Why Po1A in C6507 ?

[ashish.sehgal1]

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
1      Po1(SU)         LACP      Gi5/1(P)   Gi5/2(P)
1      Po1A(SU)        LACP      Gi4/23(P)  Gi4/24(P)

can anyone explain why Po1A is created.

My understanding:

if we use two or more set of interfaces from different slots, it creates PoxA.

[Mark Malone]

Hi

Actually it happens when you bundle ports together that are miss matched incompatible

http://www.cisco.com/c/en/us/support/docs/lan-switching/etherchannel/19642-126.html#po1a

Secondary Aggregator Ports Po1A or Po2A are Created

A secondary aggregator port will be created in the LACP process when the ports you are bundling are not compatible with each other, or with their remote peers. The secondary aggregator port will have the ports which are compatible with others.

Switch#show etherchannel summary
Flags:  D - down        P - in port-channel
        I - stand-alone s - suspended
        H - Hot-standby (LACP only)
        R - Layer3      S - Layer2
        U - in use      f - failed to allocate aggregator

        u - unsuitable for bundling
Number of channel-groups in use: 6
Number of aggregators:           8

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------
1      Po1(SU)         LACP      Gi1/16(P)  Gi10/1(P)  Gi10/2(P)
2      Po2(SD)         LACP
2      Po2A(SU)        LACP      Gi1/15(P)  Gi10/3(P)  Gi10/4(P)
3      Po3(SU)         LACP      Gi1/14(P)  Gi10/5(P)  Gi10/6(P)
4      Po4(SD)         LACP
4      Po4A(SU)        LACP      Gi1/13(P)  Gi10/7(P)  Gi10/8(P)
5      Po5(SU)         LACP      Gi1/12(P)  Gi10/9(P)  Gi10/10(P)
6      Po6(SU)         LACP      Gi1/11(P)  Gi10/11(P) Gi10/12(P)