Does anyone know a workaround for the following STP bug in dynamips? I am using the .net topology provided with my dynamips Vol II workbook. I've bumped into this many times before and can't seem to figure out what's causing it.... Sometimes reloading a device gets me by it. Sometimes adding a vlan to vtp, applying it, removing it from vtp, and exiting will fix it. Sometimes nothing seems to fix it and I'm just flat stuck. Today, here's my experience.
BB3 - Eth0/0 (204.12.1.254/24) <----> SW3 fas 1/0 - Access vlan 73 <-----> SW3 fas 1/10 TRUNKED TO SW2 fas 1/10 <--------> SW2 fas 1/13 TRUNKED TO SW4 fas 1/10 <-------> SW4 fas 1/15 - Access vlan 73 <----> SW1 1/15 - L3 port (204.12.1.7/24)
All of the relevant ports show as forwarding in Spanning Tree and are configured correctly. If I add a VLAN onto a VTP Server, all switches get the new VLAN -- meaning that trunking is working fine. Also VTP pruning is not enabled. The problem is that I cannot ping through from SW1 to BB3's Eth0/0 address. Below is output of the show spanning-tree vlan 73 on the relevant trunk links. I believe that the BPDUs sent and received under each interface is not good. I've even seen where multiple switches in the topology seem to believe they are the Spanning-Tree root bridge.
Either way, none of the switches have SW1's fas1/15 mac address in their CAM tables.
On SW3:
Port 51 (FastEthernet1/10) of VLAN73 is forwarding
Port path cost 19, Port priority 128, Port Identifier 128.51.
Designated root has priority 32768, address cc06.077c.000b
Designated bridge has priority 32768, address cc07.0c8c.000b
Designated port id is 128.51, designated path cost 19
Timers: message age 3, forward delay 0, hold 0
Number of transitions to forwarding state: 1
BPDU: sent 1, received 1104
On SW2:
Port 51 (FastEthernet1/10) of VLAN73 is forwarding
Port path cost 19, Port priority 128, Port Identifier 128.51.
Designated root has priority 32768, address cc06.077c.000b
Designated bridge has priority 32768, address cc07.0c8c.000b
Designated port id is 128.51, designated path cost 19
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
BPDU: sent 1128, received 1
Port 54 (FastEthernet1/13) of VLAN73 is forwarding
Port path cost 19, Port priority 128, Port Identifier 128.54.
Designated root has priority 32768, address cc06.077c.000b
Designated bridge has priority 32768, address cc07.0c8c.000b
Designated port id is 128.54, designated path cost 19
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
BPDU: sent 1171, received 3
On SW4:
Port 51 (FastEthernet1/10) of VLAN73 is forwarding
Port path cost 19, Port priority 128, Port Identifier 128.51.
Designated root has priority 32768, address cc06.077c.000b
Designated bridge has priority 32768, address cc07.0c8c.000b
Designated port id is 128.54, designated path cost 19
Timers: message age 3, forward delay 0, hold 0
Number of transitions to forwarding state: 1
BPDU: sent 3, received 1198