draft-ietf-forces-framework-01.txt   draft-ietf-forces-framework-02.txt 
Internet Draft L. Yang Internet Draft L. Yang
Expiration: March 2003 Intel Labs Expiration: April 2003 Intel Corp.
File: draft-ietf-forces-framework-01.txt R. Dantu File: draft-ietf-forces-framework-02.txt R. Dantu
Working Group: ForCES Netrake Corp. Working Group: ForCES Univ. of Texas Dallas
T. Anderson T. Anderson
Intel Labs Intel Corp.
Sept 2002 Oct 2002
ForCES Architectural Framework ForCES Architectural Framework
draft-ietf-forces-framework-01.txt draft-ietf-forces-framework-02.txt
Status of this Memo Status of this Memo
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Abstract
This document defines the architectural framework for ForCES
(Forwarding and Control Element Separation) network elements (NE),
and identifies the associated entities and the interaction among
them. This framework is intended to satisfy the requirements
specified in the ForCES requirements draft [FORCES-REQ].
Table of Contents
1. Definitions.....................................................2
2. Introduction to Forwarding and Control Element Separation
(ForCES)...........................................................4
3. Architecture....................................................7
3.1. Control Elements and Fr Reference Point....................8
3.2. Forwarding Elements and Fi reference point.................8
3.3. CE Managers...............................................11
3.4. FE Managers...............................................11
4. Operational Phases.............................................11
4.1. Pre-association Phase.....................................12
4.1.1. Fl Reference Point...................................12
4.1.2. Ff Reference Point...................................13
4.1.3. Fc Reference Point...................................13
4.2. Post-association Phase and Fp reference point.............14
4.2.1. Proximity and Interconnect between CEs and FEs.......14
4.2.2. Association Establishment............................14
4.2.3. Steady-state Communication...........................15
4.2.4. Data Packets across Fp reference point...............16
4.2.5. Proxy FE.............................................17
4.3. Association Re-establishment..............................17
5. Applicability to RFC1812.......................................18
5.1. General Router Requirements...............................18
5.2. Link Layer................................................19
5.3. Internet Layer Protocols..................................20
5.4. Internet Layer Forwarding.................................20
5.5. Transport Layer...........................................21
5.6. Application Layer -- Routing Protocols....................21
5.7. Application Layer -- Network Management Protocol..........21
6. Summary........................................................22
7. Security Considerations........................................22
8. Intellectual Property Right....................................22
9. References.....................................................22
9.1. Normative References......................................22
9.2. Informative References....................................23
10. Acknowledgments...............................................23
11. Authors' Addresses............................................23
Conventions used in this document Conventions used in this document
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 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in [RFC-2119]. this document are to be interpreted as described in [RFC-2119].
1. Abstract 1. Definitions
This document defines the architectural framework for ForCES network
elements (NE), and identifies the associated entities and the
interaction among them. This framework is intended to satisfy the
requirements specified in the ForCES requirements draft [FORCES-
REQ].
2. Definitions
A set of terminology associated with the ForCES requirements is A set of terminology associated with the ForCES requirements is
defined in [FORCES-REQ] and we only include the ones that are most defined in [FORCES-REQ] and we only include the ones that are most
relevant to this document here. relevant to this document here.
Forwarding Element (FE) - A logical entity that implements the Forwarding Element (FE) - A logical entity that implements the
ForCES protocol. FEs use the underlying hardware to provide per- ForCES protocol. FEs use the underlying hardware to provide per-
packet processing and handling as directed by a CE via the ForCES packet processing and handling as directed by a CE via the ForCES
protocol. protocol.
Control Element (CE) - A logical entity that implements the ForCES Control Element (CE) - A logical entity that implements the ForCES
protocol and uses it to instruct one or more FEs how to process protocol and uses it to instruct one or more FEs how to process
packets. CEs handle functionality such as the execution of control packets. CEs handle functionality such as the execution of control
and signaling protocols. and signaling protocols.
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ForCES Network Element (NE) - An entity composed of one or more CEs ForCES Network Element (NE) - An entity composed of one or more CEs
and one or more FEs. To entities outside a NE, the NE represents a and one or more FEs. To entities outside a NE, the NE represents a
single point of management. Similarly, a NE usually hides its single point of management. Similarly, a NE usually hides its
internal organization from external entities. internal organization from external entities.
Pre-association Phase - The period of time during which a FE Manager Pre-association Phase - The period of time during which a FE Manager
(see below) and a CE Manager (see below) are determining which FE (see below) and a CE Manager (see below) are determining which FE
and CE should be part of the same network element. Any partitioning and CE should be part of the same network element. Any partitioning
of PFEs and PCEs occurs during this phase. of PFEs and PCEs occurs during this phase.
skipping to change at line 99 skipping to change at line 140
messages themselves. This protocol could be a single protocol or messages themselves. This protocol could be a single protocol or
could consist of multiple protocols working together. could consist of multiple protocols working together.
FE Manager - A logical entity that operates in the pre-association FE Manager - A logical entity that operates in the pre-association
phase and is responsible for determining to which CE(s) a FE should phase and is responsible for determining to which CE(s) a FE should
communicate. This process is called CE discovery and may involve communicate. This process is called CE discovery and may involve
the FE manager learning the capabilities of available CEs. A FE the FE manager learning the capabilities of available CEs. A FE
manager may use anything from a static configuration to a pre- manager may use anything from a static configuration to a pre-
association phase protocol (see below) to determine which CE(s) to association phase protocol (see below) to determine which CE(s) to
use. Being a logical entity, a FE manager might be physically use. Being a logical entity, a FE manager might be physically
Yang, et. al. Expires March 2003 [Page 2]
combined with any of the other logical entities mentioned in this combined with any of the other logical entities mentioned in this
section. section.
CE Manager - A logical entity that operates in the pre-association CE Manager - A logical entity that operates in the pre-association
phase and is responsible for determining to which FE(s) a CE should phase and is responsible for determining to which FE(s) a CE should
communicate. This process is called FE discovery and may involve communicate. This process is called FE discovery and may involve
the CE manager learning the capabilities of available FEs. A CE the CE manager learning the capabilities of available FEs. A CE
manager may use anything from a static configuration to a pre- manager may use anything from a static configuration to a pre-
association phase protocol (see below) to determine which FE to use. association phase protocol (see below) to determine which FE to use.
Being a logical entity, a CE manager might be physically combined Being a logical entity, a CE manager might be physically combined
with any of the other logical entities mentioned in this section. with any of the other logical entities mentioned in this section.
Pre-association Phase Protocol - A protocol between FE managers and Pre-association Phase Protocol - A protocol between FE managers and
CE managers that is used to determine which CEs or FEs to use. A CE managers that is used to determine which CEs or FEs to use. A
pre-association phase protocol may include a CE and/or FE capability pre-association phase protocol may include a CE and/or FE capability
discovery mechanism. Note that this capability discovery process is discovery mechanism. Note that this capability discovery process is
Yang, et. al. Expires April 2003 [Page 3]
wholly separate from (and does not replace) that used within the wholly separate from (and does not replace) that used within the
ForCES protocol. However, the two capability discovery mechanisms ForCES protocol. However, the two capability discovery mechanisms
may utilize the same FE model. may utilize the same FE model.
FE Model - A model that describes the logical processing functions FE Model - A model that describes the logical processing functions
of a FE. of a FE.
ForCES Protocol Element - A FE or CE. ForCES Protocol Element - A FE or CE.
3. Introduction to Forwarding and Control Element Separation (ForCES) 2. Introduction to Forwarding and Control Element Separation (ForCES)
An IP network element (NE) appears to external entities as a An IP network element (NE) appears to external entities as a
monolithic piece of network equipment, e.g., a router, NAT, monolithic piece of network equipment, e.g., a router, NAT,
firewall, or load balancer. Internally, however, an IP network firewall, or load balancer. Internally, however, an IP network
element (NE) (such as a router or switch) is composed of numerous element (NE) (such as a router) is composed of numerous logically
logically separated entities that cooperate to provide a given separated entities that cooperate to provide a given functionality
functionality (such as routing or IP switching). Two types of (such as routing). Two types of network element components exist:
network element components exist: control element (CE) in control control element (CE) in control plane and forwarding element (FE) in
plane and forwarding element (FE) in forwarding plane (or data forwarding plane (or data plane). Forwarding elements typically are
plane). Forwarding elements typically are ASIC, network-processor, ASIC, network-processor, or general-purpose processor-based devices
or general-purpose processor-based devices that handle data path that handle data path operations for each packet. Control elements
operations for each packet. Control elements are typically based on are typically based on general-purpose processors that provide
general-purpose processors that provide control functionality like control functionality like routing and signaling protocols.
routing and signaling protocols.
ForCES aims to define a framework and associated protocol(s) to ForCES aims to define a framework and associated protocol(s) to
standardize the exchange of information between the control plane standardize information exchange between the control and forwarding
and the forwarding plane. Having standard mechanisms between the CEs plane. Having standard mechanisms allows CEs and FEs to become
and FEs allow these components to be physically separated. This physically separated standard components. This physical separation
physical separation accrues several benefits to the ForCES accrues several benefits to the ForCES architecture. Separate
architecture. Separate components would allow component vendors to components would allow component vendors to specialize in one
specialize in one component without having to become experts in all component without having to become experts in all components.
components. It also allows CEs and FEs from different component Standard protocol also allows CEs and FEs from different component
vendors to interoperate with each other and hence it becomes vendors to interoperate with each other and hence it becomes
possible for system vendors to integrate together CEs and FEs from possible for system vendors to integrate together CEs and FEs from
different component vendors. This translates into a lot more design different component vendors. This interoperability translates into a
choices and flexibility to the system vendors. Overall, ForCES will lot more design choices and flexibility to the system vendors.
Overall, ForCES will enable rapid innovation in both the control and
Yang, et. al. Expires March 2003 [Page 3] forwarding planes while maintaining interoperability. Scalability is
enable rapid innovation in both the control and forwarding planes also easily provided by this architecture in that additional
while maintaining interoperability. Scalability is also easily forwarding or control capacity can be added to existing network
provided by this architecture in that additional forwarding or elements without the need for forklift upgrades.
control capacity can be added to existing network elements without
the need for forklift upgrades.
One example of such physical separation is at the blade level. One example of such physical separation is at the blade level.
Figure 1 shows an example configuration of a router, with two Figure 1 shows such an example configuration of a router, with two
control blades and multiple router (forwarding) blades, all control blades and multiple router (forwarding) blades, all
interconnected into a switch fabric backplane. In such chassis interconnected into a switch fabric backplane. In such chassis
configuration, the control blades are the CEs while the router configuration, the control blades are the CEs while the router
blades are FEs, and the switch fabric backplane provides the blades are FEs, and the switch fabric backplane provides the
physical interconnect for all the blades. Routers today with this physical interconnect for all the blades. Control blade A may be the
kind of configuration use proprietary interface for messaging primary CE while control blade B is the backup CE providing
between CEs and FEs. The goal of ForCES is to replace such redundancy. It is also possible to have a redundant switch fabric
proprietary interface with a standard protocol. With a standard for high availability support. Routers today with this kind of
protocol like ForCES implemented on all blades, it becomes possible configuration use proprietary interface for messaging between CEs
for control blades from vendor X and routing blades from vendor Y to
work seamlessly together in one chassis. Yang, et. al. Expires April 2003 [Page 4]
and FEs. The goal of ForCES is to replace such proprietary interface
with a standard protocol. With a standard protocol like ForCES
implemented on all blades, it becomes possible for control blades
from vendor X and routing blades from vendor Y to work seamlessly
together in one chassis.
------------------------- ------------------------- ------------------------- -------------------------
| Control Blade A | | Control Blade B | | Control Blade A | | Control Blade B |
| (CE) | | (CE) | | (CE) | | (CE) |
------------------------- ------------------------- ------------------------- -------------------------
^ | ^ | ^ | ^ |
| | | | | | | |
| V | V | V | V
--------------------------------------------------------- ---------------------------------------------------------
| Switch Fabric Backplane | | Switch Fabric Backplane |
skipping to change at line 200 skipping to change at line 243
|Router | |Router | |Router | |Router | |Router | |Router |
|Blade #1 | |Blade #2 | |Blade #N | |Blade #1 | |Blade #2 | |Blade #N |
| (FE) | | (FE) | | (FE) | | (FE) | | (FE) | | (FE) |
------------ ------------ ------------ ------------ ------------ ------------
^ | ^ | ^ | ^ | ^ | ^ |
| | | | | | | | | | | |
| V | V | V | V | V | V
Figure 1. A router configuration example with separate blades. Figure 1. A router configuration example with separate blades.
Another level of physical separation between the CEs and FEs can be
at the box level. In such configuration, all the CEs and FEs are
physically separated boxes, interconnected with some kind of high
speed LAN connection (like Gigabit Ethernet). These separated CEs
and FEs are only one hop away from each other within a local area
network. The CEs and FEs communicate to each other by running
ForCES, and the collection of these CEs and FEs together become one
routing unit to the external world. Figure 2 shows such an example.
Yang, et. al. Expires March 2003 [Page 4]
In this example, the same physical interconnect (Ethernet) is shared
for both CE-to-FE and FE-to-FE communication. However, that does not
have to be the case. One reason to use different interconnect might
be that CE-to-FE interconnect does not have to be as fast as the FE-
to-FE interconnect, so the more expensive fast ports can be saved
for FE-to-FE. The separate interconnects may also provide
reliability and redundancy benefits for the NE.
------- ------- ------- -------
| CE1 | | CE2 | | CE1 | | CE2 |
------- ------- ------- -------
^ ^ ^ ^
| | | |
V V V V
============================================ Ethernet ============================================ Ethernet
^ ^ ^ ^ ^ ^
| | | | | |
V V V V V V
------- ------- -------- ------- ------- --------
| FE#1| | FE#2| | FE#n | | FE#1| | FE#2| | FE#n |
------- ------- -------- ------- ------- --------
^ | ^ | ^ | ^ | ^ | ^ |
| | | | | | | | | | | |
| V | V | V | V | V | V
Figure 2. A router configuration example with separate boxes. Figure 2. A router configuration example with separate boxes.
Another level of physical separation between the CEs and FEs can be
at the box level. In such configuration, all the CEs and FEs are
physically separated boxes, interconnected with some kind of high
Yang, et. al. Expires April 2003 [Page 5]
speed LAN connection (like Gigabit Ethernet). These separated CEs
and FEs are only one hop away from each other within a local area
network. The CEs and FEs communicate to each other by running
ForCES, and the collection of these CEs and FEs together become one
routing unit to the external world. Figure 2 shows such an example.
In both examples shown here, the same physical interconnect is used
for both CE-to-FE and FE-to-FE communication. However, that does not
have to be the case. One reason to use different interconnect is
that CE-to-FE interconnect does not have to be as fast as the FE-to-
FE interconnect, so the more expensive fast connections can be saved
for FE-to-FE only. The separate interconnects may also provide
reliability and redundancy benefits for the NE.
------------------------------------------------- -------------------------------------------------
| | | | | | | | | | | | | |
|OSPF |RIP |BGP |CAC |LDP | | |OSPF |RIP |BGP |CAC |LDP | |
| | | | | | | | | | | | | |
------------------------------------------------- -------------------------------------------------
| ForCES Interface | | ForCES Interface |
------------------------------------------------- -------------------------------------------------
^ ^ ^ ^
ForCES | |data ForCES | |data
control | |packets control | |packets
skipping to change at line 261 skipping to change at line 305
------------------------------------------------- -------------------------------------------------
| | | | | | | | | | | | | |
|LPM Fwd|Meter |Shaper |NAT |Classi-| | |LPM Fwd|Meter |Shaper |NAT |Classi-| |
| | | | |fier | | | | | | |fier | |
------------------------------------------------- -------------------------------------------------
| FE resources | | FE resources |
------------------------------------------------- -------------------------------------------------
Figure 3. Examples of CE and FE functions Figure 3. Examples of CE and FE functions
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Some examples of control functions that can be implemented in the CE Some examples of control functions that can be implemented in the CE
include routing protocols like RIP, OSPF and BGP, control and include routing protocols like RIP, OSPF and BGP, control and
signaling protocols like CAC (Call Admission Control), LDP (Label signaling protocols like CAC (Call Admission Control), LDP (Label
Distribution Protocol) for MPLS, etc. Examples of forwarding Distribution Protocol) for MPLS, etc. Examples of forwarding
functions in FE include LPM (longest prefix match) forwarder, functions in FE include LPM (longest prefix match) forwarder,
classifiers, traffic shaper, meter, NAT, etc. Figure 3 shows a classifiers, traffic shaper, meter, NAT, etc. Figure 3 shows a
diagram with examples in both CE and FE. Any given NE may contain diagram with examples in both CE and FE. Any given NE may contain
one or many of these CE and FE functions in it. The diagram also one or many of these CE and FE functions in it. The diagram also
shows that ForCES protocol is used to transport both the control shows that ForCES protocol is used to transport both the control
messages for ForCES itself and the data packets that are messages for ForCES itself and the data packets that are
originated/destined from/to the control functions in CE (e.g., originated/destined from/to the control functions in CE (e.g.,
routing packets). Section 5.2.4 provides more detail on this. routing packets). Section 5.2.4 provides more detail on this.
A set of requirements for control and forwarding separation is A set of requirements for control and forwarding separation is
identified in [FORCES-REQ]. This document describes a ForCES identified in [FORCES-REQ]. This document describes a ForCES
Yang, et. al. Expires April 2003 [Page 6]
architecture that satisfies the architectural requirements of that architecture that satisfies the architectural requirements of that
document and defines a framework for ForCES network elements and document and defines a framework for ForCES network elements and
associated entities to facilitate protocol definition. associated entities to facilitate protocol definition.
4. Architecture 3. Architecture
This section defines the ForCES architectural framework and the This section defines the ForCES architectural framework and the
associated logical components. This ForCES framework defines associated logical components. This ForCES framework defines
components of ForCES NEs including several ancillary components. components of ForCES NEs including several ancillary components.
These components may be connected in different kinds of topologies These components may be connected in different kinds of topologies
for flexible packet processing. for flexible packet processing.
--------------------------------------- ---------------------------------------
| ForCES Network Element | | ForCES Network Element |
-------------- Fc | -------------- -------------- | -------------- Fc | -------------- -------------- |
skipping to change at line 315 skipping to change at line 360
| | | | | | | | | | | | | | | | | | | |
----+--+--+--+----------+--+--+--+----- ----+--+--+--+----------+--+--+--+-----
| | | | | | | | | | | | | | | |
| | | | | | | | | | | | | | | |
Fi/f Fi/f Fi/f Fi/f
Figure 4. ForCES Architectural Diagram Figure 4. ForCES Architectural Diagram
The diagram in Figure 4 shows the logical components of the ForCES The diagram in Figure 4 shows the logical components of the ForCES
architecture and their relationships. There are two kinds of architecture and their relationships. There are two kinds of
Yang, et. al. Expires March 2003 [Page 6]
components inside a ForCES network element: control element (CE) and components inside a ForCES network element: control element (CE) and
forwarding element (FE). The framework allows multiple instances of forwarding element (FE). The framework allows multiple instances of
CE and FE inside one NE. Each FE contains one or more physical media CE and FE inside one NE. Each FE contains one or more physical media
interfaces for receiving and transmitting packets from/to the interfaces for receiving and transmitting packets from/to the
external world. The aggregation of these FE interfaces becomes the external world. The aggregation of these FE interfaces becomes the
NEs external interfaces. In addition to the external interfaces, NEs external interfaces. In addition to the external interfaces,
there must also exist some kind of interconnect within the NE so there must also exist some kind of interconnect within the NE so
that the CE and FE can communicate with each other, and one FE can that the CE and FE can communicate with each other, and one FE can
forward packets to another FE. The diagram also shows two entities forward packets to another FE. The diagram also shows two entities
outside of the ForCES NE: CE Manager and FE Manager. These two outside of the ForCES NE: CE Manager and FE Manager. These two
entities provide configuration to the corresponding CE or FE in the entities provide configuration to the corresponding CE or FE in the
pre-association phase (see Section 5.1). There is no defined role pre-association phase (see Section 5.1). There is no defined role
for FE Manager and CE Manager in post-association phase, thus these for FE Manager and CE Manager in post-association phase, thus these
logical components are not considered part of the ForCES NE. logical components are not considered part of the ForCES NE.
Yang, et. al. Expires April 2003 [Page 7]
For convenience, the logical interactions between these components For convenience, the logical interactions between these components
are labeled by reference points Fp, Fc, Ff, Fr, Fl, and Fi, as shown are labeled by reference points Fp, Fc, Ff, Fr, Fl, and Fi, as shown
in Figure 4. The FE external interfaces are labeled as Fi/f. More in Figure 4. The FE external interfaces are labeled as Fi/f. More
detail is provided in Section 4 and 5 for each of these reference detail is provided in Section 4 and 5 for each of these reference
points. All these reference points are important in understanding points. All these reference points are important in understanding
the ForCES architecture, however, the ForCES protocol is only the ForCES architecture, however, the ForCES protocol is only
defined over one reference point -- Fp. defined over one reference point -- Fp.
The interface between two ForCES NEs is identical to the interface The interface between two ForCES NEs is identical to the interface
between two conventional routers and these two NEs exchange the between two conventional routers and these two NEs exchange the
protocol packets through the external interfaces at Fi/f. ForCES NEs protocol packets through the external interfaces at Fi/f. ForCES NEs
connect to existing routers transparently. connect to existing routers transparently.
4.1. Control Elements and Fr Reference Point 3.1. Control Elements and Fr Reference Point
It is not necessary to define any protocols across the Fr reference It is not necessary to define any protocols across the Fr reference
point to enable control and forwarding separation for simple point to enable control and forwarding separation for simple
configurations like single CE and multiple FEs. However, this configurations like single CE and multiple FEs. However, this
architecture permits multiple CEs to be present in a network architecture permits multiple CEs to be present in a network
element. In cases where an implementation uses multiple CEs, it is element. In cases where an implementation uses multiple CEs, it is
expected the invariant that the CEs and FEs together appear as a expected the invariant that the CEs and FEs together appear as a
single NE MUST be maintained. single NE MUST be maintained.
Multiple CEs may be used for redundancy, load sharing, distributed Multiple CEs may be used for redundancy, load sharing, distributed
skipping to change at line 370 skipping to change at line 414
also be serviced by any of the other CEs. In both redundancy and also be serviced by any of the other CEs. In both redundancy and
load sharing, the CEs involved are equivalently capable. The only load sharing, the CEs involved are equivalently capable. The only
difference between these two cases is in terms of how many active difference between these two cases is in terms of how many active
CEs there are. Distributed control is the case where two or more CEs there are. Distributed control is the case where two or more
CEs are concurrently active but where certain requests can only be CEs are concurrently active but where certain requests can only be
serviced by certain CEs. serviced by certain CEs.
When multiple CEs are employed in a ForCES NE, their internal When multiple CEs are employed in a ForCES NE, their internal
organization is considered an implementation issue that is beyond organization is considered an implementation issue that is beyond
the scope of ForCES. CEs are wholly responsible for coordinating the scope of ForCES. CEs are wholly responsible for coordinating
Yang, et. al. Expires March 2003 [Page 7]
amongst themselves via the Fr reference point to provide consistency amongst themselves via the Fr reference point to provide consistency
and synchronization. However, ForCES does not define the and synchronization. However, ForCES does not define the
implementation or protocols used between CEs, nor does it define how implementation or protocols used between CEs, nor does it define how
to distribute functionality among CEs. Nevertheless, ForCES will to distribute functionality among CEs. Nevertheless, ForCES will
support mechanisms for CE redundancy or fail over, and it is support mechanisms for CE redundancy or fail over, and it is
expected that vendors will provide redundancy or fail over solutions expected that vendors will provide redundancy or fail over solutions
within this framework. within this framework.
4.2. Forwarding Elements and Fi reference point 3.2. Forwarding Elements and Fi reference point
FEs perform per-packet processing and handling as directed by CEs. FEs perform per-packet processing and handling as directed by CEs.
FEs have no initiative of their own. Instead, FEs are slaves and FEs have no initiative of their own. Instead, FEs are slaves and
only do as they are told. FEs may communicate with one or more CEs only do as they are told. FEs may communicate with one or more CEs
concurrently across reference point Fp. FEs have no notion of CE concurrently across reference point Fp. FEs have no notion of CE
Yang, et. al. Expires April 2003 [Page 8]
redundancy, load sharing, or distributed control. Instead, FEs redundancy, load sharing, or distributed control. Instead, FEs
accept commands from any CE authorized to control them, and it is up accept commands from any CE authorized to control them, and it is up
to the CEs to coordinate among themselves to achieve redundancy, to the CEs to coordinate among themselves to achieve redundancy,
load sharing or distributed control. The idea is to keep FEs as load sharing or distributed control. The idea is to keep FEs as
simple and dumb as possible so that FEs can focus its resource on simple and dumb as possible so that FEs can focus its resource on
the packet processing functions. the packet processing functions.
------- Fr ------- ------- Fr -------
| CE1 | ------| CE2 | | CE1 | ------| CE2 |
------- ------- ------- -------
skipping to change at line 424 skipping to change at line 468
issuing commands to the FEs, it might need to recheck the FEs' state issuing commands to the FEs, it might need to recheck the FEs' state
and instruct FEs whether or not it is ok to preserve their current and instruct FEs whether or not it is ok to preserve their current
state. state.
Distributed control can be achieved in the similar fashion, without Distributed control can be achieved in the similar fashion, without
much intelligence on the part of FEs. For example, FEs can be much intelligence on the part of FEs. For example, FEs can be
configured to detect RSVP and BGP protocol packets, and forward RSVP configured to detect RSVP and BGP protocol packets, and forward RSVP
packets to one CE and BGP packets to another CE. Hence, FEs may need packets to one CE and BGP packets to another CE. Hence, FEs may need
to do packet filtering for forwarding packets to specific CEs. to do packet filtering for forwarding packets to specific CEs.
Yang, et. al. Expires March 2003 [Page 8]
This architecture permits multiple FEs to be present in a NE. This architecture permits multiple FEs to be present in a NE.
[FORCES-REQ] dictates that the ForCES protocol MUST be able to scale [FORCES-REQ] dictates that the ForCES protocol MUST be able to scale
to at least hundreds of FEs (see [FORCES-REQ] Section 5, requirement to at least hundreds of FEs (see [FORCES-REQ] Section 5, requirement
#11). Each of these FEs may potentially have a different set of #11). Each of these FEs may potentially have a different set of
packet processing functions, with different media interfaces. FEs packet processing functions, with different media interfaces. FEs
are responsible for basic maintenance of layer-2 connectivity with are responsible for basic maintenance of layer-2 connectivity with
other FEs and with external entities. Many layer-2 media include other FEs and with external entities. Many layer-2 media include
sophisticated control protocols. The FORCES protocol (over the Fp sophisticated control protocols. The FORCES protocol (over the Fp
reference point) will be able to carry messages for such protools so reference point) will be able to carry messages for such protools so
that, in keeping with the "dumb FE model" the CE can provide that, in keeping with the "dumb FE model, the CE can provide
appropriate intelligence and control over these media. appropriate intelligence and control over these media.
When multiple FEs are present, ForCES requires that packets MUST be When multiple FEs are present, ForCES requires that packets MUST be
able to arrive at the NE by one FE and leave the NE via a different able to arrive at the NE by one FE and leave the NE via a different
Yang, et. al. Expires April 2003 [Page 9]
FE (See [FORCES-REQ], Section 5, Requirement #3). Packets that FE (See [FORCES-REQ], Section 5, Requirement #3). Packets that
enter the NE via one FE and leave the NE via a different FE are enter the NE via one FE and leave the NE via a different FE are
transferred between FEs across the Fi reference point. The Fi transferred between FEs across the Fi reference point. The Fi
reference point is a separate protocol from the Fp reference point reference point is a separate protocol from the Fp reference point
and is not currently defined by the ForCES architecture. and is not currently defined by the ForCES architecture.
FEs could be connected in different kinds of topologies and packet FEs could be connected in different kinds of topologies and packet
processing may spread across several FEs in the topology. Hence, processing may spread across several FEs in the topology. Hence,
logical packet flow may be different from physical FE topology. logical packet flow may be different from physical FE topology.
Figure 6 provides some topology examples. When it is necessary to Figure 6 provides some topology examples. When it is necessary to
forward packets between FEs, CE needs to understand the FE topology. forward packets between FEs, CE needs to understand the FE topology.
The FE topology can be queried from FEs by CEs. If the most common The FE topology can be queried from FEs by CEs.
FE topology is full mesh among FEs, ForCES can assume it as the
default topology for FEs and hence no query is needed for such
default cases.
----------------- -----------------
| CE | | CE |
----------------- -----------------
^ ^ ^ ^ ^ ^
/ | \ / | \
/ v \ / v \
/ ----- \ / ------- \
/ +->|FE3|<-+ \ / +->|FE3|<-+ \
v | ----- | v / | | | | \
v | ------- | v
------- | | ------- ------- | | -------
| FE1 |<-+ +->| FE2 | | FE1 |<-+ +->| FE2 |
| |<--------------->| |
------- ------- ------- -------
^ | ^ | ^ | ^ |
| | | | | | | |
| v | v | v | v
(a) Full mesh among FE1, FE2 and FE3. (a) Full mesh among FE1, FE2 and FE3.
----------- -----------
| CE | | CE |
----------- -----------
Yang, et. al. Expires March 2003 [Page 9]
^ ^ ^ ^ ^ ^ ^ ^
/ | | \ / | | \
/------ | | ------\ /------ | | ------\
v v v v v v v v
------- ------- ------- ------- ------- ------- ------- -------
| FE1 |<->| FE2 |<->| FE3 |<->| FE4 | | FE1 |<->| FE2 |<->| FE3 |<->| FE4 |
------- ------- ------- ------- ------- ------- ------- -------
^ | ^ | ^ | ^ | ^ | ^ | ^ | ^ |
| | | | | | | | | | | | | | | |
| v | v | v | v | v | v | v | v
(b) Multiple FEs in a daisy chain (b) Multiple FEs in a daisy chain
Yang, et. al. Expires April 2003 [Page 10]
^ | ^ |
| v | v
----------- -----------
| FE1 |<-----------------------| | FE1 |<-----------------------|
----------- | ----------- |
^ ^ | ^ ^ |
/ \ | / \ |
| ^ / \ ^ | V | ^ / \ ^ | V
v | v v | v ---------- v | v v | v ----------
--------- --------- | | --------- --------- | |
skipping to change at line 519 skipping to change at line 562
| ----------- | | ----------- |
| | ^ | | | ^ |
| v | | | v | |
| | | |
|----------------------------------------| |----------------------------------------|
(c) Multiple FEs connected by a ring (c) Multiple FEs connected by a ring
Figure 6. Some examples of FE topology. Figure 6. Some examples of FE topology.
4.3. CE Managers 3.3. CE Managers
CE managers are responsible for determining which FEs a CE should CE managers are responsible for determining which FEs a CE should
control. It is legitimate for CE managers to be hard-coded with the control. It is legitimate for CE managers to be hard-coded with the
knowledge of with which FEs its CEs should communicate. A CE manager knowledge of with which FEs its CEs should communicate. A CE manager
may also be physically embedded into a CE and be implemented as a may also be physically embedded into a CE and be implemented as a
simple keypad or other direct configuration mechanism on the CE. simple keypad or other direct configuration mechanism on the CE.
Finally, CE managers may be physically and logically separate Finally, CE managers may be physically and logically separate
entities that configure the CE with FE information via such entities that configure the CE with FE information via such
mechanisms as COPS-PR [RFC3084] or SNMP [RFC1157]. mechanisms as COPS-PR [RFC3084] or SNMP [RFC1157].
Yang, et. al. Expires March 2003 [Page 10] 3.4. FE Managers
4.4. FE Managers
FE managers are responsible for determining to which CE any FE managers are responsible for determining to which CE any
particular FE should initially communicate. Like CE managers, no particular FE should initially communicate. Like CE managers, no
restrictions are placed on how a FE manager decides to which CEs its restrictions are placed on how a FE manager decides to which CEs its
FEs should communicate, nor are restrictions placed on how FE FEs should communicate, nor are restrictions placed on how FE
managers are implemented. managers are implemented.
5. Operational Phases 4. Operational Phases
Both FEs and CEs require some configuration in place before they can Both FEs and CEs require some configuration in place before they can
start information exchange and function as a coherent network start information exchange and function as a coherent network
element. Two operational phases are identified in this framework -- element. Two operational phases are identified in this framework --
pre-association and post-association. pre-association and post-association.
5.1.Pre-association Phase Yang, et. al. Expires April 2003 [Page 11]
4.1.Pre-association Phase
Pre-association phase is the period of time during which a FE Pre-association phase is the period of time during which a FE
Manager and a CE Manager are determining which FE and CE should be Manager and a CE Manager are determining which FE and CE should be
part of the same network element. The protocols used during this part of the same network element. The protocols used during this
phase may include all or some of the message exchange over Fl, Ff phase may include all or some of the message exchange over Fl, Ff
and Fc reference points. However, all these may be optional and none and Fc reference points. However, all these may be optional and none
of this is within the scope of ForCES protocol. of this is within the scope of ForCES protocol.
5.1.1. Fl Reference Point 4.1.1. Fl Reference Point
FE Manager FE CE Manager CE FE Manager FE CE Manager CE
| | | | | | | |
| | | | | | | |
|(security exchange) | | |(security exchange) | |
1|<------------------------------>| | 1|<------------------------------>| |
| | | | | | | |
|(a list of CEs and their attributes) | |(a list of CEs and their attributes) |
2|<-------------------------------| | 2|<-------------------------------| |
| | | | | | | |
skipping to change at line 583 skipping to change at line 626
CE managers and FE managers may communicate across the Fl reference CE managers and FE managers may communicate across the Fl reference
point in the pre-association phase in order to determine which CEs point in the pre-association phase in order to determine which CEs
and FEs should communicate with each other. Communication across and FEs should communicate with each other. Communication across
the Fl reference point is optional in this architecture. No the Fl reference point is optional in this architecture. No
requirements are placed on this reference point. requirements are placed on this reference point.
CE managers and FE managers may be operated by different entities. CE managers and FE managers may be operated by different entities.
The operator of the CE manager may not want to divulge, except to The operator of the CE manager may not want to divulge, except to
specified FE managers, any characteristics of the CEs it manages. specified FE managers, any characteristics of the CEs it manages.
Yang, et. al. Expires March 2003 [Page 11]
Similarly, the operator of the FE manager may not want to divulge FE Similarly, the operator of the FE manager may not want to divulge FE
characteristics, except to authorized entities. As such, CE characteristics, except to authorized entities. As such, CE
managers and FE managers may need to authenticate one another. managers and FE managers may need to authenticate one another.
Subsequent communication between CE managers and FE managers may Subsequent communication between CE managers and FE managers may
require other security functions such as privacy, non-repudiation, require other security functions such as privacy, non-repudiation,
freshness, and integrity. freshness, and integrity.
Once the necessary security functions have been performed, the CE Once the necessary security functions have been performed, the CE
and FE managers communicate to determine which CEs and FEs should and FE managers communicate to determine which CEs and FEs should
communicate with each other. At the very minimum, the CE and FE communicate with each other. At the very minimum, the CE and FE
managers need to learn of the existence of available FEs and CEs managers need to learn of the existence of available FEs and CEs
respectively. This discovery process may or may not entail one or respectively. This discovery process may or may not entail one or
both managers learning the capabilities of the discovered ForCES both managers learning the capabilities of the discovered ForCES
Yang, et. al. Expires April 2003 [Page 12]
protocol elements. Figure 7 shows an example of possible message protocol elements. Figure 7 shows an example of possible message
exchange between CE manager and FE manager over Fl reference point. exchange between CE manager and FE manager over Fl reference point.
5.1.2. Ff Reference Point 4.1.2. Ff Reference Point
FE Manager FE CE Manager CE FE Manager FE CE Manager CE
| | | | | | | |
| | | | | | | |
|(security exchange) |(security exchange) |(security exchange) |(security exchange)
1|<------------>|authentication 1|<----------->|authentication 1|<------------>|authentication 1|<----------->|authentication
| | | | | | | |
|(FE ID, attributes) |(CE ID, attributes) |(FE ID, attributes) |(CE ID, attributes)
2|<-------------|request 2|<------------|request 2|<-------------|request 2|<------------|request
| | | | | | | |
skipping to change at line 631 skipping to change at line 674
The Ff reference point is used to inform forwarding elements of the The Ff reference point is used to inform forwarding elements of the
association decisions made by FE managers in pre-association phase. association decisions made by FE managers in pre-association phase.
Only authorized entities may instruct a FE with respect to which CE Only authorized entities may instruct a FE with respect to which CE
should control it. Therefore, privacy, integrity, freshness, and should control it. Therefore, privacy, integrity, freshness, and
authentication are necessary between FE manager and FEs when the FE authentication are necessary between FE manager and FEs when the FE
manager is remote to the FE. Once the appropriate security has been manager is remote to the FE. Once the appropriate security has been
established, FE manager instructs FEs across this reference point to established, FE manager instructs FEs across this reference point to
join a new NE or to disconnect from an existing NE. Figure 8 shows join a new NE or to disconnect from an existing NE. Figure 8 shows
example of message exchange over Ff reference point. example of message exchange over Ff reference point.
Note that when the FE manager function may be co-located with the FE Note that the FE manager function may be co-located with the FE
(such as by manual keypad entry of the CE IP address), in which case (such as by manual keypad entry of the CE IP address), in which case
this reference point is reduced to a built-in function. this reference point is reduced to a built-in function.
5.1.3. Fc Reference Point 4.1.3. Fc Reference Point
Yang, et. al. Expires March 2003 [Page 12]
The Fc reference point is used to inform control elements of the The Fc reference point is used to inform control elements of the
association decisions made by CE managers in pre-association phase. association decisions made by CE managers in pre-association phase.
When the CE manager is remote, only authorized entities may instruct When the CE manager is remote, only authorized entities may instruct
a CE to control certain FEs. Privacy, integrity, freshness and a CE to control certain FEs. Privacy, integrity, freshness and
authentication are also required across this reference point in such authentication are also required across this reference point in such
a configuration. Once appropriate security has been established, a configuration. Once appropriate security has been established,
the CE manager instructs CEs as to which FEs they should control and the CE manager instructs CEs as to which FEs they should control and
how they should control them. Figure 7 shows example of message how they should control them. Figure 7 shows example of message
exchange over Fc reference point. exchange over Fc reference point.
As with the FE manager and FEs, configurations are possible where As with the FE manager and FEs, configurations are possible where
the CE manager and CE are co-located and no protocol is used for the CE manager and CE are co-located and no protocol is used for
this function. this function.
5.2. Post-association Phase and Fp reference point Yang, et. al. Expires April 2003 [Page 13]
4.2. Post-association Phase and Fp reference point
Post-association phase is the period of time during which a FE and Post-association phase is the period of time during which a FE and
CE have been configured with information necessary to contact each CE have been configured with information necessary to contact each
other and includes both communication establishment and steady-state other and includes both association establishment and steady-state
communication. The communication between CE and FE is performed communication. The communication between CE and FE is performed
across the Fp ("p" meaning protocol) reference point. ForCES across the Fp ("p" meaning protocol) reference point. ForCES
protocol is exclusively used for all communication across the Fp protocol is exclusively used for all communication across the Fp
reference point. reference point.
5.2.1. Proximity and Interconnect between CEs and FEs 4.2.1. Proximity and Interconnect between CEs and FEs
The ForCES Working Group has made a conscious decision that the The ForCES Working Group has made a conscious decision that the
first version of ForCES will not be designed to support first version of ForCES will not be designed to support
configurations where the CE and FE are located arbitrarily in the configurations where the CE and FE are located arbitrarily in the
network. In particular, ForCES is intended for "very close" CE/FE network. In particular, ForCES is intended for "very close" CE/FE
localities in IP networks, as defined by ForCES Applicability localities in IP networks, as defined by ForCES Applicability
Statement ([FORCES-APP]). Very Close localities consist of control Statement ([FORCES-APP]). Very Close localities consist of control
and forwarding elements that either are components in the same and forwarding elements that either are components in the same
physical box, or are separated at most by one local network hop. physical box, or are separated at most by one local network hop.
CEs and FEs can be connected by a variety of interconnect CEs and FEs can be connected by a variety of interconnect
technologies, including Ethernet connections, backplanes, ATM (cell) technologies, including Ethernet connections, backplanes, ATM (cell)
fabrics, etc. ForCES should be able to support each of these fabrics, etc. ForCES should be able to support each of these
interconnects (see [FORCES-REQ] Section 5, requirement #1). ForCES interconnects (see [FORCES-REQ] Section 5, requirement #1). ForCES
will make use of an existing RFC2914 compliant L4 protocol with will make use of an existing RFC2914 compliant L4 protocol with
adequate reliability, security and congestion control (e.g. TCP, adequate reliability, security and congestion control (e.g. TCP,
SCTP) for transport purposes. SCTP) for transport purposes.
5.2.2. Association Establishment 4.2.2. Association Establishment
As an example, figure 9 shows some of the message exchange that need As an example, figure 9 shows some of the message exchange that need
to happen before the association between CE and FE is fully to happen before the association between CE and FE is fully
established. Typically, FE would need to inform the CE of its own established. Typically, FE would need to inform the CE of its own
capability and its topology in relation to other FEs. The capability capability and its topology in relation to other FEs. The capability
of FE is represented by FE model, described in another separate of FE is represented by FE model, described in another separate
document. The model would allow FE to describe what kind of packet document. The model would allow FE to describe what kind of packet
processing functions it contains, in what order these processing processing functions it contains, in what order these processing
happen, what kind of configurable parameters it allows, what happen, what kind of configurable parameters it allows, what
Yang, et. al. Expires March 2003 [Page 13]
statistics it collects and what events it might throw, etc. Once statistics it collects and what events it might throw, etc. Once
such information is available to CE, CE sends all the necessary such information is available to CE, CE sends all necessary
configuration to FE so that FE can start receiving and processing configuration to FE so that FE can start receiving and processing
packets. For example, CE might need to send a snapshot of the packets. For example, CE might need to send a snapshot of the
current routing table to FE so that FE can start routing packets current routing table to FE so that FE can start routing packets
correctly. Once FE starts accepting packets for processing, we say correctly. Once FE starts accepting packets for processing, we say
the association of this FE with its CE is now established. From then the association of this FE with its CE is now established. From then
on, CE and FE enter steady-state communication as described in on, CE and FE enter steady-state communication as described next.
5.2.2.
FE CE FE CE
| | | |
|(Hello, are you there?)| |(Hello, are you there?)|
1|<----------------------| 1|<----------------------|
Yang, et. al. Expires April 2003 [Page 14]
| | | |
|(Yes. let me join the NE please.) |(Yes. let me join the NE please.)
2|---------------------->| 2|---------------------->|
| | | |
|(Security exchange.) | |(Security exchange.) |
3|<--------------------->| 3|<--------------------->|
| | | |
|(What kind of FE are you? -- capability query) |(What kind of FE are you? -- capability query)
4|<----------------------| 4|<----------------------|
| | | |
skipping to change at line 739 skipping to change at line 781
|(I am ready to go. Shall I?) |(I am ready to go. Shall I?)
9|---------------------->| 9|---------------------->|
| | | |
|(Go ahead!) | |(Go ahead!) |
10|<----------------------| 10|<----------------------|
| | | |
Figure 9. Example of message exchange between CE and FE Figure 9. Example of message exchange between CE and FE
over Fp to establish NE association over Fp to establish NE association
5.2.3. Steady-state Communication 4.2.3. Steady-state Communication
Yang, et. al. Expires March 2003 [Page 14]
Once an association is established between the CE and the FE, the Once an association is established between the CE and the FE, the
ForCES protocol is used by the CE and the FE over Fp reference point ForCES protocol is used by the CE and the FE over Fp reference point
to exchange information to facilitate packet processing. to exchange information to facilitate packet processing.
FE CE FE CE
| | | |
|(Add these new routes.)| |(Add these new routes.)|
1|<----------------------| 1|<----------------------|
| | | |
|(Successful.) | |(Successful.) |
2|---------------------->| 2|---------------------->|
| | | |
| | | |
| |
|(Query some stats.) | |(Query some stats.) |
1|<----------------------| 1|<----------------------|
| | | |
|(Reply with stats collected.) |(Reply with stats collected.)
2|---------------------->| 2|---------------------->|
| |
Yang, et. al. Expires April 2003 [Page 15]
| | | |
| | | |
|(My port is down, with port #.) |(My port is down, with port #.)
1|---------------------->| 1|---------------------->|
| | | |
|(Route to this port instead...) |(Route to this port instead...)
2|<----------------------| 2|<----------------------|
| | | |
| | | |
Figure 10. Examples of message exchange between CE and FE Figure 10. Examples of message exchange between CE and FE
over Fp during steady-state communication over Fp during steady-state communication
Based on the information acquired through CEs' control processing, Based on the information acquired through CEs' control processing,
CEs will frequently need to manipulate the packet-forwarding CEs will frequently need to manipulate the packet-forwarding
behaviors of their FE(s) by sending instructions to FEs. For behaviors of their FE(s) by sending instructions to FEs. For
example, Figure 10 shows one such message exchange in which CE sends example, Figure 10 shows message exchange examples in which CE sends
new routes to FE so that FE can add them to its routing table. CE new routes to FE so that FE can add them to its routing table. CE
can also query FE for statistics collected by FE and FE can also can also query FE for statistics collected by FE and FE can also
notify CE of some important events, like interface up and down, etc. notify CE of some important events, like interface up and down, etc.
Figure 8 also shows such examples.
5.2.4. Data Packets across Fp reference point 4.2.4. Data Packets across Fp reference point
Control packets (such as RIP, OSPF messages) addressed to any of
NE's interfaces are typically redirected by the receiving FE to its
CE, and CE may originate packets and have its FE deliver them to
other NEs. Therefore, the communication across the Fp reference
point includes not only the control messages from CEs to FEs and the
status or statistics report from FEs to CEs, but also the data
packets that are redirected between them. Moreover, one FE may be
controlled by multiple CEs. In this configuration, the control
protocols supported by the FORCES NEs may spread across multiple
Yang, et. al. Expires March 2003 [Page 15]
CEs. For example, one CE may support OSPF and another supports BGP.
FEs are configured to recognize these protocol packets and forward
them to the corresponding CE.
Figure 11 shows one example of how the OSPF packets originated by
router A are passed to router B. In this example, ForCES protocol is
used to transport the packets from CE to FE inside router A, and
then from FE to CE inside router B. In light of the fact that ForCES
protocol is responsible to transport both the control messages and
the data packets between CE and FE over Fp reference point, it is
possible to use either a single protocol or multiple protocols to
achieve that.
--------------------- ---------------------- --------------------- ----------------------
| | | | | | | |
| +--------+ | | +--------+ | | +--------+ | | +--------+ |
| |CE(OSPF)| | | |CE(OSPF)| | | |CE(OSPF)| | | |CE(OSPF)| |
| +--------+ | | +--------+ | | +--------+ | | +--------+ |
| | | | ^ | | | | | ^ |
| |Fp | | |Fp | | |Fp | | |Fp |
| v | | | | | v | | | |
| +--------+ | | +--------+ | | +--------+ | | +--------+ |
skipping to change at line 832 skipping to change at line 848
| Router | | | Router | | | Router | | | Router | |
| A | | | B | | | A | | | B | |
---------+----------- -----------+---------- ---------+----------- -----------+----------
v ^ v ^
| | | |
| | | |
------------------->--------------- ------------------->---------------
Figure 11. Example to show data packet flow between two NEs. Figure 11. Example to show data packet flow between two NEs.
5.2.5. Proxy FE Control plane protocol packets (such as RIP, OSPF messages)
addressed to any of NE's interfaces are typically redirected by the
receiving FE to its CE, and CE may originate packets and have its FE
deliver them to other NEs. Therefore, ForCES protocol over Fp not
only transports the ForCES protocol messages between CEs and FEs,
but also encapsulates the data packets from control plane protocols.
Yang, et. al. Expires April 2003 [Page 16]
Moreover, one FE may be controlled by multiple CEs for distributed
control. In this configuration, the control protocols supported by
the FORCES NEs may spread across multiple CEs. For example, one CE
may support routing protocols like OSPF and BGP, while signaling and
admission control protocol like RSVP is supported in another CE. FEs
are configured to recognize and filter these protocol packets and
forward them to the corresponding CE.
Figure 11 shows one example of how the OSPF packets originated by
router A are passed to router B. In this example, ForCES protocol is
used to transport the packets from CE to FE inside router A, and
then from FE to CE inside router B. In light of the fact that ForCES
protocol is responsible to transport both the control messages and
the data packets between CE and FE over Fp reference point, it is
possible to use either a single protocol or multiple protocols to
achieve that.
4.2.5. Proxy FE
In the case where a physical FE cannot implement (e.g., due to the In the case where a physical FE cannot implement (e.g., due to the
lack of a general purpose CPU) the ForCES protocol directly, a proxy lack of a general purpose CPU) the ForCES protocol directly, a proxy
FE can be used in the middle of Fp reference point. This allows the FE can be used in the middle of Fp reference point. This allows the
CE communicate to the physical FE via the proxy by using ForCES, CE communicate to the physical FE via the proxy by using ForCES,
while the proxy manipulates the physical FE using some intermediary while the proxy manipulates the physical FE using some intermediary
form of communication (e.g., a non-ForCES protocol or DMA). In such form of communication (e.g., a non-ForCES protocol or DMA). In such
an implementation, the combination of the proxy and the physical FE an implementation, the combination of the proxy and the physical FE
becomes one logical FE entity. becomes one logical FE entity.
5.3. Association Re-establishment 4.3. Association Re-establishment
FEs and CEs may join and leave NEs dynamically (see [FORCES-REQ] FEs and CEs may join and leave NEs dynamically (see [FORCES-REQ]
Section 5, requirements #12 and #13). When a FE or CE leaves the NE, Section 5, requirements #12). When a FE or CE leaves the NE, the
the association with the NE is broken. If the leaving party rejoins association with the NE is broken. If the leaving party rejoins a NE
later, to re-establish the association, it may or may not need to
Yang, et. al. Expires March 2003 [Page 16] re-enter the pre-association phase. Loss of association can also
a NE later, to re-establish the association, it may or may not need
to re-enter the pre-association phase. Loss of association can also
happen unexpectedly due to loss of connection between the CE and the happen unexpectedly due to loss of connection between the CE and the
FE. Therefore, the framework allows the bi-directional transition FE. Therefore, the framework allows the bi-directional transition
between these two phases, but the ForCES protocol is only applicable between these two phases, but the ForCES protocol is only applicable
for the post-association phase. However, the protocol should provide for the post-association phase. However, the protocol should provide
mechanisms to support association re-establishment (see [FORCES-REQ] mechanisms to support association re-establishment (see [FORCES-REQ]
Section 5, requirement #7). Section 5, requirement #7).
Let's use the example in Figure 5 to see what happens when the The example in Figure 5 is used to illustrate what happens when the
association is broken and later re-established again. Section 4.2 association is broken and later re-established again. Section 4.2
already explains what happens if CE1 fails and how CE2 can take already explains what happens if CE1 fails and how CE2 can take
over. Note that if no CE redundancy is provided, FEs need to be told over. If no CE redundancy is provided, at the association
at the association establishment time what to do in the case of CE establishment phase FEs need to be told what to do in the case of CE
failure. FEs may be told to stop packet processing all together if failure. FEs may be told to stop packet processing all together if
its CE fails. Or, FEs may be told to continue forwarding packets its CE fails. Or, FEs may be told to continue forwarding packets for
even in the face of CE failure. No matter what, it needs to be part a limited time even in the face of CE failure. No matter what the
of the configuration when the association is established. instruction is, it needs to be part of the configuration when the
association is established.
Let's now look at the case when FE1 leaves the NE temporarily, Yang, et. al. Expires April 2003 [Page 17]
assuming CE1 is the working CE for the moment. FE1 may voluntarily In the same example in Figure 5, assuming CE1 is the working CE for
decides to leave the association. Or, it is more likely that FE1 the moment, what would happen if it is one of the FEs, say FE1,
stops functioning simply due to unexpected failure. In former case, leaves the NE temporarily? FE1 may voluntarily decide to leave the
CE1 receives a "leave-association request" from FE1. In the latter, association. Or, FE1 may stop functioning simply due to unexpected
CE1 detects the failure of FE1 by some other mean. In both cases, failure. In former case, CE1 receives a "leave-association request"
CE1 would keep a note of such event for FE1 while continue from FE1. In the latter, CE1 detects the failure of FE1 by some
commanding FE2. When FE1 decides to rejoin again, or when it is back other mean. In both cases, CE1 keeps a note of such event from FE1
up again from the failure, FE1 would need to re-discover its master while continue commanding FE2. When FE1 decides to rejoin again, or
(CE). This can be achieved by several means. It may re-enter the when it is back up again from the failure, FE1 needs to re-discover
pre-association phase and get that information from its FE manager. its master (CE). This can be achieved by several means. It may re-
It may retrieve the previous CE information from its cache, if it enter the pre-association phase and get that information from its FE
decides that the information is still valid. Or, that information manager. It may retrieve the previous CE information from its cache,
can be simply hard-coded or pre-configured into it. Once it if it can validate the information freshness. Once it discovers its
discovers its CE, it starts message exchange with CE to re-establish CE, it starts message exchange with CE to re-establish the
the association just as outlined in Figure 9, with the possible association just as outlined in Figure 9, with the possible
exception that it might be able to bypass the transport of the exception that it might be able to bypass the transport of the
complete initialization information. Suppose that FE1 still have its complete initialization information. Suppose that FE1 still has its
routing table and other state information from the last association, routing table and other state information from the last association,
instead of sending all the information again from scratch, it can instead of sending all the information again from scratch, it can
choose to use more efficient mechanism to re-sync up the state with choose to use more efficient mechanism to re-sync up the state with
its CE. For example, a checksum of the state might give a quick its CE. For example, a checksum of the state might give a quick
indication of whether or not the state is in-sync with its CE. By indication of whether or not the state is in-sync with its CE. By
comparing its state with CE first, it sends information update only comparing its state with CE first, it sends information update only
if it is needed. if it is needed.
6. Applicability to RFC1812 5. Applicability to RFC1812
[FORCES-REQ] Section 5, requirement #9 dictates that "All proposed [FORCES-REQ] Section 5, requirement #9 dictates that "All proposed
ForCES architecture MUST explain how that architecture may be ForCES architecture MUST explain how that architecture supports all
applied to support all of a router's functions as defined in of the router functions as defined in [RFC1812]." RFC1812 discusses
[RFC1812]." RFC1812 discusses many important requirements for IPv4 many important requirements for IPv4 routers from the link layer to
routers from the link layer to the application layer. This section the application layer. This section addresses the relevant
requirements in RFC1812 for implementing IPv4 routers based on
Yang, et. al. Expires March 2003 [Page 17] ForCES architecture and explain how ForCES satisfies these
addresses the relevant requirements for implementing IPv4 routers
based on ForCES architecture and how ForCES satisfies these
requirements. requirements.
6.1. General Router Requirements 5.1. General Router Requirements
Routers have at least two or more logical interfaces. When CEs and Routers have at least two or more logical interfaces. When CEs and
FEs are separated by ForCES within a single NE, some additional FEs are separated by ForCES within a single NE, some additional
interfaces are needed for intra-NE communications. Figure 12 shows interfaces are needed for intra-NE communications. Figure 12 shows
an example to illustrate that. This NE contains one CE and two FEs. an example to illustrate that. This NE contains one CE and two FEs.
Each FE has four interfaces; two of them are used for receiving and Each FE has four interfaces; two of them are used for receiving and
transmitting packets to the external world, while the other two are transmitting packets to the external world, while the other two are
for intra-NE connections. CE has two logical interfaces #9 and #10, for intra-NE connections. CE has two logical interfaces #9 and #10,
connected to interfaces #3 and #6 from FE1 and FE2, respectively. connected to interfaces #3 and #6 from FE1 and FE2, respectively.
Interface #4 and #5 are connected for FE1-FE2 communication. So this Interface #4 and #5 are connected for FE1-FE2 communication.
router NE provides four external interfaces (#1, 2, 7 and 8). Therefore, this router NE provides four external interfaces (#1, 2,
7 and 8).
IPv4 routers must implement IP to support its packet forwarding
function, which is driven by its FIB (Forwarding Information Base).
Yang, et. al. Expires April 2003 [Page 18]
This Internet layer forwarding (see [RFC1812] Section 5)
functionality naturally belongs to FEs in the ForCES architecture.
--------------------------------- ---------------------------------
| router NE | | router NE |
| ----------- ----------- | | ----------- ----------- |
| | FE1 | | FE2 | | | | FE1 | | FE2 | |
| ----------- ----------- | | ----------- ----------- |
| 1| 2| 3| 4| 5| 6| 7| 8| | | 1| 2| 3| 4| 5| 6| 7| 8| |
| | | | | | | | | | | | | | | | | | | |
| | | | +----+ | | | | | | | | +----+ | | | |
| | | | | | | | | | | | | | | |
skipping to change at line 941 skipping to change at line 987
| | | -------------- | | | | | | -------------- | | |
| | | | CE | | | | | | | | CE | | | |
| | | -------------- | | | | | | -------------- | | |
| | | | | | | | | | | |
-----+--+----------------+--+---- -----+--+----------------+--+----
| | | | | | | |
| | | | | | | |
Figure 12. A router NE example with four interfaces. Figure 12. A router NE example with four interfaces.
IPv4 routers must implement IP to support its packet forwarding
function, which is driven by its FIB (Forwarding Information Base).
This Internet layer forwarding (see [RFC1812] Section 5)
functionality naturally belongs to FEs in the ForCES architecture.
A router may implement transport layer protocols (like TCP and UDP) A router may implement transport layer protocols (like TCP and UDP)
that are required to support application layer protocols (see that are required to support application layer protocols (see
[RFC1812] Section 6). One important class of application protocols [RFC1812] Section 6). One important class of application protocols
is routing protocols (see [RFC1812] Section 7). In ForCES is routing protocols (see [RFC1812] Section 7). In ForCES
architecture, routing protocols are naturally implemented by CEs. architecture, routing protocols are naturally implemented by CEs.
Routing protocols require routers communicate with each other. This Routing protocols require routers communicate with each other. This
communication between CEs in different routers is supported in communication between CEs in different routers is supported in
ForCES by the FEs' ability to redirect data packets ForCES by FEs' ability to redirect data packets addressed to routers
addressed to routers (i.e., NEs) and CEs' ability to originate (i.e., NEs) and CEs' ability to originate packets and have them
packets and have them delivered by their FEs. This communication delivered by their FEs. This communication occurs across Fp
reference point inside each router and between neighboring routers'
Yang, et. al. Expires March 2003 [Page 18] external interfaces, as illustrated in Figure 11.
occurs across Fp reference point inside each router and between
neighboring routers' interfaces, as illustrated in Figure 11.
6.2.Link Layer 5.2.Link Layer
Since FEs own all the external interfaces for the router, FEs need Since FEs own all the external interfaces for the router, FEs need
to conform to the link layer requirements in RFC1812. Theoretically, to conform to the link layer requirements in RFC1812. Arguably, ARP
ARP support may be implemented in either CEs or FEs. As we will see support may be implemented in either CEs or FEs. As we will see
later, a number of behaviors that RFC1812 mandates fall into this later, a number of behaviors that RFC1812 mandates fall into this
category -- they may be performed by the FE and may be performed by category -- they may be performed by the FE and may be performed by
the CE. A general guideline is needed to ensure interoperability the CE. A general guideline is needed to ensure interoperability
between separated control and forwarding planes. The guideline we between separated control and forwarding planes. The guideline we
offer here is that CEs are required to be capable of these offer here is that in general CEs are required to be capable of
operations while FEs may or may not choose to implement them. FE these kind of operations while FEs may or may not choose to
model should indicate its capabilities in this regard. implement them. FE model should indicate its capabilities in this
regard so that CEs can decide where these functions are implemented.
Interface parameters, including MTU, IP address, etc., must be Interface parameters, including MTU, IP address, etc., must be
configurable by CEs via ForCES. CEs must be able to determine configurable by CEs via ForCES. CEs must be able to determine
Yang, et. al. Expires April 2003 [Page 19]
whether a physical interface in an FE is available to send packets whether a physical interface in an FE is available to send packets
or not. FEs must also inform CEs the status change of the interfaces or not. FEs must also inform CEs the status change of the interfaces
(like link up/down) via ForCES. (like link up/down) via ForCES.
6.3.Internet Layer Protocols 5.3.Internet Layer Protocols
Both FEs and CEs must implement IP protocol and all mandatory Both FEs and CEs must implement IP protocol and all mandatory
extensions as RFC1812 specified. CEs should implement IP options extensions as RFC1812 specified. CEs should implement IP options
like source route and record route while FEs may choose to implement like source route and record route while FEs may choose to implement
those as well. Timestamp option should be implemented by FEs to those as well. Timestamp option should be implemented by FEs to
insert the timestamp most accurately. FE must interpret the IP insert the timestamp most accurately. FE must interpret the IP
options that it understands and preserve the rest unchanged for use options that it understands and preserve the rest unchanged for use
by CEs. Both FEs and CEs might choose to silently discard packets by CEs. Both FEs and CEs might choose to silently discard packets
without sending ICMP errors, but such events should be logged and without sending ICMP errors, but such events should be logged and
counted. FEs can report statistics for such events to CEs via counted. FEs may report statistics for such events to CEs via
ForCES. ForCES.
When multiple FEs are involved to process packets, the appearance of When multiple FEs are involved to process packets, the appearance of
single NE must be strictly maintained. For example, Time-To-Live single NE must be strictly maintained. For example, Time-To-Live
(TTL) must be decremented only once within a single NE. For example, (TTL) must be decremented only once within a single NE. For example,
it can be always decremented by the last FE with egress function. it can be always decremented by the last FE with egress function.
FEs must receive and process normally any packets with a broadcast FEs must receive and process normally any packets with a broadcast
destination address or a multicast destination address that the destination address or a multicast destination address that the
router has asked to receive. When IP multicast is supported in router has asked to receive. When IP multicast is supported in
routers, IGMP is implemented in CEs. CEs are also required of ICMP routers, IGMP is implemented in CEs. CEs are also required of ICMP
support, while it is optional for FEs to support ICMP. Such an support, while it is optional for FEs to support ICMP. Such an
option can be communicated to CEs as part of the FE model. option can be communicated to CEs as part of the FE model.
Therefore, FEs can always rely upon CEs to send out ICMP error Therefore, FEs can always rely upon CEs to send out ICMP error
messages, but FEs also have the option to generate ICMP error messages, but FEs also have the option to generate ICMP error
messages themselves. messages themselves.
6.4.Internet Layer Forwarding 5.4.Internet Layer Forwarding
Yang, et. al. Expires March 2003 [Page 19] IP forwarding is implemented by FEs. When the routing table is
IP forwarding is implemented by FEs. After routing protocol update updated at CEs, ForCES is used to send the new route entries from
its routing tables at CEs, ForCES is used to send the new routing CEs to FEs. Each FE has its own forwarding table and uses this table
table entries from CEs to FEs. Each FE has its own routing table and to direct packets to the next hop interface.
uses this table to direct packets to the next hop interface.
Upon receiving IP packets, FE verifies the IP header and process Upon receiving IP packets, FE verifies the IP header and processes
most of the IP options. Some options can't be processed until the most of the IP options. Some options can't be processed until the
routing decision has been made. Routing decision is made after routing decision has been made. Routing decision is made after
examining the destination IP address. If the destination address examining the destination IP address. If the destination address
belongs to the router itself, the packets are forwarded to CE. belongs to the router itself, the packets are filtered and either
Otherwise, FE determines the next hop IP address by looking up in processed locally or forwarded to CE, depending upon the
its routing table. FE also determines the network interface it uses instructions set-up by CE. Otherwise, FE determines the next hop IP
to send the packets. Sometimes FE may need to forward the packets to address by looking up in its forwarding table. FE also determines
another FE before packets can be forwarded out to the next hop. the network interface it uses to send the packets. Sometimes FE may
Right before packets are forwarded out to the next hop, FE need to forward the packets to another FE before packets can be
decrements TTL by 1 and processes any IP options that cannot be forwarded out to the next hop. Right before packets are forwarded
processed before. FE performs any IP fragmentation if necessary, out to the next hop, FE decrements TTL by 1 and processes any IP
determines link layer address (e.g., by ARP), and encapsulates the options that cannot be processed before. FE performs any IP
IP datagram (or each of the fragments thereof) in an appropriate fragmentation if necessary, determines link layer address (e.g., by
link layer frame and queues it for output on the interface selected.
Yang, et. al. Expires April 2003 [Page 20]
ARP), and encapsulates the IP datagram (or each of the fragments
thereof) in an appropriate link layer frame and queues it for output
on the interface selected.
Other options mentioned in RFC1812 for IP forwarding may also be Other options mentioned in RFC1812 for IP forwarding may also be
implemented at FEs, for example, packet filtering. implemented at FEs, for example, packet filtering.
FEs typically forward packets destined locally to CEs. FEs may also FEs typically forward packets destined locally to CEs. FEs may also
forward exceptional packets (packets that FEs don't know how to forward exceptional packets (packets that FEs don't know how to
handle) to CEs. CEs are required to handle packets forwarded by FEs handle) to CEs. CEs are required to handle packets forwarded by FEs
for whatever different reasons. It might be necessary for ForCES to for whatever different reasons. It might be necessary for ForCES to
attach some meta-data with the packets to indicate the reasons of attach some meta-data with the packets to indicate the reasons of
forwarding from FEs to CEs. Upon receiving packets with meta-data forwarding from FEs to CEs. Upon receiving packets with meta-data
skipping to change at line 1053 skipping to change at line 1098
and management protocols. If CEs are to process the packets by and management protocols. If CEs are to process the packets by
themselves, CEs may choose to discard the packets, or modify and re- themselves, CEs may choose to discard the packets, or modify and re-
send the packets. CEs may also originate new packets and deliver send the packets. CEs may also originate new packets and deliver
them to FEs for further forwarding. them to FEs for further forwarding.
Any state change during router operation must also be handled Any state change during router operation must also be handled
correctly according to RFC1812. For example, when an FE ceases correctly according to RFC1812. For example, when an FE ceases
forwarding, the entire NE may continue forwarding packets, but it forwarding, the entire NE may continue forwarding packets, but it
needs to stop advertising routes that are affected by the failed FE. needs to stop advertising routes that are affected by the failed FE.
6.5.Transport Layer 5.5.Transport Layer
Transport layer is typically implemented at CEs to support higher Transport layer is typically implemented at CEs to support higher
layer application protocols like routing protocols. In practice, layer application protocols like routing protocols. In practice,
this means that most CEs implement both the Transmission Control this means that most CEs implement both the Transmission Control
Protocol (TCP) and the User Datagram Protocol (UDP). Protocol (TCP) and the User Datagram Protocol (UDP).
Both CEs and FEs need to implement ForCES protocol. If some layer-4 Both CEs and FEs need to implement ForCES protocol. If some layer-4
transport is used to support ForCES, then both CEs and FEs need to transport is used to support ForCES, then both CEs and FEs need to
implement the L4 transport and ForCES protocols. It is possible that implement the L4 transport and ForCES protocols. It is possible that
all FEs inside an NE implements only one such protocol entity. all FEs inside an NE implements only one such protocol entity.
Yang, et. al. Expires March 2003 [Page 20] 5.6. Application Layer -- Routing Protocols
6.6. Application Layer -- Routing Protocols
Both interior routing protocols and exterior routing protocols are Both interior routing protocols and exterior routing protocols are
implemented on CEs. The routing packets originated by CEs are implemented on CEs. The routing packets originated by CEs are
forwarded to FEs for delivery. The results of such protocols (like forwarded to FEs for delivery. The results of such protocols (like
routing table update) are communicated to FEs via ForCES. routing table update) are communicated to FEs via ForCES.
6.7. Application Layer -- Network Management Protocol 5.7. Application Layer -- Network Management Protocol
RFC1812 also dictates "Routers MUST be manageable by SNMP." (see RFC1812 also dictates "Routers MUST be manageable by SNMP." (see
[RFC1157] Section 8) In general, for post-association phase, most [RFC1157] Section 8) In general, for post-association phase, most
external management tasks (including SNMP) SHOULD be done through external management tasks (including SNMP) should be done through
interaction with the CE in order to support the appearance of a interaction with the CE in order to support the appearance of a
single functional device. Therefore, it is recommended that SNMP single functional device. Therefore, it is recommended that SNMP
management agent be implemented by CEs and the SNMP messages sent to management agent be implemented by CEs and the SNMP messages
FEs be redirected to their CEs. This also requires that ForCES In received by FEs be redirected to their CEs. AgentX framework defined
certain conditions (e.g. CE/FE disconnection), it may be useful to
allow SNMP to be used to diagnose and repair problems. However, care
should be taken when exercising such mechanisms and guidelines are
provided in [FORCES-REQ], Section 5, requirement #4.
7. Summary Yang, et. al. Expires April 2003 [Page 21]
in RFC2741 may be applied here such that CEs act in the role of
master agent to process SNMP protocol messages while FEs act in the
role of subagent to provide access to the MIB objects residing on
FEs. AgentX protocol messages between the master agent (CE) and the
subagent (FE) are encapsulated and transported via ForCES, just like
data packets from any other application layer protocols.
6. Summary
This document defines an architectural framework for ForCES. It This document defines an architectural framework for ForCES. It
identifies the relevant components for an ForCES network element, identifies the relevant components for a ForCES network element,
including (one or more) FEs, (one or more) CEs, FE manager including (one or more) FEs, (one or more) CEs, one optional FE
(optional), and CE manager (optional). It also identifies the manager, and one optional CE manager. It also identifies the
interaction among these components and discusses all the major interaction among these components and discusses all the major
reference points. It is important to point out that, among all the reference points. It is important to point out that, among all the
reference points, only the interface between CEs and FEs is within reference points, only the interface between CEs and FEs is within
the scope of ForCES. ForCES alone may not be enough to support all the scope of ForCES. ForCES alone may not be enough to support all
different NE configurations. However, we believe ForCES is the most desirablet NE configurations. However, we believe that ForCES is the
important element in realizing the physical separation and most important element in realizing physical separation and
interoperability of CEs and FEs, and hence the first interface that interoperability of CEs and FEs, and hence the first interface that
ought to be standardized. Simple and useful configurations can still ought to be standardized. Simple and useful configurations can still
be implemented with only CE-FE interface being standardized, e.g., be implemented with only CE-FE interface being standardized, e.g.,
single CE with full-meshed FEs and static configuration without the single CE with full-meshed FEs and static configuration without the
need for CE/FE managers. need for CE/FE managers.
8. Security Considerations 7. Security Considerations
The security necessary across each reference point except Fp is The security necessary across each reference point except Fp is
discussed throughout the document. In general, the physical discussed throughout the document. In general, the physical
separation of two entities usually requires much stricter security separation of two entities usually requires much stricter security
measurement in place. For example, we pointed out in Section 5.1 measurement in place. For example, we pointed out in Section 5.1
that authentication becomes necessary between CE manager and FE that authentication becomes necessary between CE manager and FE
manager, between CE and CE manager, between FE and FE manager in manager, between CE and CE manager, between FE and FE manager in
some configuration. The physical separation of CE and FE also some configuration. The physical separation of CE and FE also
imposes serious security requirement for ForCES protocol. The imposes serious security requirement for ForCES protocol. The
security requirements for reference point Fp (i.e., ForCES protocol) security requirements for reference point Fp (i.e., ForCES protocol)
are discussed in detail in [FORCES-REQ] Section 8. are discussed in detail in [FORCES-REQ] Section 8.
Yang, et. al. Expires March 2003 [Page 21] 8. Intellectual Property Right
9. Intellectual Property Right
The authors are not aware of any intellectual property right issues The authors are not aware of any intellectual property right issues
pertaining to this document. pertaining to this document.
10. Normative References 9. References
[RFC2914] S. Floyd, "Congestion Control Principles", RFC2914, 9.1. Normative References
September 2000.
[RFC1157] J. Case, et. al., "A Simple Network Management Protocol [RFC1157] J. Case, et. al., "A Simple Network Management Protocol
(SNMP)", RFC1157, May 1990. (SNMP)", RFC1157, May 1990.
[RFC3084] K. Chan, et. al., "COPS Usage for Policy Provisioning
(COPS-PR)", RFC3084, March 2001.
[RFC1812] F. Baker, "Requirements for IP Version 4 Routers", [RFC1812] F. Baker, "Requirements for IP Version 4 Routers",
RFC1812, June 1995. RFC1812, June 1995.
11. Informative References Yang, et. al. Expires April 2003 [Page 22]
[RFC2741] M. Daniele, et. al., "Agent Extensibility (AgentX)
Protocol Version 1", RFC2741, Jan 2000.
[RFC2914] S. Floyd, "Congestion Control Principles", RFC2914,
September 2000.
[RFC3084] K. Chan, et. al., "COPS Usage for Policy Provisioning
(COPS-PR)", RFC3084, March 2001.
9.2. Informative References
[FORCES-REQ] T. Anderson, et. al., "Requirements for Separation of [FORCES-REQ] T. Anderson, et. al., "Requirements for Separation of
IP Control and Forwarding", work in progress, February 2002, <draft- IP Control and Forwarding", work in progress, July 2002, <draft-
ietf-forces-requirements-02.txt>. ietf-forces-requirements-06.txt>.
[FORCES-APP] A. Crouch, et. al., "ForCES Applicability Statement", [FORCES-APP] A. Crouch, et. al., "ForCES Applicability Statement",
work in progress, February 2002, <draft-ietf-forces-applicability- work in progress, June 2002, <draft-ietf-forces-applicability-
00.txt>. 00.txt>.
12. Acknowledgments 10. Acknowledgments
Joel M. Halpern gave us many insightful comments and suggestions and Joel M. Halpern gave us many insightful comments and suggestions and
pointed out several major issues. Many of our colleagues and people pointed out several major issues. Many of our colleagues and people
in the ForCES mailing list also provided valuable feedback. in the ForCES mailing list also provided valuable feedback.
13. Authors' Addresses 11. Authors' Addresses
Lily L. Yang Lily L. Yang
Intel Labs Intel Corp., MS JF3-206,
2111 NE 25th Avenue 2111 NE 25th Avenue
Hillsboro, OR 97124 USA Hillsboro, OR 97124 USA
Phone: +1 503 264 8813 Phone: +1 503 264 8813
Email: lily.l.yang@intel.com Email: lily.l.yang@intel.com
Ram Dantu Ram Dantu
Netrake Corporation University of Texas Dallas
3000 Technology Drive 2601 North Flyod Road
Plano, Texas 75074 Richardson Texas 75082
Phone: +1 214 291 1111 Phone: +1 972 883 4653
Email: ramd@netrake.com Email: ram.dantu@utdallas.edu
Todd A. Anderson Todd A. Anderson
Intel Corp.
Yang, et. al. Expires March 2003 [Page 22]
Intel Labs
2111 NE 25th Avenue 2111 NE 25th Avenue
Hillsboro, OR 97124 USA Hillsboro, OR 97124 USA
Phone: +1 503 712 1760 Phone: +1 503 712 1760
Email: todd.a.anderson@intel.com Email: todd.a.anderson@intel.com
1. Abstract........................................................1 Yang, et. al. Expires April 2003 [Page 23]
2. Definitions.....................................................1
3. Introduction to Forwarding and Control Element Separation
(ForCES)...........................................................3
4. Architecture....................................................6
4.1. Control Elements and Fr Reference Point....................7
4.2. Forwarding Elements and Fi reference point.................8
4.3. CE Managers...............................................10
4.4. FE Managers...............................................11
5. Operational Phases.............................................11
5.1. Pre-association Phase.....................................11
5.1.1. Fl Reference Point...................................11
5.1.2. Ff Reference Point...................................12
5.1.3. Fc Reference Point...................................12
5.2. Post-association Phase and Fp reference point.............13
5.2.1. Proximity and Interconnect between CEs and FEs.......13
5.2.2. Association Establishment............................13
5.2.3. Steady-state Communication...........................14
5.2.4. Data Packets across Fp reference point...............15
5.2.5. Proxy FE.............................................16
5.3. Association Re-establishment..............................16
6. Applicability to RFC1812.......................................17
6.1. General Router Requirements...............................18
6.2. Link Layer................................................19
6.3. Internet Layer Protocols..................................19
6.4. Internet Layer Forwarding.................................19
6.5. Transport Layer...........................................20
6.6. Application Layer -- Routing Protocols....................21
6.7. Application Layer -- Network Management Protocol..........21
7. Summary........................................................21
8. Security Considerations........................................21
9. Intellectual Property Right....................................22
10. Normative References..........................................22
11. Informative References........................................22
12. Acknowledgments...............................................22
13. Authors' Addresses............................................22
Yang, et. al. Expires March 2003 [Page 23]
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