[c-nsp] IS-IS Multiarea on 12.2 SR

[Jared Gillis]

Oliver Boehmer (oboehmer) wrote:
> Jared,
> 
>> I've been having quite a few adventures with IS-IS over the last few
> weeks
>> and have finally hit a wall, so I'm hoping someone here can give me a
> hand.
>> Basically, I need to build a network with IS-IS multiarea as described
> here:
> http://www.cisco.com/en/US/products/ps6599/products_data_sheet09186a0080
> 0e97
>> 80.html
> 
> I reckon you need to build this for IP? ISIS multiarea is only supported
> for CLNS routing, as stated in the above link under "Restrictions".

I do need this for IP routing, not CLNS. If the feature is only supported for ISO CLNS and not IP routing, why does it work on my lab of 2600s running 12.3 latest, with the exact same config, also in an IP-only environment?
Really, my only need is to prevent my L1 routers from learning the entire area's routes, but my network design requires me to directly connect my L2 router to an L1 (i.e. no room for a L2/L1 between them). I just need the L1 routers to get a default towards its directly attached L2, and the L2 backbone to learn the L1's routes. This is essentially a TS-NSSA in OSPF. If there's some other way I can get this behavior with IS-IS, I'm all ears.

>> Secondarily, if we can't have true IS-IS multiarea, we may be able to
>> simulate it by manually redistributing from the L1 instances to the L2
>> instances, and setting default-information originate on the L1
> instances. I
>> attempted this in the lab, and while the commands are accepted and
> appear to
>> be good, neither redist nor default origination is actually happening.
>> Does anyone have any suggestions on this front? Redist and default
>> origination should "just work".
> 
> not sure what you mean here as an alternative. You can use
> "default-information originate" to originate a 0.0.0.0/0 in the node's
> LSPs (instead of using the attached-bit from the L1L2 node, possibly
> along with "never-set-attached-bit" and "ingore-attached-bit" knobs to
> control ATT bit  behaviour), but the L1 -> L2 advertisement requires a
> "proper" ISIS design (i.e. no multi-area config when using it for IP).

I have default-information originate on my upstream router, towards the L1 it is connected to. The L1 has no default route in it's table, and is not apparently receiving the ATT bit, as it's not sending traffic towards the upstream. In any case, if I can't get L1->L2 advertisement, the point is moot.

> 
> 	oli