From: ccie2be (ccie2be@nyc.rr.com)
Date: Mon Oct 20 2003 - 11:43:35 GMT-3
Hi group,
I'm hoping to resolve a couple of IS-IS questions/issues:
1) In Doyle's Routing TCP/IP vol I chapter on IS-IS, he emphasizes the fact
that in a IP only, multi-area IS-IS network, the IS-IS process doesn't know
how to interpret the ATT bit which means that Level 1 routers don't know route
packets to other areas. Doyle then presents two methods to overcome this
problem.
However, in the freely downloadable chapter on IS-IS from Cisco Press,
http://ciscopress.com/catalog/ccnp.asp?session_id={DFB54D2A-5AB6-4B7E-9BA1-BC
4657301EA4}
no mention is made of this issue and in the multi-area examples, multi-area
routing works without employing either of the methods Doyle says is necessary.
Are Doyle's methods of overcoming this problem no longer needed? If so, why
is that?
2) In Cisco's IS-IS documentation it says,
router isis [area tag]
Use the area tag arguments to identify the area to which this IS-IS router
instance is assigned. A value for tag is required if you are configuring
multiple IS-IS areas.
But, in all the examples I've seen in both Doyle and in the above chapter,
the "router isis" didn't ever include an "area tag" even though the router
might be connected to another area. Can someone explain and give examples of
when the area tag is needed or not needed?
Thanks in advance, dt
This archive was generated by hypermail 2.1.4 : Mon Nov 24 2003 - 07:53:05 GMT-3