From: Gustavo Novais (gustavo.novais@novabase.pt)
Date: Tue Dec 27 2005 - 19:16:23 GMT-3
I think you've reached an interesting point, but perhaps overkill. If we track the /32 to the hub on R4 on that route-map we could policy route to wherever we wanted. But we would still have to deal with ospf neighborship through the ppp link. If we could do a sort of "backup interface track (route)".
But then again I'm going to the field of creative configuration... :) Not a topic on CCIE lab!
Gustavo Novais
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Wang Dehong-DWANG1
Sent: terga-feira, 27 de Dezembro de 2005 22:05
To: Gustavo Novais; Christian Sica; Chula Bandara; Cisco certification
Subject: RE: [SPAM] - RE: [SPAM] - RE: [SPAM] - RE: [SPAM] - RE: Other ways of solving it --- frame-relay backup - Sending mail server found on dnsbl.njabl.org - Sending mail server found on relays.ordb.org - Sending mail server found on relays.ordb.org -
Is policy routing another option?
set ip next-hop verify-availability and enhanced object tracking.
http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123tcr/1
23tip2r/ip2_s1gt.htm#wp1091258
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Gustavo Novais
Sent: Tuesday, December 27, 2005 3:37 PM
To: Christian Sica; Chula Bandara; Cisco certification
Subject: RE: [SPAM] - RE: [SPAM] - RE: [SPAM] - RE: [SPAM] - RE: Other
ways of solving it --- frame-relay backup - Sending mail server found on
dnsbl.njabl.org - Sending mail server found on relays.ordb.org - Sending
mail server found on relays.ordb.org - Se
The ospf flood reduction feature suits you when you want to reduce
flooding of the LSAs of OSPF. Instead of flooding them every 30 min, you
set them with a DNA bit, and you do not flood them.
You do not suppress hellos with this feature (do a deb ip ospf hello to
see). Hence you are still using the link :)
Gustavo Novais
-----Original Message-----
From: Christian Sica [mailto:csica@liweb.net]
Sent: terga-feira, 27 de Dezembro de 2005 21:27
To: Gustavo Novais; 'Chula Bandara'; 'Cisco certification '
Subject: [SPAM] - RE: [SPAM] - RE: [SPAM] - RE: [SPAM] - RE: Other ways
of solving it --- frame-relay backup - Sending mail server found on
dnsbl.njabl.org - Sending mail server found on relays.ordb.org - Sending
mail server found on relays.ordb.org - Sending m
I guess you could look at this two ways. First, if they are looking for
you to use the backup interface command to take the ppp link down when
the frame is up, you could accomplish this with a tunnel interface and
use the backup command on it. When properly configured the tunnel will
go down if R5 loses its frame connection to R4, thus triggering the
backup ppp link and restoring connectivity.
The other way to look at it is to configure OSPF to use the frame as
primary and limit as much traffic over the ppp link unless the frame
connection is down. As you mentioned, we can accomplish this using
cost. The demand circuit may help by limiting hello's, but you may want
to look into using the ospf flood-reduction command instead. It is
better suited for dedicated links. Here is more info:
http://www.cisco.com/warp/public/104/dc.html
Perhaps when Brian D. or Briam M. return from their holiday they can
shed a little light on this and what they had in mind for a solution. I
would be very interested on what the intended solution is.
Regards,
Christian
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Gustavo Novais
Sent: Tuesday, December 27, 2005 3:25 PM
To: Christian Sica; Chula Bandara; Cisco certification
Subject: RE: [SPAM] - RE: [SPAM] - RE: [SPAM] - RE: Other ways of
solving it
--- frame-relay backup - Sending mail server found on dnsbl.njabl.org -
Sending mail server found on relays.ordb.org - Sending mail server found
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Hi
What I thought of was just to increase ospf cost on the ppp link, so
that it is not used by "regular" traffic. Besides that, we must not
forget that although the cost is high, the OSPF hello packets are still
flowing through it. So, suppress them. To do that - ip ospf
demand-circuit.
Does that mean that if I ping R5 side of the link from R4 it will not
use the directly connected route? No. But I this is the best I can
figure out given the restrictions.
I'd just wish that the IEWB solutions guide were out before my exam, to
clear that kind of doubts... but I guess I won't be so lucky.
Gustavo Novais
-----Original Message-----
From: Christian Sica [mailto:csica@liweb.net]
Sent: terga-feira, 27 de Dezembro de 2005 20:15
To: Gustavo Novais; 'Chula Bandara'; 'Cisco certification '
Subject: [SPAM] - RE: [SPAM] - RE: [SPAM] - RE: Other ways of solving it
--- frame-relay backup - Sending mail server found on dnsbl.njabl.org -
Sending mail server found on relays.ordb.org - Sending mail server found
on relays.ordb.org
Gustavo,
Ok, this one got me to thinking so I lab'd it up. Your right, the frame
mapping restriction is only from spoke to spoke, and as you stated OSPF
PtMP fixes that. I don't think that dialer watch will help either since
it will not take the circuit out of service if the watched route remains
in the routing table. The only service that allows us to do that is the
backup command. Now you mentioned before that the physical interface
will have to go down in order for the backup interface to trigger, so
guess that means we cannot use the backup command on the serial
interface. What is another way we can accomplish it?
Christian
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Gustavo Novais
Sent: Tuesday, December 27, 2005 2:02 PM
To: Christian Sica; Chula Bandara; Cisco certification
Subject: RE: [SPAM] - RE: [SPAM] - RE: Other ways of solving it ---
frame-relay backup - Sending mail server found on dnsbl.njabl.org -
Sending mail server found on relays.ordb.org
The wording of the section 2.2 says that I must not use dynamic mappings
AND not use static mapping BETWEEN the spokes. That is because later on
OSPF section you have to configure ospf point-to-multipoint network on
the interfaces, which will generate a /32 to the hub. Then by routing
you are able to reach the other spoke.
If this was an ISDN environment I would not hesitate about configuring
dialer-watch to backup this. But it isn't.
Are you suggesting some kind of tracking of the /32 route injected by
ospf p2mp in order to trigger the backup?
Is that possible on a dedicated-line-backup-environment?
Gustavo Novais
-----Original Message-----
From: Christian Sica [mailto:csica@liweb.net]
Sent: terga-feira, 27 de Dezembro de 2005 18:53
To: Gustavo Novais; 'Chula Bandara'; 'Cisco certification '
Subject: [SPAM] - RE: [SPAM] - RE: Other ways of solving it ---
frame-relay backup - Sending mail server found on dnsbl.njabl.org -
Sending mail server found on relays.ordb.org
Gustavo,
True, the backup feature will not detect a pvc failure. It will only go
down if it stops receiving LMI from the local frame switch. So there
must be another way, and there is. I would recommend going back and
looking at your config for section 2.2. Your config is using physical
interfaces, so that means sub interfaces are out of the question.
However, you are also not allowed to use either dynamic or static
mapping. So, the question is, how did you configure your frame
connection here to meet these requirements?
Thanks,
Christian
-----Original Message-----
From: Gustavo Novais [mailto:gustavo.novais@novabase.pt]
Sent: Tuesday, December 27, 2005 1:34 PM
To: Christian Sica; Chula Bandara; Cisco certification
Subject: RE: [SPAM] - RE: Other ways of solving it --- frame-relay
backup - Sending mail server found on dnsbl.njabl.org
Hi,
I see your point, but the backup feature only allows me to backup an
interface that is physically down. As we know, the fact of one PVC going
down on a major interface does not trigger the backup interface up.
I still have not cleared completely out this issue, and that is why I've
sent this mail to the group. This was based on IEWB v3.0 lab 19. If any
of the authors wish to pronunciate...
Thank you
Gustavo Novais
-----Original Message-----
From: Christian Sica [mailto:csica@liweb.net]
Sent: terga-feira, 27 de Dezembro de 2005 18:01
To: Gustavo Novais; 'Chula Bandara'; 'Cisco certification '
Subject: [SPAM] - RE: Other ways of solving it --- frame-relay backup -
Sending mail server found on dnsbl.njabl.org
I don't see how using the "ip ospf demand-circuit" feature will help you
here. This command was designed to allow an OSPF adjacency to remain up
without sending constant hello packets out the interface. This was
usefull for ISDN since it would allow the neighborship to form over the
ISDN link without keeping the ISDN circuit up. I would suggest you look
at the "backup" feature. Look at the wording, "Configure the network in
such a way that this link is only used if R4 (a spoke) loses its
connection to the frame-relay cloud." So, if you just set the cost of
the PPP link to say 1000, does that meet the requirements? Is that
enough to prevent any traffic from using the circuit unless the frame
circuit is down? Try it out.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Gustavo Novais
Sent: Tuesday, December 27, 2005 9:54 AM
To: Chula Bandara; Cisco certification
Subject: RE: Other ways of solving it --- frame-relay backup
Yes,
I think that both of them (increasing cost and demand-circuit) must be
used.
Increase cost because we do not wish the circuit to be used, and Demand
Circuit to suppress hellos, and then effectively we do NOT use the ppp
link.
I think that either of those used by its own would not guarantee that
you would not use the ppp link (unless FR goes down on R4)
Gustavo Novais
________________________________
From: Chula Bandara [mailto:chula_bandara@hotmail.com]
Sent: terga-feira, 27 de Dezembro de 2005 14:48
To: Gustavo Novais
Subject: RE: Other ways of solving it --- frame-relay backup
I think , you can also do a ip ospf demand-circuit over a point-to-point
circuit.
________________________________
From: "Gustavo Novais" <gustavo.novais@novabase.pt>
Reply-To: "Gustavo Novais" <gustavo.novais@novabase.pt>
To: "Cisco certification " <ccielab@groupstudy.com>
Subject: Other ways of solving it --- frame-relay backup
Date: Tue, 27 Dec 2005 14:27:18 -0000
Hello group,
I have a task where I'm asked to do a backup of a frame-relay
circuit
using OSPF. The backup line is a dedicated serial line
encapsulated with
ppp. The wording is as follow:
Configure area 0 on the ppp link between R4 and R5
The ppp link will be a backup of of frame-relay connection
between
R4
and R5 (both using major interfaces, R5 hub, R4 spoke).
Configure the
network in such a way that this link is only used if R4 (a
spoke) loses
its connection to the frame-relay cloud.
My obvious solution to this is just to increase the ospf cost of
the
interfaces involved on the ppp link, in order that it does not
show up
as the preferred path between R4 and R5.
My doubt is that perhaps this solution may be too obvious, and
perhaps I
am missing something...
Any suggestions or alternative ways of doing this? Am I just
being
paranoid about complexity?
Thank you
Gustavo Novais
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