BGP/EIGRP routing

Discussion in 'Cisco' started by MC, Apr 17, 2007.

  1. MC

    MC Guest

    OK, I thought I had this working, but I have a local EIGRP LAN learned
    route and a BGP WAN learned route, I want the BGP learned route to be
    prefered unless goes away then will use the EIGRP learned route.


    However, when route are learned by one, the other never supercedes the
    other.

    If BGP is the route learned at the time, EIRGP can come and go and never
    overrides the BGP route, If EIGRP route is the one learned at the time
    (clearing BGP routes) BGP learned routes can come and go but the EIGRP
    learned route will be the one always in the routing table until clearing
    the EIGRP routes.

    What am I missing, not had much sleep so not thinking well but need to
    figure this out.

    Thanks much for the help.
     
    MC, Apr 17, 2007
    #1
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  2. MC

    Thrill5 Guest

    The EIGRP learned route will be preferred over the BGP route because the
    EIGRP route is an "internal" route and the BGP is "external". You can try
    to fix this by adjusting the metrics of the BGP routes when redistributing
    them into EIGRP. But I don't think this will fix your problem because by
    default EIGRP has an admin distance of 90, and I believe BGP is 110 and the
    routes are being learned on the router running both EIGRP and BGP. To see
    this, do a "show ip route" and you will see that the EIGRP routes have a
    lower "Admin" distance than the BGP routes. Each route will show the metric
    like [90/92922], where the number before the "/" is the admin distance, and
    the number afterward is the routing metric. The routing metric is only used
    if the admin distance is the same.

    Scott


    "MC" <> wrote in message
    news:nrbVh.24523$...
    > OK, I thought I had this working, but I have a local EIGRP LAN learned
    > route and a BGP WAN learned route, I want the BGP learned route to be
    > prefered unless goes away then will use the EIGRP learned route.
    >
    >
    > However, when route are learned by one, the other never supercedes the
    > other.
    >
    > If BGP is the route learned at the time, EIRGP can come and go and never
    > overrides the BGP route, If EIGRP route is the one learned at the time
    > (clearing BGP routes) BGP learned routes can come and go but the EIGRP
    > learned route will be the one always in the routing table until clearing
    > the EIGRP routes.
    >
    > What am I missing, not had much sleep so not thinking well but need to
    > figure this out.
    >
    > Thanks much for the help.
     
    Thrill5, Apr 18, 2007
    #2
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  3. MC

    MC Guest

    Thrill5 wrote:
    > The EIGRP learned route will be preferred over the BGP route because the
    > EIGRP route is an "internal" route and the BGP is "external". You can try
    > to fix this by adjusting the metrics of the BGP routes when redistributing
    > them into EIGRP. But I don't think this will fix your problem because by
    > default EIGRP has an admin distance of 90, and I believe BGP is 110 and the
    > routes are being learned on the router running both EIGRP and BGP. To see
    > this, do a "show ip route" and you will see that the EIGRP routes have a
    > lower "Admin" distance than the BGP routes. Each route will show the metric
    > like [90/92922], where the number before the "/" is the admin distance, and
    > the number afterward is the routing metric. The routing metric is only used
    > if the admin distance is the same.
    >
    > Scott
    >
    >
    > "MC" <> wrote in message
    > news:nrbVh.24523$...
    >> OK, I thought I had this working, but I have a local EIGRP LAN learned
    >> route and a BGP WAN learned route, I want the BGP learned route to be
    >> prefered unless goes away then will use the EIGRP learned route.
    >>
    >>
    >> However, when route are learned by one, the other never supercedes the
    >> other.
    >>
    >> If BGP is the route learned at the time, EIRGP can come and go and never
    >> overrides the BGP route, If EIGRP route is the one learned at the time
    >> (clearing BGP routes) BGP learned routes can come and go but the EIGRP
    >> learned route will be the one always in the routing table until clearing
    >> the EIGRP routes.
    >>
    >> What am I missing, not had much sleep so not thinking well but need to
    >> figure this out.
    >>
    >> Thanks much for the help.

    >
    >

    That is what I thought.

    However, the behavior on my router is that if the BGP route is learned
    first, EIGRP learned route never overrides until I clear the BGP route ?

    That is what is confusing ?

    Thanks much for the help.
     
    MC, Apr 18, 2007
    #3
  4. MC

    Merv Guest

    On Apr 18, 6:40 am, MC <> wrote:
    > Thrill5 wrote:
    > > The EIGRP learned route will be preferred over the BGP route because the
    > > EIGRP route is an "internal" route and the BGP is "external". You can try
    > > to fix this by adjusting the metrics of the BGP routes when redistributing
    > > them into EIGRP. But I don't think this will fix your problem because by
    > > default EIGRP has an admin distance of 90, and I believe BGP is 110 and the
    > > routes are being learned on the router running both EIGRP and BGP. To see
    > > this, do a "show ip route" and you will see that the EIGRP routes have a
    > > lower "Admin" distance than the BGP routes. Each route will show the metric
    > > like [90/92922], where the number before the "/" is the admin distance, and
    > > the number afterward is the routing metric. The routing metric is only used
    > > if the admin distance is the same.

    >
    > > Scott

    >
    > > "MC" <> wrote in message
    > >news:nrbVh.24523$...
    > >> OK, I thought I had this working, but I have a local EIGRP LAN learned
    > >> route and a BGP WAN learned route, I want the BGP learned route to be
    > >> prefered unless goes away then will use the EIGRP learned route.

    >
    > >> However, when route are learned by one, the other never supercedes the
    > >> other.

    >
    > >> If BGP is the route learned at the time, EIRGP can come and go and never
    > >> overrides the BGP route, If EIGRP route is the one learned at the time
    > >> (clearing BGP routes) BGP learned routes can come and go but the EIGRP
    > >> learned route will be the one always in the routing table until clearing
    > >> the EIGRP routes.

    >
    > >> What am I missing, not had much sleep so not thinking well but need to
    > >> figure this out.

    >
    > >> Thanks much for the help.

    >
    > That is what I thought.
    >
    > However, the behavior on my router is that if the BGP route is learned
    > first, EIGRP learned route never overrides until I clear the BGP route ?
    >
    > That is what is confusing ?
    >
    > Thanks much for the help.



    That would be a bug
     
    Merv, Apr 18, 2007
    #4
  5. MC

    Darren Green Guest

    "Thrill5" <> wrote in message
    news:...
    > The EIGRP learned route will be preferred over the BGP route because the
    > EIGRP route is an "internal" route and the BGP is "external". You can try
    > to fix this by adjusting the metrics of the BGP routes when redistributing
    > them into EIGRP. But I don't think this will fix your problem because by
    > default EIGRP has an admin distance of 90, and I believe BGP is 110 and
    > the routes are being learned on the router running both EIGRP and BGP. To
    > see this, do a "show ip route" and you will see that the EIGRP routes have
    > a lower "Admin" distance than the BGP routes. Each route will show the
    > metric like [90/92922], where the number before the "/" is the admin
    > distance, and the number afterward is the routing metric. The routing
    > metric is only used if the admin distance is the same.
    >
    > Scott
    >

    eBGP has an AD of 20 and iBGP a default AD of 200. As EIGRP is 90 this would
    ordanarily be preferred over iBGP but not eBGP.

    There is no config to go off so it would be difficult to say whether other
    influencing factors relating to EIGRP or BGP were causing the issue.

    Regards

    Darren
     
    Darren Green, Apr 18, 2007
    #5
  6. MC

    John Agosta Guest

    "MC" <> wrote in message
    news:nrbVh.24523$...
    > OK, I thought I had this working, but I have a local EIGRP LAN learned
    > route and a BGP WAN learned route, I want the BGP learned route to be
    > prefered unless goes away then will use the EIGRP learned route.
    >
    >


    You do not state how BGP learns the route in question - Is it an iBGP path
    or an eBGP path ?

    Why don't you show us the following two outputs:

    show ip route

    and

    show ip bgp
     
    John Agosta, Apr 18, 2007
    #6
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