Frame-relay and summarization

Ibbywannit · ‎04-09-2008

Dear respected peers and Gurus,

I've been racking my brains here. Doing an exercise and have managed to get full connectivity throughout the frame - i've added a seed metric and was just wondering if the frame "switch" is seen as totally transparent.

When i see the metric to the destination:

0 E1 172.29.136.0 [110/1582] via 172.29.136.3, 01:02:29, Serial 1/0

Now this cost would be fine IF there was only one link (running at 64K), but there are 3. 1 to the frame, 1 from the frame and the 1 over RIP on the Fa0/0. Now i understand that OSPF runs a default seed matric of 20 which would account for the Fa0/0 link - but what about the additional links in the frame-relay network? 100000000/64000 = 1562.5 + 20 = 1582, but there are 2 links...

Also, i can't for the life of me seem to summarize my RIP routes into OSPF. The spokes see the routes (which are 5.5.5.5, 6.6.6.6 and 7.7.7.7) but when i try to summarize

R1(config)#router ospf 20

R1(config-router)#summary-address 5.0.0.0 248.0.0.0

Nothing...

I'm sure i'm doing something wrong. I would try to do it with manual summarization, but i know that the mask can't be less than the classful value (ie: /8).

Thanking you all in advance

Kevin Dorrell · ‎04-09-2008

The frame connection is regarded as a single link. As far as layer-3 is concerned, it is a single link. If you want it to us a different cost than the calculated one, then you will have to configure the cost, or the nominal bandwidth, manually. The cost is concerned with bandwidth, and the bandwidth across the FRS is 64K.

BTW, the cost need not be the same in each direction. Each router counts its own cost to get onto the network, but does not take the receiver's cost into account. So asymetric paths are possible.

As for your summary, I have not tried a supernet summary, but I think it should work, provided R1 is actually the ASBR. But I think you want more like summary-address 4.0.0.0 252.0.0.0. That would summarize networks 4 to 7.

Kevin Dorrell

Luxembourg

Ibbywannit · ‎04-09-2008

I like your explanations (and your blog by the way ;)) - i'm forever in your shadow. The BTW comment was a master-stroke because "it just so happens" that the bandwidth configurations were different on both sides of the link. Excellent explanation - deserves a 5.

Kevin Dorrell · ‎04-10-2008

Thank you for your kind words. I really don't want to shadow anyone .. I would prefer to enlighten where I can! And where I cannot, I want to learn, and that is what it's all about. Thanks.

Kevin Dorrell

Luxembourg

Ibbywannit · ‎04-09-2008

I like your explanations (and your blog by the way ;)) - i'm forever in your shadow. The BTW comment was a master-stroke because "it just so happens" that the bandwidth configurations were different on both sides of the link. Excellent explanation - deserves a 5.