07-29-2009 05:50 PM - edited 03-04-2019 05:35 AM
I am trying to setup a Multisite Multihoming WAN configuration between two sites and three ISP's. I have two routers at site A both on different ISP's and a single router at site B on another ISP. I am able to control traffic at site A using a combination of local preference and AS prepending to send traffic to the router of my chosing. I have a similar configuration setup at site B also with local preference AS prepending, however the I cannot get the traffic to cooperate. Here is the current BGP configuration at site B.
router bgp as_number
no synchronization
no bgp enforce-first-as
bgp log-neighbor-changes
network x.x.x.x mask 255.255.255.0
network y.y.y.y mask 255.255.255.0
neighbor z.z.z.z remote-as 32007
neighbor z.z.z.z ebgp-multihop 255
neighbor z.z.z.z send-community
neighbor z.z.z.z.z route-map as out
neighbor z.z.z.z.z remote-as remote_as
no auto-summary
route-map as permit 10
match as-path 10
set as-path prepend as_number as_number as_number as_number as_number
set community remote_as:80
Any help is greatly appreciated
07-29-2009 10:09 PM
Hi Ryan,
If you have one connection to one ISP at site B, then I don't quite get what traffic characteristic you would like to influence.
Can you please clarify?
Thanks:
Istvan
07-30-2009 06:17 AM
What I am attempting to accomplish with this is the ability to be able to announce the prefix that I am currently using at Site A with Site B so that if I am unable to reach Site A for whatever reason the Prefix will fail over to Site B.
I have narrowed the issue down to the fact that despite the fact that I have configured the prefix at site A to be announced at site B it is actually not being announced due to the non-existence of the route in the routing table. I have tried to add an ip route x.x.x.x 255.255.255.0 null0 200 route but that seems to send all traffic destined for the x.x.x.x network to a black hole.
Any input is greatly appreciated.
Thank you
07-30-2009 09:38 AM
This may be long but I need to understand.
Site A - Primary
Site B - Back-up
Site A announce 10.1.1.0/24
Site B announce 10.1.1.0/24 higher meds
I understand the IP's are not specific for you, it helps me see it.
From your routers have you verified the BGP announcements?
sh ip bgp neigh
Have you gone to a looking glass to see the routes?
sh ip bgp
sh ip bgp 10.1.1.0
Can you post the config for both sites?
router bgp
routes
route maps
prefix-lists
Also a sh ip bgp neigh
You can replace public IP's with private, it would help.
07-30-2009 09:57 AM
here are the scrubbed bgp configurations from the routers:
Site A Router 1
router bgp 1
no synchronization
bgp log-neighbor-changes
network 10.1.1.0 mask 255.255.255.0
neighbor 172.16.0.209 remote-as 2828
neighbor 172.16.0.209 ebgp-multihop 255
neighbor 172.16.0.209 send-community
neighbor 172.16.0.209 route-map AS-1_out out
no auto-summary
route-map AS-1_out permit 10
set community 2828:1512
Site A Router 2
router bgp 1
no synchronization
bgp log-neighbor-changes
network 10.1.1.0 mask 255.255.255.0
neighbor 192.16.2.237 remote-as 174
neighbor 192.16.2.237 ebgp-multihop 255
neighbor 192.16.2.237 send-community
neighbor 192.16.2.237 route-map PREPEND out
no auto-summary
route-map PREPEND permit 10
set as-path prepend 1 1 1 1
set community 174:70
Site B Router 1
router bgp 1
no synchronization
no bgp enforce-first-as
bgp log-neighbor-changes
network 10.1.1.0 mask 255.255.255.0
network 10.2.1.0 mask 255.255.255.0
neighbor 206.223.138.126 remote-as 2
neighbor 206.223.138.126 send-community
neighbor 206.223.138.126 route-map AS1 out
neighbor 206.223.138.254 remote-as 2
neighbor 206.223.138.254 send-community
neighbor 206.223.138.254 route-map AS14739 out
no auto-summary
route-map AS1 permit 10
match as-path 10
set as-path prepend 1 1 1 1 1
set community 2:80
BGP table version is 6722447, local router ID is 206.223.138.192
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
*> 10.2.1.0.0/24 0.0.0.0 0 32768 i
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