From: Gustavo Novais (gustavo.novais@novabase.pt)
Date: Thu Aug 25 2005 - 14:24:46 GMT-3
Not if you use backup interface, instead of dialer-watch! :)
Thank you for your suggestions
Gustavo
-----Original Message-----
From: marvin greenlee [mailto:marvin@ccbootcamp.com]
Sent: quinta-feira, 25 de Agosto de 2005 18:22
To: Gustavo Novais; ccielab@groupstudy.com
Subject: RE: Dialer backup without demand circuit
[bcc][faked-from][bayes]
With OSPF traffic as uninteresting, something has to initiate the call.
The probe traffic can keep the line up after OSPF converges, but when
the line initially drops, the router will not have a route to the remote
network to send the probe traffic. The SNMP kicks up the line, and then
the OSPF can converge. If you just point the probe at the other end of
the ISDN connection, it would keep the line up the whole time.
Marvin Greenlee, CCIE#12237, CCSI# 30483 Network Learning Inc
marvin@ccbootcamp.com www.ccbootcamp.com (Cisco Training)
-----Original Message-----
From: Gustavo Novais [mailto:gustavo.novais@novabase.pt]
Sent: Thursday, August 25, 2005 2:27 AM
To: marvin greenlee; ccielab@groupstudy.com
Subject: RE: Dialer backup without demand circuit
[bcc][faked-from][bayes]
Hummm, interesting solution!
Didn't think about SNMP... Do you really need it? The probes are always
on, so whenever you lose primary link you will always have traffic to
kick in, if you point the probes to the remote isdn side.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
marvin greenlee
Sent: quinta-feira, 25 de Agosto de 2005 0:44
To: Gustavo Novais; ccielab@groupstudy.com
Subject: RE: Dialer backup without demand circuit
[bcc][faked-from][bayes]
We had a similar discussion a few days ago on another message board.
OSPF over ISDN without using demand circuit, backup interface, or dialer
watch:
OSPF - not interesting traffic
SMNP - interesting
ICMP - interesting
*** Step 1 - kick up the line if primary goes down ***
snmp-server enable traps snmp linkdown
snmp-server host 56.56.56.5 TEST
! The address 56.56.56.5 is the address of the remote side of the ISDN.
! SNMP traffic needs to be interesting in your dialer list.
! Sending the trap for link-status is on by default. Disable for other
interfaces.
int bri0/0
no snmp trap link-status
int dialer 1
no snmp trap link-status
int eth0/0
no snmp trap link-status
! Make sure that it is enabled for the Serial interface.
int ser0/1
snmp trap link-status
*** Step 2 - keep the line up if primary is down ***
Traffic Generation - keep the line up
Configure a SAA probe to ping a remote network.
rtr 2
type echo prot ip 2.2.2.2
frequency 15
rtr schedule 2 life forever start now
Note: ICMP traffic will need to be defined as interesting for ISDN.
***
The probe traffic would normally be sent out the serial link, because
that is where the route to the distant network would be. When the serial
line goes down, the SNMP trap triggers the dial, and OSPF can establish
an adjacency and learn a route for the distant network via the ISDN
line. With ICMP traffic defined as interesting, the probe traffic will
be sent out the ISDN interface, and will keep the line up. When the
serial line comes back up, OSPF will reconverge, and the route via the
serial network will be preferred. Since the ICMP traffic is no longer
passing over the ISDN connection, the ISDN connection will time out
after the idle timeout value.
Marvin Greenlee, CCIE#12237, CCSI# 30483 Network Learning Inc
marvin@ccbootcamp.com www.ccbootcamp.com (Cisco Training)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Gustavo Novais
Sent: Wednesday, August 24, 2005 1:26 PM
To: ccielab@groupstudy.com
Subject: Dialer backup without demand circuit [bcc][faked-from][bayes]
Importance: Low
Hello group
I'm doing an exercise where I have a setup speaking OSPF
R2---FR---R4
| |
ISDN FR
| |
R5---FR---R6
|
R7
I'm told the following:
Configure ISDN link between R2 and R5 in the same area. Configure these
routers such that OSPF hello messages do NOT bring up the link, do NOT
use ip ospf demand circuit to accomplish this task.
Configure R5 such that if FR link to R6 and/or the ethernet link to R7
goes down it will automatically bring up ISDN and have full conectivity
to all networks
My guess initially was to deny ospf packets on dialer-list of R2 and R5,
to the first part. I tried ip ospf flood reduction to see if I could
maintin neighborship up as with demand circuit, but tests showed that ip
ospf flood reduction didn't suppress hellos as on demand-circuit does,
so neighborship R5-R2 went down, but that would be fine according to the
question.
I'm left to two options for the second part.
ONE - I thought about dialer-watching routes from R6 and R7. The
problem is that dialer watch does a AND (all watched routes must be
down) and I need a OR of the routes. (LOGIC OR one, other or both)
So, no dialer-watch here.
TWO - backup interfaces - I can configure BRI as backup of both Serial
to R6 and ethernet to R7. That would work, IF I still allowed OSPF
hellos to be interesting traffic crossing the ISDN. The backup interface
is activated when Serial OR Ethernet go down. The problem is that I do
not have interesting traffic to trigger ISDN link and maintain it up, so
I'm dead...
Am I missing something? Is the exercise impossible? Perhaps if I define
some kind of RTR probe that matches interesting traffic when ethernet or
serial are down...
Any help is welcome...
Thanks
Gustavo
This archive was generated by hypermail 2.1.4 : Sun Sep 04 2005 - 17:01:20 GMT-3