| Mike West 2003-08-31, 2:28 pm |
| I've got a question that I'm hoping some of you gurus can straighten me out
on. It's a question regarding a Case Study in Kennedy Clark's book 'Cisco
LAN Switching'. The question is regarding a couple of sentences on Page
752, regarding 'Design 1', using MLS. This design uses an ATM core with a
common subnet on LANE modules for the MDF switches. The core uses VLAN 250
and that VLAN is pruned from the trunk link between the MDF switches in each
building. My question comes from the last 2 sentences in the first
paragraph on Page 752. The sentences are....For VLAN 250, the backbone
VLAN, Cat-B1-0A is configured as the primary Root Bridge (not shown here)
with Cat-B2-0B as the secondary. This allows Cat-B2-0B to take over as the
Root Bridge for the core in the event that connectivity is lost to Building
1.
Now I'll admit, ATM is one of my weak points. But, I was under the
impression that STP was not a concern with an ATM core, since I thought LANE
automatically creates a loop-free topology within the ATM core itself (from
Chapter 15, bottom of page 662). If that's the case, why would there be
concern for configuring a primary and secondary root for the core.
Thanks in advance for any info,
Mike
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