3640 router, BGP-4, and 2x ISPs

Discussion in 'Cisco' started by darktiger, Jun 30, 2005.

  1. darktiger

    darktiger Guest

    First, I would like to say I my knowledge of BGP can fit on the edge
    of an atom. The other protocols, no problem, but BGP...

    We have 2x ISPs, an AT&T T1 and a 5.8Ghz backbone (3Mbps). We have one
    AS number and our ISP has their routers set in a way that allows our IP
    addresses from AT&T to flow over our 5.8Ghz. line...

    Here is our dilema, we don't exactly have the highest budget, so our
    router is a 3640. It has the 32MB Flash, 128MB DRAM. However, when I
    plug both the T1 and the Airspeed connection into the router, it
    reboots due to the high number of BGP routes. Our ISP was going to give
    us a new IOS version that was smaller, saying that it would free up
    some space, but that sounds like a duct-tape fix to me.

    I was reading online and saw that some people have their routers set
    to only have one set of BGP routes, but I have no clue what to search
    under to find more data on that. Also, with that method can our IP's
    still be routed over the active connection?

    With our current IOS+BGP config+only one ISP plugged in, our router
    bogs down every-so-often. It is fairly bad when you do a show run and
    get noting, at least show start still works...

    Any help would be appreciated. I really know very little about BGP.

    Scott Brown
    City of Sandy
    darktiger, Jun 30, 2005
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  2. First of all you've to setup default route to one of your upstream providers.
    In second step setup prefix-list on your bgp sessions to cut off prefixes longer
    than /24. If it dosen't help you'll have to cut more (/23 or more).

    Tomasz Paszkowski, Jun 30, 2005
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  3. Your ISP should be able to do this. Most ISPs that offer BGP ask you to
    tell them what set of routes you want them to send. The choices usually

    1) Just a default route
    2) Routes to the networks of the ISP and their directly-connected
    3) All routes

    Contact your ISP, tell them to send you just a default route, and you
    should be all set.
    Barry Margolin, Jul 1, 2005
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