[c-nsp] PBR / EEM / OSPF SNMP MIB

[Arie Vayner (avayner)]

Adam,

You could use an EEM applet based on the "event routing protocol <ospf>" event detector, which can trigger a script when a certain route is added or removed from the RIB.
The scripts could apply, remove or modify the route-map applied on your interface.

I would suggest you have the route-maps pre-configured, and you only change the route-map policy applied on the interface dynamically.

Arie

-----Original Message-----
From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Adam Greene
Sent: Saturday, October 25, 2014 07:58
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] PBR / EEM / OSPF SNMP MIB

Hi,

 

Somewhat complicated conditional routing question to run by you all .

 

This is on a 3750 switch, 12.2(25)SEE2.

 

We want to route traffic sourced from a particular IP range out a particular interface. This is simple to do using Policy Based Routing.

 

However, we want that route to be conditional upon the existence of a particular route in the OSPF RIB, in this case an external type 2 default route with a metric of 100. 

 

I understand that PBR only supports matches on source IP and packet length.
On the 3750, it also does not support object tracking.

 

This article suggests we could use EEM to track SNMP MIB objects and remove the PBR depending on the value returned by an SNMP poll:
https://supportforums.cisco.com/document/31461/policy-based-routing-pbr-trac
king-catalyst-3xxx-switches-workaround-using-eem. 

 

So the question is . can SNMP be used to track whether an external type 2 default route with a metric of 100 is present in the OSPF RIB?

 

Thanks,

Adam

 

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