draft-ietf-idr-best-external-03.txt   draft-ietf-idr-best-external-04.txt 
Network Working Group P. Marques Network Working Group P. Marques
Internet-Draft Internet-Draft
Intended status: Standards Track R. Fernando Expires: October 22, 2011 R. Fernando
Expires: September 10, 2011 E. Chen E. Chen
P. Mohapatra P. Mohapatra
Cisco Systems Cisco Systems
March 9, 2011 H. Gredler
Juniper Networks
April 20, 2011
Advertisement of the best external route in BGP Advertisement of the best external route in BGP
draft-ietf-idr-best-external-03.txt draft-ietf-idr-best-external-04
Abstract Abstract
The base BGP specifications prevent a BGP speaker from advertising The current BGP-4 protocol specification [RFC4271] states that the
any route that is not the best route for a BGP destination. This selection process chooses the best path for a given route which is
document specifies a modification of this rule. Routes are divided added to the Loc-Rib and advertised to all peers.
into two categories, "external" and "internal". A specification is
provided for choosing a "best external route" (for a particular value Previous versions [RFC1771] of the specification defined a different
of the Network Layer Reachability Information). A BGP speaker is rule for Internal BGP Updates. Given that Internal paths are not re-
then allowed to advertise its "best external route" to its internal advertised to Internal peers, it was specified that the best of the
BGP peers, even if that is not the best route for the destination. external paths, as determined by the path selection tie breaking
The document explains why advertising the best external route can algorithm, would be advertised to Internal peers.
improve convergence time without causing routing loops. Additional
benefits include reduction of inter-domain churn and avoidance of This document extends that procedure to operate in environments where
permanent route oscillation. The document also generalizes the Route Reflection [RFC4456] or Confederations [RFC5065] are used and
notions of "internal" and "external" so that they can be applied to explains why advertising the additional routing information can
Route Reflector Clusters and Autonomous System Confederations. improve convergence time without causing routing loops.
Additional benefits include reduction of inter-domain churn and
avoidance of permanent route oscillation.
Status of this Memo Status of this Memo
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provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on October 22, 2011.
This Internet-Draft will expire on September 10, 2011.
Copyright Notice Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the Copyright (c) 2011 IETF Trust and the persons identified as the
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 5 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 5
2. Algorithm for selection of best external route . . . . . . . . 5 3. Generalization . . . . . . . . . . . . . . . . . . . . . . . . 6
3. Advertisement Rules . . . . . . . . . . . . . . . . . . . . . 6 4. Algorithm for selection of the Adj-RIB-OUT path . . . . . . . 7
4. Consistency between routing and forwarding . . . . . . . . . . 6 5. Advertisement Rules . . . . . . . . . . . . . . . . . . . . . 9
5. Applications . . . . . . . . . . . . . . . . . . . . . . . . . 8 6. Consistency between routing and forwarding . . . . . . . . . . 10
5.1. Fast Connectivity Restoration . . . . . . . . . . . . . . 8 7. Applications . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.2. Inter-Domain Churn Reduction . . . . . . . . . . . . . . . 9 8. Fast Connectivity Restoration . . . . . . . . . . . . . . . . 13
5.3. Reducing Persistent IBGP oscillation . . . . . . . . . . . 9 9. Inter-Domain Churn Reduction . . . . . . . . . . . . . . . . . 14
6. Deployment Considerations . . . . . . . . . . . . . . . . . . 9 10. Reducing Persistent IBGP oscillation . . . . . . . . . . . . . 15
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9 11. Deployment Considerations . . . . . . . . . . . . . . . . . . 16
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17
9. Security Considerations . . . . . . . . . . . . . . . . . . . 10 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
10. Normative References . . . . . . . . . . . . . . . . . . . . . 10 14. Security Considerations . . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 15. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21
1. Introduction 1. Introduction
The base BGP specifications prevent a BGP speaker from advertising Earlier versions of the BGP-4 protocol specification [RFC1771]
any route that is not the best route for a BGP destination. This prescribed different route advertisement rules for Internal and
document specifies a modification of this rule. Routes are divided External peers. While the overall best path would be advertised to
into two categories, "external" and "internal". A specification is External peers, Internal peers are advertised the best of the
provided for choosing a "best external route" (for a particular value externally received paths.
of the Network Layer Reachability Information). A BGP speaker is
then allowed to advertise its "best external route" to its internal
BGP peers, even if that is not the best route for the destination.
The document explains why advertising the best external route can
improve convergence time without causing routing loops. Additional
benefits include reduction of inter-domain churn and avoidance of
permanent route oscillation.
The document also generalizes the notions of "internal" and This Internal advertisement rule was never implemented as specified
"external" so that they can be applied to Route Reflector Clusters and was latter dropped from the protocol. There is a trade-off in
[RFC4456] and Autonomous System Confederations [RFC5065]. More advertising the "best-external" route versus the behavior that became
specifically, two routers in the same route reflector cluster having common standard of not advertising the route when the selected best
an IBGP session between them are defined to be "internal" peers, path is received from an Internal peer. By not advertising
whereas two routers in different clusters having an IBGP session are information in this case it is possible to reduce state both in the
defined to be "external" peers. Similarly, two routers in the same local BGP speaker as well as in the network overall. Early BGP
member AS of a confederation having an IBGP session between them are implementations where very concerned with reducing state as they
"internal" peers, whereas two routers in different member ASs of a where limited to relatively low memory footprints (e.g. 16 MB).
confederation having a confed EBGP session between them are defined There is also the possible concern regarding advertising a path
to be "external" peers. The definition of "best external route" different than the path that has been selected for forwarding.
ensues from this definition in that it is the most preferred route
among those received from the "external" neighbors.
Advertising the best external route, when different from the best However, advertising the best external route, when different from the
route, presents additional information into an IBGP mesh which may be best route, presents additional information into an IBGP mesh which
of value for several purposes including: may be of value for several purposes including:
o Faster restoration of connectivity, by providing additional paths, o Faster restoration of connectivity. By providing additional
that may be used to fail over in case the primary path becomes paths, that may be used to fail over in case the primary path
invalid or is withdrawn. becomes invalid or is withdrawn.
o Reducing inter-domain churn and traffic blackholing due to the o Reducing inter-domain churn and traffic black-holing due to the
readily available alternate path. readily available alternate path.
o Reducing the potential for situations of permanent IBGP route o Reducing the potential for situations of permanent IBGP route
oscillation, as discussed in some scenarios [RFC3345]. oscillation [RFC3345].
o Improving selection of lower MED routes from the same neighboring o Improving selection of lower MED routes from the same neighboring
AS. AS.
This document defines procedures to select the best external route This document defines procedures to select the best external route
for each destination. It also describes how above benefits are for each peer. It also describes how above benefits are realized
realized with best external route announcement with the help of with best external route announcement with the help of certain
certain scenarios. scenarios.
1.1. Requirements Language 2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
2. Algorithm for selection of best external route 3. Generalization
Given that the intent in advertising an external route, when the best The BGP-4 protocol [RFC1771] has extended with two alternative
route for the same destination is an internal route, is to provide mechanisms that provide ways to reduce the operational complexity of
additional information into the IBGP mesh into which a route is route distribution within an AS: Route Reflection [RFC4456] and
participating, it is desirable to take into account the routes Confederations [RFC5065]. It is important to be able to express
received from internal neighbors in the selection process. route advertisement rules in the context of both of these mechanisms.
We propose a route selection algorithm that selects a total order When Route Reflection is used, Internal peers are further classified
between routes and which selects the same best route as the one depending of the reflection cluster they belong to. Non-client
currently specified [RFC4271]. internal peers form one BGP peering mesh. Each set of RR clients
with the same "cluster-id" configuration forms a separate mesh.
In order to achieve this, we need to introduce the concept of route When selecting the path to add to the Adj-RIB-OUT, this document
group. For a given NLRI, suppose the BGP decision process has run specifies that the path that originate from the same mesh MAY be
excluded from consideration. This results in an Adj-RIB-OUT
selection per mesh (the set of non-client peers or a specific
cluster).
Similarly, when BGP Confederations are used, each confederated AS is
a BGP mesh. As with the Route Reflection scenario, when selecting
the path to add to the Adj-RIB-OUT, routes from the same mesh MAY be
excluded.
4. Algorithm for selection of the Adj-RIB-OUT path
The objective of this protocol extension is to improve the quality of
the routing information known to a particular BGP mesh with minimum
additional cost in terms of processing and state.
Towards that goal, it is useful to define a total order between the
Adj-RIB-In routes which provides both the same overall best path as
the algorithm defined in the current BGP-4 specification [RFC4271] as
well as an ordering of alternate routes. Using this total order it
is then computationally efficient to select the path for a specific
Adj-RIB-OUT by excluding the routes that have been received from the
BGP mesh corresponding to the peer (or set of peers).
In order to achieve this, it is helpful to introduce the concept of
path group. A group is the set of paths that compare as equal
through all the steps prior to the MED comparison step (as defined in through all the steps prior to the MED comparison step (as defined in
section 9.1.2.2 of [RFC4271]. Look at the set of routes that are section 9.1.2.2 of RFC 4271 [RFC4271] and have been received from the
still under consideration at that time. Now partition this set into same neighbor AS.
a number of disjoint route groups, where two routes are in the same
group if and only if the neighbor AS of each route is the same.
Routes are ordered within a group via MED or subsequent route Paths are ordered within a group via MED or subsequent route
selection rules. selection rules.
The order of all routes for the same destination is determined by the In pseudo-code:
order of the best route in each group.
function compare(path_1, path_2) {
cmp_result cmp = selection_steps_before_med(path_1, path_2);
if (cmp != cmp_result.equal) {
return cmp;
}
if (neighbor_as(path_1) == neighbor_as(path_2)) {
return selection_steps_after_med(path_1, path_2);
}
if (is_group_best(path_1)) {
if (!is_group_best(path_2)) {
return cmp_result.greater_than;
}
return selection_steps_after_med(path_1, path_2);
} else {
if (is_group_best(path_2)) {
return cmp_result.less_than;
}
/* Compare the best paths of respective groups */
return compare(group_best(path_1), group_best(path_2));
}
}
As an example, the following set of received routes: As an example, the following set of received routes:
Path AS MED rtr_id +------+----+-----+--------+
a 1 10 10 | Path | AS | MED | rtr_id |
b 2 5 1 +------+----+-----+--------+
c 1 5 5 | a | 1 | 10 | 10 |
d 2 20 20 | | | | |
e 2 30 30 | b | 2 | 5 | 1 |
f 3 10 20 | | | | |
Figure 1: Path Attribute Table | c | 1 | 5 | 5 |
| | | | |
| d | 2 | 20 | 20 |
| | | | |
| e | 2 | 30 | 30 |
| | | | |
| f | 3 | 10 | 20 |
+------+----+-----+--------+
Path Attribute Table
Would yield the following order (from the most to the least Would yield the following order (from the most to the least
preferred): preferred):
b < d < e < c < a < f b < d < e < c < a < f
In this example, comparison of the best route within each group In this example, comparison of the best path within each group
provides the sequence (b < c < f). The remaining routes are ordered provides the sequence (b < c < f). The remaining paths are ordered
in relation to their respective group best. in relation to their respective group best.
The first route in the above ordering is indeed the best route for a The first path in the ordering above is the best overall path for a
given destination. Eliminating the best route and executing the given NLRI. When selecting a path for a particular Adj-RIB-Out (or
above steps leads us to a new total order of the routes. The route set of RIB-Outs) an implementation MAY choose to select the first
to be advertised to a particular domain is selected by choosing the path in the global order which was not received from the same BGP
most preferred route that is external to that particular domain in mesh (as defined above) as the target peer (or peers).
the above order. Note that whenever the overall best route is
external it will automatically be selected by this algorithm.
3. Advertisement Rules
1. In an AS domain, if a router has installed an internal route as 5. Advertisement Rules
best, it should advertise its "best external route" (as defined
in the draft) to its internal neighbors.
2. In a Cluster domain, if a router (route reflector) has installed 1. When advertising a route to a non-client Internal peer, a BGP
an external route as best, it should advertise its "best internal speaker MAY choose to select the first path in order that did not
route" to its external neighbors. (Advertising to internal originate from the same BGP mesh (i.e. the set of non-client
neighbors is unchanged.) Similarly, if the route reflector has Internal peers) whenever the best overall path has been received
installed an internal route as best, it should advertise its from this mesh and would be suppressed by the Internal BGP non-
"best external route" to its internal (client) peers. In order readvertisement rule.
for the reflector to be able to advertise the best external route
into the cluster, it is necessary that client-to-client
reflection be disabled, since its advertisement may otherwise
contain the best route within the cluster domain.
3. In a Confederation Member domain, if a router (confederation 2. When advertising a route to a Route Reflection client peer, in
border router) has installed an internal route as best, it case the overall best path has been received from the same
advertises its best external route to its internal neighbors. cluster, a BGP speaker MUST be able to advertise the best overall
However, if it has installed an external route as best, it path to all the members of the cluster other than the originator,
advertises its best internal route to its external neighbors. unless "client-to-client" reflection is disabled. The
implementation MAY choose to advertise an alternate path to the
specific peer that originates the best overall path by excluding
from consideration all paths with the same originator-id.
4. Consistency between routing and forwarding 3. When "client-to-client" reflection is disabled and the cluster is
operating as a mesh, a Route Reflector MAY opt to advertise to
the cluster the preferred path from the set of paths not received
from the cluster. While this deployment mode is currently
uncommon, it can be a practical way to guarantee path diversity
inside the cluster.
The BGP protocol, as defined in [RFC1771], specifies that a BGP 4. A confederation border route MAY choose to advertise an alternate
speaker shall advertise to its internal peers the route with the path towards its Internal BGP mesh or towards a con-fed member AS
highest degree of preference among routes to the same destination following the same procedure as defined above.
received from external neighbors.
This section discusses problems present with the approach described 6. Consistency between routing and forwarding
in [RFC1771] and the next section offers an alternative algorithm to
select a best external route which can be advertised to an IBGP mesh.
The internal update advertisement rules contained in the original The internal update advertisement rules contained in the original
BGP-4 specification [RFC1771] can lead to situations where traffic is BGP-4 specification [RFC1771] can lead to situations where traffic is
forwarded through a route other than the route advertised by BGP. forwarded through a route other than the route advertised by BGP.
Inconsistencies between forwarding and routing are highly Inconsistencies between forwarding and routing are highly
undesirable. Service providers use BGP with the dual objective of undesirable. Service providers use BGP with the dual objective of
learning reachability information and expressing policy over network learning reach-ability information and expressing policy over network
resources. The latter assumes that forwarding follows routing resources. The latter assumes that forwarding follows routing
information. information.
Consider the Autonomous system presented in figure 1, where r1 ... r4 Consider the Autonomous system presented in figure 1, where r1 ... r4
are members of a single IBGP mesh and routes a, b, and c are received are members of a single IBGP mesh and routes a, b, and c are received
from external peers. from external peers.
AS 1 (c) AS 1 (c)
| |
+----+ +----+ +----+ +----+
| r1 |...........| r2 | | r1 |...........| r2 |
+----+ +----+ +----+ +----+
. .
. .
. .
. .
. .
. .
+----+ +----+ +----+ +----+
| r3 |...........| r4 | --- ebgp --- AS X | r3 |...........| r4 | --- ebgp --- AS X
+----+ +----+ +----+ +----+
/ \ / \
/ \ / \
AS 1 (a) AS 2 (b) AS 1 (a) AS 2 (b)
Figure 2: Inconsistency in Routing Inconsistency in Routing
Path AS MED rtr_id
a 1 10 1
b 2 5 10
c 1 5 5
Figure 3: Path Attribute Table - 2 +------+----+-----+--------+
| Path | AS | MED | rte_id |
+------+----+-----+--------+
| a | 1 | 10 | 1 |
| | | | |
| b | 2 | 5 | 10 |
| | | | |
| c | 1 | 5 | 5 |
+------+----+-----+--------+
Following the rules as specified in [RFC1771], router r3 will select Path Attribute Table
path (b) received from AS 2 as its overall best to install in the
Loc-Rib, since path (b) is preferable to path (c), the lowest MED Following the rules as specified in RFC 1771 [RFC1771], router r3
route from AS 1. However for the purposes of Internal Update route will select path (b) received from AS 2 as its overall best to
selection, it will ignore the presence of path (c), and elect (a) as install in the Loc-Rib, since path (b) is preferable to path (c), the
its advertisement, via the router-id tie-breaking rule. lowest MED route from AS 1. However for the purposes of Internal
Update route selection, it will ignore the presence of path (c), and
elect (a) as its advertisement, via the router-id tie-breaking rule.
In this scenario, router r4 will receive (c) from r1 and (a) from r3. In this scenario, router r4 will receive (c) from r1 and (a) from r3.
It will pick the lowest MED route (c) and advertise it out via ebgp It will pick the lowest MED route (c) and advertise it out via IBGP
to AS X. However at this point routing is inconsistent with to AS X. However at this point routing is inconsistent with
forwarding as traffic received from AS X will be forwarded towards AS forwarding as traffic received from AS X will be forwarded towards AS
2, while the ebgp advertisement is being made for an AS 1 path. 2, while the IBGP advertisement is being made for an AS 1 path.
Routing policies are typically specified in terms of neighboring Routing policies are typically specified in terms of neighboring
ASes. In the situation above, assuming that AS 1 is network for AS-es. In the situation above, assuming that AS 1 is network for
which this AS provides transit services while AS 2 and AS X are peer which this AS provides transit services while AS 2 and AS X are peer
networks, one can easily see how the inconsistency between routing networks, one can easily see how the inconsistency between routing
and forwarding would lead to transit being inadvertently provided and forwarding would lead to transit being inadvertently provided
between AS X and AS 2. This could lead to persistent forwarding between AS X and AS 2. This could lead to persistent forwarding
loops. loops.
Inconsistency between routing and forwarding may happen, whenever a Inconsistency between routing and forwarding may happen, whenever a
bgp speaker chooses to advertise an external route into IBGP that is GP speaker chooses to advertise an external route into IBGP that is
different from the overall best route and its overall best is different from the overall best route and its overall best is
external. external.
5. Applications 7. Applications
8. Fast Connectivity Restoration
5.1. Fast Connectivity Restoration
When two exits are available to reach a particular destination and When two exits are available to reach a particular destination and
one is preferred over the other, the availability of an alternate one is preferred over the other, the availability of an alternate
path provides fast connectivity restoration when the primary path path provides fast connectivity restoration when the primary path
fails. fails.
Restoration can be quick since the alternate path is already at hand. Restoration can be quick since the alternate path is already at hand.
The border router could precompute the backup route and preinstall it The border router could recompute the backup route and perinatal it
in FIB ready to be switched when the primary goes away. Note that in FIB ready to be switched when the primary goes away. Note that
this requires the border router that's the backup to also preinstall this requires the border router that's the backup to also perinatal
the secondary path and switch to it on failure. the secondary path and switch to it on failure.
5.2. Inter-Domain Churn Reduction 9. Inter-Domain Churn Reduction
Within an AS, the non availability of backup best leads to a border Within an AS, the non availability of backup best leads to a border
router sending a withdraw upstream when the primary fails. This router sending a withdraw upstream when the primary fails. This
leads to inter-domain churn and packet loss for the time the network leads to inter-domain churn and packet loss for the time the network
takes to converge to the alternate path. Having the alternate path takes to converge to the alternate path. Having the alternate path
will reduces the churn and eliminates packet loss. will reduces the churn and eliminates packet loss.
5.3. Reducing Persistent IBGP oscillation 10. Reducing Persistent IBGP oscillation
Advertising the best external route, according to the algorithm Advertising the best external route, according to the algorithm
described in this document will reduce the possibility of route described in this document will reduce the possibility of route
oscillation by introducing additional information into the IBGP oscillation by introducing additional information into the IBGP
system. system.
For a permanent oscillation condition to occur, it is necessary that For a permanent oscillation condition to occur, it is necessary that
a circular dependency between paths occurs such that the selection of a circular dependency between paths occurs such that the selection of
a new best path by a router, in response to a received IBGP a new best path by a router, in response to a received IBGP
advertisement, causes the withdrawal of information that another advertisement, causes the withdrawal of information that another
router depends on in order to generate the original event. router depends on in order to generate the original event.
In vanilla BGP, when only the best overall route is advertised, as in In vanilla BGP, when only the best overall route is advertised, as in
most implementations, oscillation can occur whenever there are 2 or most implementations, oscillation can occur whenever there are 2 or
clusters/sub-ASes such that at least one cluster has more than one clusters/sub-AS-es such that at least one cluster has more than one
path that can potentially contribute to the dependency. path that can potentially contribute to the dependency.
6. Deployment Considerations 11. Deployment Considerations
The mechanism specified in the draft allows a BGP speaker to The mechanism specified in the draft allows a BGP speaker to
advertise a route that is not the best route used for forwarding. advertise a route that is not the best route used for forwarding.
This is a departure from the current behavior. However, consistency This is a departure from the current behavior. However, consistency
in the path selection process across the AS is still guaranteed since in the path selection process across the AS is still guaranteed since
the ingress routers will not choose the best-external route as the the ingress routers will not choose the best-external route as the
best route for a destination in steady state (for the same reason best route for a destination in steady state (for the same reason
that the BGP speaker announcing the best-external route chose an IBGP that the BGP speaker announcing the best-external route chose an IBGP
route as best instead of the externally learnt route). Though it is route as best instead of the externally learnt route). Though it is
possible to alter this assurance by defining route policies on IBGP possible to alter this assurance by defining route policies on IBGP
sessions, use of such policies in IBGP is not recommended, especially sessions, use of such policies in IBGP is not recommended, especially
with best-external announcement turned on in the network. It is also with best-external announcement turned on in the network. It is also
worth noting that such inconsistency in routing and forwarding is worth noting that such inconsistency in routing and forwarding is
mitigated in a tunneled network. mitigated in a tunneled network.
7. Acknowledgments 12. Acknowledgments
This document greatly benefits from the comments of Yakov Rekhter, This document greatly benefits from the comments of Yakov Rekhter,
John Scudder, Eric Rosen, Jenny Yuan, and Jay Borkenhagen. John Scudder, Eric Rosen, Jenny Yuan, Jay Borkenhagen, Salkat Ray and
Jakob Heitz.
8. IANA Considerations 13. IANA Considerations
This document has no actions for IANA. This document has no actions for IANA.
9. Security Considerations 14. Security Considerations
There are no additional security risks introduced by this design. There are no additional security risks introduced by this design.
10. Normative References 15. References
[RFC1771] Rekhter, Y. and T. Li, "A Border Gateway Protocol 4 [RFC1771] Rekhter, Y. and T. Li, "A Border Gateway Protocol 4
(BGP-4)", RFC 1771, March 1995. (BGP-4)", RFC 1771, March 1995.
[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, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3345] McPherson, D., Gill, V., Walton, D., and A. Retana, [RFC3345] McPherson, D., Gill, V., Walton, D., and A. Retana,
"Border Gateway Protocol (BGP) Persistent Route "Border Gateway Protocol (BGP) Persistent Route
Oscillation Condition", RFC 3345, August 2002. Oscillation Condition", RFC 3345, August 2002.
skipping to change at page 10, line 43 skipping to change at page 21, line 13
System Confederations for BGP", RFC 5065, August 2007. System Confederations for BGP", RFC 5065, August 2007.
Authors' Addresses Authors' Addresses
Pedro Marques Pedro Marques
Email: pedro.r.marques@gmail.com Email: pedro.r.marques@gmail.com
Rex Fernando Rex Fernando
Cisco Systems Cisco Systems
170 W. Tasman Drive 170 W. Tasman Dr.
San Jose, CA 95134 San Jose, CA 95134
USA US
Email: rex@cisco.com Email: rex@cisco.com
Enke Chen Enke Chen
Cisco Systems Cisco Systems
170 W. Tasman Drive 170 W. Tasman Dr.
San Jose, CA 95134 San Jose, CA 95134
USA US
Email: enkechen@cisco.com Email: enkechen@cisco.com
Pradosh Mohapatra Pradosh Mohapatra
Cisco Systems Cisco Systems
170 W. Tasman Drive 170 W. Tasman Dr.
San Jose, CA 95134 San Jose, CA 95134
USA US
Email: pmohapat@cisco.com Email: pmohapat@cisco.com
Hannes Gredler
Juniper Networks
1194 N. Mathilda Ave.
Sunnyvale, CA 94089
US
Email: hannes@juniper.net
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