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  1. Member tomset's Avatar
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    #1

    Default Best way to send EIGRP default route to a single router?

    Hey guys,

    Quick question - I have a hub and spoke network at work and I'm looking for the best way to propagate a default route to my spoke routers running EIGRP. I want to be able to send this default route via EIGRP to the spoke router without other routers learning about this default route. What's the best way to do this?

    (I know I could just do a "ip route 0.0.0.0 0.0.0.0 *next hop*" but I'm looking for a way to do this using EIGRP. Also, doesn't the "ip default-network" command propagate the default route to all EIGRP routers?)
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    #2
    HUB:
    -if)#ip summary-address eigrp 1 0.0.0.0 0.0.0.0

    SPOKE:
    Gateway of last resort is 10.1.1.1 to network 0.0.0.0

    10.0.0.0/24 is subnetted, 1 subnets
    C 10.1.1.0 is directly connected, Serial1/0
    D* 0.0.0.0/0 [90/2297856] via 10.1.1.1, 00:00:06, Serial1/0

    Would that meet your needs?
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  4. Member tomset's Avatar
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    #3
    I appreciate the quick reply, it looks like that would work.

    Here's a related question - which is generally regarded as the better method for spoke routers:

    1. Use a default static route (ip route 0.0.0.0 0.0.0.0 *next hop*) and not use any routing protocols on the spoke router. The hub router would be running EIGRP and redistribute the static route going to the spoke router.

    OR

    2. Use EIGRP on the spoke router (assume all other routers are using EIGRP) and reduce the size of the spoke router's routing table with ip summary-address, distribute lists, or ip default-network. Also, use the "EIGRP stub" command on the spoke router.


    Is there an advantage of using one method over the other??

    It seems to me that just using a static default route would be best because the router doesn't have to use CPU/memory resources while running EIGRP. If anyone could give me some advantages of running EIGRP in this instance, I would appreciate it!
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    #4
    this may help

    http://www.cisco.com/warp/public/105/default.html

    the summary-address is and eigrp specific command
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  6. Member tomset's Avatar
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    #5
    Quote Originally Posted by darkuser
    this may help

    http://www.cisco.com/warp/public/105/default.html

    the summary-address is and eigrp specific command
    Yeah, I've read through that document before. However, it only describes the various options regarding the configuration of gateways of last resort. There's no discussion on which method is preferred.

    I'd like to keep all of my routers in the EIGRP domain for the sake of consistency, but I'm struggling to find a good reason to do so on my spoke routers when a static default route seems to be the most efficient way to reach the hub routers.
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    #6
    I just happen to read about this yesterday. According to the CCIE TCP/IP Routing, using eigrp stub seems to be the method they mention when configuring routers in a hub and spoke environment. The exact reason why one would use stub routing over static routes, or vice versa, is a good question.
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  8. Netlurker cisco_trooper's Avatar
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    #7
    Don't forget about the subnets connected to your stub router. How is the rest of your network going to know how to reach these subnets?

    Stub routing allows the stub router to advertise information regarding its connected and summary addresses, but keeps the stub router from being queried, eliminating the possibility that stub router will cause stuck in active conditions or other instabilities throughout the rest of the network.

    Hope that helps.
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  9. Netlurker cisco_trooper's Avatar
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    #8
    As for the default route, I would configure a static at the hub router and advertise it via EIGRP.

    At your stub routers I would configure a distribute list to accept only the default route.

    If there are any routers connected to your hub that you do not want to receive the default route, configure a distribute list so that they don't accept that default route.

    With this solution you have the benefits of running EIGRP on those stub routers, so you don't have to configure static routes to everything. This should scale better.

    Hope that helps.
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    #9
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