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

[Adam Greene]

Arie,

I apologize for the late reply. Thank you VERY much for this suggestion. I
really appreciate it!!

Thanks,
Adam

-----Original Message-----
From: Arie Vayner (avayner) [mailto:avayner at cisco.com] 
Sent: Saturday, October 25, 2014 5:28 PM
To: Adam Greene; cisco-nsp at puck.nether.net
Subject: RE: [c-nsp] PBR / EEM / OSPF SNMP MIB

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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