From: Olopade Olorunloba (lolopade@ipnxnigeria.net)
Date: Wed Oct 26 2005 - 19:47:00 GMT-3
On Cisco IOS where the IPv4 family does not show by the default, simply
disable default IPv4 session by giving the command no bgp default ipv4.
This will cause the IOS to now show the IPv4 session, and the operation will
be like what Scott has described here, because after adding a neighbor, you
will still need to go to the IPv4 address family to activate it.
Regards
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Andrew Lissitz (alissitz)
Sent: 26 October 2005 18:18
To: swm@emanon.com; The Great Ryan; Cisco certification
Cc: comserv@groupstudy.com
Subject: RE: Different Command Format on BGP routing process
Nice Scott ... Thanks for the perspective on how to view the configs /
address families.
Cisco .. Confuses people?
-----Original Message-----
From: Scott Morris [mailto:swm@emanon.com]
Sent: Wednesday, October 26, 2005 1:08 PM
To: Andrew Lissitz (alissitz); 'The Great Ryan'; 'Cisco certification'
Cc: comserv@groupstudy.com
Subject: RE: Different Command Format on BGP routing process
No difference actually. IPv4 is the default address family used. Some
newer versions of the IOS automatically put the "address-family ipv4"
stuff there, I think just to avoid confusion with people using multiple
families.
In the R&S lab, the only one to be concerned with is the IPv6 address
family. In the SP lab, you may need the vpnv4 (MPLS VPNs) and/or
multicast as well.
All the address-family ipv4 part does is help to separate things so that
we
(humans) are less confused. Apparantly this hasn't been entirely
successful! (grin)
Always remember, there are two parts to the BGP configuration pieces.
Thinking of it this was (since BGP is an application not really an IP
routing protocol) will help you think things through!
There's first the "connections" piece which establishes your basic
connection to your neighbor. This will include the neighbor statement,
and update-source, remote-as, ebgp-multihop parameters and things like
that.
Then there's the RIB pieces. Each RIB is different. A single neighbor
may talk multiple RIB/update types. You may have 20 neighbors, and only
10 of them talk about IPv4 information. That's why each neighbor should
be activated in the appropriate RIBs they will share information with.
Then any filtering (RIB-based stuff) or network commands go under the
address families.
It's hard to follow when you're first getting into this MBGP stuff
because in generic, all-purpose BGP where we only run IPv4, it's all
just right there, not separated. But if we start thinking about the
pieces involved, then the address families suddenly aren't all that bad!
:)
Scott
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Andrew Lissitz (alissitz)
Sent: Wednesday, October 26, 2005 11:42 AM
To: The Great Ryan; Cisco certification
Cc: comserv@groupstudy.com
Subject: RE: Different Command Format on BGP routing process
Hey Ryan,
Afaik this command is used for inter-as mvpns (mpls vpn customers with
links in two or more ISPs).
There are different options for the different address families.
Curiosity... is this needed for a lab you are working on?
Once you type address-fam ipv4 (without a VRF at the end) you will be
working in the same default address family you have when you type router
bgp x. Now ... try getting rid of the command address-fam ipv4 ... once
you typed it, IOS really wants to keep it there. You will need to
either continue to work with this address-fam listed or remove bgp and
re-add bgp.
Strange how you can not get rid of this address-fam since it is the
default address family for bgp.
Does this answer your question Ryan?
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
The Great Ryan
Sent: Wednesday, October 26, 2005 8:20 AM
To: Cisco certification
Subject: Different Command Format on BGP routing process
Hi Group,
There is any different result if I use the following to enable BGP ?
Router(config)# router bgp 65412
Router(config-router)# neighbor 192.168.0.1 remote-as 65412
Router(config-router)# neighbor 192.168.0.1 ebgp-multihop 255
Router(config)# router bgp 65412
Router(config-router)# neighbor 192.168.0.1 remote-as 65412
Router(config-router)# address-family ipv4 Router(config-router-af)#
neighbor 192.168.0.1 activate Router(config-router-af)# neighbor
192.168.0.1 ebgp-multihop 255
I found something very interesting. the command "neighbor 192.168.0.1
next-hop-unchanged" will never display in the first format but it takes
effect when I use some show command. I'm afraid that if I write erase
the configuration and paste the configuration again, it will miss this
command.
Any have this experience before ?
Thanks !
Ryan
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