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BGP Question

Rick Morris
Level 6
Level 6

LAB Set-up

I have 2 CE routers running BGP with a PE router for site A

I have the mirror set-up for Site B

My issue is now running BGP between the two PE's and getting the routes to propagate between them.

How is this done?

CARRIER-A#sh ip bgp sum

BGP router identifier 210.1.1.1, local AS number 209

BGP table version is 2, main routing table version 2

2 network entries using 264 bytes of memory

3 path entries using 156 bytes of memory

3/1 BGP path/bestpath attribute entries using 444 bytes of memory

1 BGP AS-PATH entries using 24 bytes of memory

0 BGP route-map cache entries using 0 bytes of memory

0 BGP filter-list cache entries using 0 bytes of memory

Bitfield cache entries: current 1 (at peak 2) using 32 bytes of memory

BGP using 920 total bytes of memory

BGP activity 13/11 prefixes, 25/22 paths, scan interval 60 secs

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd

123.2.2.2 4 209 77 76 2 0 0 01:10:39 1

208.10.10.1 4 1000 8780 8692 2 0 0 01:13:04 1

208.10.10.2 4 1000 1482 1465 2 0 0 01:13:02 1

CARRIER-A#sh ip bgp neigh 123.2.2.2 adv

BGP table version is 2, local router ID is 210.1.1.1

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*> 63.10.10.0/24 208.10.10.1 0 100 0 1000 i

Total number of prefixes 1

CARRIER-A#sh ip bgp neigh 123.2.2.2 ro

BGP table version is 2, local router ID is 210.1.1.1

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

* i63.20.20.0/24 208.20.20.1 0 100 0 1000 i

Total number of prefixes 1

CARRIER-A#ping 63.20.20.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 63.20.20.1, timeout is 2 seconds:

.....

Success rate is 0 percent (0/5)

CARRIER-A#sh ip route 63.20.20.1

% Subnet not in table

CARRIER-A#sh ip bgp 63.20.20.1

BGP routing table entry for 63.20.20.0/24, version 0

Paths: (1 available, no best path)

Not advertised to any peer

1000

208.20.20.1 (inaccessible) from 123.2.2.2 (210.2.2.1)

Origin IGP, metric 0, localpref 100, valid, internal

router bgp 209

no synchronization

bgp log-neighbor-changes

neighbor 123.2.2.2 remote-as 209

neighbor 123.2.2.2 ebgp-multihop 2

neighbor 123.2.2.2 update-source Loopback10

neighbor 123.2.2.2 version 4

neighbor 208.10.10.1 remote-as 1000

neighbor 208.10.10.1 ebgp-multihop 2

neighbor 208.10.10.1 update-source Loopback0

neighbor 208.10.10.1 version 4

neighbor 208.10.10.1 default-originate

neighbor 208.10.10.1 route-map MONROE-IN in

neighbor 208.10.10.1 route-map MONROE-OUT out

neighbor 208.10.10.2 remote-as 1000

neighbor 208.10.10.2 ebgp-multihop 2

neighbor 208.10.10.2 update-source Loopback0

neighbor 208.10.10.2 version 4

neighbor 208.10.10.2 default-originate

neighbor 208.10.10.2 route-map MONROE-IN in

neighbor 208.10.10.2 route-map MONROE-OUT out

no auto-summary

24 Replies 24

Rick

Sorry for delay in replying but looks like Giuseppe has been helping out.

See you've made a few changes regarding AS numbers. Is this all you changed in configs ie. can i still use the configs you posted before.

Can you also post "sh ip route" from Carrier A, "sh ip route" from carrier B and "sh ip bgp"/"sh ip route" from CE-A in site B.

Promise i'll stay with it this time :-)

Jon

no worries Jon...I understand how things go throughout the day.

I have enjoyed this a lot and have seen you and Guiseppe comment on previous posts as well as others and knew I would get great guidance.

I am hoping to be on more and assist as you have done, even with my limited knowledge, it is stretching me.

Rick

Just had a look at configs. On carrier A & carrier B under bgp config can you change -

router bgp 209

synchronisation

to

router bgp 209

no synchronisation

Jon

Hello Rick,

Jon's right you need to disable synchronization too or each device waits for the IGP to have the route before passing the eBGP advertisement to the iBGP peer.

Hope to help

Giuseppe

This just keeps getting more weird.

I have made the change to no sync, but had done that before and it did not work, now it appears to be working.

So from the carrier to carrier I am able to ping:

CARRIER-A#sh ip bgp 63.20.20.1

BGP routing table entry for 63.20.20.0/24, version 3

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

Multipath: eBGP

Not advertised to any peer

64513

123.2.2.2 from 123.2.2.2 (210.2.2.1)

Origin IGP, metric 0, localpref 100, valid, internal, best

CARRIER-A#sh ip route 63.20.20.1

Routing entry for 63.20.20.0/24

Known via "bgp 209", distance 200, metric 0

Tag 64513, type internal

Last update from 123.2.2.2 00:44:00 ago

Routing Descriptor Blocks:

* 123.2.2.2, from 123.2.2.2, 00:44:00 ago

Route metric is 0, traffic share count is 1

AS Hops 1

Route tag 64513

CARRIER-A#sh ip bgp 63.20.20.1

BGP routing table entry for 63.20.20.0/24, version 3

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

Multipath: eBGP

Not advertised to any peer

64513

123.2.2.2 from 123.2.2.2 (210.2.2.1)

Origin IGP, metric 0, localpref 100, valid, internal, best

CARRIER-A#ping 63.20.20.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 63.20.20.1, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/3/4 ms

CARRIER-B#sh ip bgp 63.10.10.1

BGP routing table entry for 63.10.10.0/24, version 3

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

Not advertised to any peer

64512

123.1.1.2 from 123.1.1.2 (210.1.1.1)

Origin IGP, metric 0, localpref 100, valid, internal, best

CARRIER-B#sh ip route 63.10.10.1

Routing entry for 63.10.10.0/24

Known via "bgp 209", distance 200, metric 0

Tag 64512, type internal

Last update from 123.1.1.2 00:44:56 ago

Routing Descriptor Blocks:

* 123.1.1.2, from 123.1.1.2, 00:44:56 ago

Route metric is 0, traffic share count is 1

AS Hops 1

Route tag 64512

CARRIER-B#ping 63.10.10.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 63.10.10.1, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/4 ms

This is working, thank you!!!

Now I tried this one step in and it did not work......

HPTR001-A#ping 63.10.10.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 63.10.10.1, timeout is 2 seconds:

.....

Success rate is 0 percent (0/5)

HPTR001-A#sh ip bgp 63.10.10.1

BGP routing table entry for 0.0.0.0/0, version 7

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

Not advertised to any peer

209

123.2.2.1 from 123.2.2.1 (210.2.2.1)

Origin IGP, metric 0, localpref 100, valid, external, best

I am getting default routes from the PE router (Carrier B) I should just send my traffic to Carrier B and Carrier B does have it in its table it should get there, but it does not.

Sorry I feel like a big pain in the butt on this.

Hello Rick,

>> I have made the change to no sync, but had done that before and it did not work, now it appears to be working.

Before you had the same AS number on CE nodes so you couldn't see the effect of no sync command.

Hope to help

Giuseppe

ahh...you are correct!

Oh I wish I could blink my eyes and make it all work.

Now to figure out why I cannot ping end to end.

Rick

What device is HPTR001 ?

If you try a traceroute from that device how far do you get ?

Jon

in the topology it looks like this

hptr001a -- carrierB -- carrierA -- monr001a

I also have redundant connections at each customer edge

so in my rack it looks like this

monr001A

monr001B

carrierA

carrierB

hptr001A

hptr001B

monr001A | | hptr001A

|----carrierA----carrierB----|

monr001B | | hptr001B

HPTR001-A#traceroute 63.10.10.1

Type escape sequence to abort.

Tracing the route to 63.10.10.1

1 157.130.0.9 [AS 209] 0 msec 0 msec 0 msec

2 * * *

3 * * *

the 157.130.0.9 is the serial IP of the carrier router.

CARRIER-B#sh ip int b

Interface IP-Address OK? Method Status Protocol

FastEthernet0/0 172.16.0.2 YES manual up up

Service-Engine0/0 unassigned YES NVRAM administratively down down

FastEthernet0/1 unassigned YES NVRAM administratively down down

Serial0/0/0 157.130.0.9 YES manual up up

Serial0/1/0 157.130.0.13 YES manual up up

Serial0/3/0 unassigned YES unset administratively down down

Loopback0 123.2.2.1 YES manual up up

Loopback10 123.2.2.2 YES manual up up

Loopback100 210.2.2.1 YES manual up up

Found it.

My carrier routers did not know the routes between the CE connected routes.

I added redistribute connected so now all those routes are in the routing table and it worked.

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