[c-nsp] Conditionnal routing based on OSPF / IP SLA

[David Prall]

Your static route is the same as a connected interface. Connected always
beats static. You don't have any redistribution or network statements
defined under router bgp, so how is this network getting installed, so it
can be advertised to the neighbor? R2 has the same interface connected, you
are using the same subnet on both R1 and R2. R2 has a network statement
defined, so R2 advertises it to R1 and R3. R1 has the same interface
connected. I'd write an EEM script that tracks this particular route, if the
route goes away no shut the serial interface. Don't know why you would want
to do this on a serial interface and have both up at the same time. If it is
switching gear outside the routers that will flip it over, then the serial
interface should be down until that happens.

David

--
http://dcp.dcptech.com



-----Original Message-----
From: Henry-Nicolas Tourneur [mailto:hntourneur at autempspourmoi.be] 
Sent: Wednesday, November 30, 2011 4:11 AM
To: 'David Prall'; cisco-nsp at puck.nether.net
Subject: RE: [c-nsp] Conditionnal routing based on OSPF / IP SLA

Hi David,

Actually I do not want to track the interface status but ensure that a ping
is working.
This is because the router will not be directly connected to the router to
monitor.

Here's a quick overview of the lab setup:

    Se0/1:0        Se0/1:0
	\              |
	 \             |
	  R1 --1000--- R2
	   \          /  
	    \        /
	     10    1000 
	      \    /
	       \  /
		  R3

3 routers connected using OSPF with the specified costs and a full mesh BGP
network.
I want R1 to stop announcing route to se0/1:0 IP range when the IP address
of R2 (10.0.1.2) can't be pinged anymore.
At that time, the traffic destinated to that range should go to R2.

You can find the results of show track when the IP address is reachable or
not in attachment (R1_commands).
Also the config of each router is in attachment.

Thanks for your help,

-----Original Message-----
From: David Prall [mailto:dcp at dcptech.com]
Sent: mardi 29 novembre 2011 15:02
To: 'Henry-Nicolas Tourneur'; cisco-nsp at puck.nether.net
Subject: RE: [c-nsp] Conditionnal routing based on OSPF / IP SLA

So why not just track the interface status? The static should go away if the
interface goes down? What does "sh track" show you? On your track object, I
always use state instead of reachability.

The following should accomplish what you are trying to do. If se0/1:0 is
down then it won't be advertised.
ip route 17.4.240.40 255.255.255.240 Se0/1:0 10.0.1.2 tag 1755

David

--
http://dcp.dcptech.com



-----Original Message-----
From: Henry-Nicolas Tourneur [mailto:hntourneur at autempspourmoi.be]
Sent: Tuesday, November 29, 2011 3:30 AM
To: 'David Prall'; cisco-nsp at puck.nether.net
Subject: RE: [c-nsp] Conditionnal routing based on OSPF / IP SLA

Hello David,

I tried the following, pretty straightforward setup.
I'v a full mesh iBGP running on 3 lab routers and OSPF between them (simple
triangle).

The IP to be checked is on a /30 in between R1 & R2, when this go down, I
want R1 to stop announcing the ip route (should disappear on R3).
The tag 1755 is to force the route to be advertised through iBGP and not
OSPF.

If the IP to be checked goes down, I can see that the SLA Monitor status
goes to down but yet, R1 keep advertising the route.

Any idea why? 

ip sla monitor 1
 type echo protocol ipIcmpEcho 10.0.1.2
 timeout 800
 frequency 2
!

ip sla monitor schedule 1 life forever start-time now track 100 rtr 1
reachability

ip route 17.4.240.40 255.255.255.240 Se0/1:0 tag 1755 track 100

Thanks in advance :)

Henry-Nicolas Tourneur.


-----Original Message-----
From: David Prall [mailto:dcp at dcptech.com]
Sent: jeudi 24 novembre 2011 19:20
To: 'Henry-Nicolas Tourneur'; cisco-nsp at puck.nether.net
Subject: RE: [c-nsp] Conditionnal routing based on OSPF / IP SLA

You can do this with track objects and static routing, then redistribute the
static into ospf. You could use a conditional route-map like they do in the
example for default as well. But I think putting a static in and
redistributing it will be much easier.

David

--
http://dcp.dcptech.com



-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Henry-Nicolas
Tourneur
Sent: Thursday, November 24, 2011 10:28 AM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] Conditionnal routing based on OSPF / IP SLA

Hi all,

 

I'm currently trying to make a Cisco router to announce one network
statement based on the result of an IP Sla probe.

Currently, I found this tutorial:

 

http://hackingcisco.blogspot.com/2011/03/lab-33-ospf-conditional-default-rou
ting.html

 

But it's only for "default-information", I would need this for a particular
route.

 

Does anybody have an idea how to do this?

 

Thanks and regards,

 

Henry-Nicolas Tourneur.

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