[nsp] Re: Redistributing static subnets via separate OSPF process

[Robert A. Hayden]

On Sun, 5 Oct 2003, Gert Doering wrote:

> Actually I think the problem is "it won't redistribute a route that is 
> not actually being *used*" - so when you do "redistribute OSPF", it will
> pick up all OSPF routes that are currently also in the main routing
> table (due to best administrative distance).  Which is not the case here,
> because those prefixes are already there as a static.

However, you can specify the specific OSPF process to redistribute, so why
would it pick up everything in the table?

For example:

router ospf 10
 ...
 redistribute ospf 15 subnets
 ...

router ospf 15
 redistribute static subnets
 distribute list 50 out

access-list 50 permit 10.0.1.0 0.0.0.255
access-list 50 deny 0.0.0.0 0.0.0.0

(this is from memory, so the syntax may be a little horked, but you get 
the idea)

In that sense, I would expect OSPF 10 to ignore general routes in the 
routing table unless specifically told to pass them along.  I don't use 
"redistribute connected subnets" and instead use network statements to 
populate the announcement pool.  Dunno if this is considered "right", but 
it provides me with the degree of control I like.

In the above example, I'd expect ospf 15 to announce 10.0.1.0 and quash 
(via the distribute list) 0.0.0.0.  Then, OSPF 10 will pass the 
announcement to 10.0.1.0 to everyone talking on that process.  Of course, 
this is what I expect.  Obviously, it ain't working like that and I have a 
sense I'm just not groking something really simple.

I like to use separate OSPF process for various customers on the network
that I exchange routes with (this is a university backbone, btw).  This
allows me to tweak each ones' distribute lists and routing session as
needed and then tell OSPF 10 to redistribute their specific process back 
to the backbone.

- Robert