From: dredeze (dredeze@hotmail.com)
Date: Thu Feb 06 2003 - 21:18:06 GMT-3
Actually OSPF demand-circuit is a useless command when using back
interface. When you execute backup interface command it puts the bri0
interface in standby mode. So no traffic is going to cross until the
serial interface is in a down/down state. So an dialer-list blocking
traffic is really useless.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
sam
Sent: Thursday, February 06, 2003 5:47 PM
To: ccielab@groupstudy.com
Subject: ISDN again - Preventing OSPF traffic from bringing up a
secondary line
Sorry for the lengthy post. got some doubts and wanted to clear 'em up.
QN: I got another one here...
BRI is configured as a backup for the serial link.
Let us say that I do not want to bring up my BRI interface which is
defined in the same OSPF area as my primary link.
____ ____
| |s0 -------------- s0| |
| r1 | | r2 |
| |bri0 ---------- bri0| |
~~~~ ~~~~
I can go into say R2's BRI0 and configure
(a) ip ospf demand-circuit
(b) deny ospf traffic to bri0 (seen below in excerpt from Doc. CD on
Dialer Watch)
access-list 101 remark Define Interesting Traffic
access-list 101 deny ospf any any
!Mark OSPF as uninteresting.
!This will prevent OSPF hellos from keeping the link up.
Access-list 101 permit ip any any
dialer-list 1 protocol ip list 101
!Interesting traffic is defined by access-list 101.
!This is applied to BRI0 using dialer-group 1.
Question: Do both actions provide the same results? The most obvious
scenario would be to use
Ip ospf demand-circuit, in my opinion. or even better, use
dialer watch or floating static.
But what are the implications then ? (a) or (b) ?
Am I correct to say that the dialer group command is used to define
interesting traffic. Denying OSPF traffic means that the ISDN connection
will not be brought up by OSPF hellos. Once the DDR has been activated
on the BRI interfaces, the dialer group's restrictions on OSPF traffic
WILL NOT apply to traffic flowing through the BRI link.
TIA
Sam Sena
.
.
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