There won't be loops - Due to Originator ID
See My Output
Client Switch 3750 Configured
=========================
interface Loopback0
ip address 200.1.1.1 255.255.255.0
end
interface Vlan1
ip address 172.20.1.1 255.255.255.0
router bgp 64512
no synchronization
bgp log-neighbor-changes
network 10.0.0.0
neighbor 172.20.1.2 remote-as 64512
neighbor 172.20.1.2 transport path-mtu-discovery
neighbor 172.20.1.3 remote-as 64512
neighbor 172.20.1.3 transport path-mtu-discovery
no auto-summary
!
ip classless
ip route 10.0.0.0 255.0.0.0 Null0 254
2 Routers - which 1 of them is 3550 and second is 1841 Reflectors
==================================================
Router 1841
=================================
interface Loopback0
ip address 200.10.10.10 255.255.255.0
end
interface FastEthernet0/0
ip address 172.20.1.3 255.255.255.0
duplex auto
speed auto
end
router bgp 64512
no synchronization
bgp log-neighbor-changes
network 20.0.0.0
neighbor 172.20.1.1 remote-as 64512
neighbor 172.20.1.1 route-reflector-client
neighbor 172.20.1.2 remote-as 64512
no auto-summary
!
3550
=============
interface Loopback0
ip address 200.20.20.20 255.255.255.0
end
interface Vlan1
ip address 172.20.1.2 255.255.255.0
end
router bgp 64512
no synchronization
bgp log-neighbor-changes
network 30.0.0.0
neighbor 172.20.1.1 remote-as 64512
neighbor 172.20.1.1 route-reflector-client
neighbor 172.20.1.3 remote-as 64512
no auto-summary
!
ip route 30.0.0.0 255.0.0.0 Null0 254
OUTPUT
===================
Switch# Debug ip bgp updates
Switch# Clear ip bgp 64512
01:08:19: %BGP-5-ADJCHANGE: neighbor 172.20.1.2 Up
01:08:19: BGP(0): 172.20.1.2 send UPDATE (format) 10.0.0.0/8, next
172.20.1.1, metric 0, path Local
01:08:19: %BGP-5-ADJCHANGE: neighbor 172.20.1.3 Up
01:08:19: BGP(0): updgrp 1 - 172.20.1.2 updates replicated for neighbors:
01:08:19: BGP(0): 172.20.1.3 send UPDATE (format) 10.0.0.0/8, next
172.20.1.1, metric 0, path Local
01:08:19: BGP(0): updgrp 1 - 172.20.1.3 updates replicated for neighbors:
01:08:19: BGP(0): 172.20.1.2 rcvd UPDATE w/ attr: nexthop 172.20.1.2, origin
i, localpref 100, metric 0
01:08:19: BGP(0): 172.20.1.2 rcvd 30.0.0.0/8
01:08:19: BGP(0): 172.20.1.2 rcvd UPDATE w/ attr: nexthop 172.20.1.3, origin
i, localpref 100, metric 0, originator 200.10.10.10, clusterlist
200.20.20.20
01:08:19: BGP(0): 172.20.1.2 rcvd 20.0.0.0/8
01:08:19: BGP(0): Revise route installing 1 of 1 routes for 20.0.0.0/8 ->
172.20.1.3(main) to main IP table
01:08:19: BGP(0): Revise route installing 1 of 1 routes for 30.0.0.0/8 ->
172.20.1.2(main) to main IP table
01:08:19: BGP(0): updgrp 1 - 172.20.1.2 updates replicated for neighbors:
172.20.1.3
01:08:19: BGP(0): 172.20.1.3 rcvd UPDATE w/ attr: nexthop 172.20.1.3, origin
i, localpref 100, metric 0
01:08:19: BGP(0): 172.20.1.3 rcvd 20.0.0.0/8
01:08:19: BGP(0): 172.20.1.3 rcvd UPDATE w/ attr: nexthop 172.20.1.2, origin
i, localpref 100, metric 0, originator 200.20.20.20, clusterlist
200.10.10.10
01:08:19: BGP(0): 172.20.1.3 rcvd 30.0.0.0/8
01:08:19: BGP(0): Revise route installing 1 of 1 routes for 20.0.0.0/8 ->
172.20.1.3(main) to main IP table
01:08:19: BGP(0): updgrp 1 - 172.20.1.2 updates replicated for neighbors:
172.20.1.3
Switch#
Switch#
Switch#
Switch#telnet 172.20.1.2
Trying 172.20.1.2 ... Open
User Access Verification
Username: cisco
Password:
3550#clear ip bgp 6441 512
3550#telnet 172.
01:08:40: %BGP-5-ADJCHANGE: neighbor 172.20.1.2 Down Peer closed the
session20.1.3
Trying 172.20.1.3 ... Open
Router#
01:08:40: BGP(0): Revise route installing 1 of 1 routes for 30.0.0.0/8 ->
172.20.1.2(main) to main IP table
01:08:40: BGP(0): updgrp 1 - 172.20.1.3 updates replicated for neighbors:
01:08:41: BGP(0): 172.20.1.3 rcv UPDATE about 30.0.0.0/8 -- withdrawn
01:08:41: BGP(0): no valid path for 30.0.0.0/8
01:08:41: BGP(0): nettable_walker 30.0.0.0/8 no best path
01:08:41: BGP(0): updgrp 1 - 172.20.1.3 updates replicated for
neighbors:clear ip b
01:08:43: BGP(0): 172.20.1.3 rcvd UPDATE w/ attr: nexthop 172.20.1.2, origin
i, localpref 100, metric 0, originator 200.20.20.20, clusterlist
200.10.10.10
01:08:43: BGP(0): 172.20.1.3 rcvd 30.0.0.0/8
01:08:43: BGP(0): Revise route installing 1 of 1 routes for 30.0.0.0/8 ->
172.20.1.2(main) to main IP table
01:08:43: BGP(0): updgrp 1 - 172.20.1.3 updates replicated for neighbors:
01:08:44: %BGP-5-ADJCHANGE: neighbor 172.20.1.2 Up
01:08:44: BGP(0): 172.20.1.2 rcvd UPDATE w/ attr: nexthop 172.20.1.2, gp
origin i, localpref 100, metric 0
01:08:44: BGP(0): 172.20.1.2 rcvd 30.0.0.0/8
01:08:44: BGP: 172.20.1.2 Local router is the Originator; Discard update
01:08:44: BGP(0): 172.20.1.2 rcv UPDATE w/ attr: nexthop 172.20.1.2, origin
i, localpref 100, metric 0, originator 172.20.1.1, clusterlist 200.20.20.20
200.10.10.10, path , community , extended community , SSA attribute
01:08:44: BGPSSA ssacount is 0
01:08:44: BGP(0): 172.20.1.2 rcv UPDATE about 10.0.0.0/8 -- DENIED due to:
ORIGINATOR is us;
01:08:4464512
Router#: BGP(0): 172.20.1.2 rcvd UPDATE w/ attr: nexthop 172.20.1.3, origin
i, localpref 100, metric 0, originator 200.10.10.10, clusterlist
200.20.20.20
01:08:44: BGP(0): 172.20.1.2 rcvd 20.0.0.0/8
01:08:44: BGP(0): Revise route installing 1 of 1 routes for 30.0.0.0/8 ->
172.20.1.2(main) to main IP table
01:08:44: BGP(0): 172.20.1.2 send UPDATE (format) 10.0.0.0/8, next
172.20.1.1, metric 0, path Local
01:08:44: BGP(0): updgrp 1 - 172.20.1.2 updates replicated for neighbors:
01:08:44: BGP(0): updgrp 1 - 172.20.1.2 updates replicated for neighbors:
172.20.1.3
01:08:44: BGP(0): 172.20.1.2 rcv UPDATE about 10.0.0.0/8 -- withdrawn
01:08:46: BGP(0): 172.20.1.2 rcv UPDATE about 20.0.0.0/8 -- withdrawn
01:08:46: BGP(0): no valid path for 20.0.0.0/8
01:08:46: %BGP-5-ADJCHANGE: neighbor 172.20.1.3 Down Peer closed the session
01:08:46: BGP(0): nettable_walker 20.0.0.0/8 no best path
01:08:46: BGP(0): updgrp 1 - 172.20.1.2 updates replicated for neighbors:
01:08:46: %BGP-5-ADJCHANGE: neighbor 172.20.1.3 Up
01:08:46: BGP(0): 172.20.1.3 rcvd UPDATE w/ attr: nexthop 172.20.1.3, origin
i, localpref 100, metric 0
01:08:46: BGP(0): 172.20.1.3 rcvd 20.0.0.0/8
01:08:46: BGP(0): Revise route installing 1 of 1 routes for 20.0.0.0/8 ->
172.20.1.3(main) to main IP table
01:08:46: BGP(0): 172.20.1.3 send UPDATE (format) 10.0.0.0/8, next
172.20.1.1, metric 0, path Local
01:08:46: BGP(0): updgrp 1 - 172.20.1.3 updates replicated for neighbors:
01:08:46: BGP(0): updgrp 1 - 172.20.1.3 updates replicated for neighbors:
172.20.1.2
01:08:46: BGP(0): 172.20.1.2 rcvd UPDATE w/ attr: nexthop 172.20.1.3, origin
i, localpref 100, metric 0, originator 200.10.10.10, clusterlist
200.20.20.20
01:08:46: BGP(0): 172.20.1.2 rcvd 20.0.0.0/8
01:08:46: BGP: 172.20.1.3 Local router is the Originator; Discard update
01:08:46: BGP(0): 172.20.1.3 rcv UPDATE w/ attr: nexthop 172.20.1.3, origin
i, localpref 100, metric 0, originator 172.20.1.1, clusterlist 200.10.10.10
200.20.20.20, path , community , extended community , SSA attribute
01:08:46: BGPSSA ssacount is 0
01:08:46: BGP(0): 172.20.1.3 rcv UPDATE about 10.0.0.0/8 -- DENIED due to:
ORIGINATOR is us;
01:08:46: BGP(0): 172.20.1.3 rcvd UPDATE w/ attr: nexthop 172.20.1.2, origin
i, localpref 100, metric 0, originator 200.20.20.20, clusterlist
200.10.10.10
01:08:46: BGP(0): 172.20.1.3 rcvd 30.0.0.0/8
01:08:46: BGP(0): 172.20.1.3 rcv UPDATE about 10.0.0.0/8 -- withdrawn
Router#
Router#
Router#exi
[Connection to 172.20.1.3 closed by foreign host]
- Show quoted text -
On Mon, May 11, 2009 at 2:15 PM, marish shah <contactmarish_at_gmail.com>wrote:
> Hi Experts,
> One Q in bgp we use for loop prevention splithorzain That
> ibgp cannot passed received routes to other ibgp .But when we use rout
> reflector this rule failed.Then we have two options 1: originating ID 2:
> Cluster ID
> If we are using single route reflector then we use originating ID and if
> we
> have multiple route reflector then we use cluster ID to ovoid route
> feedback.
> Please correct me If I put any thing wrong.
>
> So my Q is if we have multiple route reflector and we are not using cluster
> ID then what happen there is loop or it use any other thing ?
>
>
>
> Thanks.
>
>
> Blogs and organic groups at http://www.ccie.net
>
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Received on Mon May 11 2009 - 14:28:09 ART
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