static to bgp redistribution issue

Vinayaka Raman · ‎08-25-2012

Hello All,

I had a problem this morning and need your suggestion. We had a limited window so could not extend the troublesooting

router bgp 65457

no synchronization

bgp log-neighbor-changes

network 10.52.232.248 mask 255.255.255.248

aggregate-address 10.52.232.0 255.255.248.0 summary-only

redistribute static

neighbor 147.225.59.241 remote-as 65000

neighbor 147.225.59.241 route-map increase_weight in

default-metric 100000

no auto-summary

show run | s ip route

ip route 10.50.252.0 255.255.255.0 10.52.237.250 21

ip route 10.52.236.0 255.255.252.0 10.52.232.58

ip route 192.168.235.251 255.255.255.255 10.52.237.250

route-map increase_weight, permit, sequence 10

Match clauses:

ip address (access-lists): 10

Set clauses:

weight 40000

Policy routing matches: 0 packets, 0 bytes

route-map increase_weight, permit, sequence 20

Match clauses:

Set clauses:

Policy routing matches: 0 packets, 0 bytes

show access-lists 10

Standard IP access list 10

10 permit 10.50.252.0, wildcard bits 0.0.0.255 (5248 matches)

show ip bgp 10.50.252.0

BGP routing table entry for 10.50.252.0/24, version 781545

Paths: (1 available, best #1, table Default-IP-Routing-Table)

Not advertised to any peer

65000 65000, (aggregated by 65457 10.50.252.254)

147.225.59.241 from 147.225.59.241 (159.24.197.199)

Origin IGP, localpref 100, weight 40000, valid, external, atomic-aggregate, best

show ip route 10.50.252.0

Routing entry for 10.50.252.0/24

Known via "bgp 65457", distance 20, metric 0

Tag 65000, type external

Advertised by bgp 65457 (self originated)

Last update from 147.225.59.241 01:51:08 ago

Routing Descriptor Blocks:

* 147.225.59.241, from 147.225.59.241, 01:51:08 ago

Route metric is 0, traffic share count is 1

AS Hops 2

Route tag 65000

10.50.252.0/24 is the prefix advertsied by remote site A

We want CR1 (in data center) to advertise 10.50.252.0/24 as soon as remote site MPLS goes down.

So we increased the weight by calling in bound route-map on CR1, so that CR1 learns this from its

ebgp peer(as long as the remote site MPLS is up). When remote site MPLS is down, we found that the route

is not advertised to any peer.

unfortunately, i lost the show ip bgp 10.50.252.0/24 on cr1 when remote site MPLS was down. there was

a route with weight 32768 but "not advertised to peer) not sure why

Regards Vinayak

John Blakley · ‎08-25-2012

The weight attribute is locally significant, but it will always advertise this route if it's in the table. I'm assuming that you're learning the route from the remote peer, in which case the same route is going to have an AD of 20. Your static has an AD of 21 meaning that it won't be in the routing table until the BGP peering times out (3 minutes by default). This is going to be a timing issue I believe. How long did you wait?

The weight attribute isn't advertised to peers and it's used to affect outbound traffic. It would help if you could draw up a topology to show us how you're laid out.

On another note, if you're wanting CR1 to advertise the route, these configs need to be done on that router and not the one that you're trying to create the failover for. Is the CR1 router configured exactly like this one? I'm assuming that you've posted the config for the "remote site."

HTH,

John

*** Please rate useful posts ***

HTH, John *** Please rate all useful posts ***

Vinayaka Raman · ‎08-25-2012

the configruation i have pasted in my initial discussion is for CR1

remote site just have an aggregate address to advertise the prefix 10.60.252.0

Regards Vinayak

Vinayaka Raman · ‎09-01-2012

i ve been working with cisco tac since morning, we couldnot fix this issue..

we are trying to advertise 10.50.252./24 into the cloud from CR1 when remote site is down and it isnot working

any help is highly appreacated

when remote site mpls is down, pls find bgp table and debug logs

CR1#show ip bgp 10.50.252.0

BGP routing table entry for 10.50.252.0/24, version 823316

Paths: (1 available, best #1, table Default-IP-Routing-Table)

Flag: 0x820

Not advertised to any peer

Local

0.0.0.0 from 0.0.0.0 (10.52.232.254)

Origin IGP, metric 0, localpref 100, weight 32768, valid, sourced, local, best

____________________________________________________________________________________________________________

Sep 1 00:58:28.981: BGP(0): 147.225.59.241 send UPDATE (format) 10.50.252.0/24, next 147.225.59.242, metric 0, path Local

Sep 1 00:58:28.985: BGP(0): 147.225.59.241 rcvd UPDATE w/ attr: nexthop 147.225.59.241, origin i, path 65000 65000

Sep 1 00:58:28.985: BGP(0): 147.225.59.241 rcvd 10.50.252.0/24

Sep 1 00:58:28.985: BGP(0): Revise route installing 1 of 1 routes for 10.50.252.0/24 -> 147.225.59.241(main) to main IP table

Sep 1 00:58:28.985: BGP(0): 147.225.59.241 send unreachable 10.50.252.0/24

Sep 1 00:58:28.985: BGP(0): 147.225.59.241 send UPDATE 10.50.252.0/24 -- unreachable

Sep 1 00:58:28.989: BGP(0): route 10.50.252.0/24 down

Sep 1 00:58:28.989: BGP(0): 147.225.59.241 rcv UPDATE about 10.50.252.0/24 -- withdrawn

Sep 1 00:58:28.989: BGP(0): no valid path for 10.50.252.0/24

Sep 1 00:58:28.989: BGP(0): nettable_walker 10.50.252.0/24 no best path

Sep 1 00:58:28.993: BGP(0): route 10.50.252.0/24 up

Sep 1 00:58:28.993: BGP(0): nettable_walker 10.50.252.0/24 route sourced locally

Sep 1 00:58:59.741: BGP(0): 147.225.59.241 send UPDATE (format) 10.50.252.0/24, next 147.225.59.242, metric 0, path Local

Sep 1 00:58:59.753: BGP(0): 147.225.59.241 rcvd UPDATE w/ attr: nexthop 147.225.59.241, origin i, path 65000 65000

Sep 1 00:58:59.753: BGP(0): 147.225.59.241 rcvd 10.50.252.0/24

Sep 1 00:58:59.753: BGP(0): Revise route installing 1 of 1 routes for 10.50.252.0/24 -> 147.225.59.241(main) to main IP table

Sep 1 00:58:59.753: BGP(0): 147.225.59.241 send unreachable 10.50.252.0/24

Sep 1 00:58:59.753: BGP(0): 147.225.59.241 send UPDATE 10.50.252.0/24 -- unreachable

Sep 1 00:58:59.753: BGP(0): route 10.50.252.0/24 down

Sep 1 00:58:59.757: BGP(0): 147.225.59.241 rcv UPDATE about 10.50.252.0/24 -- withdrawn

Sep 1 00:58:59.757: BGP(0): no valid path for 10.50.252.0/24

Sep 1 00:58:59.757: BGP(0): nettable_walker 10.50.252.0/24 no best path

Sep 1 00:58:59.757: BGP(0): route 10.50.252.0/24 up

Sep 1 00:58:59.757: BGP(0): nettable_walker 10.50.252.0/24 route sourced locally

Sep 1 00:59:30.513: BGP(0): 147.225.59.241 send UPDATE (format) 10.50.252.0/24, next 147.225.59.242, metric 0, path Local

Sep 1 00:59:30.521: BGP(0): 147.225.59.241 rcvd UPDATE w/ attr: nexthop 147.225.59.241, origin i, path 65000 65000

Sep 1 00:59:30.521: BGP(0): 147.225.59.241 rcvd 10.50.252.0/24

Sep 1 00:59:30.521: BGP(0): Revise route installing 1 of 1 routes for 10.50.252.0/24 -> 147.225.59.241(main) to main IP table

Sep 1 00:59:30.521: BGP(0): 147.225.59.241 send unreachable 10.50.252.0/24

Sep 1 00:59:30.521: BGP(0): 147.225.59.241 send UPDATE 10.50.252.0/24 -- unreachable

Sep 1 00:59:30.521: BGP(0): route 10.50.252.0/24 down

Sep 1 00:59:30.525: BGP(0): 147.225.59.241 rcv UPDATE about 10.50.252.0/24 -- withdrawn

Sep 1 00:59:30.525: BGP(0): no valid path for 10.50.252.0/24

Sep 1 00:59:30.525: BGP(0): nettable_walker 10.50.252.0/24 no best path

Sep 1 00:59:30.529: BGP(0): route 10.50.252.0/24 up

Sep 1 00:59:30.529: BGP(0): nettable_walker 10.50.252.0/24 route sourced locally

Sep 1 01:00:01.258: BGP(0): 147.225.59.241 send UPDATE (format) 10.50.252.0/24, next 147.225.59.242, metric 0, path Local

Sep 1 01:00:01.266: BGP(0): 147.225.59.241 rcvd UPDATE w/ attr: nexthop 147.225.59.241, origin i, path 65000 65000

Sep 1 01:00:01.266: BGP(0): 147.225.59.241 rcvd 10.50.252.0/24

Sep 1 01:00:01.266: BGP(0): Revise route installing 1 of 1 routes for 10.50.252.0/24 -> 147.225.59.241(main) to main IP table

Sep 1 01:00:01.266: BGP(0): 147.225.59.241 send unreachable 10.50.252.0/24

Sep 1 01:00:01.266: BGP(0): 147.225.59.241 send UPDATE 10.50.252.0/24 -- unreachable

Sep 1 01:00:01.266: BGP(0): route 10.50.252.0/24 down

Sep 1 01:00:01.278: BGP(0): 147.225.59.241 rcv UPDATE about 10.50.252.0/24 -- withdrawn

Sep 1 01:00:01.278: BGP(0): no valid path for 10.50.252.0/24

Sep 1 01:00:01.278: BGP(0): nettable_walker 10.50.252.0/24 no best path

Sep 1 01:00:01.278: BGP(0): route 10.50.252.0/24 up

Sep 1 01:00:01.278: BGP(0): nettable_walker 10.50.252.0/24 route sourced locally

Sep 1 01:00:32.130: BGP(0): 147.225.59.241 send UPDATE (format) 10.50.252.0/24, next 147.225.59.242, metric 0, path Local

Sep 1 01:00:32.138: BGP(0): 147.225.59.241 rcvd UPDATE w/ attr: nexthop 147.225.59.241, origin i, path 65000 65000

Sep 1 01:00:32.138: BGP(0): 147.225.59.241 rcvd 10.50.252.0/24

Sep 1 01:00:32.138: BGP(0): Revise route installing 1 of 1 routes for 10.50.252.0/24 -> 147.225.59.241(main) to main IP table

Sep 1 01:00:32.138: BGP(0): 147.225.59.241 send unreachable 10.50.252.0/24

Sep 1 01:00:32.138: BGP(0): 147.225.59.241 send UPDATE 10.50.252.0/24 -- unreachable

Sep 1 01:00:32.138: BGP(0): route 10.50.252.0/24 down

Sep 1 01:00:32.142: BGP(0): 147.225.59.241 rcv UPDATE about 10.50.252.0/24 -- withdrawn

Sep 1 01:00:32.142: BGP(0): no valid path for 10.50.252.0/24

Sep 1 01:00:32.142: BGP(0): nettable_walker 10.50.252.0/24 no best path

Sep 1 01:00:32.142: BGP(0): route 10.50.252.0/24 up

Sep 1 01:00:32.142: BGP(0): nettable_walker 10.50.252.0/24 route sourced locally

Sep 1 01:00:35.482: %SYS-5-CONFIG_I: Configured from console by chennaa on vty2 (100.9.254.100)

Sep 1 01:01:02.886: BGP(0): 147.225.59.241 send UPDATE (format) 10.50.252.0/24, next 147.225.59.242, metric 0, path Local

Sep 1 01:01:02.890: BGP(0): 147.225.59.241 rcvd UPDATE w/ attr: nexthop 147.225.59.241, origin i, path 65000 65000

Sep 1 01:01:02.890: BGP(0): 147.225.59.241 rcvd 10.50.252.0/24

Sep 1 01:01:02.890: BGP(0): Revise route installing 1 of 1 routes for 10.50.252.0/24 -> 147.225.59.241(main) to main IP table

Sep 1 01:01:02.890: BGP(0): 147.225.59.241 send unreachable 10.50.252.0/24

Sep 1 01:01:02.890: BGP(0): 147.225.59.241 send UPDATE 10.50.252.0/24 -- unreachable

Sep 1 01:01:02.894: BGP(0): route 10.50.252.0/24 down

Sep 1 01:01:02.894: BGP(0): 147.225.59.241 rcv UPDATE about 10.50.252.0/24 -- withdrawn

Sep 1 01:01:02.894: BGP(0): no valid path for 10.50.252.0/24

Sep 1 01:01:02.894: BGP(0): nettable_walker 10.50.252.0/24 no best path

Sep 1 01:01:02.898: BGP(0): route 10.50.252.0/24 up

Sep 1 01:01:02.898: BGP(0): nettable_walker 10.50.252.0/24 route sourced locally

Sep 1 01:01:33.678: BGP(0): 147.225.59.241 send UPDATE (format) 10.50.252.0/24, next 147.225.59.242, metric 0, path Local

Sep 1 01:01:33.682: BGP(0): 147.225.59.241 rcvd UPDATE w/ attr: nexthop 147.225.59.241, origin i, path 65000 65000

Sep 1 01:01:33.682: BGP(0): 147.225.59.241 rcvd 10.50.252.0/24

Sep 1 01:01:33.682: BGP(0): Revise route installing 1 of 1 routes for 10.50.252.0/24 -> 147.225.59.241(main) to main IP table

Sep 1 01:01:33.682: BGP(0): 147.225.59.241 send unreachable 10.50.252.0/24

Sep 1 01:01:33.682: BGP(0): 147.225.59.241 send UPDATE 10.50.252.0/24 -- unreachable

Sep 1 01:01:33.686: BGP(0): route 10.50.252.0/24 down

Sep 1 01:01:33.686: BGP(0): 147.225.59.241 rcv UPDATE about 10.50.252.0/24 -- withdrawn

Sep 1 01:01:33.686: BGP(0): no valid path for 10.50.252.0/24

Sep 1 01:01:33.686: BGP(0): nettable_walker 10.50.252.0/24 no best path

Sep 1 01:01:33.690: BGP(0): route 10.50.252.0/24 up

Sep 1 01:01:33.690: BGP(0): nettable_walker 10.50.252.0/24 route sourced locally

Sep 1 01:02:04.371: BGP(0): 147.225.59.241 send UPDATE (format) 10.50.252.0/24, next 147.225.59.242, metric 0, path Local

Sep 1 01:02:04.375: BGP(0): 147.225.59.241 rcvd UPDATE w/ attr: nexthop 147.225.59.241, origin i, path 65000 65000

Sep 1 01:02:04.375: BGP(0): 147.225.59.241 rcvd 10.50.252.0/24

Sep 1 01:02:04.375: BGP(0): Revise route installing 1 of 1 routes for 10.50.252.0/24 -> 147.225.59.241(main) to main IP table

Sep 1 01:02:04.375: BGP(0): 147.225.59.241 send unreachable 10.50.252.0/24

Sep 1 01:02:04.375: BGP(0): 147.225.59.241 send UPDATE 10.50.252.0/24 -- unreachable

Sep 1 01:02:04.379: BGP(0): route 10.50.252.0/24 down

Sep 1 01:02:04.379: BGP(0): 147.225.59.241 rcv UPDATE about 10.50.252.0/24 -- withdrawn

Sep 1 01:02:04.379: BGP(0): no valid path for 10.50.252.0/24

Sep 1 01:02:04.379: BGP(0): nettable_walker 10.50.252.0/24 no best path

Sep 1 01:02:04.383: BGP(0): route 10.50.252.0/24 up

Sep 1 01:02:04.383: BGP(0): nettable_walker 10.50.252.0/24 route sourced locally

Sep 1 01:02:35.227: BGP(0): 147.225.59.241 send UPDATE (format) 10.50.252.0/24, next 147.225.59.242, metric 0, path Local

Sep 1 01:02:35.231: BGP(0): 147.225.59.241 rcvd UPDATE w/ attr: nexthop 147.225.59.241, origin i, path 65000 65000

Sep 1 01:02:35.231: BGP(0): 147.225.59.241 rcvd 10.50.252.0/24

Sep 1 01:02:35.231: BGP(0): Revise route installing 1 of 1 routes for 10.50.252.0/24 -> 147.225.59.241(main) to main IP table

Sep 1 01:02:35.231: BGP(0): 147.225.59.241 send unreachable 10.50.252.0/24

Sep 1 01:02:35.231: BGP(0): 147.225.59.241 send UPDATE 10.50.252.0/24 -- unreachable

Sep 1 01:02:35.235: BGP(0): route 10.50.252.0/24 down

Sep 1 01:02:35.239: BGP(0): 147.225.59.241 rcv UPDATE about 10.50.252.0/24 -- withdrawn

Sep 1 01:02:35.239: BGP(0): no valid path for 10.50.252.0/24

Sep 1 01:02:35.239: BGP(0): nettable_walker 10.50.252.0/24 no best path

Sep 1 01:02:35.239: BGP(0): route 10.50.252.0/24 up

Sep 1 01:02:35.239: BGP(0): nettable_walker 10.50.252.0/24 route sourced locally

Sep 1 01:03:05.919: BGP(0): 147.225.59.241 send UPDATE (format) 10.50.252.0/24, next 147.225.59.242, metric 0, path Local

Sep 1 01:03:05.927: BGP(0): 147.225.59.241 rcvd UPDATE w/ attr: nexthop 147.225.59.241, origin i, path 65000 65000

Sep 1 01:03:05.927: BGP(0): 147.225.59.241 rcvd 10.50.252.0/24

Sep 1 01:03:05.927: BGP(0): Revise route installing 1 of 1 routes for 10.50.252.0/24 -> 147.225.59.241(main) to main IP table

Sep 1 01:03:05.927: BGP(0): 147.225.59.241 send unreachable 10.50.252.0/24

Sep 1 01:03:05.927: BGP(0): 147.225.59.241 send UPDATE 10.50.252.0/24 -- unreachable

Sep 1 01:03:05.927: BGP(0): route 10.50.252.0/24 down

Sep 1 01:03:05.931: BGP(0): 147.225.59.241 rcv UPDATE about 10.50.252.0/24 -- withdrawn

Sep 1 01:03:05.931: BGP(0): no valid path for 10.50.252.0/24

Sep 1 01:03:05.931: BGP(0): nettable_walker 10.50.252.0/24 no best path

Sep 1 01:03:05.931: BGP(0): route 10.50.252.0/24 up

Sep 1 01:03:05.931: BGP(0): nettable_walker 10.50.252.0/24 route sourced locally

Sep 1 01:03:36.691: BGP(0): 147.225.59.241 send UPDATE (format) 10.50.252.0/24, next 147.225.59.242, metric 0, path Local

Sep 1 01:03:36.711: BGP(0): 147.225.59.241 rcvd UPDATE w/ attr: nexthop 147.225.59.241, origin i, path 65000 65000

Sep 1 01:03:36.711: BGP(0): 147.225.59.241 rcvd 10.50.252.0/24

Sep 1 01:03:36.711: BGP(0): Revise route installing 1 of 1 routes for 10.50.252.0/24 -> 147.225.59.241(main) to main IP table

Sep 1 01:03:36.711: BGP(0): 147.225.59.241 send unreachable 10.50.252.0/24

Sep 1 01:03:36.711: BGP(0): 147.225.59.241 send UPDATE 10.50.252.0/24 -- unreachable

Sep 1 01:03:36.711: BGP(0): route 10.50.252.0/24 down

Sep 1 01:03:36.715: BGP(0): 147.225.59.241 rcv UPDATE about 10.50.252.0/24 -- withdrawn

Sep 1 01:03:36.715: BGP(0): no valid path for 10.50.252.0/24

Sep 1 01:03:36.715: BGP(0): nettable_walker 10.50.252.0/24 no best path

Sep 1 01:03:36.719: BGP(0): route 10.50.252.0/24 up

Sep 1 01:03:36.719: BGP(0): nettable_walker 10.50.252.0/24 route sourced locally

Sep 1 01:04:07.431: BGP(0): 147.225.59.241 send UPDATE (format) 10.50.252.0/24, next 147.225.59.242, metric 0, path Local

Sep 1 01:04:07.439: BGP(0): 147.225.59.241 rcvd UPDATE w/ attr: nexthop 147.225.59.241, origin i, path 65000 65000

Sep 1 01:04:07.439: BGP(0): 147.225.59.241 rcvd 10.50.252.0/24

Sep 1 01:04:07.439: BGP(0): Revise route installing 1 of 1 routes for 10.50.252.0/24 -> 147.225.59.241(main) to main IP table

Sep 1 01:04:07.439: BGP(0): 147.225.59.241 send unreachable 10.50.252.0/24

Sep 1 01:04:07.439: BGP(0): 147.225.59.241 send UPDATE 10.50.252.0/24 -- unreachable

Sep 1 01:04:07.439: BGP(0): route 10.50.252.0/24 down

Sep 1 01:04:07.443: BGP(0): 147.225.59.241 rcv UPDATE about 10.50.252.0/24 -- withdrawn

Sep 1 01:04:07.443: BGP(0): no valid path for 10.50.252.0/24

Sep 1 01:04:07.443: BGP(0): nettable_walker 10.50.252.0/24 no best path

Sep 1 01:04:07.443: BGP(0): route 10.50.252.0/24 up

Sep 1 01:04:07.443: BGP(0): nettable_walker 10.50.252.0/24 route sourced locally

Sep 1 01:04:38.152: BGP(0): 147.225.59.241 send UPDATE (format) 10.50.252.0/24, next 147.225.59.242, metric 0, path Local

Sep 1 01:04:38.160: BGP(0): 147.225.59.241 rcvd UPDATE w/ attr: nexthop 147.225.59.241, origin i, path 65000 65000

Sep 1 01:04:38.160: BGP(0): 147.225.59.241 rcvd 10.50.252.0/24

Sep 1 01:04:38.160: BGP(0): Revise route installing 1 of 1 routes for 10.50.252.0/24 -> 147.225.59.241(main) to main IP table

Sep 1 01:04:38.160: BGP(0): 147.225.59.241 send unreachable 10.50.252.0/24

Sep 1 01:04:38.160: BGP(0): 147.225.59.241 send UPDATE 10.50.252.0/24 -- unreachable

Sep 1 01:04:38.160: BGP(0): route 10.50.252.0/24 down

Sep 1 01:04:38.164: BGP(0): 147.225.59.241 rcv UPDATE about 10.50.252.0/24 -- withdrawn

Sep 1 01:04:38.164: BGP(0): no valid path for 10.50.252.0/24

Sep 1 01:04:38.168: BGP(0): nettable_walker 10.50.252.0/24 no best path

Sep 1 01:04:38.168: BGP(0): route 10.50.252.0/24 up

Sep 1 01:04:38.168: BGP(0): nettable_walker 10.50.252.0/24 route sourced locally

Sep 1 01:05:08.952: BGP(0): 147.225.59.241 send UPDATE (format) 10.50.252.0/24, next 147.225.59.242, metric 0, path Local

Sep 1 01:05:08.960: BGP(0): 147.225.59.241 rcvd UPDATE w/ attr: nexthop 147.225.59.241, origin i, path 65000 65000

Sep 1 01:05:08.960: BGP(0): 147.225.59.241 rcvd 10.50.252.0/24

Sep 1 01:05:08.960: BGP(0): Revise route installing 1 of 1 routes for 10.50.252.0/24 -> 147.225.59.241(main) to main IP table

Sep 1 01:05:08.960: BGP(0): 147.225.59.241 send unreachable 10.50.252.0/24

Sep 1 01:05:08.960: BGP(0): 147.225.59.241 send UPDATE 10.50.252.0/24 -- unreachable

Sep 1 01:05:08.964: BGP(0): route 10.50.252.0/24 down

Sep 1 01:05:08.972: BGP(0): 147.225.59.241 rcv UPDATE about 10.50.252.0/24 -- withdrawn

Sep 1 01:05:08.972: BGP(0): no valid path for 10.50.252.0/24

Sep 1 01:05:08.972: BGP(0): nettable_walker 10.50.252.0/24 no best path

Sep 1 01:05:08.976: BGP(0): route 10.50.252.0/24 up

Sep 1 01:05:08.976: BGP(0): nettable_walker 10.50.252.0/24 route sourced locally

Sep 1 01:05:38.968: BGP(0): 147.225.59.241 send UPDATE (format) 10.50.252.0/24, next 147.225.59.242, metric 0, path Local

Sep 1 01:05:38.984: BGP(0): 147.225.59.241 rcvd UPDATE w/ attr: nexthop 147.225.59.241, origin i, path 65000 65000

Sep 1 01:05:38.984: BGP(0): 147.225.59.241 rcvd 10.50.252.0/24

Sep 1 01:05:38.984: BGP(0): Revise route installing 1 of 1 routes for 10.50.252.0/24 -> 147.225.59.241(main) to main IP table

Sep 1 01:05:38.984: BGP(0): 147.225.59.241 send unreachable 10.50.252.0/24

Sep 1 01:05:38.984: BGP(0): 147.225.59.241 send UPDATE 10.50.252.0/24 -- unreachable

Sep 1 01:05:38.984: BGP(0): route 10.50.252.0/24 down

Sep 1 01:05:39.036: BGP(0): 147.225.59.241 rcv UPDATE about 10.50.252.0/24 -- withdrawn

Sep 1 01:05:39.036: BGP(0): no valid path for 10.50.252.0/24

Sep 1 01:05:39.036: BGP(0): nettable_walker 10.50.252.0/24 no best path

Sep 1 01:05:39.036: BGP(0): route 10.50.252.0/24 up

Sep 1 01:05:39.040: BGP(0): nettable_walker 10.50.252.0/24 route sourced locally

Sep 1 01:06:09.492: BGP(0): 147.225.59.241 send UPDATE (format) 10.50.252.0/24, next 147.225.59.242, metric 0, path Local

Sep 1 01:06:09.504: BGP(0): 147.225.59.241 rcvd UPDATE w/ attr: nexthop 147.225.59.241, origin i, path 65000 65000

Sep 1 01:06:09.504: BGP(0): 147.225.59.241 rcvd 10.50.252.0/24

Sep 1 01:06:09.504: BGP(0): Revise route installing 1 of 1 routes for 10.50.252.0/24 -> 147.225.59.241(main) to main IP table

Sep 1 01:06:09.504: BGP(0): 147.225.59.241 send unreachable 10.50.252.0/24

Sep 1 01:06:09.504: BGP(0): 147.225.59.241 send UPDATE 10.50.252.0/24 -- unreachable

Sep 1 01:06:09.504: BGP(0): route 10.50.252.0/24 down

Sep 1 01:06:09.528: BGP(0): 147.225.59.241 rcv UPDATE about 10.50.252.0/24 -- withdrawn

Sep 1 01:06:09.528: BGP(0): no valid path for 10.50.252.0/24

Sep 1 01:06:09.528: BGP(0): nettable_walker 10.50.252.0/24 no best path

Sep 1 01:06:09.528: BGP(0): route 10.50.252.0/24 up

Sep 1 01:06:09.528: BGP(0): nettable_walker 10.50.252.0/24 route sourced locally

Sep 1 01:06:40.197: BGP(0): 147.225.59.241 send UPDATE (format) 10.50.252.0/24, next 147.225.59.242, metric 0, path Local

Sep 1 01:06:40.213: BGP(0): 147.225.59.241 rcvd UPDATE w/ attr: nexthop 147.225.59.241, origin i, path 65000 65000

Sep 1 01:06:40.217: BGP(0): 147.225.59.241 rcvd 10.50.252.0/24

Sep 1 01:06:40.217: BGP(0): Revise route installing 1 of 1 routes for 10.50.252.0/24 -> 147.225.59.241(main) to main IP table

Sep 1 01:06:40.217: BGP(0): 147.225.59.241 send unreachable 10.50.252.0/24

Sep 1 01:06:40.217: BGP(0): 147.225.59.241 send UPDATE 10.50.252.0/24 -- unreachable

Sep 1 01:06:40.217: BGP(0): route 10.50.252.0/24 down

Sep 1 01:06:40.273: BGP(0): 147.225.59.241 rcv UPDATE about 10.50.252.0/24 -- withdrawn

Sep 1 01:06:40.273: BGP(0): no valid path for 10.50.252.0/24

Sep 1 01:06:40.273: BGP(0): nettable_walker 10.50.252.0/24 no best path

Sep 1 01:06:40.273: BGP(0): route 10.50.252.0/24 up

Sep 1 01:06:40.273: BGP(0): nettable_walker 10.50.252.0/24 route sourced locally

Sep 1 01:07:10.941: BGP(0): 147.225.59.241 send UPDATE (format) 10.50.252.0/24, next 147.225.59.242, metric 0, path Local

Sep 1 01:07:10.945: BGP(0): 147.225.59.241 rcvd UPDATE w/ attr: nexthop 147.225.59.241, origin i, path 65000 65000

Sep 1 01:07:10.945: BGP(0): 147.225.59.241 rcvd 10.50.252.0/24

Sep 1 01:07:10.945: BGP(0): Revise route installing 1 of 1 routes for 10.50.252.0/24 -> 147.225.59.241(main) to main IP table

Sep 1 01:07:10.945: BGP(0): 147.225.59.241 send unreachable 10.50.252.0/24

Sep 1 01:07:10.945: BGP(0): 147.225.59.241 send UPDATE 10.50.252.0/24 -- unreachable

Sep 1 01:07:10.945: BGP(0): route 10.50.252.0/24 down

Sep 1 01:07:10.949: BGP(0): 147.225.59.241 rcv UPDATE about 10.50.252.0/24 -- withdrawn

Sep 1 01:07:10.949: BGP(0): no valid path for 10.50.252.0/24

Sep 1 01:07:10.949: BGP(0): nettable_walker 10.50.252.0/24 no best path

Sep 1 01:07:10.953: BGP(0): route 10.50.252.0/24 up

Sep 1 01:07:10.953: BGP(0): nettable_walker 10.50.252.0/24 route sourced locally

Sep 1 01:07:16.685: %SYS-5-CONFIG_I: Configured from console by chennaa on vty2 (100.9.254.100)

Sep 1 01:07:41.741: BGP(0): 147.225.59.241 send UPDATE (format) 10.50.252.0/24, next 147.225.59.242, metric 0, path Local

Sep 1 01:07:41.773: BGP(0): 147.225.59.241 rcvd UPDATE w/ attr: nexthop 147.225.59.241, origin i, path 65000 65000

Sep 1 01:07:41.773: BGP(0): 147.225.59.241 rcvd 10.50.252.0/24

Sep 1 01:07:41.773: BGP(0): Revise route installing 1 of 1 routes for 10.50.252.0/24 -> 147.225.59.241(main) to main IP table

Sep 1 01:07:41.777: BGP(0): 147.225.59.241 send unreachable 10.50.252.0/24

Sep 1 01:07:41.777: BGP(0): 147.225.59.241 send UPDATE 10.50.252.0/24 -- unreachable

Regards Vinayak

mahmoodmkl · ‎09-03-2012

Hi,

Please let us know whether you want to route the traffic from Core 1 through IGP and advertise it through BGP once the remote site is down.

If it is the above scenario i suggest u look for BGP backdoor.

Thanks

Vinayaka Raman · ‎09-03-2012

Nope..I want cr1 to route via ebgp to reach the remote site and advertise the same route when remote site is down

Sent from Cisco Technical Support iPad App

Regards Vinayak

Giuseppe Larosa · ‎09-03-2012

Hello Vinayaka,

from the debug output that you have provided the behaviour is the following

>>

Sep 1 01:03:05.931: BGP(0): route 10.50.252.0/24 up

1)Sep 1 01:03:05.931: BGP(0): nettable_walker 10.50.252.0/24 route sourced locally

2) Sep 1 01:03:36.691: BGP(0): 147.225.59.241 send UPDATE (format) 10.50.252.0/24, next 147.225.59.242, metric 0, path Local

3) Sep 1 01:03:36.711: BGP(0): 147.225.59.241 rcvd UPDATE w/ attr: nexthop 147.225.59.241, origin i, path 65000 65000

Sep 1 01:03:36.711: BGP(0): 147.225.59.241 rcvd 10.50.252.0/24

4) Sep 1 01:03:36.711: BGP(0): Revise route installing 1 of 1 routes for 10.50.252.0/24 -> 147.225.59.241(main) to main IP table

Sep 1 01:03:36.711: BGP(0): 147.225.59.241 send unreachable 10.50.252.0/24

Sep 1 01:03:36.711: BGP(0): 147.225.59.241 send UPDATE 10.50.252.0/24 -- unreachable

After BGP withdrawn of subnet 10.50.252.0/24 from BGP peer 147.225.59.241

the locally generated BGP route (result of redistribution of the floating static route) is locally installed. 1)

The locally installed route is sent to the eBGP peer 147.225.59.241 2)

As soon as BGP peer receives the route 10.50.252.0/24 it sends back a new BGP update. 3)

The new eBGP update is installed in the IP routing yable with next-hop 147.225.59.241 for its higher weight 40000 ( I suppose).

At this point we cannot see in debug output, but the local node stops to advertise the local route and then the eBGP peer 147.225.59.241 sends an unreachable and the route is removed from routing table.

All this process repeats multiple times in the debug output with the result that the route is not successfully advertised to the MPLS cloud as it would be expected.

The real issue is why the eBGP peer 147.225.59.241 sends back the route for IP subnet 10.50.252.0/24 after having received it from the local CE node. ( point 3) in the log selection )

This should not happen the route should be accepted and propagated to the the MPLS backbone.

To further investigate it would be necessary to see configuration of BGP peer

147.225.59.241 to understand its behaviour.

Hope to help

Giuseppe

Vinayaka Raman · ‎09-04-2012

thank you..i am working with proivder to get the PE configuration..will keep you posted..

Regards Vinayak

milan.kulik · ‎09-04-2012

Hi,

you are using the same BGP AS number in your Data Centre and the remote site, aren't you?

I believe the problem might be the as-overide configured on the PE router.

Without that, your CR1 router would refuse it's 10.50.252.0/24 prefix advertised back by the PE router.

So you need to distinguish the 10.50.252.0/24 prefix advertised by the remote site and the same prefix advertised back from the PE only.

You could add some community to the prefix when advertised by the remote site, e.g.

And modify the route-map increase_weight to match the community addtionally.

Or you could prepend the AS number 5 times to the prefix when advertised by the remote site.

And match the AS_PATH to include 65000 5 times again additionally in the route-map increase_weight.

HTH,

Milan

Vinayaka Raman · ‎09-04-2012

Hello Milan,

Thanks for the note.

BUT..

Before I tried implementing this configuration on data center, I actually tried this simulating in one of router connected to the same MPLS mesh and it worked fine.

This remote site also has the same AS number.

This is the configuration...It is a lab router but connected to our mpls cloud

LAB2821-2#show run | s bgp

router bgp 65457

bgp log-neighbor-changes

network 10.40.220.248 mask 255.255.255.248

network 10.200.1.26 mask 255.255.255.255

network 100.31.3.16 mask 255.255.255.248

network 100.172.136.0 mask 255.255.255.0

network 192.168.24.0

aggregate-address 10.40.220.0 255.255.252.0 summary-only

neighbor 152.164.152.169 remote-as 65000

I added a redistribute static and an in bound route-map to increase the weight. But I did not test for same subnet..

It worked well..

However, I will think about this ..

For community attribute I need to work with the provider for allowing it.

As path length should be easy and in my hands

Regards Vinayak

Vinayaka Raman · ‎09-07-2012

please find PE configuration

Remote site PE configuration:

PE :152.177.186.242

RP/0/7/CPU0:bdt2ge01#show running-config router bgp 65000 vrf V292060:O
Fri Sep 7 10:54:21.481 UTC
router bgp 65000
vrf V292060:OwensCorning
rd 65000:292060
bgp bestpath med always
address-family ipv4 unicast
   redistribute connected route-policy Concord
   redistribute static
!
neighbor 152.177.186.242
   remote-as 65457
   timers 12 36
   address-family ipv4 unicast
    route-policy pass-all-in in
    maximum-prefix 25000 90
    route-policy pass-all-out out
    as-override
   !
!
!
!

Data Center site PE configuration:

RP/0/7/CPU0:bdt2ge01#

Backup - Lyon

lyones02#show config | b address-family ipv4 vrf V116532:O
address-family ipv4 vrf V116532:OwensCorning
no synchronization
bgp suppress-inactive
redistribute connected route-map Concord
redistribute static
neighbor 68.139.65.250 remote-as 65457
neighbor 68.139.65.250 timers 12 36
neighbor 68.139.65.250 activate
neighbor 68.139.65.250 as-override
neighbor 68.139.65.250 route-map RT_FLT in
neighbor 68.139.65.250 maximum-prefix 25000 90
neighbor 147.225.59.242 remote-as 65457
neighbor 147.225.59.242 timers 12 36
neighbor 147.225.59.242 activate
neighbor 147.225.59.242 as-override
neighbor 147.225.59.242 route-map RT_FLT in
neighbor 147.225.59.242 maximum-prefix 25000 90
exit-address-family
!

Regards Vinayak

milan.kulik · ‎09-07-2012

Hi,

I still believe it should be possible to configure on your HQ CE router a route-map denying the prefix 10.50.252.0/24 received from the PE with AS_PATH=65000 65000.

So you only need to be sure that under normal conditions the AS_PATH is different - by prepending on the remote site, e.g., if necessary.

BR,

Milan

Vinayaka Raman · ‎09-07-2012

Hi Milan, I rephrase my requirement.

I wanted HQ and rest of the remote site to route via MPLS full mesh, as long as remote site MPLS is up. This is a normal scenario in MPLS.

When my remote site MPLS is down, I want HQ to advertise this prefix so that all rest of the remote sites can now route via HQ.

I did not understand why do we need to block the prefix received by HQ CE ? Please explain.

Regards Vinayak

milan.kulik · ‎09-07-2012

Hi,

as Giuseppe showed in his reply, when the remot site stops advertising the prefix, your CE router starts to advertise it to the PE correctly:

Sep 1 01:03:05.931: BGP(0): route 10.50.252.0/24 up

1)Sep 1 01:03:05.931: BGP(0): nettable_walker 10.50.252.0/24 route sourced locally

2) Sep 1 01:03:36.691: BGP(0): 147.225.59.241 send UPDATE (format) 10.50.252.0/24, next 147.225.59.242, metric 0, path Local

But the PE is advertising that prefix back to your CE router:

3) Sep 1 01:03:36.711: BGP(0): 147.225.59.241 rcvd UPDATE w/ attr: nexthop 147.225.59.241, origin i, path 65000 65000

Sep 1 01:03:36.711: BGP(0): 147.225.59.241 rcvd 10.50.252.0/24

Due to the weight attribute configured on your CE router for ALL prefixes received from the PE this prefix beats the prefix originated by your CE :

4) Sep 1 01:03:36.711: BGP(0): Revise route installing 1 of 1 routes for 10.50.252.0/24 -> 147.225.59.241(main) to main IP table

Sep 1 01:03:36.711: BGP(0): 147.225.59.241 send unreachable 10.50.252.0/24

Sep 1 01:03:36.711: BGP(0): 147.225.59.241 send UPDATE

10.50.252.0/24 -- unreachable

To break this deadlock you need to refuse the prefix received in 3). (As it would if the as-override were not configured on the PE router.)

And that's what I'm suggesting.

HTH,

Milan

Giuseppe Larosa · ‎09-07-2012

Hello Vinayaka,

Milan is on spot with his suggestion.

The idea is to make the correct BGP advertisement sent by remote site different from the reflected back advertisement that the SP PE node is sending to HQ CE during the failure.

The simplest criteria is the AS path length and this is Milan's idea.

So or you perform AS path prepending on the HQ CE when advertising the backup route or you perform it on remote site when advertising the primary route.

At this point you can discriminate inbound the reflected route and deny it based on prefix and AS path.

For the AS override present in the PE node each instance of your BGP AS number should be substituted with AS 65000 ( provider AS to you).

In any case the PE node behaviour is not correct even if configured with AS override it should not reflect back the route and Milan's suggestion is a good workaround.

Note: I haven't seen anything strange in PE configuration I see that it is an IOS XR device,

Hope to help

Giuseppe