EIGRP

Hey,

 

Why do we receive a /32 prefix with EIGRP ?

 

example :

Rack1SW1#sho ip route eigrp
     129.1.0.0/16 is variably subnetted, 8 subnets, 3 masks
D       129.1.3.128/25 [90/2172672] via 129.1.17.1, 00:00:16, Vlan17
D       129.1.3.0/25 [90/2172672] via 129.1.17.1, 00:00:16, Vlan17
D       129.1.13.0/24 [90/2170112] via 129.1.17.1, 00:00:16, Vlan17
D       129.1.13.3/32 [90/2170112] via 129.1.17.1, 00:00:16, Vlan17
D       129.1.23.2/32 [90/2682112] via 129.1.17.1, 00:00:16, Vlan17
D       129.1.23.0/24 [90/2682112] via 129.1.17.1, 00:00:16, Vlan17
     150.1.0.0/24 is subnetted, 4 subnets
D       150.1.3.0 [90/2298112] via 129.1.17.1, 00:00:17, Vlan17
D       150.1.2.0 [90/2810112] via 129.1.17.1, 00:00:17, Vlan17
D       150.1.1.0 [90/130816] via 129.1.17.1, 00:00:17, Vlan17

 

i mean why do we get the /32 routes and when ?

thx

 

Comments

  • because the mask configured on the interface is /32..

  • as a matter of fact the mask configure on the interface is a /24 mask

     

    thx,

    hadi

  • can u explain which type of interface it is ? and what the topology.. cos as per my knowledge eigrp do send the network mask in the routing updates..

    Peace

  • check lab 12 the eigrp section :)

     

    the links are p-2-p

  • You have a /24 in there as well.

    My guess would be PPP that happens to be exchanging a peer neighbor-route. 

    You have /32 AND /24 there.

    I'll be the other side shows a different /32.  :)

    Scott







    ----- Original Message -----
    From: "hadi" <[email protected]>
    Sent: Tue, March 31, 2009 4:37
    Subject: [CCIE R&S] EIGRP


    Hey,

     

    Why do we receive a /32 prefix with EIGRP ?

     

    example :

    Rack1SW1#sho ip route eigrp
         129.1.0.0/16 is variably subnetted, 8 subnets, 3 masks
    D       129.1.3.128/25 [90/2172672] via 129.1.17.1, 00:00:16, Vlan17
    D       129.1.3.0/25 [90/2172672] via 129.1.17.1, 00:00:16, Vlan17
    D       129.1.13.0/24 [90/2170112] via 129.1.17.1, 00:00:16, Vlan17
    D       129.1.13.3/32 [90/2170112] via 129.1.17.1, 00:00:16, Vlan17
    D       129.1.23.2/32 [90/2682112] via 129.1.17.1, 00:00:16, Vlan17
    D       129.1.23.0/24 [90/2682112] via 129.1.17.1, 00:00:16, Vlan17
         150.1.0.0/24 is subnetted, 4 subnets
    D       150.1.3.0 [90/2298112] via 129.1.17.1, 00:00:17, Vlan17
    D       150.1.2.0 [90/2810112] via 129.1.17.1, 00:00:17, Vlan17
    D       150.1.1.0 [90/130816] via 129.1.17.1, 00:00:17, Vlan17

     

    i mean why do we get the /32 routes and when ?

    thx

     



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  • thx scott,

    as a matter of fact i am running PPP but why do i advertise them in EIGRP ?

     

     

    regards,

    hadi

  • Because, most likely, in your EIGRP configuration you put the "network" command with the /24 mask which encompasses EVERY link within that range.

    So (I forgot the IP's we had specifically now), if you had:

    10.1.1.0/24 as your subnet
    10.1.1.1 on your router
    10.1.1.2 on the other router

    Your "show ip route connected" would look like:

    C 10.1.1.0/24   Serial0/0
    C 10.1.1.2/32   Serial0/0

    If you put "network 10.1.1.0 0.0.0.255" under router eigrp, you'd get both.

    If you put "network 10.1.1.1 0.0.0.0" under router eigrp, you'd only get the /24 network!

    HTH,

    Scott







    ----- Original Message -----
    From: "hadi" <[email protected]>
    Sent: Sun, April 5, 2009 23:42
    Subject: Re: [CCIE R&S] EIGRP


    thx scott,

    as a matter of fact i am running PPP but why do i advertise them in EIGRP ?

     

     

    regards,

    hadi



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  • thx for the quick reply

     

    that's were the confusion starts. i always use 0.0.0.0 as a wildcard mask :)

     

    i mean if it was a /24 mas i would have agreed but it's a 0.0.0.0 mask

     

    thx,

    hadi

  • Do BOTH sides have a 0.0.0.0 mask?

    Any other cause for overlap?  Now, back in the day of dialer interfaces, I spent PLENTY of time with this problem with OSPF.  I honestly don't recall spending much time with it and EIGRP.  So my best guess would be that the other side doesn't have that mask (or has multiple network statements) which is why you are RECEIVING both.

    But on your end, since you can verify you only have one 0.0.0.0 mask, can you look in your topology table and see whether your own /32 is being added/sent?

    I'm not in front of routers at the moment (airport) otherwise I'd slap it up real quick to see if I've just forgotten some little tidbit about EIGRP.  Happens every now and then. ;0

    Scott







    ----- Original Message -----
    From: "hadi" <[email protected]>
    Sent: Mon, April 6, 2009 7:18
    Subject: Re: [CCIE R&S] EIGRP


    thx for the quick reply

     

    that's were the confusion starts. i always use 0.0.0.0 as a wildcard mask :)

     

    i mean if it was a /24 mas i would have agreed but it's a 0.0.0.0 mask

     

    thx,

    hadi



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