From: Jason Sinclair (sinclairj@xxxxxxxxxxxxxxx)
Date: Thu Mar 14 2002 - 23:18:12 GMT-3
Henry,
Remember that IGP is some internal routing protocol. The reason that we have
synch is so that we know that if we advertise a route via BGP (either iBGP
or eBGP) we can reach that route internally. If you have a full iBGP mesh
then you can disable synch as you know that you can internally reach that
prefix. Remember also that you may have one single border router running
eBGP and not have internal BGP speakers, hence you may redistribute your
eBGP learnt routes to your IGP. (a better setup would be to have a default
out and not use BGP in this case). Another scenario would be as follows:
RtrA
(AS200)---------------RtrB(AS300)-------------RtrC(AS300)-------------Rtr4(N
o BGP)
EBGP IBGP
IGP
If you have a prefix on 4 that you want 3 to advertise your prefix must be
in the IGP table (or synch disabled) for BGP to advertise the route. Does
this sort of clear this up?
Regards,
Jason Sinclair
Manager, Network Support Group
POWERTEL
Ground Level, 55 Clarence Street,
SYDNEY NSW 2000
AUSTRALIA
office: + 61 2 8264 3820
mobile: + 61 416 105 858
* sinclairj@powertel.com.au
-----Original Message-----
From: H C [mailto:henchou@hotmail.com]
Sent: Friday, 15 March 2002 10:42
To: ccielab@groupstudy.com
Subject: RE: IBGP redistribution
Hi all,
I have a more basic question. Would someone clarify the
relationship
between iBGP and IGP? BGP synchronization exists so iBGP
will wait until
IGP has propagated within the AS then advertise it outside
of AS. BGP RR
exists because iBGP needs fully meshed with peers and may
not scale for very
large networks. If I'm running IGP and redistribute with
BGP, where would
iBGP play? I guess I'm not seeing this relationship
clearly. Thanks if
anyone would shed some light.
Henry
From: "Michael Jia" <mjia@cisco.com>
Reply-To: "Michael Jia" <mjia@cisco.com>
To: "ccielab" <ccielab@groupstudy.com>
Subject: RE: IBGP redistribution
Date: Thu, 14 Mar 2002 15:39:15 -0800
Hi, all
Thank you all for the quick reply. the command
"bgp redistribute-internal" indeed injects ibgp routes
into IGP.
It will be very easy to create conflict routes by using
this command and should be planned carefully before
doint it.
Thanks again.
Michael
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 10:57:09 GMT-3