Re: BGP neighborship problem

One interesting point here is that the router will not try to form adjacency
if the eBGP neighbor is reached via default route, but they will negotiate
the session normally if the neighbor start the connection.

In other words: to form adjacence is enough that only one router reaches to
the neighbor via non default route.

Kratz

2011/10/15 garry baker <baker.garry_at_gmail.com>

> "To avoid the accidental creation of loops through oscillating routes,
> the multihop session will not be established if the only route to the
> multihop peer's address is the default route (0.0.0.0). "
>
>
> neighbor {ip-address | peer-group-name} ebgp-multihop
>
>
> Allow BGP sessions, even when the neighbor is not on a directly
> connected segment. The multihop session is not established if the only
> route to the multi-hop peer's address is the default route (0.0.0.0).
>
> --
> Garry L. Baker
>
> "With sufficient thrust, pigs fly just fine..." - RFC 1925
>
>
>
> On Sat, Oct 15, 2011 at 8:49 PM, CCIE KID <eliteccie_at_gmail.com> wrote:
> > Yes i know there is just a default route . THis is a EBGP peer and i know
> i
> > can ping the other ends loopback with my loopback but i cant form
> > neighborship
> > Is there any logic for this ? Is this a inherent BGP behaviour or it is
> > just a TCP implementation .
> >
> > Can someone give me the reason why BGP is not taking the default route
> >
> >
> >
> >
> >
> > On Sat, Oct 15, 2011 at 11:13 PM, garry baker <baker.garry_at_gmail.com>
> wrote:
> >>
> >> R1(config)#do sh debug
> >> IP routing:
> >> BGP debugging is on for address family: IPv4 Unicast
> >>
> >> R1(config)#
> >> *Mar 1 01:57:08.247: BGP: 2.2.2.2 active open failed - no route to
> >> peer, open active delayed 29174ms (35000ms max, 28% jitter)
> >>
> >> R1(config)#do sh ip route 2.2.2.2
> >> % Network not in table
> >>
> >> --
> >> Garry L. Baker
> >>
> >> "With sufficient thrust, pigs fly just fine..." - RFC 1925
> >>
> >>
> >>
> >> On Sat, Oct 15, 2011 at 7:08 PM, CCIE KID <eliteccie_at_gmail.com> wrote:
> >> > Hi fellas,
> >> >
> >> > I have a simple topology R1----------------------------R2 R1 is
> >> > forming neighbourship with R2's loopback and viceversa. I have a
> >> > default
> >> > route configured to reach loopback.
> >> > Why BGP cant form a neighbourship with a peer with a default route?
> Why
> >> > it
> >> > needs a unicast exact route to form a peer?
> >> > What is the logic behind this ? Can anyone explain me the logic?
> >> >
> >> > --
> >> > With Warmest Regards,
> >> >
> >> > CCIE KID
> >> > CCIE#29992 (Security)
> >> >
> >> >
> >> > Blogs and organic groups at http://www.ccie.net
> >> >
> >> >
> _______________________________________________________________________
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> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >
> >
> >
> > --
> > With Warmest Regards,
> >
> > CCIE KID
> > IN PURSUIT OF CCIE
>
>
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>
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