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ebgp-multi-hop connection

wgranada1
Level 1
Level 1

Hi everyone how are things? I have a quick quesiton here. I'm trying to create a ebgp-multihop connection but the problem is it never establishes. I don't have any access-list on the interface so it is wide open, I've been looking at this for a while now so everything looks ok to me. I know I'm missing something but anyways here is my config:

router bgp 60301

neighbor 192.168.50.50 remote-as 64637

neighbor 192.168.50.50 ebgp-multihop 5

neighbor 192.168.50.50 update-source FastEthernet1/15

neighbor 192.168.50.50 version 4

neighbor 192.168.50.50 soft-reconfiguration inbound

neighbor 192.168.50.50 prefix-list from-interim in

neighbor 192.168.50.50 prefix-list to-interm out

when I do a sh ip bgp neigh 192.168.50.50 I see the bgp state as active but not established. I've done a soft clear and clear but nothing as of yet. Thank you in advance!!

1 Accepted Solution

Accepted Solutions

Warren,

You can use the loopback interface as the update-source for the eBGP and iBGP session.

Regards,

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México

View solution in original post

23 Replies 23

Rick Morris
Level 6
Level 6

Who is providing the number of hops?

Do you know what it is suppose to be?

Is this peering with a vendor or yourself?

If your peer is directly connected to you then you will not have multiple hops, if you are peering with a router on the other side of a router then your hop count will be 2 and so on.

Martin Parry
Level 3
Level 3

Hi

Do you have a route to 192.168.50.50 in your routing table? as you are configuring this as multihop I am assuming that you are not directly connected to the 192.168.50.50 interface.

Thank you for the quick response I will try to answer your questions at once. I'm peering with another router that isn't mine inorder for me to get to the 192.168.50.50 peer I have to go through my eth 1/15 which is connected to his 10.16.4.176/30(I'm 177 and he is 178) Yes I have a static route that points to 10.16.4.178:

ip route 192.168.50.50 255.255.255.255 10.16.4.178

Harold Ritter
Cisco Employee
Cisco Employee

Warren,

A couple of things you might want to check.

1. Is there a route to 192.168.50.50?

2. Try an extended ping to 192.168.50.50 with the address of fa1/5 as the source.

3. Make sure that the neighbor address on the side matches the address of fa1/5 and that 192.168.50.50 matches the source addresses used on the BGP peer.

Regards,

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México

Yes there is a route:

sfschirt4#sh ip route 192.168.50.50

Routing entry for 192.168.50.50/32

Known via "static", distance 1, metric 0

Redistributing via ospf 1

Routing Descriptor Blocks:

* 10.16.4.178

Route metric is 0, traffic share count is 1

Also I can ping:

sfschirt4#ping 10.128.184.105 source 172.19.80.9

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 192.168.50.50, timeout is 2 seconds:

Packet sent with a source address of 10.16.4.177

!!!!!

Success rate is 100 percent (5/5), round-trip

min/avg/max = 1/1/4 ms

Are you able to see the configuration of there end to check what they have configured for your peering?

Yes he has emailed me his config:

router bgp 64637

no synchronization

neighbor 172.19.103.45 remote-as 64821

neighbor 172.19.103.45 ebgp-multihop 5

neighbor 172.19.103.45 update-source Loopback1

neighbor 172.19.103.45 soft-reconfiguration inbound

neighbor 172.19.103.45 prefix-list Routes-from-Futures in

neighbor 172.19.103.45 prefix-list Routes-to-Futures out

no auto-summary

172.19.103.45 is my loopback address I don't have the routing though. He is also away from the office so it will be hard to get a hold of him today. Didn't want to wait till monday just trying to make sure I'm good on my end.

this remote as is wrong.

it has 64821

and you have configured on your end

router bgp 60301

Warren

Your bgp AS number

router bgp 60301

So why does his config say

neighbor 172.19.103.45 remote-as 64821 ie.

AS = 64821

Jon

Warren,

As other mentionned, the remote-as is wrong and should be 60301.

Also, 172.19.103.45 is your loopback address, so you should configure your loopback address as the update-source rather than fa1/5.

One more thing, make sure loopback1 address on the remote side is 192.168.50.50, as this is the address used as the update-source.

Regards,

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México

Hi

The configs dont seem to match at all.

The AS number is not correct.

You are trying to peer with a source address of your fastethernet interface, and they are trying to peer with your loopback interface.

I was looking over the config and noticed that I have an internal peering as well that is also using the loopback as well if I source from teh new connection as suggested will that affect what is already there?

router bgp 64821

no synchronization

bgp router-id 172.19.103.45

bgp log-neighbor-changes

redistribute ospf 1 match internal external 1 external 2 route-map to-VNET

neighbor VNET peer-group

neighbor VNET remote-as 64820

neighbor VNET update-source FastEthernet1/0

neighbor VNET version 4

neighbor VNET soft-reconfiguration inbound

neighbor VNET prefix-list from-VNET in

neighbor VNET prefix-list to-VNET out

neighbor VNET route-map from-VNET-LOCALPREF in

neighbor VNET route-map to-VNET-PREPEND out

neighbor VNET filter-list 17 out

neighbor SFS-INTERNAL peer-group

neighbor SFS-INTERNAL remote-as 64821

neighbor SFS-INTERNAL update-source Loopback0

neighbor 10.128.184.105 remote-as 64637

neighbor 10.128.184.105 ebgp-multihop 5

neighbor 10.128.184.105 update-source FastEthernet1/15

neighbor 10.128.184.105 version 4

neighbor 10.128.184.105 soft-reconfiguration inbound

neighbor 10.128.184.105 prefix-list from-interim in

neighbor 10.128.184.105 prefix-list to-interm out

neighbor 172.19.98.50 peer-group VNET

neighbor 172.19.103.30 peer-group SFS-INTERNAL

no auto-summary

Warren,

"debug ip bgp" should give you a lot more information on why the session is not coming up.

Regards,

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México

Warren,

The extended ping should be to 192.168.50.50 rather than 10.128.184.105 and should also use the address of fa1/5 as the source.

Regards,

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
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