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Community Member

How to configure the default route in a HRSP and BGP multihomed ?

How can I configure the default route for outgoing traffic in the HSRP and multihomed Border Gateway Protocol (BGP) network connecting to two ISPs?

There are two routers – Router 1 and Router 2 are in AS 9999, which has external BGP (eBGP) peering with ISP-A (AS 300) and ISP-B (AS 400) respectively. R1 and R2 are also configured for HSRP over a common Ethernet segment. Hosts on the same Ethernet segment have a default route pointing towards the HSRP address.

To optimize the memory usage, I use the AS_PATH to filter incoming full BGP updates so that Router 1 and Router 2 accept only routes originated from the ISP and its directly connected Autonomous Systems ISP. The rest of the networks which don't belong to the ISPs and their customer AS follow the default route pointing toward Router 1’s ISP-A.

How can we configure the outgoing default to Router 1's ISP? redistribute static route into BGP perhaps ..??

In the event of link failure toward Router1's ISP-A, how to configure the default route to follow Router 2's ISP-B ? floating static route perhaps ??

3 REPLIES

Re: How to configure the default route in a HRSP and BGP multiho

Have HSRP track the R1 and R2 ISP facing interface so if it goes down HSRP will fail over. Second, you can have both ISPs send you a BGP default route (neighbor x.x.x.x default-originate) and you can set a higher local preference on ISP A's default route.

Floating statics would also work.

Hope that helps.

Steve

Community Member

Re: How to configure the default route in a HRSP and BGP multiho

The HSRP track is what I plan to implement. If I request both ISPs to send the full route including the BGP default route, but do you think the following AS-Path would filter incoming BGP default route.

ip as-path access-list 85 permit ^701_[0-9]*$

Thanks !!

Andy

Re: How to configure the default route in a HRSP and BGP multiho

In that example AS701 would originate the default route (path=701), so it would match your as-path and be permitted into your AS.

Steve

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