Re: clarification of a BGP command

From: David C Prall (dcp@xxxxxxxxxxx)
Date: Wed Jan 03 2001 - 00:18:17 GMT-3


   
The redistirbution charicteristics are per RFC1403, as copied below. In most
cases you would not want to do this, since iBGP must be fully meshed to work
properly. The real reason to do this, is in the case of two networks
connecting. One running iBGP and the other running OSPF, in this case you
can redistribute all of your iBGP routes into OSPF for the other network.

2.2. Importing BGP routes into OSPF

      1. BGP implementations SHOULD allow an AS to control
           announcements of BGP-learned routes into OSPF.
           Implementations SHOULD support such control with the
           granularity of a single network. Implementations SHOULD also
           support such control with the granularity of an autonomous
           system, where the autonomous system may be either the
           autonomous system that originated the route or the autonomous
           system that advertised the route to the local system
           (adjacent autonomous system).

           o The default MUST be to export no routes from BGP into
                OSPF. Administrators must configure every route they
                wish to import.

                A configuration parameter MAY allow an administrator to
                configure an ASBR to import all the BGP routes into the
                OSPF routing domain.

      2. The administrator MUST be able to configure the OSPF cost and
           the OSPF metric type of every route imported into OSPF.

           o The OSPF cost MUST default to 1; the OSPF metric type
                MUST default to type 2.

      3. Routes learned via BGP from peers within the same AS MUST not
           be imported into OSPF.

      4. The ASBR MUST never generate a default route into the OSPF
           routing domain unless explicitly configured to do so.

           A possible criterion for generating default into an IGP is to
           allow the administrator to specify a set of (network route,
           AS_PATH, default route cost, default route type) tuples. If
           the ASBR learns of the network route for an element of the
           set, with the corresponding AS_PATH, then it generates a
           default route into the OSPF routing domain, with cost
           "default route cost" and type, "default route type". The
           lowest cost default route will then be injected into the OSPF
           routing domain.

           This is the recommended method for originating default routes
           in the OSPF routing domain.

David C Prall dcp@dcptech.com http://dcp.dcptech.com
----- Original Message -----
From: "Curtis Phillips" <phillipscurtis@netscape.net>
To: <ccielab@groupstudy.com>
Sent: Tuesday, January 02, 2001 11:39 AM
Subject: clarification of a BGP command

> Hello,
>
> Has anyone used the "bgp redistribute-internal" command?
> The somewhat spartan documentation I have found indicates that
> it is to redistribute internal BGP routes into either RIP or OSPF.
>
> Does the application of the command cause this to happen to immediately or
> does it have to preceed the redistribution of BGP into either of these
thus
> allowing internal BGP routes as well as external routes to be
redistributed?
>
> Does anyone know of a specific application that might help with
understanding
> the significance of this?
>
> Thanks,
>
> Curtis
>
>



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