From: Scott Morris (swm@emanon.com)
Date: Wed Oct 26 2005 - 14:24:30 GMT-3
Interesting thought, but not necessarily!
You CAN use the BGP Multicast family to exchange RPF information about
multicast sources, but aren't required to unless you have multiple MSDP
peers. (even then, it's workable without it depending on your network
design)
IMHO, in the future for R&S you'll want to have some experience with the
multicast family, but for now, likely not. In the SP exam, it's probably a
good way for Inter-AS multicast trees (aka through the Internet) to work
well together!
Scott
-----Original Message-----
From: simon hart [mailto:simon@harttel.com]
Sent: Wednesday, October 26, 2005 1:17 PM
To: Scott Morris; 'Andrew Lissitz (alissitz)'; 'The Great Ryan'; 'Cisco
certification'
Cc: comserv@groupstudy.com
Subject: RE: Different Command Format on BGP routing process
Hi Scott,
MSDP is on the blueprint, so I guess there maybe call for MBGP for multicast
Simon
PS good explanation on the 'Application' rather than 'Routing Protocol'
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of Scott
Morris
Sent: 26 October 2005 18:07
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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