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m.kafka
Enthusiast

Can I control routing updates through IP SLA or a tracking object?

Hi all,

Scenario:

 
-
| link down +---- + /-----\
|---------X-| SW1 |---------| RT1 |--\
| +-----+ \-----/ \
| no updates for X -->| /-----\
|Netw X | RT3 |----
| updates for X --> \-----/
| +---- + /-----\ /
|-----------| SW1 |---------| RT2 |--/
| +---- + \-----/
-

Any elegant idea how to keep RT1 from announcing Netw X if there is no connectivity like sketched out above?

The only way I can think of is to create a tracking object and write eem-scripts which would add/remove a command.

"ip ospf [number] area [number]"

on the interface which are triggered by the tracking object going up or down.

I could not find any route filters, distribute lists etc which are directly controlled by a tracking object.

TIA, MiKa

5 REPLIES 5
Georg Pauwen
VIP Master

Hello,

the below script should work. You simply add and remove the network based on reachability:

track 1 rtr 1 reachability
delay down 10 up 40
ip sla 1
icmp-echo x.x.x.x source-interface GigabitEthernet0/0
frequency 10
ip sla schedule 1 life forever start-time now
!
event track 1 state down
event manager applet ospf_network_remove
action 1.0 cli command "enable"
action 2.0 cli command "config t"
action 3.0 cli command "router ospf 1"
action 4.0 cli command "no network x.x.x.x y.y.y.y area x"
action 5.0 cli command "end"

event track 1 state up
event manager applet ospf_network_add
action 1.0 cli command "enable"
action 2.0 cli command "config t"
action 3.0 cli command "router ospf 1"
action 4.0 cli command "network x.x.x.x y.y.y.y area x"
action 5.0 cli command "end"

Hi George,

that's what I meant -although I would prefer the "ip ospf area" command on the interface...

Ever seen direct control over routing advertisements based on IP SLA or track objects?

Rgds, MiKa

Mika,

the only thing I can think of, and I am not sure if this is what you want, is IP route metrics threshold tracking (see the link below).

Other than that, an IP SLA combined with an EEM script pretty much lets you configure anything you want...

http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipapp/configuration/15-mt/iap-15-mt-book/iap-eot.html#GUID-1019123F-B1AF-4623-93B5-A81A4DF3A5F7

Hi Georg,

the link you sent is rather the other way round: the tracking object depends on the routing table entry, I wanted the routing advertisement depending on the tracking state. I have seen that feature.

Thx for your answers,

MiKa

Hello,

honestly I have not (yet) seen that feature. Tracking with static routes is fairly common, but that is not what you want. The idea is to use static route tracking INSTEAD of using a dynamic routing problem, so I am not sure there is a way to accomplish this without EEM...