Routing Event Detector - OSPF and MPLS

[katerina.dardoufa]

Dear community,

I have the following issue which I thought I  cοuld solve using EEM, but after reading many of the relative posts I  have come to a blank!

Here is the problem:

My company is  migrating to GETVPN and we use OSPF to connect to our provider. On its  PEs the provider has set max-lsa to 3000, where 3000 is the sum of all  LSAs of my company's routers connected to that specific PE. For  super-extra redundancy we want to still use our previous backup  connection, so when either the main line, or the ADSL line fail (these  are not on our router, but on the CPE), traffic can be routed through  the backup-ISDN. We are also using OSPF in our internal network, and the  IP address of the ISDN-backup and that of the connection to the  provider (CPE) belong to the same ospf area.

When the ip address  of the BRI is participating in OSPF,  LSAs advertised to the PE are  about 2000 for every remote site, so on the PE the max-lsa number is  very quickly reached, resulting in loss of connectivity!!! For the time  being ISDN is not participating in OSPF so as to overcome the above  issue.

I was wondering if you can think of a way to add  the ISDN in the routing process, when connectivity through the main and  DSL link fail, but without sending the LSAs sent through the BRI to the  provider. The reverse process is also needed (when main line and ADSL  come back up).

I had Routing Event Detector in mind,  but I don't know how to trigger an action when a route stops being in  the routing table. If it stops being in the routing table (for example  routes learnt from fa0/1 which is the connection with the CPE) the ISDN  should be triggered. If routes from fa0/1 reappear, then the ISDN must  immediatly come down and as I understand it for all the time ISDN is up,  no LSAs should be sent to the provider, because if they are  connectivity to all other routers on the PE will probably be lost!

Maybe there is another way to accomlish the above without EEM?

Maybe the problem is something I need to run by the Routing Section?

Thanks in advance

Katerina

[Joe Clarke]

For some of the OSPF-specific questions, you should run those by WAN Routing & Switching.  But for the EEM routing ED, you can detect when a specific network is removed from the routing table, but not on a specific interface.  However, you can do the interface check from within your policy.  For example, say you want to trigger when 10.1.1.0/24 is removed from the routing table, but only when that route was learned through Fa0/1:

event manager applet route-watch
 event routing network 10.1.1.0/24 type remote protocol ospf
 action 001 if $_routing_lastinterface ne "FastEthernet0/1"
 action 002  exit
 action 003 end
 ...

The "..." would be the other actions you need to do to bring up your ISDN interface.

[katerina.dardoufa]

Joseph,

Thank you for your reply! The answer to my question came through WAN Routing & Switching, but the info you provided will be useful for future reference

Thanks for your assistance,

Katerina