Thursday, July 30, 2009

STP Part 1

Tonight I read chapter 3 in the CCNP BCMSN Official Exam Certification Guide. It covered a lot of Layer 2/3 switching information. However it mostly covered how frames travel through a switched network, and the CAM table (content addressable memory better known as the MAC address-table), along with the TCAM table (ternary content addressable memory; which is used for acl storage within a table format). Good stuff!

I also dove back into STP, spanning tree protocol in the first video (of 4 for STP), in my computer based training courses.

BPDU's are transmitted every 2 seconds to multicast address 01-80-c2-00-00-00 in the types of:
  1. topology change notification (TCN) - change in network topology
  2. configuration - Used for STP calculations and the root bridge will originate these while the non-root bridges will forward them
Bridge ID equals the bridge priority appended with the mac address
(i.e. 32768:1f:23:45:67:89:90). Lowest BID wins STP root-bridge election.

Commands that I saw during this lesson:
show spanning-tree vlan [id]
(interface) spanning-tree cost [1-200000000] - does a cost adjustment for ALL vlans
(interface) spanning-tree vlan [id] cost [1-200000000] - changes for a vlan in pvstp

STP Costs
10 MBPS - 100
100MBPS - 19
1GBPS - 4
10 GBPS - 2

Numbered List

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