Redistributing static default route in ospf

sameermunj · ‎06-13-2009

In my setup i have a internet link coming from service provider with last mile as Metro etherent.I am pointing the default route towards my service provider router.My problem is whenever the internet link is going down,because of metro ethernet the wan interface of my router is not going down and static route remains in the routing table and to avoid the same i am doing object tracking with Tack-RTR.I am doing ospf with my L3 switch towards lan side and in OSPF i am not using the default-information originate always to redistribute the static default route.

can yu please suggest how i can redistribute this static default route into my ospf.As the route is tracked whenever my metro link will go down route will go out of routing table and same will not be announced in OSPF towards internal lan.

Giuseppe Larosa · ‎06-13-2009

Hello Sameer,

you have fixed with object tracking the problem of fault detection.

Redistributing a default static route in OSPF is not supported.

You can use

router ospf

default-information originate

As soon as the object tracking detects a failure the static default route is removed from IP routing table and this triggers an OSPF action with the withdrawn (removal) of the external LSA representing the default route.

Simply you have to omit the always keyword

See also the recent thread about BGP default an d OSPF.

Hope to help

Giuseppe

sameermunj · ‎06-13-2009

i am attaching the schematic of the setup.

i am running ospf between my L3 switch and internet router.Both the internet links are coming on metro ethernet so am using tracking with the default route pointed towards ISP.Same default route needs to be announced in ospf.

Giuseppe Larosa · ‎06-13-2009

Hello Sameer,

I confirm what I wrote in my first post.

You can manipulate attributes of OSPF default route using a route map.

router ospf 10

defaul-information originate route-map name

type 1

I see you have multiple exit points so I would use O E1 type and if I'm not wrong we have already discussed about this setup there was a link missing at those times.

Hope to help

Giuseppe

sameermunj · ‎06-15-2009

yes u r correct that time we were planning to do bgp but presently setup working with static route.i ahve tested teh config you suggested and its working fine.when metro link goes down,default route disappear from RT and nt getting distributed in ospf.I ma making both links active so not putting any matric and L3 switches get 2 default route with equal cost (OSPF max path 2 defined)..

didnt get about teh routemap u mentioned in ur post.

Giuseppe Larosa · ‎06-15-2009

Hello Sameer,

the route-map in the default-originate command can be used to check some additional conditions that have to be true (for example the next-hop but it is more useful when using also eBGP) and to set some attributes of the default route to be generated like metric type seed metric and route tag.

In your case with static routes I just would change the metric type to E1 and this can be done directly with an option on the default-originate command

router ospf 10

default-information originate metric-type 1

see

http://www.cisco.com/en/US/docs/ios/iproute/command/reference/irp_osp1.html#wp1012794

so you can be sure that the most convenient default route is used also in case of a link failure with load balancing in normal conditions.

Hope to help

Giuseppe

sameermunj · ‎06-15-2009

Hi

Thats right.for engp last time u mentioned about the route-map with attributes like to check weather the default route getting from egbp peer or not. i ahve that config ready.once w eshift from static to ebgp i will chenge that configuration.as u mentioned presently i wont require any route map.only thing need to change the route type as type 1.

thanks for help