From: ccie2be (ccie2be@nyc.rr.com)
Date: Tue Oct 12 2004 - 10:45:18 GMT-3
I hate it when I forget these little but crucial details.
Thanks, Tim
----- Original Message -----
From: "Geert Nijs" <geert.nijs@simac.be>
To: "ccie2be" <ccie2be@nyc.rr.com>; "Group Study" <ccielab@groupstudy.com>
Sent: Tuesday, October 12, 2004 9:35 AM
Subject: RE: IE Lab 7 - Using deny in ip prefix lists
You are denying all routes. Prefix list should be:
ip prefix-list ADV seq 5 deny 54.3.7.0/24
ip prefix-list ADV seq 10 deny 54.3.7.254/32
ip prefix-list ADV seq 15 permit 0.0.0.0/0 le 32
Regards,
Geert #13729
________________________________
From: nobody@groupstudy.com on behalf of ccie2be
Sent: Tue 10/12/2004 0:56
To: Group Study
Subject: IE Lab 7 - Using deny in ip prefix lists
Hi guys,
I'm stump by this one.
R6 is connected to BB1 via subnet 54.3.7.0/24 and to R2 via 204.12.3.0/24.
R2 is config'd to only accept rip updates from R6. Here's R2's config:
router rip
version 2
network 204.12.3.0
distribute-list gateway R6 in
no auto-summary
!
ip prefix-list R6 seq 5 permit 204.12.3.6/32
And, here's the config for R6:
router rip
version 2
network 54.0.0.0
network 150.3.0.0
network 163.3.0.0
network 204.12.3.0
distribute-list prefix ADV out
distribute-list gateway R2 in
no auto-summary
!
ip prefix-list ADV seq 5 deny 54.3.7.0/24
ip prefix-list ADV seq 10 deny 54.3.7.254/32
ip prefix-list ADV seq 15 permit 0.0.0.0/0
!
ip prefix-list R2 seq 5 permit 204.12.3.2/32
I'm trying to get R2 to accept updates from which include subnet 150.3.0.0
and
163.3.0.0 but it seems that I can't achieve this by using the above prefix
list ADV which denies the routes I don't want R2 to get.
However, everything works if instead of denying the routes I don't want R2
to
get, I just explicitly permit the routes R2 should get.
In other words, the following prefix list works:
ip prefix-list ADV seq 5 permit 163.3.6.0/24
ip prefix-list ADV seq 10 permit 150.3.0.0/24
I don't understand this. Why is it OK to explicitly allow routes I want
advertised and implicitly deny everything else but it's not OK to explicitly
deny the routes I don't want and implicitly allow everything else?
It doesn't make sense. Can someone explain this? I'd be tremendously
grateful.
Thanks, Tim
This archive was generated by hypermail 2.1.4 : Sat Nov 06 2004 - 17:11:46 GMT-3