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Webcast-Catalyst9k
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BGP multi-router multi-homing

I have a location with 2 routers, each connected to a different ISP. We have an AS #.(lets say its 40000). What do I need to do to make ISP 1 on ROUTER 1 more preferred outbound for all traffic, and ISP 2 on ROUTER 2 more preffered for all inbound traffic including our Live IP's(5.5.5.5 255.255.255.0)?

I've already found the examples on the site, but its not working since they all have 2 live ip schemes and we only have 1.

NETWORK:

ISP1(AS 3000)-->ROUTER1(10.1.1.1/24)

---CORE SWITCH---

(10.1.1.2/24)ROUTER2<--(AS 700)ISP2

sample bgp config:

router bgp 40000

no synchronization

bgp log-neighbor-changes

bgp dampening

network 5.5.5.0

neighbor 10.1.1.2 remote-as 40000

neighbor 10.1.1.2 next-hop-self

neighbor 4.4.4.1 remote-as 3000

neighbor 4.4.4.1 version 4

no auto-summary

router bgp 40000

no synchronization

bgp log-neighbor-changes

bgp dampening

network 5.5.5.0

neighbor 10.1.1.1 remote-as 40000

neighbor 10.1.1.1 next-hop-self

neighbor 3.3.3.1 remote-as 700

neighbor 3.3.3.1 version 4

no auto-summary

1 REPLY
Silver

Re: BGP multi-router multi-homing

Hi,

Well if you want to prefer a path for all outgoing traffic then I would suggest that you configure the local-preference value on the router to ISP1 to something greater than the default of 100, you can do this via the "bgp default local-pref" command;

http://www.cisco.com/en/US/docs/ios/iproute/command/reference/irp_bgp1.html#wp1012875

This will ensure that all BGP routers will prefer this outgoing path than any other, assuming you do not config any Weight parameter on other BGP routers.

For incoming, you can use MED or AS Path Pre-pending, I would suggest you try as path pre-pending, to do this, create route-map and then set the as pre pend statements accordingly,

eg,

route-map setpre

set as-path prepend 40000 40000

and apply to bgp neighbour outgoing, ISP1.

Check out the BGP best path process to find out how this works...

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094431.shtml

HTH

LR

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