From: Scott Morris (swm@emanon.com)
Date: Tue Aug 30 2005 - 23:32:00 GMT-3
Well, that describes a reason why, yes. But at the end of it, it's because
the specification says so. :) Remember that "ebgp multihop" is technically
against the spec as well. eBGP peers are supposed to share a common
physical link between them to avoid any of these reachability or next-hop
issues.
Scott
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
KSGoh
Sent: Tuesday, August 30, 2005 10:24 PM
To: Cisco certification
Subject: Re: Discover BGP neighbor!
yes..
there is only 2 routes, route to internal network, and 0.0.0.0 route to my
bgp peer...
thats how i configure my BGP last time..and it runs for at least 6 months
wihout problem, recently i got a problem where all received BGP routes are
flapping (appear 15sec, then disapper for approx 15 sec)..
the solution is to add a more specific route (eg. 202.x.x.x x.x.x.x s0/0 )
the behaviour is kind of strange, where i can always ping to my bgp peer,
when i do a sh ip bgp x.x.x.x it will say my bgp peer (inaccesible) .. when
my bgp route dissapear..
try to simulat the same problem in my home lab.. and cannot get the same
result..
i read from the cisco documentation is says that "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)."
is this the reason why we cannot use default route to discover our
neighbor..?
----- Original Message -----
From: "Scott Morris" <swm@emanon.com>
To: "'KSGoh'" <kianseng.goh@gmail.com>; "'Cisco certification'"
<ccielab@groupstudy.com>
Sent: Wednesday, August 31, 2005 10:15 AM
Subject: RE: Discover BGP neighbor!
> And you had no other route to the neighbor but the 0/0?
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> KSGoh
> Sent: Tuesday, August 30, 2005 10:08 PM
> To: Cisco certification
> Subject: Re: Discover BGP neighbor!
>
> but i had tried on real 25xx routers running ios 12.3, i had no problem in
> forming the adjacencies...
>
> ----- Original Message -----
> From: "Scott Morris" <swm@emanon.com>
> To: "'KSGoh'" <kianseng.goh@gmail.com>; "'Cisco certification'"
> <ccielab@groupstudy.com>
> Sent: Wednesday, August 31, 2005 9:49 AM
> Subject: RE: Discover BGP neighbor!
>
>
>> It means what it says. :)
>>
>> The BGP RFC states that default routes can't be used for session
>> reachability.
>>
>> Scott
>>
>> -----Original Message-----
>> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>> KSGoh
>> Sent: Tuesday, August 30, 2005 9:39 PM
>> To: Cisco certification
>> Subject: Discover BGP neighbor!
>>
>> i remember seeeing some article about we cannot use default route to
>> discover our BGP neighbor, we need a more specific route.. with default
>> route, we may be able to ping the neighbor, but bgp will not form
>> neighbor
>> adjacencies..
>>
>> any idea what did ths means?
>>
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