One of the offshoots of ISIS *currently* is that L1 routers blindly default to
the closest L2 router. Not only does this introduce potential routing
sub-optimalities, but it also breaks BGP MEDs if AS border routers were to be
in L1 with a L2 backbone.
This is why most provides run only one level.
There is work in the IETF ISIS WG that's addressing this very thing, among
others. Have a look at the drafts under the WG on the IETF web server...
-danny
This archive was generated by hypermail 2b29 : Sun Aug 04 2002 - 04:12:08 EDT