BGP Question

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Jul 29th, 2009
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I am trying to setup HSRP to Provide Redundancy in a Multihomed BGP Network and need some assistance. We basically have a firewall cluster which is connected to both the primary ISP router and the backup ISP router .I am trying to configure BGP between the primary ISP CPE router and the backup ISP CPE router .I would also like to setup HSRP so that the firewall just points to the HSRP ip as the gateway . My question is , can we setup HSRP in such a way that if there is a BGP routing issue in the primary ISP cloud , the traffic automatically fails over to the backup . I was going through Cisco website and i found that there are three ways of configuring HSRP tracking . One is to track the physical serial interface , the other is to track the line protocol on the serial interface and the third one is to track a route advertized by the primary ISP . Is there a way to track a combination of these three ? Also is it possible to track the default BGP route advertized by the ISP ? Any help is greatly appreciated .

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Giuseppe Larosa Wed, 07/29/2009 - 10:45
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Hello Sireesha,

you can combine different tracking and each one will decrement the HSRP priority by 10 by default.

The difference between the two nominal priorities decide how many trackings have to fail before switchover.


HSRP supports also the use of object tracking that provides more flexibility for example the usage of probes to test reachability of some key address of ISP1.


However, if you provide an horizontal link between the two border routers and you implement an iBGP session between the two devices you are fine and the HSRP check doesn't need to be so "smart"


Hope to help

Giuseppe


sireesha.jasthi Wed, 07/29/2009 - 12:04
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Thanks for your prompt response , do you have any documentation on different ways of setting up HSRP for BGP failover ? Please advise...

Joseph W. Doherty Wed, 07/29/2009 - 18:30
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"I am trying to configure BGP between the primary ISP CPE router and the backup ISP CPE router"


BTW, if you do that, you wouldn't really need HSRP tracking, although it would avoid a needless hop through your primary edge router. Reason I mention this, is the situation such that avoiding the extra hop is worth the HSRP tracking implementation and support effort?


" Is there a way to track a combination of these three ?"


If you track a route from the ISP, it should be (immediately?) withdrawn if, for instance, the interface goes down. So, is multiple tracking really necessary?

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