[nsp] IS-IS L1 Internal Reachability not propogated in Level2 LSPs

From: Martin, Christian (CMartin@mercury.balink.com)
Date: Thu Jun 22 2000 - 09:27:09 EDT


Cisco folk, sorry for the JUNOS question here, but I know there are some of
you lurking out there that may have an answer to this...

It appears that, at least in JUNOS 4.0, IP Internal Reachabilty TLV data is
not sent in L2 LSPs for subnets directly connected to the router. Here is
the topology:

 
|-----------0---------------0====================0----------------0---------
---|
     ^ ^ ^ ^ ^ ^ ^ ^ ^
 x.L1-PTP L1-IS y.L1 L1/L2 A.L2-PTP L1/L2 z.L1-PTP L1-IS
k.L1-LAN

The 0 represents an IS, and the - represents a L1 ckt, the = is L2. The
x.L1-PTP represents subnet x, on a PTP L1 circuit.

The leftmost L1/L2 router is an M40 running 4.0, the rest are GSRs running
12.0. I can see both x and y subnets throughout the area to which they
belong, however, I cannot see y in the right L1/L2 GSR's L2 LSPDB, which
then prevents the rest of the L2 IS's connected to it from seeing a path
back to that area. Therefore, the L1/L2 GSR does not see y in its L2 LSPDB.
In fact, it has no TLV 128 entries for any subnet connected to the M40, and
no other L2 IS connected to the M40 sees the TLV. On the other hand, the
M40 does see z in its L2 LSPDB. I suppose I could create a policy to export
direct routes into IS-IS, but wouldn't this make them IP external? This
changes their preference, which would break routing if there is another L2
Cisco in the area, because it would learn about y through L1 LSPs and send
them to other L2 routers in L2 LSPs as TLV 128 instead of 130.

TIA,
chris



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