from 0 to 7 in
order to align the SRH total lenght on a 8-octet boundary.
o When a router inspecting the SRH encounters the Padding TLV, it
MUST assume that no other TLV (other than the HMAC) follow the
Padding TLV.
3.1.5. HMAC TLV 3.1.2. HMAC TLV
HMAC TLV is optional and contains the HMAC information. The HMAC TLV HMAC TLV is optional and contains the HMAC information. The HMAC TLV
has the following format: has the following format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | RESERVED | | Type | Length | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HMAC Key ID (4 octets) | | HMAC Key ID (4 octets) |
skipping to change at page 15, line 16 skipping to change at page 10, line 42
o HMAC: 32 octets. o HMAC: 32 octets.
o HMAC and HMAC Key ID usage is described in Section 6 o HMAC and HMAC Key ID usage is described in Section 6
The Following applies to the HMAC TLV: The Following applies to the HMAC TLV:
o When present, the HMAC TLV MUST be encoded as the last TLV of the o When present, the HMAC TLV MUST be encoded as the last TLV of the
SRH. SRH.
o If the HMAC TLV is present, the SRH H-Flag (Figure 4) MUST be set. o If the HMAC TLV is present, the SRH H-Flag (Figure 2) MUST be set.
Nodes processing SRH SHOULD process the HMAC TLV only when the
H-Flag is set, and local policy.
o When the H-flag is set in the SRH, the router inspecting the SRH o When the H-flag is set in the SRH, the router inspecting the SRH
MUST find the HMAC TLV in the last 38 octets of the SRH. MUST find the HMAC TLV in the last 38 octets of the SRH.
3.1.6. NSH Carrier TLV 3.2. SRH Processing
The NSH Carrier TLV is a container used in order to carry TLVs that
have been defined in [RFC8300]. The NSH Carrier TLV has the
following format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// NSH Carried Object //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: to be assigned by IANA (suggested value 6).
o Length: the total length of the TLV.
o Flags: 8 bits. No flags are defined in this document. SHOULD be
set to 0 on transmission and MUST be ignored on receipt.
o NSH Carried Object: the content of the TLV which consists of the
NSH data as defined in [RFC8300].
3.2. SRH and RFC8200 behavior
The SRH being a new type of the Routing Header, it also has the same
properties:
SHOULD only appear once in the packet.
Only the router whose address is in the DA field of the packet
header MUST inspect the SRH.
Therefore, Segment Routing in IPv6 networks implies that the segment Extension header processing is as defined in RFC8200 for packets
identifier (i.e.: the IPv6 address of the segment) is moved into the destined to a local IPv6 address. If SRH is present, it is processed
DA of the packet. as follows (DA represents the destination address in the IPv6
header):
The DA of the packet changes at each segment termination/completion 1. IF the DA is in My Local SID Table
and therefore the final DA of the packet MUST be encoded as the last 2. The function associated with the DA is processed.
segment of the path. (Examples are as described in section 4).
3. ELSE
4. Treat the extension header as unrecognized
and process as defined in RFC8200 section 4.4.
4. SRH Functions 4. SRH Functions
Segment Routing architecture, as defined in Segment Routing architecture, as defined in
[I-D.ietf-spring-segment-routing] defines a segment as an instruction [I-D.ietf-spring-segment-routing] defines a segment as an instruction
or, more generally, a set of instructions (function). or, more generally, a set of instructions (function).
In this section we review two functions that may be associated to a In this section we review two functions that may be associated to a
segment: segment:
o End: the endpoint (End) function is the base of the source routing o End: the endpoint (End) function is the base of the source routing
paradigm. It consists of updating the DA with the next segment paradigm. It consists of updating the DA with the next segment
and forward the packet accordingly. and forward the packet accordingly.
o End.X: The endpoint layer-3 cross-connect function. o End.X: The endpoint layer-3 cross-connect function.
More functions are defined in Other functions may be defined in other documents.
[I-D.filsfils-spring-srv6-network-programming].
4.1. Endpoint Function (End) 4.1. Endpoint Function (End)
The Endpoint function (End) is the most basic function. The Endpoint function (End) is the most basic function.
When the endpoint node receives a packet destined to DA "S" and S is When the endpoint node receives a packet destined to DA "S" and S is
an entry in the MyLocalSID table and the function associated with S an entry in the My Local SID Table and the function associated with S
in that entry is "End" then the endpoint does: in that entry is "End" then the endpoint does:
1. IF SegmentsLeft > 0 THEN 1. IF SegmentsLeft > 0 THEN
2. decrement SL 2. decrement SL
3. update the IPv6 DA with SRH[SL] 3. update the IPv6 DA with SRH[SL]
4. FIB lookup on updated DA 4. FIB lookup on updated DA
5. forward accordingly to the matched entry 5. forward accordingly to the matched entry
6. ELSE 6. ELSE IF SID is assigned to an interface
7. drop the packet 7. proceed to process the next header
8. ELSE
9. drop the packet
It has to be noted that: It has to be noted that:
o The End function performs the FIB lookup in the forwarding table o The End function performs the FIB lookup in the forwarding table
of the ingress interface. of the ingress interface.
o If the FIB lookup matches a multicast state, then the related
Reverse Path Forwarding (RPF) check must be considered successful.
o An SRv6-capable node MUST include the FlowLabel of the IPv6 header o An SRv6-capable node MUST include the FlowLabel of the IPv6 header
in its hash computation for ECMP load-balancing. in its hash computation for ECMP load-balancing as described in
Section 5.4.
o By default, a local SID bound to the End function does not allow
the decapsulation of an outer header. As a consequence, an End
SID cannot be the last SID of an SRH and cannot be the DA of a
packet without SRH.
o If the decapsulation is desired, then another function must be
bound to the SID (e.g., End.DX6 defined in
[I-D.filsfils-spring-srv6-network-programming]). This prevents
any unintentional decapsulation by the segment endpoint node. The
details of the advertisement of a SID in the control plane are
outside the scope of this document (e.g.,
[I-D.previdi-idr-segment-routing-te-policy],
[I-D.dawra-bgp-srv6-vpn] and [I-D.bashandy-isis-srv6-extensions].
4.2. End.X: Endpoint with Layer-3 cross-connect 4.2. End.X: Endpoint with Layer-3 cross-connect
When the endpoint node receives a packet destined to DA "S" and S is When the endpoint node receives a packet destined to DA "S" and S is
an entry in the MyLocalSID table and the function associated with S an entry in the My Local SID Table and the function associated with S
in that entry is "End.X" then the endpoint does: in that entry is "End.X" then the endpoint does:
1. IF SegmentsLeft > 0 THEN 1. IF SegmentsLeft > 0 THEN
2. decrement SL 2. decrement SL
3. update the IPv6 DA with SRH[SL] 3. update the IPv6 DA with SRH[SL]
4. forward to layer-3 adjacency bound to the SID "S" 4. forward to layer-3 adjacency bound to the SID "S"
5. ELSE 5. ELSE
6. drop the packet 6. drop the packet
It has to be noted that: It has to be noted that:
o If an array of layer-3 adjacencies is bound to the End.X SID, then o If an array of layer-3 adjacencies is bound to the End.X SID, one
one entry of the array is selected based on a hash of the packet's entry of the array is selected based on a hash of the packet's
header (at least SA, DA, Flow Label). header as described in Section 5.4
o An End.X function does not allow decaps. An End.X SID cannot be o An End.X function does not allow decaps. An End.X SID cannot be
the last SID of an SRH and cannot be the DA of a packet without the last SID of an SRH and cannot be the DA of a packet without
SRH. SRH.
o The End.X function is required to express any traffic-engineering o The End.X function is required to express an explicit path through
policy. an IP network.
o The End.X function is the SRv6 instantiation of a Adjacency SID as o The End.X function is the SRv6 instantiation of a Adjacency SID as
defined in [I-D.ietf-spring-segment-routing]. defined in [I-D.ietf-spring-segment-routing].
o Note that with SR-MPLS ([I-D.ietf-spring-segment-routing-mpls]), o Note that with SR-MPLS ([I-D.ietf-spring-segment-routing-mpls]),
an AdjSID is typically preceded by a PrefixSID. This is unlikely an AdjSID is typically preceded by a PrefixSID. This is unlikely
in SRv6 as most likely an End.X SID is globally routed address of in SRv6, most likely an End.X SID is globally routed address of N.
N.
o If a node N has 30 outgoing interfaces to 30 neighbors, usually o If a node N has 30 outgoing interfaces to 30 neighbors, usually
the operator would explicitly instantiate 30 End.X SID's at N: one the operator would explicitly instantiate 30 End.X SIDs at N: one
per layer-3 adjacency to a neighbor. Potentially, more End.X per layer-3 adjacency to a neighbor. Potentially, more End.X
could be explicitly defined (groups of layer-3 adjacencies to the could be explicitly defined (groups of layer-3 adjacencies to the
same neighbor or to different neighbors). same neighbor or to different neighbors).
o If node N has a bundle outgoing interface I to a neighbor Q made o If node N has a bundle outgoing interface I to a neighbor Q made
of 10 member links, N may allocate up to 11 End.X local SID's for of 10 member links, N may allocate up to 11 End.X local SIDs for
that bundle: one for the bundle itself and then up to one for each that bundle: one for the bundle itself and then up to one for each
member link. This is the equivalent of the L2-Link Adj SID in SR- member link. This is the equivalent of the L2-Link Adj SID in SR-
MPLS ([I-D.ietf-isis-l2bundles]). MPLS ([I-D.ietf-isis-l2bundles]).
5. SR Nodes 5. SR Nodes
There are different types of nodes that may be involved in segment There are different types of nodes that may be involved in segment
routing networks: source nodes that originate packets with an SRH, routing networks: source nodes that originate packets with an SRH,
transit nodes that forward packets having an SRH and segment endpoint transit nodes that forward packets having an SRH and segment endpoint
nodes that MUST process the SRH. nodes that MUST process the SRH.
5.1. Source SR Node 5.1. Source SR Node
A Source SR Node can be any node originating an IPv6 packet with its A Source SR Node can be any node originating an IPv6 packet with its
IPv6 and Segment Routing Headers. This include either: IPv6 and Segment Routing Headers. This include either:
A host originating an IPv6 packet. A host originating an IPv6 packet.
An SR domain ingress router encapsulating a received IPv6 packet An SR domain ingress router encapsulating a received packet in an
into an outer IPv6 header followed by an SRH. outer IPv6 header followed by an SRH.
The mechanism through which a Segment List is derived is outside of The mechanism through which a Segment List is derived is outside the
the scope of this document. As an example, the Segment List may be scope of this document. As an example, the Segment List may be
obtained through: obtained through:
Local path computation. Local path computation.
Local configuration. Local configuration.
Interaction with a centralized controller delivering the path. Interaction with a centralized controller delivering the path.
Any other mechanism. Any other mechanism.
The following are the steps of the creation of the SRH: The following are the steps of the creation of the SRH:
Next Header and Hdr Ext Len fields are set as specified in Next Header and Hdr Ext Len fields are set as specified in
[RFC8200]. [RFC8200].
Routing Type field is set as TBD (to be allocated by IANA, Routing Type field is set as TBD (to be allocated by IANA,
suggested value 4). suggested value 4).
The DA of the packet is set with the value of the first segment. The DA of the packet is set with the value of the first segment.
).
The first element of the segment list is the last segment (the The first element of the segment list is the last segment (the
final DA of the packet). The second element is the penultimate final DA of the packet). The second element is the penultimate
segment and so on. segment and so on.
In other words, the Segment List is encoded in the reverse order In other words, the Segment List is encoded in the reverse order
of the path. of the path.
The Segments Left field is set to n-1 where n is the number of The Segments Left field is set to n-1 where n is the number of
elements in the Segment List. elements in the Segment List.
The Last_Entry field is set to n-1 where n is the number of The Last_Entry field is set to n-1 where n is the number of
elements in the Segment List. elements in the Segment List.
The packet is sent out towards the packet's DA (the first
segment).
HMAC TLV may be set according to Section 6. HMAC TLV may be set according to Section 6.
If the segment list contains a single segment and there is no need If the segment list contains a single segment and there is no need
for information in flag or TLV, then the SRH MAY be omitted. for information in flag or TLV, then the SRH MAY be omitted.
The packet is sent towards the packet's DA (the first segment).
5.2. Transit Node 5.2. Transit Node
As specified in [RFC8200], the only node who is allowed to inspect As specified in [RFC8200], the only node who is allowed to inspect
the Routing Extension Header (and therefore the SRH), is the node the Routing Extension Header (and therefore the SRH), is the node
corresponding to the DA of the packet. Any other transit node MUST corresponding to the DA of the packet. Any other transit node MUST
NOT inspect the underneath routing header and MUST forward the packet NOT inspect the underneath routing header and MUST forward the packet
towards the DA and according to the IPv6 routing table. towards the DA and according to the IPv6 routing table.
In the example case described in Section 2.3.2, when SR capable nodes As a generic security measure, any service provider will block any
are connected through an overlay spanning multiple third-party packet destined to one of its internal routers, especially if these
infrastructure, it is safe to send SRH packets (i.e.: packet having a packets have an extension header in it.
Segment Routing Header) between each other overlay/SR-capable nodes
as long as the segment list does not include any of the transit
provider nodes. In addition, as a generic security measure, any
service provider will block any packet destined to one of its
internal routers, especially if these packets have an extended header
in it.
5.3. SR Segment Endpoint Node 5.3. SR Segment Endpoint Node
The SR segment endpoint node is the node whose MyLocalSID table The SR segment endpoint node is the node whose My Local SID
contains an entry for the DA of the packet. Table contains an entry for the DA of the packet.
The segment endpoint node executes the function bound to the SID as The segment endpoint node executes the function bound to the SID as
per the matched MyLocalSID entry (Section 4). per the matched My Local SID entry (Section 4).
5.4. Load Balancing and ECMP
Within an SR domain, an SR source node encapsulates a packet in an
outer IPv6 header for transport to an endpoint. The SR source node
MUST impose a Flow Label computed based on the inner packet. The
computation of the flow label is as recommended in [RFC6438] for the
sending TEP.
At any transit node within an SR domain, the flow label MUST be used
as defined in [RFC6438] to calculate the ECMP hash toward the
destination address.
At an SR segment endpoint node, the flow label MUST be used as
defined in [RFC6438] to calculate any ECMP hash used to forward the
processed packet to the next segment.
6. Security Considerations 6. Security Considerations
This section analyzes the security threat model, the security issues This section analyzes the security threat model, the security issues
and proposed solutions related to the new Segment Routing Header. and proposed solutions related to the new Segment Routing Header.
The Segment Routing Header (SRH) is simply another type of the The Segment Routing Header (SRH) is simply another type of the
routing header as described in RFC 8200 [RFC8200] and is: routing header as described in [RFC8200] and is:
o Added by an SR edge router when entering the segment routing o Added by an SR edge router when entering the segment routing
domain or by the originating host itself. The source host can domain or by the originating host itself. The source host can
even be outside the SR domain; even be outside the SR domain;
o inspected and acted upon when reaching the destination address of o inspected and acted upon when reaching the destination address of
the IP header per RFC 8200 [RFC8200]. the IP header per [RFC8200].
Per RFC8200 [RFC8200], routers on the path that simply forward an Per [RFC8200], routers on the path that simply forward an IPv6 packet
IPv6 packet (i.e. the IPv6 destination address is none of theirs) (i.e. the IPv6 destination address is none of theirs) will never
will never inspect and process the content of the SRH. Routers whose inspect and process the content of the SRH. Routers whose one
one interface IPv6 address equals the destination address field of interface IPv6 address equals the destination address field of the
the IPv6 packet MUST parse the SRH and, if supported and if the local IPv6 packet MUST parse the SRH and, if supported and if the local
configuration allows it, MUST act accordingly to the SRH content. configuration allows it, MUST act accordingly to the SRH content.
As specified in RFC8200 [RFC8200], the default behavior of a non SR- As specified in [RFC8200], the default behavior of a non SR-capable
capable router upon receipt of an IPv6 packet with SRH destined to an router upon receipt of an IPv6 packet with SRH destined to an address
address of its, is to: of its, is to:
o ignore the SRH completely if the Segment Left field is 0 and o ignore the SRH completely if the Segment Left field is 0 and
proceed to process the next header in the IPv6 packet; proceed to process the next header in the IPv6 packet;
o discard the IPv6 packet if Segment Left field is greater than 0, o discard the IPv6 packet if Segment Left field is greater than 0,
it MAY send a Parameter Problem ICMP message back to the Source it MAY send a Parameter Problem ICMP message back to the Source
Address. Address.
6.1. Threat model 6.1. Threat model
6.1.1. Source routing threats 6.1.1. Source routing threats
Using an SRH is similar to source routing, therefore it has some Using an SRH is similar to source routing, therefore it has some
well-known security issues as described in RFC4942 [RFC4942] section well-known security issues as described in [RFC4942] section 2.1.1
2.1.1 and RFC5095 [RFC5095]: and [RFC5095]:
o amplification attacks: where a packet could be forged in such a o amplification attacks: where a packet could be forged in such a
way to cause looping among a set of SR-enabled routers causing way to cause looping among a set of SR-enabled routers causing
unnecessary traffic, hence a Denial of Service (DoS) against unnecessary traffic, hence a Denial of Service (DoS) against
bandwidth; bandwidth;
o reflection attack: where a hacker could force an intermediate node o reflection attack: where a hacker could force an intermediate node
to appear as the immediate attacker, hence hiding the real to appear as the immediate attacker, hence hiding the real
attacker from naive forensic; attacker from naive forensic;
o bypass attack: where an intermediate node could be used as a o bypass attack: where an intermediate node could be used as a
stepping stone (for example in a De-Militarized Zone) to attack stepping stone (for example in a De-Militarized Zone) to attack
another host (for example in the datacenter or any back-end another host (for example in the datacenter or any back-end
server). server).
6.1.2. Applicability of RFC 5095 to SRH 6.1.2. Applicability of RFC 5095 to SRH
First of all, the reader must remember this specific part of section First of all, the reader must remember this specific part of section
1 of RFC5095 [RFC5095], "A side effect is that this also eliminates 1 of [RFC5095], "A side effect is that this also eliminates benign
benign RH0 use-cases; however, such applications may be facilitated RH0 use-cases; however, such applications may be facilitated by
by future Routing Header specifications.". In short, it is not future Routing Header specifications.". In short, it is not
forbidden to create new secure type of Routing Header; for example, forbidden to create new secure type of Routing Header; for example,
RFC 6554 (RPL) [RFC6554] also creates a new Routing Header type for a [RFC6554] (RPL) also creates a new Routing Header type for a specific
specific application confined in a single network. application confined in a single network.
In the segment routing architecture described in In the segment routing architecture described in
[I-D.ietf-spring-segment-routing] there are basically two kinds of [I-D.ietf-spring-segment-routing] there are basically two kinds of
nodes (routers and hosts): nodes (routers and hosts):
o nodes within the SR domain, which is within one single o nodes within the SR domain, which is within one single
administrative domain, i.e., where all nodes are trusted anyway administrative domain, i.e., where all nodes are trusted anyway
else the damage caused by those nodes could be worse than else the damage caused by those nodes could be worse than
amplification attacks: traffic interception, man-in-the-middle amplification attacks: traffic interception, man-in-the-middle
attacks, more server DoS by dropping packets, and so on. attacks, more server DoS by dropping packets, and so on.
o nodes outside of the SR domain, which is outside of the o nodes outside of the SR domain, which is outside of the
administrative segment routing domain hence they cannot be trusted administrative segment routing domain hence they cannot be trusted
because there is no physical security for those nodes, i.e., they because there is no physical security for those nodes, i.e., they
can be replaced by hostile nodes or can be coerced in wrong can be replaced by hostile nodes or can be coerced in wrong
behaviors. behaviors.
The main use case for SR consists of the single administrative domain The main use case for SR consists of the single administrative domain
where only trusted nodes with SR enabled and configured participate where only trusted nodes with SR enabled and configured participate
in SR: this is the same model as in RFC6554 [RFC6554]. All non- in SR: this is the same model as in [RFC6554]. All non-trusted nodes
trusted nodes do not participate as either SR processing is not do not participate as either SR processing is not enabled by default
enabled by default or because they only process SRH from nodes within or because they only process SRH from nodes within their domain.
their domain.
Moreover, all SR nodes ignore SRH created by outsiders based on Moreover, all SR nodes ignore SRH created by outsiders based on
topology information (received on a peering or internal interface) or topology information (received on a peering or internal interface) or
on presence and validity of the HMAC field. Therefore, if on presence and validity of the HMAC field. Therefore, if
intermediate nodes ONLY act on valid and authorized SRH (such as intermediate nodes ONLY act on valid and authorized SRH (such as
within a single administrative domain), then there is no security within a single administrative domain), then there is no security
threat similar to RH-0. Hence, the RFC 5095 [RFC5095] attacks are threat similar to RH-0. Hence, the [RFC5095] attacks are not
not applicable. applicable.
6.1.3. Service stealing threat 6.1.3. Service stealing threat
Segment routing is used for added value services, there is also a Segment routing is used for added value services, there is also a
need to prevent non-participating nodes to use those services; this need to prevent non-participating nodes to use those services; this
is called 'service stealing prevention'. is called 'service stealing prevention'.
6.1.4. Topology disclosure 6.1.4. Topology disclosure
The SRH may also contains IPv6 addresses of some intermediate SR- The SRH may also contains IPv6 addresses of some intermediate SR-
nodes in the path towards the destination, this obviously reveals nodes in the path towards the destination, this obviously reveals
those addresses to the potentially hostile attackers if those those addresses to the potentially hostile attackers if those
attackers are able to intercept packets containing SRH. On the other attackers are able to intercept packets containing SRH. On the other
hand, if the attacker can do a traceroute whose probes will be hand, if the attacker can do a traceroute whose probes will be
forwarded along the SR path, then there is little learned by forwarded along the SR path, then there is little learned by
intercepting the SRH itself. intercepting the SRH itself.
6.1.5. ICMP Generation 6.1.5. ICMP Generation
Per section 4.4 of RFC8200 [RFC8200], when destination nodes (i.e. Per Section 4.4 of [RFC8200], when destination nodes (i.e. where the
where the destination address is one of theirs) receive a Routing destination address is one of theirs) receive a Routing Header with
Header with unsupported Routing Type, the required behavior is: unsupported Routing Type, the required behavior is:
o If Segments Left is zero, the node must ignore the Routing header o If Segments Left is zero, the node must ignore the Routing header
and proceed to process the next header in the packet. and proceed to process the next header in the packet.
o If Segments Left is non-zero, the node must discard the packet and o If Segments Left is non-zero, the node must discard the packet and
send an ICMP Parameter Problem, Code 0, message to the packet's send an ICMP Parameter Problem, Code 0, message to the packet's
Source Address, pointing to the unrecognized Routing Type. Source Address, pointing to the unrecognized Routing Type.
This required behavior could be used by an attacker to force the This required behavior could be used by an attacker to force the
generation of ICMP message by any node. The attacker could send generation of ICMP message by any node. The attacker could send
packets with SRH (with Segment Left set to 0) destined to a node not packets with SRH (with Segment Left not set to 0) destined to a node
supporting SRH. Per RFC8200 [RFC8200], the destination node could not supporting SRH. Per [RFC8200], the destination node could
generate an ICMP message, causing a local CPU utilization and if the generate an ICMP message, causing a local CPU utilization and if the
source of the offending packet with SRH was spoofed could lead to a source of the offending packet with SRH was spoofed could lead to a
reflection attack without any amplification. reflection attack without any amplification.
It must be noted that this is a required behavior for any unsupported It must be noted that this is a required behavior for any unsupported
Routing Type and not limited to SRH packets. So, it is not specific Routing Type and not limited to SRH packets. So, it is not specific
to SRH and the usual rate limiting for ICMP generation is required to SRH and the usual rate limiting for ICMP generation is required
anyway for any IPv6 implementation and has been implemented and anyway for any IPv6 implementation and has been implemented and
deployed for many years. deployed for many years.
skipping to change at page 23, line 27 skipping to change at page 18, line 18
are based on a key-hashed message authentication code (HMAC). are based on a key-hashed message authentication code (HMAC).
The security-related fields in the SRH are instantiated by the HMAC The security-related fields in the SRH are instantiated by the HMAC
TLV, containing: TLV, containing:
o HMAC Key-id, 32 bits wide; o HMAC Key-id, 32 bits wide;
o HMAC, 256 bits wide (optional, exists only if HMAC Key-id is not o HMAC, 256 bits wide (optional, exists only if HMAC Key-id is not
0). 0).
The HMAC field is the output of the HMAC computation (per RFC 2104 The HMAC field is the output of the HMAC computation (per [RFC2104])
[RFC2104]) using a pre-shared key identified by HMAC Key-id and of using a pre-shared key identified by HMAC Key-id and of the text
the text which consists of the concatenation of: which consists of the concatenation of:
o the source IPv6 address; o the source IPv6 address;
o Last Entry field; o Last Entry field;
o an octet of bit flags; o an octet of bit flags;
o HMAC Key-id; o HMAC Key-id;
o all addresses in the Segment List. o all addresses in the Segment List.
skipping to change at page 26, line 29 skipping to change at page 21, line 15
packet with an SRH generated by a non-cooperative SR domain. packet with an SRH generated by a non-cooperative SR domain.
If the validation fails, then these packets MUST be dropped, ICMP If the validation fails, then these packets MUST be dropped, ICMP
error messages (parameter problem) SHOULD be generated (but rate error messages (parameter problem) SHOULD be generated (but rate
limited) and SHOULD be logged. limited) and SHOULD be logged.
6.3.2. Nodes outside of the SR domain 6.3.2. Nodes outside of the SR domain
Nodes outside of the SR domain cannot be trusted for physical Nodes outside of the SR domain cannot be trusted for physical
security; hence, they need to request by some trusted means (outside security; hence, they need to request by some trusted means (outside
of the scope of this document) a complete SRH for each new connection the scope of this document) a complete SRH for each new connection
(i.e. new destination address). The received SRH MUST include an (i.e. new destination address). The received SRH MUST include an
HMAC TLV which is computed correctly (see Section 6.2). HMAC TLV which is computed correctly (see Section 6.2).
When an outside node sends a packet with an SRH and towards an SR When an outside node sends a packet with an SRH and towards an SR
domain ingress node, the packet MUST contain the HMAC TLV (with a domain ingress node, the packet MUST contain the HMAC TLV (with a
Key-id and HMAC fields) and the the destination address MUST be an Key-id and HMAC fields) and the the destination address MUST be an
address of an SR domain ingress node . address of an SR domain ingress node .
The ingress SR router, i.e., the router with an interface address The ingress SR router, i.e., the router with an interface address
equals to the destination address, MUST verify the HMAC TLV. equal to the destination address, MUST verify the HMAC TLV.
If the validation is successful, then the packet is simply forwarded If the validation is successful, then the packet is simply forwarded
as usual for an SR packet. As long as the packet travels within the as usual for an SR packet. As long as the packet travels within the
SR domain, no further HMAC check needs to be done. Subsequent SR domain, no further HMAC check needs to be done. Subsequent
routers in the SR domain MAY verify the HMAC TLV when they process routers in the SR domain MAY verify the HMAC TLV when they process
the SRH (i.e. when they are the destination). the SRH (i.e. when they are the destination).
If the validation fails, then this packet MUST be dropped, an ICMP If the validation fails, then this packet MUST be dropped, an ICMP
error message (parameter problem) SHOULD be generated (but rate error message (parameter problem) SHOULD be generated (but rate
limited) and SHOULD be logged. limited) and SHOULD be logged.
skipping to change at page 28, line 13 skipping to change at page 22, line 47
maintained by IANA: maintained by IANA:
Suggested Description Reference Suggested Description Reference
Value Value
---------------------------------------------------------- ----------------------------------------------------------
4 Segment Routing Header (SRH) This document 4 Segment Routing Header (SRH) This document
This document request IANA to create and maintain a new Registry: This document request IANA to create and maintain a new Registry:
"Segment Routing Header TLVs" "Segment Routing Header TLVs"
7.1. Segment Routing Header TLVs Register 7.1. Segment Routing Header Flags Register
This document requests the creation of a new IANA managed registry to
identify SRH Flags Bits. The registration procedure is "Expert
Review" as defined in [RFC8126]. Suggested registry name is "Segment
Routing Header Flags". Flags is 8 bits, the following bits are
defined in this document:
Suggested Description Reference
Bit
-----------------------------------------------------
4 HMAC This document
7.2. Segment Routing Header TLVs Register
This document requests the creation of a new IANA managed registry to This document requests the creation of a new IANA managed registry to
identify SRH TLVs. The registration procedure is "Expert Review" as identify SRH TLVs. The registration procedure is "Expert Review" as
defined in [RFC8126]. Suggested registry name is "Segment Routing defined in [RFC8126]. Suggested registry name is "Segment Routing
Header TLVs". A TLV is identified through an unsigned 8 bit Header TLVs". A TLV is identified through an unsigned 8 bit
codepoint value. The following codepoints are defined in this codepoint value. The following codepoints are defined in this
document: document:
Suggested Description Reference Suggested Description Reference
Value Value
----------------------------------------------------- -----------------------------------------------------
1 Ingress Node TLV This document 5 HMAC TLV This document
2 Egress Node TLV This document 128 Pad0 TLV This document
3 Opaque Container TLV This document 129 PadN TLV This document
4 Padding TLV This document
5 HMAC TLV This document
6 NSH Carrier TLV This document
8. Implementation Status 8. Implementation Status
This section is to be removed prior to publishing as an RFC. This section is to be removed prior to publishing as an RFC.
8.1. Linux 8.1. Linux
Name: Linux Kernel v4.14 Name: Linux Kernel v4.14
Status: Production Status: Production
skipping to change at page 30, line 21 skipping to change at page 25, line 15
11. References 11. References
11.1. Normative References 11.1. Normative References
[FIPS180-4] [FIPS180-4]
National Institute of Standards and Technology, "FIPS National Institute of Standards and Technology, "FIPS
180-4 Secure Hash Standard (SHS)", March 2012, 180-4 Secure Hash Standard (SHS)", March 2012,
<http://csrc.nist.gov/publications/fips/fips180-4/ <http://csrc.nist.gov/publications/fips/fips180-4/
fips-180-4.pdf>. fips-180-4.pdf>.
[I-D.ietf-spring-segment-routing]
Filsfils, C., Previdi, S., Ginsberg, L., Decraene, B.,
Litkowski, S., and R. Shakir, "Segment Routing
Architecture", draft-ietf-spring-segment-routing-15 (work
in progress), January 2018.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", [RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)",
RFC 4303, DOI 10.17487/RFC4303, December 2005, RFC 4303, DOI 10.17487/RFC4303, December 2005,
<https://www.rfc-editor.org/info/rfc4303>. <https://www.rfc-editor.org/info/rfc4303>.
[RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation [RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation
skipping to change at page 31, line 5 skipping to change at page 26, line 5
Litkowski, S., Horneffer, M., and R. Shakir, "Source Litkowski, S., Horneffer, M., and R. Shakir, "Source
Packet Routing in Networking (SPRING) Problem Statement Packet Routing in Networking (SPRING) Problem Statement
and Requirements", RFC 7855, DOI 10.17487/RFC7855, May and Requirements", RFC 7855, DOI 10.17487/RFC7855, May
2016, <https://www.rfc-editor.org/info/rfc7855>. 2016, <https://www.rfc-editor.org/info/rfc7855>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200, (IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017, DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>. <https://www.rfc-editor.org/info/rfc8200>.
[RFC8300] Quinn, P., Ed., Elzur, U., Ed., and C. Pignataro, Ed., [RFC8354] Brzozowski, J., Leddy, J., Filsfils, C., Maglione, R.,
"Network Service Header (NSH)", RFC 8300, Ed., and M. Townsley, "Use Cases for IPv6 Source Packet
DOI 10.17487/RFC8300, January 2018, Routing in Networking (SPRING)", RFC 8354,
<https://www.rfc-editor.org/info/rfc8300>. DOI 10.17487/RFC8354, March 2018,
<https://www.rfc-editor.org/info/rfc8354>.
11.2. Informative References 11.2. Informative References
[I-D.bashandy-isis-srv6-extensions]
Ginsberg, L., Bashandy, A., Filsfils, C., Decraene, B.,
and Z. Hu, "IS-IS Extensions to Support Routing over IPv6
Dataplane", draft-bashandy-isis-srv6-extensions-02 (work
in progress), March 2018.
[I-D.dawra-bgp-srv6-vpn]
(Unknown), (., Dawra, G., Filsfils, C., Dukes, D.,
Brissette, P., Camarillo, P., Leddy, J.,
daniel.voyer@bell.ca, d., daniel.bernier@bell.ca, d.,
Steinberg, D., Raszuk, R., Decraene, B., and S.
Matsushima, "BGP Signaling of IPv6-Segment-Routing-based
VPN Networks", draft-dawra-bgp-srv6-vpn-00 (work in
progress), March 2017.
[I-D.filsfils-spring-srv6-interop] [I-D.filsfils-spring-srv6-interop]
Filsfils, C., Clad, F., Camarillo, P., Abdelsalam, A., Filsfils, C., Clad, F., Camarillo, P., Abdelsalam, A.,
Salsano, S., Bonaventure, O., Horn, J., and J. Liste, Salsano, S., Bonaventure, O., Horn, J., and J. Liste,
"SRv6 interoperability report", draft-filsfils-spring- "SRv6 interoperability report", draft-filsfils-spring-
srv6-interop-00 (work in progress), March 2018. srv6-interop-00 (work in progress), March 2018.
[I-D.filsfils-spring-srv6-network-programming] [I-D.filsfils-spring-srv6-network-programming]
Filsfils, C., Li, Z., Leddy, J., daniel.voyer@bell.ca, d., Filsfils, C., Li, Z., Leddy, J., daniel.voyer@bell.ca, d.,
daniel.bernier@bell.ca, d., Steinberg, D., Raszuk, R., daniel.bernier@bell.ca, d., Steinberg, D., Raszuk, R.,
Matsushima, S., Lebrun, D., Decraene, B., Peirens, B., Matsushima, S., Lebrun, D., Decraene, B., Peirens, B.,
skipping to change at page 32, line 19 skipping to change at page 26, line 48
segment-routing-extensions-15 (work in progress), December segment-routing-extensions-15 (work in progress), December
2017. 2017.
[I-D.ietf-ospf-ospfv3-segment-routing-extensions] [I-D.ietf-ospf-ospfv3-segment-routing-extensions]
Psenak, P., Filsfils, C., Previdi, S., Gredler, H., Psenak, P., Filsfils, C., Previdi, S., Gredler, H.,
Shakir, R., Henderickx, W., and J. Tantsura, "OSPFv3 Shakir, R., Henderickx, W., and J. Tantsura, "OSPFv3
Extensions for Segment Routing", draft-ietf-ospf-ospfv3- Extensions for Segment Routing", draft-ietf-ospf-ospfv3-
segment-routing-extensions-11 (work in progress), January segment-routing-extensions-11 (work in progress), January
2018. 2018.
[I-D.ietf-spring-ipv6-use-cases]
Brzozowski, J., Leddy, J., Filsfils, C., Maglione, R., and
M. Townsley, "IPv6 SPRING Use Cases", draft-ietf-spring-
ipv6-use-cases-12 (work in progress), December 2017.
[I-D.ietf-spring-resiliency-use-cases]
Filsfils, C., Previdi, S., Decraene, B., and R. Shakir,
"Resiliency use cases in SPRING networks", draft-ietf-
spring-resiliency-use-cases-12 (work in progress),
December 2017.
[I-D.ietf-spring-segment-routing]
Filsfils, C., Previdi, S., Ginsberg, L., Decraene, B.,
Litkowski, S., and R. Shakir, "Segment Routing
Architecture", draft-ietf-spring-segment-routing-15 (work
in progress), January 2018.
[I-D.ietf-spring-segment-routing-mpls] [I-D.ietf-spring-segment-routing-mpls]
Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., Bashandy, A., Filsfils, C., Previdi, S., Decraene, B.,
Litkowski, S., and R. Shakir, "Segment Routing with MPLS Litkowski, S., and R. Shakir, "Segment Routing with MPLS
data plane", draft-ietf-spring-segment-routing-mpls-12 data plane", draft-ietf-spring-segment-routing-mpls-13
(work in progress), February 2018. (work in progress), April 2018.
[I-D.previdi-idr-segment-routing-te-policy]
Previdi, S., Filsfils, C., Mattes, P., Rosen, E., and S.
Lin, "Advertising Segment Routing Policies in BGP", draft-
previdi-idr-segment-routing-te-policy-07 (work in
progress), June 2017.
[RFC1940] Estrin, D., Li, T., Rekhter, Y., Varadhan, K., and D. [RFC1940] Estrin, D., Li, T., Rekhter, Y., Varadhan, K., and D.
Zappala, "Source Demand Routing: Packet Format and Zappala, "Source Demand Routing: Packet Format and
Forwarding Specification (Version 1)", RFC 1940, Forwarding Specification (Version 1)", RFC 1940,
DOI 10.17487/RFC1940, May 1996, DOI 10.17487/RFC1940, May 1996,
<https://www.rfc-editor.org/info/rfc1940>. <https://www.rfc-editor.org/info/rfc1940>.
[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- [RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104, Hashing for Message Authentication", RFC 2104,
DOI 10.17487/RFC2104, February 1997, DOI 10.17487/RFC2104, February 1997,
<https://www.rfc-editor.org/info/rfc2104>. <https://www.rfc-editor.org/info/rfc2104>.
[RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering: [RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering:
Defeating Denial of Service Attacks which employ IP Source Defeating Denial of Service Attacks which employ IP Source
Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827, Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827,
May 2000, <https://www.rfc-editor.org/info/rfc2827>. May 2000, <https://www.rfc-editor.org/info/rfc2827>.
[RFC4302] Kent, S., "IP Authentication Header", RFC 4302,
DOI 10.17487/RFC4302, December 2005,
<https://www.rfc-editor.org/info/rfc4302>.
[RFC4942] Davies, E., Krishnan, S., and P. Savola, "IPv6 Transition/ [RFC4942] Davies, E., Krishnan, S., and P. Savola, "IPv6 Transition/
Co-existence Security Considerations", RFC 4942, Co-existence Security Considerations", RFC 4942,
DOI 10.17487/RFC4942, September 2007, DOI 10.17487/RFC4942, September 2007,
<https://www.rfc-editor.org/info/rfc4942>. <https://www.rfc-editor.org/info/rfc4942>.
[RFC5308] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308,
DOI 10.17487/RFC5308, October 2008,
<https://www.rfc-editor.org/info/rfc5308>.
[RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008,
<https://www.rfc-editor.org/info/rfc5340>.
[RFC6438] Carpenter, B. and S. Amante, "Using the IPv6 Flow Label
for Equal Cost Multipath Routing and Link Aggregation in
Tunnels", RFC 6438, DOI 10.17487/RFC6438, November 2011,
<https://www.rfc-editor.org/info/rfc6438>.
[RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6 [RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6
Routing Header for Source Routes with the Routing Protocol Routing Header for Source Routes with the Routing Protocol
for Low-Power and Lossy Networks (RPL)", RFC 6554, for Low-Power and Lossy Networks (RPL)", RFC 6554,
DOI 10.17487/RFC6554, March 2012, DOI 10.17487/RFC6554, March 2012,
<https://www.rfc-editor.org/info/rfc6554>. <https://www.rfc-editor.org/info/rfc6554>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26, Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017, RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>. <https://www.rfc-editor.org/info/rfc8126>.
 End of changes. 104 change blocks. 
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