From: Jay (ccienxtyear@hotmail.com)
Date: Wed Oct 23 2002 - 22:13:11 GMT-3
When using the ospf demand circuit, do not deny ospf in you dialer list.
Make sure you have a filter setup to deny putting back the bri subnet back
into OSPF
i.e if you are redistributing IGRP---OSPF, setup a filter to deny IGRP from
redistributing the BRI subnet back into OSPF. This I found to be the most
common root cause of the isdn link flapping even if I had it configured as
an ospf demand circuit. Also, the no peer neighbor route statments help.
thanks,
Jay
----- Original Message -----
From: "Tim Fletcher" <tim@fletchmail.net>
To: "Larson, Chris" <CLarson@usaid.gov>; "'Paglia, John
(USPC.PCT.Hopewell)'" <JPaglia@NA2.US.ML.com>; "Larson, Chris"
<CLarson@usaid.gov>; "'enginedrive2002'" <enginedrive2002@yahoo.ca>;
<ccielab@groupstudy.com>
Sent: Wednesday, October 23, 2002 4:52 PM
Subject: RE: DDR question.
> If you don't deny OSPF then the link will come up any time there is a
topology change (or other interesting traffic, but not for hellos). If you
do deny OSPF then a topology change will not bring up the circuit and routes
will not get propagated. It all depends on what you're trying to accomplish.
>
> -tim
>
> At 03:46 PM 10/23/02 -0400, Larson, Chris wrote:
> >I am not disagreeing with what you are saying.
> >
> >
> >It's just that I have never had to create a dialer-list excluding OSPF as
> >interesting traffic to keep the ISDN line quiet when using
demand-circuit.
> >If you do a dialer-list ip protocol ip permit and put the demand circuit
on
> >the bri interface..... assuming everything else is configed properly the
> >circuit should remain quiet until there is a topo change.
> >
> >
> >
> >> -----Original Message-----
> >> From: Paglia, John (USPC.PCT.Hopewell) [SMTP:JPaglia@NA2.US.ML.com]
> >> Sent: Wednesday, October 23, 2002 3:16 PM
> >> To: 'Larson, Chris'; 'enginedrive2002'; ccielab@groupstudy.com
> >> Subject: RE: DDR question.
> >>
> >> The dial-list dictates what initiates the call...demand-circuit affects
> >> activity after the call is made. 2 different animals.
> >>
> >> The ACL says 'do not start the link if the ip packet is a ospf-based ip
> >> packet, but if it's any other ip packet, let 'er rip'. Then, when for
> >> instance a ping brings the line up, OSPF sends hellos and lsa's to
> >> establish
> >> neighborings and LSA exchanges, after which demand-circuit says 'hey,
> >> there's only so much BW here, so let's just assume we're cool, and keep
> >> our
> >> proverbial mouths shut unless there is an LSA change'.
> >>
> >> Hopefully I'm helping here!!
> >> John
> >>
> >> > -----Original Message-----
> >> > From: Larson, Chris [SMTP:CLarson@usaid.gov]
> >> > Sent: Wednesday, October 23, 2002 3:00 PM
> >> > To: 'Paglia, John (USPC.PCT.Hopewell)'; 'enginedrive2002';
> >> > ccielab@groupstudy.com
> >> > Subject: RE: DDR question.
> >> >
> >> > If periodic hello's and lsa's are suppressed so they do not flood the
> >> > demand circuit. AND
> >> >
> >> > "only periodic hellos and refreshes of LSA's once the call is made"
> >> >
> >> > Then why is the 101 list needed? It says that hello's and lsa's will
not
> >> > be sent until after the call is made? Why do you need to supress them
> >> > twice?
> >> >
> >> >
> >> >
> >> > -----Original Message-----
> >> > From: Paglia, John (USPC.PCT.Hopewell) [SMTP:JPaglia@NA2.US.ML.com]
> >> > Sent: Wednesday, October 23, 2002 2:08 PM
> >> > To: 'enginedrive2002'; ccielab@groupstudy.com
> >> > Subject: RE: DDR question.
> >> >
> >> > The definition of 'demand-circuit' as per the 12.1 cmd. ref.:
> >> > Periodic hellos are suppressed and periodic refreshes of LSAs do not
> >> flood
> >> >
> >> > the demand circuit. It allows the underlying datalink layer to be
closed
> >>
> >> > when the topology is stable.
> >> > ...only periodic hellos and refreshes of LSA's once the call is made.
> >> > Thus,
> >> > you put the 'deny ospf any any' cmd. in to keep hello's from acting
as
> >> the
> >> >
> >> > 'interesting traffic' that can initialize a link. Once non-ospf
traffic
> >> > brings up the link, demand-circuit kicks in.
> >> >
> >> > Here's the link:
> >> >
> >>
<http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/i>
> p_r>
> >> > /iprprt2/1rdospf.htm#xtocid19
> >> > Watch the wrap!!!
> >> >
> >> > John
> >> >
> >> > > -----Original Message-----
> >> > > From: enginedrive2002 [SMTP:enginedrive2002@yahoo.ca]
> >> > > Sent: Wednesday, October 23, 2002 12:51 PM
> >> > > To: ccielab@groupstudy.com
> >> > > Subject: DDR question.
> >> > >
> >> > > Would someone read the doc link below, and answer a few questions:
> >> > > <http://www.cisco.com/warp/public/129/config-bri-map.html>
> >> > >
> >> > > 1. On router maui-soho-01, "ip ospf demand-circuit" is configured
> >> under
> >> > > BRI
> >> > > interface, why in the example, access-list 101 still need to have
> >> "deny
> >> > > ospf
> >> > > any any"? I have never test OSPF demand-circuit at before, but I
> >> "guess"
> >> >
> >> > > with
> >> > > the "ip ospf demand-circuit" command, it will already suppress the
> >> hello
> >> >
> >> > > packets. Would someone confirm this?
> >> > >
> >> > > 2. On router maui-nas-05, under BRI interface, the example doesn't
> >> > > configure
> >> > > any number to dial, which mean it could only answer the call. But
why
> >> in
> >> >
> >> > > the
> >> > > example, it has "dialer-group", "dialer-list" command to define
> >> > > interesting
> >> > > traffic? Just to reset the idle-timer while the BRI link is up? Any
> >> > other
> >> > > purpose here?
> >> > >
> >> > > Thank you!
> >> > >
> >> > >
> >> > > Regards,
> >> > >
> >> > >
> >> > > E.D.
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