draft-ietf-idr-bgp-optimal-route-reflection-28.txt   rfc9107.txt 
IDR Working Group R. Raszuk, Ed. Internet Engineering Task Force (IETF) R. Raszuk, Ed.
Internet-Draft NTT Network Innovations Request for Comments: 9107 NTT Network Innovations
Intended status: Standards Track B. Decraene, Ed. Category: Standards Track B. Decraene, Ed.
Expires: December 19, 2021 Orange ISSN: 2070-1721 Orange
C. Cassar C. Cassar
E. Aman E. Åman
K. Wang K. Wang
Juniper Networks Juniper Networks
June 17, 2021 August 2021
BGP Optimal Route Reflection (BGP ORR) BGP Optimal Route Reflection (BGP ORR)
draft-ietf-idr-bgp-optimal-route-reflection-28
Abstract Abstract
This document defines an extension to BGP route reflectors. On route This document defines an extension to BGP route reflectors. On route
reflectors, BGP route selection is modified in order to choose the reflectors, BGP route selection is modified in order to choose the
best route from the standpoint of their clients, rather than from the best route from the standpoint of their clients, rather than from the
standpoint of the route reflectors. Depending on the scaling and standpoint of the route reflectors themselves. Depending on the
precision requirements, route selection can be specific for one scaling and precision requirements, route selection can be specific
client, common for a set of clients or common for all clients of a for one client, common for a set of clients, or common for all
route reflector. This solution is particularly applicable in clients of a route reflector. This solution is particularly
deployments using centralized route reflectors, where choosing the applicable in deployments using centralized route reflectors, where
best route based on the route reflector's IGP location is suboptimal. choosing the best route based on the route reflector's IGP location
This facilitates, for example, best exit point policy (hot potato is suboptimal. This facilitates, for example, a "best exit point"
routing). policy ("hot potato routing").
The solution relies upon all route reflectors learning all paths The solution relies upon all route reflectors learning all paths that
which are eligible for consideration. BGP Route Selection is are eligible for consideration. BGP route selection is performed in
performed in the route reflectors based on the IGP cost from the route reflectors based on the IGP cost from configured locations
configured locations in the link state IGP. in the link-state IGP.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on December 19, 2021. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9107.
Copyright Notice Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology
3. Modifications to BGP Route Selection . . . . . . . . . . . . 4 3. Modifications to BGP Route Selection
3.1. Route Selection from a different IGP location . . . . . . 5 3.1. Route Selection from a Different IGP Location
3.1.1. Restriction when BGP next hop is a BGP route . . . . 6 3.1.1. Restriction when the BGP Next Hop Is a BGP Route
3.2. Multiple Route Selections . . . . . . . . . . . . . . . . 6 3.2. Multiple Route Selections
4. Deployment Considerations . . . . . . . . . . . . . . . . . . 6 4. Deployment Considerations
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8 5. Security Considerations
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 6. IANA Considerations
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8 7. References
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 9 7.1. Normative References
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 7.2. Informative References
9.1. Normative References . . . . . . . . . . . . . . . . . . 9 Acknowledgments
9.2. Informative References . . . . . . . . . . . . . . . . . 10 Contributors
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses
1. Introduction 1. Introduction
There are three types of BGP deployments within Autonomous Systems There are three types of BGP deployments within Autonomous Systems
today: full mesh, confederations and route reflection. BGP route (ASes) today: full mesh, confederations, and route reflection. BGP
reflection [RFC4456] is the most popular way to distribute BGP routes route reflection [RFC4456] is the most popular way to distribute BGP
between BGP speakers belonging to the same Autonomous System. routes between BGP speakers belonging to the same AS. However, in
However, in some situations, this method suffers from non-optimal some situations, this method suffers from non-optimal path selection.
path selection.
[RFC4456] asserts that, because the IGP cost to a given point in the [RFC4456] asserts that, because the IGP cost to a given point in the
network will vary across routers, "the route reflection approach may network will vary across routers, "the route reflection approach may
not yield the same route selection result as that of the full not yield the same route selection result as that of the full IBGP
Internal BGP (IBGP) mesh approach." One practical implication of mesh approach." ("IBGP" stands for "Internal BGP".) One practical
this fact is that the deployment of route reflection may thwart the implication of this fact is that the deployment of route reflection
ability to achieve hot potato routing. Hot potato routing attempts may thwart the ability to achieve "hot potato routing". Hot potato
to direct traffic to the closest Autonomous System (AS) exit point in routing attempts to direct traffic to the closest AS exit point in
cases where no higher priority policy dictates otherwise. As a cases where no higher-priority policy dictates otherwise. As a
consequence of the route reflection method, the choice of exit point consequence of the route reflection method, the choice of exit point
for a route reflector and its clients will be the exit point that is for a route reflector and its clients will be the exit point that is
optimal for the route reflector - not necessarily the one that is optimal for the route reflector -- not necessarily the one that is
optimal for its clients. optimal for its clients.
Section 11 of [RFC4456] describes a deployment approach and a set of Section 11 of [RFC4456] describes a deployment approach and a set of
constraints which, if satisfied, would result in the deployment of constraints that, if satisfied, would result in the deployment of
route reflection yielding the same results as the IBGP full mesh route reflection yielding the same results as the IBGP full mesh
approach. This deployment approach makes route reflection compatible approach. This deployment approach makes route reflection compatible
with the application of hot potato routing policy. In accordance with the application of a hot potato routing policy. In accordance
with these design rules, route reflectors have often been deployed in with these design rules, route reflectors have often been deployed in
the forwarding path and carefully placed on the Point of Presence the forwarding path and carefully placed on the boundaries between
(POP) to core boundaries. the Point of Presence (POP) and the network core.
The evolving model of intra-domain network design has enabled The evolving model of intra-domain network design has enabled
deployments of route reflectors outside the forwarding path. deployments of route reflectors outside the forwarding path.
Initially this model was only employed for new services, e.g., IP Initially, this model was only employed for new services, e.g., IP
VPNs [RFC4364], however it has been gradually extended to other BGP VPNs [RFC4364]; however, it has been gradually extended to other BGP
services, including the IPv4 and IPv6 Internet. In such services, including the IPv4 and IPv6 Internet. In such
environments, hot potato routing policy remains desirable. environments, a hot potato routing policy remains desirable.
Route reflectors outside the forwarding path can be placed on the POP Route reflectors outside the forwarding path can be placed on the
to core boundaries, but they are often placed in arbitrary locations boundaries between the POP and the network core, but they are often
in the core of large networks. placed in arbitrary locations in the core of large networks.
Such deployments suffer from a critical drawback in the context of Such deployments suffer from a critical drawback in the context of
BGP Route Selection: A route reflector with knowledge of multiple BGP route selection: a route reflector with knowledge of multiple
paths for a given route will typically pick its best path and only paths for a given route will typically pick its best path and only
advertise that best path to its clients. If the best path for a advertise that best path to its clients. If the best path for a
route is selected on the basis of an IGP tie-break, the path route is selected on the basis of an IGP tie-break, the path
advertised will be the exit point closest to the route reflector. advertised will be the exit point closest to the route reflector.
However, the clients are in a different place in the network topology However, the clients are in a different place in the network topology
than the route reflector. In networks where the route reflectors are than the route reflector. In networks where the route reflectors are
not in the forwarding path, this difference will be even more acute. not in the forwarding path, this difference will be even more acute.
In addition, there are deployment scenarios where service providers In addition, there are deployment scenarios where service providers
want to have more control in choosing the exit points for clients want to have more control in choosing the exit points for clients
based on other factors, such as traffic type, traffic load, etc. based on other factors, such as traffic type, traffic load, etc.
This further complicates the issue and makes it less likely for the This further complicates the issue and makes it less likely for the
route reflector to select the best path from the client's route reflector to select the best path from the client's
perspective. It follows that the best path chosen by the route perspective. It follows that the best path chosen by the route
reflector is not necessarily the same as the path which would have reflector is not necessarily the same as the path that would have
been chosen by the client if the client had considered the same set been chosen by the client if the client had considered the same set
of candidate paths as the route reflector. of candidate paths as the route reflector.
2. Terminology 2. Terminology
This memo makes use of the terms defined in [RFC4271] and [RFC4456]. This memo makes use of the terms defined in [RFC4271] and [RFC4456].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. Modifications to BGP Route Selection 3. Modifications to BGP Route Selection
The core of this solution is the ability for an operator to specify The core of this solution is the ability for an operator to specify
the IGP location for which the route reflector calculates interior the IGP location for which the route reflector calculates interior
cost for the NEXT_HOP. The IGP location is defined as a node in the cost to the next hop. The IGP location is defined as a node in the
IGP topology, it is identified by an IP address of this node (e.g., a IGP topology, it is identified by an IP address of this node (e.g., a
loopback address), and may be configured on a per route reflector loopback address), and it may be configured on a per-route-reflector
basis, per set of clients, or per client basis. Such configuration basis, per set of clients, or on a per-client basis. Such
will allow the route reflector to select and distribute to a given configuration will allow the route reflector to select and distribute
set of clients routes with shortest distance to the next hops from to a given set of clients routes with the shortest distance to the
the position of the selected IGP location. This provides for freedom next hops from the position of the selected IGP location. This
of route reflector physical location, and allows transient or provides for freedom related to the route reflector's physical
permanent migration of this network control plane function to an location and allows transient or permanent migration of this network
arbitrary location with no impact to IP transit. control plane function to an arbitrary location with no impact on IP
transit.
The choice of specific granularity (route reflector, set of clients, The choice of specific granularity (route reflector, set of clients,
or client) is configured by the network operator. An implementation or client) is configured by the network operator. An implementation
is considered compliant with this document if it supports at least is considered compliant with this document if it supports at least
one such grouping category. one such grouping category.
For purposes of route selection, the perspective of a client can For purposes of route selection, the perspective of a client can
differ from that of a route reflector or another client in two differ from that of a route reflector or another client in two
distinct ways: distinct ways:
o it has a different position in the IGP topology, * It has a different position in the IGP topology.
o it can have a different routing policy. * It can have a different routing policy.
These factors correspond to the issues described earlier. These factors correspond to the issues described earlier.
This document defines, for BGP Route Reflectors [RFC4456], two This document defines, for BGP route reflectors [RFC4456], two
changes to the BGP Route Selection algorithm: changes to the BGP route selection algorithm:
o The first change, introduced in Section 3.1, is related to the IGP * The first change, introduced in Section 3.1, is related to the IGP
cost to the BGP Next Hop in the BGP decision process. The change cost to the BGP next hop in the BGP Decision Process. The change
consists of using the IGP cost from a different IGP location than consists of using the IGP cost from a different IGP location than
the route reflector itself. the route reflector itself.
o The second change, introduced in Section 3.2, is to extend the * The second change, introduced in Section 3.2, is to extend the
granularity of the BGP decision process, to allow for running granularity of the BGP Decision Process, to allow for running
multiple decisions processes using different perspective or multiple Decision Processes using different perspectives or
policies. policies.
A route reflector can implement either or both of the modifications
in order to allow it to choose the best path for its clients that the
clients themselves would have chosen given the same set of candidate
paths.
A significant advantage of these approaches is that the route A significant advantage of these approaches is that the route
reflector clients do not need to be modified. reflector's clients do not need to be modified.
3.1. Route Selection from a different IGP location 3.1. Route Selection from a Different IGP Location
In this approach, optimal refers to the decision where the interior In this approach, "optimal" refers to the decision where the interior
cost of a route is determined during step e) of [RFC4271] section cost of a route is determined during step e) of Section 9.1.2.2
9.1.2.2 "Breaking Ties (Phase 2)". It does not apply to path ("Breaking Ties (Phase 2)") of [RFC4271]. It does not apply to path
selection preference based on other policy steps and provisions. selection preference based on other policy steps and provisions.
In addition to the change specified in [RFC4456] section 9, [RFC4271] In addition to the change specified in Section 9 of [RFC4456], the
section 9.1.2.2 is modified as follows. text in step e) in Section 9.1.2.2 of [RFC4271] is modified as
follows.
The below text in step e) RFC 4271 reads:
e) Remove from consideration any routes with less-preferred | e) Remove from consideration any routes with less-preferred
interior cost. The interior cost of a route is determined by | interior cost. The interior cost of a route is determined by
calculating the metric to the NEXT_HOP for the route using the | calculating the metric to the NEXT_HOP for the route using the
Routing Table. | Routing Table.
...is replaced by this new text: This document modifies this text to read:
e) Remove from consideration any routes with less-preferred | e) Remove from consideration any routes with less-preferred
interior cost. The interior cost of a route is determined by | interior cost. The interior cost of a route is determined by
calculating the metric from the selected IGP location to the | calculating the metric from the selected IGP location to the
NEXT_HOP for the route using the shortest IGP path tree rooted at | NEXT_HOP for the route using the shortest IGP path tree rooted
the selected IGP location. | at the selected IGP location.
In order to be able to compute the shortest path tree rooted at the In order to be able to compute the shortest path tree rooted at the
selected IGP locations, knowledge of the IGP topology for the area/ selected IGP locations, knowledge of the IGP topology for the area/
level that includes each of those locations is needed. This level that includes each of those locations is needed. This
knowledge can be gained with the use of the link state IGP such as knowledge can be gained with the use of the link-state IGP, such as
IS-IS [ISO10589] or OSPF [RFC2328] [RFC5340] or via BGP-LS [RFC7752]. IS-IS [ISO10589] or OSPF [RFC2328] [RFC5340], or via the Border
When specifying logical location of a route reflector for a group of Gateway Protocol - Link State (BGP-LS) [RFC7752]. When specifying
clients one or more backup IGP locations SHOULD be allowed to be the logical location of a route reflector for a group of clients, one
specified for redundancy. Further deployment considerations are or more backup IGP locations SHOULD be allowed to be specified for
discussed in Section 4. redundancy. Further deployment considerations are discussed in
Section 4.
3.1.1. Restriction when BGP next hop is a BGP route 3.1.1. Restriction when the BGP Next Hop Is a BGP Route
In situations where the BGP next hop is a BGP route itself, the IGP In situations where the BGP next hop is a BGP route itself, the IGP
metric of a route used for its resolution SHOULD be the final IGP metric of a route used for its resolution SHOULD be the final IGP
cost to reach such next hop. Implementations which cannot inform BGP cost to reach such a next hop. Implementations that cannot inform
of the final IGP metric to a recursive next hop MUST treat such paths BGP of the final IGP metric to a recursive next hop MUST treat such
as least preferred during next hop metric comparison. However, such paths as least preferred during next-hop metric comparisons.
paths MUST still be considered valid for BGP Phase 2 Route Selection. However, such paths MUST still be considered valid for BGP Phase 2
route selection.
3.2. Multiple Route Selections 3.2. Multiple Route Selections
BGP Route Reflector as per [RFC4456] runs a single BGP Decision A BGP route reflector as per [RFC4456] runs a single BGP Decision
Process. Optimal route reflection may require multiple BGP Decision Process. BGP Optimal Route Reflection (BGP ORR) may require multiple
Processes or subsets of the Decision Process in order to consider BGP Decision Processes or subsets of the Decision Process in order to
different IGP locations or BGP policies for different sets of consider different IGP locations or BGP policies for different sets
clients. This is very similar to what is defined in [RFC7947] of clients. This is very similar to what is defined in [RFC7947],
section 2.3.2.1. Section 2.3.2.1.
If the required routing optimization is limited to the IGP cost to If the required routing optimization is limited to the IGP cost to
the BGP Next-Hop, only step e) and subsequent steps as defined in the BGP next hop, only step e) and subsequent steps as defined in
[RFC4271] section 9.1.2.2, needs to be run multiple times. [RFC4271], Section 9.1.2.2 need to be run multiple times.
If the routing optimization requires the use of different BGP If the routing optimization requires the use of different BGP
policies for different sets of clients, a larger part of the decision policies for different sets of clients, a larger part of the Decision
process needs to be run multiple times, up to the whole decision Process needs to be run multiple times, up to the whole Decision
process as defined in section 9.1 of [RFC4271]. This is for example Process as defined in Section 9.1 of [RFC4271]. This is, for
the case when there is a need to use different policies to compute example, the case when there is a need to use different policies to
different degree of preference during Phase 1. This is needed for compute different degrees of preference during Phase 1. This is
use cases involving traffic engineering or dedicating certain exit needed for use cases involving traffic engineering or dedicating
points for certain clients. In the latter case, the user may specify certain exit points for certain clients. In the latter case, the
and apply a general policy on the route reflector for a set of user may specify and apply a general policy on the route reflector
clients. Regular path selection, including IGP perspective for a set for a set of clients. Regular path selection, including IGP
of clients as per Section 3.1, is then applied to the candidate paths perspectives for a set of clients as per Section 3.1, is then applied
to select the final paths to advertise to the clients. to the candidate paths to select the final paths to advertise to the
clients.
A route reflector can implement either or both of the modifications
in order to allow it to choose the best path for its clients that the
clients themselves would have chosen given the same set of candidate
paths.
4. Deployment Considerations 4. Deployment Considerations
BGP Optimal Route Reflection provides a model for integrating the BGP ORR provides a model for integrating the client's perspective
client perspective into the BGP Route Selection decision function for into the BGP route selection Decision Process for route reflectors.
route reflectors. More specifically, the choice of BGP path takes More specifically, the choice of BGP path takes into account either
into account either the IGP cost between the client and the NEXT_HOP the IGP cost between the client and the next hop (rather than the IGP
(rather than the IGP cost from the route reflector to the NEXT_HOP) cost from the route reflector to the next hop) or other user-
or other user configured policies. configured policies.
The achievement of optimal routing between clients of different The achievement of optimal routing between clients of different
clusters relies upon all route reflectors learning all paths that are clusters relies upon all route reflectors learning all paths that are
eligible for consideration. In order to satisfy this requirement, eligible for consideration. In order to satisfy this requirement,
BGP add-path [RFC7911] needs to be deployed between route reflectors. BGP ADD-PATH [RFC7911] needs to be deployed between route reflectors.
This solution can be deployed in traditional hop-by-hop forwarding This solution can be deployed in hop-by-hop forwarding networks as
networks as well as in end-to-end tunneled environments. To avoid well as in end-to-end tunneled environments. To avoid routing loops
routing loops in networks with multiple route reflectors and hop-by- in networks with multiple route reflectors and hop-by-hop forwarding
hop forwarding without encapsulation, it is essential that the without encapsulation, it is essential that the network topology be
network topology be carefully considered in designing a route carefully considered in designing a route reflection topology (see
reflection topology (see also Section 11 of [RFC4456]). also Section 11 of [RFC4456]).
As discussed in section 11 of [RFC4456], the IGP locations of BGP As discussed in Section 11 of [RFC4456], the IGP locations of BGP
route reflectors is important and has routing implications. This route reflectors are important and have routing implications. This
equally applies to the choice of the IGP locations configured on equally applies to the choice of the IGP locations configured on
optimal route reflectors. If a backup location is provided, it is optimal route reflectors. If a backup location is provided, it is
used when the primary IGP location disappears from the IGP (i.e. used when the primary IGP location disappears from the IGP (i.e.,
fails). Just like the failure of a RR [RFC4456], it may result in fails). Just like the failure of a route reflector [RFC4456], it may
changing the paths selected and advertised to the clients and in result in changing the paths selected and advertised to the clients,
general the post-failure paths are expected to be less optimal. This and in general, the post-failure paths are expected to be less
is dependent on the IGP topologies and the IGP distance between the optimal. This is dependent on the IGP topologies and the IGP
primary and the backup IGP locations: the smaller the distance the distance between the primary and backup IGP locations: the smaller
smaller the potential impact. the distance, the smaller the potential impact.
After selecting suitable IGP locations, an operator may let one or After selecting N suitable IGP locations, an operator can choose to
multiple route reflectors handle route selection for all of them. enable route selection for all of them on all or on a subset of their
The operator may alternatively deploy one or multiple route reflector route reflectors. The operator may alternatively deploy single or
for each IGP location or create any design in between. This choice multiple (backup case) route reflectors for each IGP location or
may depend on operational model (centralized vs per region), create any design in between. This choice may depend on the
acceptable blast radius in case of failure, acceptable number of IBGP operational model (centralized vs. per region), an acceptable blast
sessions for the mesh between the route reflectors, performance and radius in the case of failure, an acceptable number of IBGP sessions
for the mesh between the route reflectors, performance, and
configuration granularity of the equipment. configuration granularity of the equipment.
With this approach, an ISP can effect a hot potato routing policy With this approach, an ISP can effect a hot potato routing policy
even if route reflection has been moved out of the forwarding plane, even if route reflection has been moved out of the forwarding plane
and hop-by-hop forwarding has been replaced by end-to-end MPLS or IP and hop-by-hop forwarding has been replaced by end-to-end MPLS or IP
encapsulation. Compared with a deployment of ADD-PATH on all encapsulation. Compared with a deployment of ADD-PATH on all
routers, BGP Optimal Route Reflection (ORR) reduces the amount of routers, BGP ORR reduces the amount of state that needs to be pushed
state which needs to be pushed to the edge of the network in order to to the edge of the network in order to perform hot potato routing.
perform hot potato routing.
Modifying the IGP location of BGP ORR does not interfere with Modifying the IGP location of BGP ORR does not interfere with
policies enforced before IGP tie-breaking (step e) of [RFC4271] policies enforced before IGP tie-breaking (step e) of [RFC4271],
section 9.1.2.2 in the BGP Decision Process. Section 9.1.2.2) in the BGP Decision Process.
Calculating routes for different IGP locations requires multiple Calculating routes for different IGP locations requires multiple
Shortest Path First (SPF) calculations and multiple (subsets of) BGP Shortest Path First (SPF) calculations and multiple (subsets of) BGP
Decision Processes, which requires more computing resources. This Decision Processes. This scenario calls for more computing
document allows for different granularity such as one Decision resources. This document allows for different granularity, such as
Process per route reflector, per set of clients or per client. A one Decision Process per route reflector, per set of clients, or per
more fine-grained granularity may translate into more optimal hot client. A more fine-grained granularity may translate into more
potato routing at the cost of more computing power. Selecting to optimal hot potato routing at the cost of more computing power.
configure an IGP location per client has the highest precision as Choosing to configure an IGP location per client has the highest
each client can be associated with their ideal (own) IGP location. precision, as each client can be associated with their ideal (own)
However, doing so may have an impact on the performance (as explained IGP location. However, doing so may have an impact on performance
above). Using an IGP location per set of clients implies a loss of (as explained above). Using an IGP location per set of clients
precision, but reduces the impact on the performance of the route implies a loss of precision but reduces the impact on the performance
reflector. Similarly, if an IGP location is selected for the whole of the route reflector. Similarly, if an IGP location is selected
routing instance, the lowest precision is achieved, but the for the whole routing instance, the lowest precision is achieved, but
performance impact is minimal. In the last mode of operation both the impact on performance is minimal. In the last mode of operation
precision as well as perfomance metrics are equal to same metrics (where an IGP location is selected for the whole routing instance),
when using route reflection as described in [RFC4456] without ORR both precision and performance metrics are equal to route reflection
extension. The ability to run fine-grained computations depends on as described in [RFC4456]. The ability to run fine-grained
the platform/hardware deployed, the number of clients, the number of computations depends on the platform/hardware deployed, the number of
BGP routes and the size of the IGP topology. In essence, sizing clients, the number of BGP routes, and the size of the IGP topology.
considerations are similar to the deployments of BGP Route Reflector. In essence, sizing considerations are similar to the deployments of
BGP route reflectors.
5. Security Considerations 5. Security Considerations
This extension provides a new metric value using additional The extension specified in this document provides a new metric value
information for computing routes for BGP route reflectors. While any using additional information for computing routes for BGP route
improperly used metric value could impact the resiliency of the reflectors. While any improperly used metric value could impact the
network, this extension does not change the underlying security resiliency of the network, this extension does not change the
issues inherent in the existing IBGP per [RFC4456]. underlying security issues inherent in the existing IBGP per
[RFC4456].
This document does not introduce requirements for any new protection This document does not introduce requirements for any new protection
measures. measures.
6. IANA Considerations 6. IANA Considerations
This document does not request any IANA allocations. This document has no IANA actions.
7. Acknowledgments
Authors would like to thank Keyur Patel, Eric Rosen, Clarence
Filsfils, Uli Bornhauser, Russ White, Jakob Heitz, Mike Shand, Jon
Mitchell, John Scudder, Jeff Haas, Martin Djernaes, Daniele
Ceccarelli, Kieran Milne, Job Snijders, Randy Bush, Alvaro Retana,
Francesca Palombini, Benjamin Kaduk, Zaheduzzaman Sarker, Lars
Eggert, Murray Kucherawy, Tom Petch and Nick Hilliard for their
valuable input.
8. Contributors
Following persons substantially contributed to the current format of
the document:
Stephane Litkowski
Cisco System
slitkows.ietf@gmail.com
Adam Chappell
GTT Communications, Inc.
Aspira Business Centre
Bucharova 2928/14a
158 00 Prague 13 Stodulky
Czech Republic
adam.chappell@gtt.net
9. References 7. References
9.1. Normative References 7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271, Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006, DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>. <https://www.rfc-editor.org/info/rfc4271>.
skipping to change at page 10, line 5 skipping to change at line 400
[RFC7911] Walton, D., Retana, A., Chen, E., and J. Scudder, [RFC7911] Walton, D., Retana, A., Chen, E., and J. Scudder,
"Advertisement of Multiple Paths in BGP", RFC 7911, "Advertisement of Multiple Paths in BGP", RFC 7911,
DOI 10.17487/RFC7911, July 2016, DOI 10.17487/RFC7911, July 2016,
<https://www.rfc-editor.org/info/rfc7911>. <https://www.rfc-editor.org/info/rfc7911>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
9.2. Informative References 7.2. Informative References
[ISO10589] [ISO10589] International Organization for Standardization,
International Organization for Standardization,
"Intermediate system to Intermediate system intra-domain "Intermediate system to Intermediate system intra-domain
routeing information exchange protocol for use in routeing information exchange protocol for use in
conjunction with the protocol for providing the conjunction with the protocol for providing the
connectionless-mode Network Service (ISO 8473)", ISO/ connectionless-mode Network Service (ISO 8473)", ISO/IEC
IEC 10589:2002, Second Edition, Nov 2002. 10589:2002, Second Edition, November 2002.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
DOI 10.17487/RFC2328, April 1998, DOI 10.17487/RFC2328, April 1998,
<https://www.rfc-editor.org/info/rfc2328>. <https://www.rfc-editor.org/info/rfc2328>.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
2006, <https://www.rfc-editor.org/info/rfc4364>. 2006, <https://www.rfc-editor.org/info/rfc4364>.
[RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
skipping to change at page 10, line 38 skipping to change at line 432
S. Ray, "North-Bound Distribution of Link-State and S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752, Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016, DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>. <https://www.rfc-editor.org/info/rfc7752>.
[RFC7947] Jasinska, E., Hilliard, N., Raszuk, R., and N. Bakker, [RFC7947] Jasinska, E., Hilliard, N., Raszuk, R., and N. Bakker,
"Internet Exchange BGP Route Server", RFC 7947, "Internet Exchange BGP Route Server", RFC 7947,
DOI 10.17487/RFC7947, September 2016, DOI 10.17487/RFC7947, September 2016,
<https://www.rfc-editor.org/info/rfc7947>. <https://www.rfc-editor.org/info/rfc7947>.
Acknowledgments
The authors would like to thank Keyur Patel, Eric Rosen, Clarence
Filsfils, Uli Bornhauser, Russ White, Jakob Heitz, Mike Shand, Jon
Mitchell, John Scudder, Jeff Haas, Martin Djernæs, Daniele
Ceccarelli, Kieran Milne, Job Snijders, Randy Bush, Alvaro Retana,
Francesca Palombini, Benjamin Kaduk, Zaheduzzaman Sarker, Lars
Eggert, Murray Kucherawy, Tom Petch, and Nick Hilliard for their
valuable input.
Contributors
The following persons contributed substantially to the current format
of the document:
Stephane Litkowski
Cisco Systems
Email: slitkows.ietf@gmail.com
Adam Chappell
GTT Communications, Inc.
Aspira Business Centre
Bucharova 2928/14a
158 00 Prague 13 Stodůlky
Czech Republic
Email: adam.chappell@gtt.net
Authors' Addresses Authors' Addresses
Robert Raszuk (editor) Robert Raszuk (editor)
NTT Network Innovations NTT Network Innovations
Email: robert@raszuk.net Email: robert@raszuk.net
Bruno Decraene (editor) Bruno Decraene (editor)
Orange Orange
skipping to change at page 11, line 4 skipping to change at line 472
Robert Raszuk (editor) Robert Raszuk (editor)
NTT Network Innovations NTT Network Innovations
Email: robert@raszuk.net Email: robert@raszuk.net
Bruno Decraene (editor) Bruno Decraene (editor)
Orange Orange
Email: bruno.decraene@orange.com Email: bruno.decraene@orange.com
Christian Cassar Christian Cassar
Email: cassar.christian@gmail.com Email: cassar.christian@gmail.com
Erik Aman Erik Åman
Email: erik.aman@aman.se Email: erik.aman@aman.se
Kevin Wang Kevin Wang
Juniper Networks Juniper Networks
10 Technology Park Drive 10 Technology Park Drive
Westford, MA 01886 Westford, MA 01886
USA United States of America
Email: kfwang@juniper.net Email: kfwang@juniper.net
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