[j-nsp] Problem with OSPF route summarization

[Jeremy Wallace]

On the Juniper boxes, summarizing external routes that are being
injected into OSPF can be done in two ways.

1- The external routes can be summarized in a policy on the ASBR. 
Junos does not have a command that will do this automatically at the
ASBR.  This will bring the external routes into the network in a Type 7
LSA.
2- Use the nssa area-range statement (as mentioned before) at the ABRs. 
Only the ABRs are allowed to summarize routes going into the backbone
area.  This will summarize the specified ranges from Type 7 LSAs into a
single Type 5 LSA.  Once the Type 5 LSA is in the network, it _cannot_
be summarized anywhere in the network.

These two methods can be used exclusively of each other, or they can be
used together maximize summarization.

HTH,

J.

J> Hi Eric,
J> 
J> I believe you can only summarise directly on the ASBR (the ex-internal
J> router where redistribution into OSPF is taking place), but if you want to
J> have all the externals in the internal area, you could make the area an
J> NSSA. Then summarising on the ABR by doing what Josef suggested, with the
J> NSSA area-range commands. 
J> 
J> HTH.