of channels and trunks...

this is very exciting...

i got some more crossed cables today specifically to experiment with etherchannel, and trunking at the same time without losing connectivity...

i now have a 4 wire trunk and a 4 wire etherchannel across the 3 switches... trunk = 2 xcables from s2 to s1, then 2 xcables from s1 to 3550... likewise for the etherchannel, 2 xcables from s2 to s1, then 2 from s1 to 3550...

as i thought would happen, the etherchannel took over and put the trunk ports in alt/blk... see below


sw2950_02#sh spann

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/1            Altn BLK 19        128.1    P2p
Fa0/2            Altn BLK 19        128.2    P2p
Po1              Root FWD 12        128.65   P2p


when i shut down the etherchannel, the network converges on the trunk, like so...


sw2950_02(config)#int po1
sw2950_02(config-if)#shut

05:46:32: %LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel1, changed
 state to down
05:46:33: %LINK-5-CHANGED: Interface FastEthernet0/5, changed state to administr
atively down
05:46:33: %LINK-5-CHANGED: Interface FastEthernet0/6, changed state to administr
atively down



the trunk is back in business...


sw2950_02(config-if)#

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/1            Root FWD 19        128.1    P2p
Fa0/2            Altn BLK 19        128.2    P2p




then



sw2950_02(config-if)#no shut
05:50:10: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/5, chang
ed state to up
05:50:10: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/6, chang
ed state to up
sw2950_02(config-if)#
05:50:11: %LINK-3-UPDOWN: Interface Port-channel1, changed state to up
05:50:12: %LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel1, changed
 state to up

and the etherchannel takes over once again...


sw2950_02(config-if)#do sh ether summ
Flags:  D - down        P - in port-channel
        I - stand-alone s - suspended
        H - Hot-standby (LACP only)
        R - Layer3      S - Layer2
        u - unsuitable for bundling
        U - in use      f - failed to allocate aggregator
        d - default port

Number of channel-groups in use: 1
Number of aggregators:           1

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------

1      Po1(SU)          -        Fa0/5(Pd)   Fa0/6(P)


but you knew this would happen...