From: Joe Mama (jsmith1234550@gmail.com)
Date: Mon Sep 17 2007 - 13:46:27 ART
Cecil, Depending on what is being asked of you, peering via loopbacks
may not be prefereable as it will take in to account multiple paths to
reach the neighbor.
With iBGP peers, this may be fine (and normally is), but with eBGP
peers especially on a lab-type of scenario, would you want your AS to
try multiple IGP paths to a neighbor in another AS or just use
rdundant eBGP exit points (in a normal failover scenario)?
So, via iBGP, loopback is a sound move most times. eBGP peering via a
loopback may not always be the most sound move (especially in a
lab-type of environment that will have IGPs knowing all of the routes
of the other ASs via redistribution (rather than controlling all AS
route propogation via eBGP.
Joe
On 9/12/07, Cecil Wilson <Cecil.Wilson@flextronics.com> wrote:
> This maybe easy but which interface is consider the outgoing
>
> interface IP?
>
> Is it the directly connected interface? What happens when the
>
> router has multiple routes to a subnet?
>
> Thanks for all input
>
>
>
>
>
> Cecil G. Wilson
>
> IT Network Services
>
> Office: (901) 215-2710
>
> Cell: (901) 601-6201
>
> cecil.wilson@flextronics.com
>
>
>
>
>
> -----Original Message-----
>
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>
> Prashant Shukla
>
> Sent: Wednesday, September 12, 2007 8:49 AM
>
> To: 'Ashok CCIE'; ccielab@groupstudy.com
>
> Subject: RE: BGP over Frame-relay
>
>
>
> Ashok,
>
>
>
> It seems you are using the loopback to peer with your I/E-BGP peers and
>
> the configs do not mention the "update-source" cmd.
>
>
>
> By default , if the update-source is not mentioned the peering is done
>
> using the outgoing interface's IP .
>
>
>
> Here it seems in the BGP peering the routers are expecting the source of
>
> the BGP TCP connection to be interface IPs rather that loop backs.
>
> (default).
>
>
>
> Would recommend using update-source with peers and Im sure the peering
>
> will be up.
>
>
>
> Have burnt my hands in the past with same.
>
>
>
>
>
> Shukla.
>
> Cisco Systems.
>
> Scott Morris <swm@emanon.com> wrote: Take a look at "debug ip packet"
>
> perhaps and you may find that the packets are coming from an IP address
>
> that the other side doesn't have listed in its neighbor table. (e.g.
>
> update-source)
>
>
>
>
>
> -----Original Message-----
>
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>
> Ashok CCIE
>
> Sent: Wednesday, September 12, 2007 7:27 AM
>
> To: ccielab@groupstudy.com
>
> Subject: BGP over Frame-relay
>
>
>
> Hi Team,
>
>
>
> I am configuring IBGP b/w loopback interfaces of two interfaces which
>
> are over Frame-relay. But my routers are not making any neighbor
>
> relationship.
>
> Why so?
>
>
>
> Config is here..
>
>
>
> R1
>
>
>
> router bgp 100
>
> no synchronization
>
> bgp router-id 2.2.2.1
>
> bgp log-neighbor-changes
>
> network 1.1.1.0 mask 255.255.255.0
>
> network 2.2.2.1 mask 255.255.255.255
>
> neighbor 2.2.2.2 remote-as 100
>
> neighbor 2.2.2.2 next-hop-self
>
> neighbor 2.2.2.3 remote-as 100
>
> neighbor 2.2.2.3 next-hop-self
>
> no auto-summary
>
>
>
> R2
>
>
>
> router bgp 100
>
> no synchronization
>
> bgp router-id 2.2.2.2
>
> bgp log-neighbor-changes
>
> network 1.1.1.0 mask 255.255.255.0
>
> network 2.2.2.2 mask 255.255.255.255
>
> neighbor 2.2.2.1 remote-as 100
>
> neighbor 2.2.2.1 ebgp-multihop 255
>
> no auto-summary
>
>
>
>
>
> Could you please help?
>
>
>
> Thanks,
>
> Ashok
>
>
>
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