08-08-2009 06:12 AM - edited 03-04-2019 05:41 AM
I have two routers in the same AS connected to the same upstream ISP. i'm trying to use router A and its link to the internet primarily and router B and its link only for backup.
my outbound plan is to have the BGP session for link A install a route to 0.0.0.0 and if this fails then a static route with a high metric to router B will be able to carry all my traffic.
my inbound plan is to advertise my class C via both BGP links however router B is setting the metric to 200 via a routemap.
On route A The ISP is only sending the origin route (0.0.0.0/0) but they are also withdrawing lots of routes as the topology of the internet changes. I'm not sure if this is interfering with my 0.0.0.0/0 but i just don't see where it is withdraw in the debugs yet sh ip bgp stats say 1 route received and 1 withdrawn.
I have tried a number of configurations but each of them usually end up with either a) the incoming route is blocked by my own route map or b) the route is received then withdrawn.
how do i get their origin route to stick in my route tables?
Thanks in advance,
Leon
08-08-2009 11:45 AM
Plz go thru below config ..............
It will help you to filter the route from ISP ..........Using prefix-list
router bgp XXXX
no synchronization
bgp log-neighbor-changes
network X.X.X.X mask 255.255.252.0 { Local Network }
network X.X.X.X mask 255.255.255.0
network X.X.X.X mask 255.255.255.0
neighbor X.X.X.X remote-as 6666
neighbor X.X.X.X timers 30 90
neighbor X.X.X.X default-originate { 1st ISP }
neighbor X.X.X.X weight 150 { 2 nd Preffered Path }
neighbor X.X.X.X prefix-list AAA in { Incoming Traffic }
neighbor X.X.X.X remote-as 6666
neighbor X.X.X.X timers 30 90
neighbor X.X.X.X default-originate { 2st ISP }
neighbor X.X.X.X weight 200 { 1 st Preffered Path }
neighbor X.X.X.X prefix-list AAA in { Incoming Traffic }
no auto-summary
ip prefix-list AAA seq 10 permit 0.0.0.0/0 { Allow only Default Route From ISP }
08-08-2009 11:48 AM
Plz go thru below config ..............
It will help you to filter the route from ISP ..........Using prefix-list
router bgp XXXX
no synchronization
bgp log-neighbor-changes
network X.X.X.X mask 255.255.252.0 { Local Network }
network X.X.X.X mask 255.255.255.0
network X.X.X.X mask 255.255.255.0
neighbor X.X.X.X remote-as 6666
neighbor X.X.X.X timers 30 90 { 1st ISP }
neighbor X.X.X.X weight 150 { 2 nd Preffered Path }
neighbor X.X.X.X prefix-list AAA in { Incoming Traffic }
neighbor X.X.X.X remote-as 6666
neighbor X.X.X.X timers 30 90 { 2st ISP }
neighbor X.X.X.X weight 200 { 1 st Preffered Path }
neighbor X.X.X.X prefix-list AAA in { Incoming Traffic }
no auto-summary
ip prefix-list AAA seq 10 permit 0.0.0.0/0 { Allow only Default Route From ISP }
08-08-2009 12:59 PM
thanks a lot. this is really getting close but i have a little problem..
Aug 8 16:45:32.988: BGP(0): x.x.x.25 rcvd 0.0.0.0/0
Aug 8 16:45:32.992: BGP(0): Revise route installing 1 of 1 routes for 0.0.0.0/0 -> x.x.x.26(main) to main IP table
Aug 8 16:45:32.992: BGP(0): route 0.0.0.0/0 down
08-11-2009 05:38 PM
please post your current config.
i gathered that
- you have 2 routers to the same isp running bgp.
- link A is primary for in and out traffic,
- link B is backup
- isp only advertise default route to you.
08-11-2009 08:48 PM
08-16-2009 09:29 PM
Hi Leon,
Check this link,it might be helpful.
http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00800945bf.shtml
Chao
Vishwa
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