I have an issue with ospf routing for a pair of 4948 we are using. They have a number of vlan interfaces, in different subnets of the same major net. They have been configured with loopback interfaces, too. I need the vlans to be known by the other 4948 and two 7604s which are ruuning ospf with the 4948s and BGP with three different SP. he loopbacksp are included in ospf with the network statement. My question is, do I need to include in the ospf config a network statement for each vlan, or would be better to just use a redistribute connected subnets?
This entire discussion digs a lot into OSPF past, and OSPF present.... There was, at one time, only two types of SPF in OSPF:
1. Full SPF run, performed whenever any change in a type 1, 2, or 3 occurred.
2. Partial SPF, performed whenever there was a change in a type 5.
So, at one time (and still, on some routers with older cold, but don't go asking me when iSPF was put in any specific code, because my memory doesn't work that way!:-) ), redistributing connected routes gave you faster SPF runs for edge changes than running network statements with passive. A change to a connected network caused all the routers to simply lop the link off the tree, and not run SPF at all, really.
So, a lot of folks ran redistribute connected because it cut down on spf runs--you had the inclusion of the type 4's, but then that was a tradeoff against the SPF runs.
Well... Now, with incremental SPF, internals which are leaf nodes only (not transit links to other nodes), are treated the same way as externals, so there is no real difference in the convergence between externals and type 3's, or leaves off type 1's, etc. So, that rational is gone entirely....
At this point in the game, it all comes down to elegance and management. If you have a special reason to segregate externals, for troubleshooting purposes, then running the internals with passive interfaces is going to be better. If you don't really care, and don't mind eating the type 4's, and more complexity in the stub area types, well, it doesn't matter either way.
Do what's easiest for you, at this point.