From: Tom Nooning (t.nooning@insightbb.com)
Date: Fri Jun 03 2005 - 05:20:18 GMT-3
What workbook/scenario is this? In ISIS you don't need a true "backbone",
there is no concept of the OSPF area 0. Level-2 routers can be in different
areas, maybe this is what the scenario is calling for?
From http://www.ciscopress.com/articles/article.asp?p=101756&rl=1 via
Google:
Describe IS-IS Level 2 routing.
Level 2 routing is routing between areas. Level 2-capable routers comprise
the IS-IS backbone and can be in separate areas. Any traffic bound for other
areas must go through a Level 2-capable router. Level 2 routing is based on
area ID.
Describe the differences in backbone require-ments between OSPF and IS-IS.
OSPF requires that an area be defined as a backbone area and that each other
area border that backbone area. Special configuration (a virtual link) is
required for any area that does not border the backbone area. IS-IS backbone
routers can reside in any area. There merely must be an unbroken chain of
Level 2 or Level 1/2 routers in order for the backbone to function.
Tom
----- Original Message -----
From: "Ralph Sherry" <yodajedi6678@yahoo.com>
To: <ccielab@groupstudy.com>
Sent: Thursday, June 02, 2005 11:57 PM
Subject: ISIS dual backbones?
>I have run accross a scenario where it seems to be calling for 2 L2 ISIS
>backbones. IS this possible? How would one of the backbones know how to
>route to a area that was only attached to the second backbone? If this
>was in OSPF I would simply configure a virtual link between the 2
>backbones.
>
>
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