[c-nsp] BGP causing dropped packets

[Tim Devries]

Hi,

 

I'm using  bgp to run with a customer on my 5505, essentially to deliver
only two default routes which I set on the CPE router using the ip
default-network command.

 

5505   192.168.2.37

  |

Fiber

  |

2621    192.168.2.38

 

The customer setup also involves another 2621 connected to another 5505, but
there is no issue there so I will leave the diagram as above for brevity.
My problem is that when I shut the eBGP session down on either end, I am
able to ping the directly attached router without any packet loss.  As soon
as the BGP session is established massive packet loss occurs on that link.
I try and ping the directly connected upstream neighbor and I see packets
being dropped all over the place.  Not so when I turn off BGP on either side
though.

 

I have tried swapping ports/RSMs/Routers on my side and swapping routers at
the client side and still see this issue.  The odd thing is the client
router used to be running a BGP session over frame which worked fine, but
when we moved interfaces to 10M Ethernet (and moved our side from a 7200 to
a 5505) this issue appeared, and despite trying a lot of things, it won't go
away.  I have other core BGP peers on that 5505 that have no issues.

 

5505 - RSM IOS 12.2(23)

2621 - Version 12.3(15b)

 

5505 Relevant config:

 

interface Loopback0

 ip address 216.249.x.y 255.255.255.255

 

interface Vlan39

 description customerA

 ip address 192.168.2.37 255.255.255.252

 mls rp vtp-domain mydomain

 mls rp ip

 

 router bgp 13802

 no synchronization

 bgp log-neighbor-changes

 timers bgp 10 20

 neighbor 192.168.254.5 remote-as 65516

 neighbor 192.168.254.5 description - 

 neighbor 192.168.254.5 ebgp-multihop 2

 neighbor 192.168.254.5 password 7 xxyy

 neighbor 192.168.254.5 update-source Loopback1

 neighbor 192.168.254.5 weight 300

 neighbor 192.168.254.5 prefix-list customerA in

 neighbor 192.168.254.5 distribute-list 2 out

 

ip route 192.168.254.5 255.255.255.255 192.168.2.38

 

ip prefix-list customerA seq 1 permit x.x.x.y

ip prefix-list customerA etc.

 

access-list 2 permit x.x.x.y

access-list 2 permit etc.

 

Customer 2621

 

interface Loopback0

 description Loopback for BGP

 ip address 192.168.254.5 255.255.255.255

 no ip proxy-arp

 

interface FastEthernet0/0

 ip address 192.168.2.38 255.255.255.252

 speed 10

 full-duplex

 

router bgp 65516

 no synchronization

 bgp log-neighbor-changes

 network 216.249.x.a mask 255.255.255.248

 network 216.249.x.b mask 255.255.255.240

 network 216.249.x.c mask 255.255.255.224

 neighbor 216.249.x.y remote-as 13802

 neighbor 216.249.x.y description 

neighbor 216.249.x.y ebgp-multihop 2

 neighbor 216.249.x.y update-source Loopback0

 neighbor 216.249.x.y password 7 xxxxxxxxxxxxxx

 neighbor 216.249.x.y weight 200

 

 neighbor 216.249.x.x remote-as 65516

 neighbor 216.249.x.x next-hop-self

 neighbor 216.249.x.x password 7 xxxxxxxxxxxxxxx

 neighbor 216.249.x.x weight 200

 

ip default-network 152.63.0.0

ip default-network 206.24.0.0

 

ip route 216.249.32.138 255.255.255.255 192.168.2.37

 

It looks pretty vanila, so I'm a bit at a loss.  I have MLS/CEF running on
the 5505 and CEF on the 2621, other than that nothing fancy on the 2621,
HSRP and a few static routes.  Memory is

fine on both ends as well.

 

What could be causing this packet loss when I run BGP?

 

Thanks,

 

Tim Devries

 

North Rock Communications Ltd.

Technical Solutions Specialist | Network

Washington Lane

Hamilton, Bermuda HM 1661

Telephone: 441-540-2700 ext. 4114