Etherchannel -1 port in Pd state in 2950 switch

Unanswered Question
Feb 6th, 2010

Hi all,


I have 2 2950 switches where there gi0/ 1 and gi 0/2 are connected with each other and performing the trunk.


sh int trunk

Port        Mode         Encapsulation  Status        Native vlan
Po1         on           802.1q         trunking      1

Port      Vlans allowed on trunk
Po1         1-4094

Port        Vlans allowed and active in management domain
Po1         1

Port        Vlans in spanning tree forwarding state and not pruned
Po1         1


Today i created the etherchannel  with the trunk ports gi01 and 02 of both switches.


2950T#sh etherchannel 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)          -        Gi0/1(Pd)   Gi0/2(P)



My question is why port gi0/1 shows as Pd---default port  ?

is this due to spann     tree loop?


many thnaks

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mahesh18 Sat, 02/06/2010 - 08:03

Hi Vijay,


Thanks for reply so the port in other states gi0/1 on both switches is it in blocking state on both ends or blocking state on 1 end only?

Ganesh Hariharan Sat, 02/06/2010 - 07:58

Hi all,


I have 2 2950 switches where there gi0/ 1 and gi 0/2 are connected with each other and performing the trunk.


sh int trunk

Port        Mode         Encapsulation  Status        Native vlan
Po1         on           802.1q         trunking      1

Port      Vlans allowed on trunk
Po1         1-4094

Port        Vlans allowed and active in management domain
Po1         1

Port        Vlans in spanning tree forwarding state and not pruned
Po1         1


Today i created the etherchannel  with the trunk ports gi01 and 02 of both switches.


2950T#sh etherchannel 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)          -        Gi0/1(Pd)   Gi0/2(P)



My question is why port gi0/1 shows as Pd---default port  ?

is this due to spann     tree loop?


many thnaks

Hi,


Genrally Catalyst 2900XL/3500XL switches maintain a notion of a default port on which to transmit traffic, such as Spanning Tree Protocol (STP), multicasts, and unknown unicasts.


Check out the below link for further information


http://www.cisco.mn/en/US/tech/tk389/tk213/technologies_tech_note09186a0080094714.shtml


Hope to help


If helpful do rate the post


Ganesh.H

Giuseppe Larosa Sat, 02/06/2010 - 08:06

Hello Mahesh,

you will find out that all traffic uses only one port of the port-channel, this platform C2950 implements port channels in this way.

So you get redundancy but only one link will be used.


We had even opened a Cisco TAC SR for this reason.


Hope to help

Giuseppe

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