From: ccie2be (ccie2be@nyc.rr.com)
Date: Tue Jan 11 2005 - 16:51:29 GMT-3
Hi guys,
Consider this just an FYI regarding the above topic.
I just spent the last couple of hours doing what appeared to be a fairly
simple
ORF configuration.
The worst part of the config is figuring out which keyword to use at the end
of the
following command:
neighbor 130.1.234.3 capability orf prefix-list <send | recieve | both>
Based on the concept of ORF, one would think that the router that wants to
send a filter to a neighbor so that the number of routes the neighbor sends it
is reduced would use the send keyword. THIS IS WRONG. It's just the
opposite.
You need to use the recieve keyword for this.
The send keyword is used on the router recieving the filter from a neighbor.
Hey, don't blame me. I didn't write IOS.
But, assuming you can keep this counter-intuitive command syntax straight in
your head,
there are a few other landmines awaiting you with this.
1) You have to configure the neighbor ... remote-as # command a 2nd time but
this time
while in address-family mode on the router that sending the inbound filter to
it's neighbor.
2) You also have to config the neighbor .... prefix-list <name> in while in
address-family mode.
Now, for those of you who are like me and don't lilke to memorize stuff like
this, well, all I can say is
sorry, you're out of luck because the material on the Doc-CD SUCKS. If you
try to follow the directions
there during the real lab, maybe you'll get it, maybe you won't, but either
way you'll eat up valuable time
trying to get right.
3) Another thing to watch out for is trying to edit your bgp config once
you've
configured ORF and it doesn't work as you hoped.
The first thing you'll notice after configuring ORF and going back to look at
your bgp
config, is that IOS puts in a lot of lines in the bgp config section. This
caught me by surprise
and had me thinking, "what the hell does all this stuff mean and do?"
I still don't really know but I can tell you this: if you try to remove just
the commands
you entered so that you can change them, it doesn't work.
My suggestion is this: Copy the good portion of the BGP to notepad.
Completely eliminate BGP
Copy the good portion back into the router and then
re-enter the ORF commands from scratch.
My last suggestion.
Don't attempt the lab without having configured ORF a few times first.
Of course, I'm not saying that ORF will be on the lab or not. I'm only saying
that if
it is on the lab and you haven't configured it before, you'll have a bitch of
a time getting it
work.
I hope this helps all of you reading this post. Many people on GS have helped
me while I've been preparing
and so I wanted to give back a bit.
Tim
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