2

I have a Cisco WS-C3750G-12S switch physically connected with ports Gi1/0/1 and Gi1/0/11 to Cisco WS-C3750G-24TS ports Gi1/0/1 and Gi1/0/27 respectively. Ports have different LACP port-priority:

WS-C3750G-12S#sh lacp internal 
Flags:  S - Device is requesting Slow LACPDUs 
        F - Device is requesting Fast LACPDUs
        A - Device is in Active mode       P - Device is in Passive mode     

Channel group 1
                            LACP port     Admin     Oper    Port        Port
Port      Flags   State     Priority      Key       Key     Number      State
Gi1/0/1   SA      bndl      1             0x1       0x1     0x102       0x3D  
Gi1/0/11  SA      bndl      2             0x1       0x1     0x10C       0x3D  
WS-C3750G-12S#

WS-C3750G-24TS#sh lacp internal
Flags:  S - Device is requesting Slow LACPDUs
        F - Device is requesting Fast LACPDUs
        A - Device is in Active mode       P - Device is in Passive mode

Channel group 1
                            LACP port     Admin     Oper    Port        Port
Port      Flags   State     Priority      Key       Key     Number      State
Gi1/0/1   SA      bndl      1             0x1       0x1     0x102       0x3D
Gi1/0/27  SA      bndl      2             0x1       0x1     0x11C       0x3D
WS-C3750G-24TS#

As seen above, ports have different LACP priorities, but are still bundled. Same can be seen with sh etherchannel 1 summary:

WS-C3750G-12S#sh etherchannel 1 summary 
Flags:  D - down        P - bundled 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

        M - not in use, minimum links not met
        u - unsuitable for bundling
        w - waiting to be aggregated
        d - default port


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

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
1      Po1(SU)         LACP      Gi1/0/1(P)  Gi1/0/11(P) 

WS-C3750G-12S#


WS-C3750G-24TS#sh etherchannel 1 summary 
Flags:  D - down        P - bundled 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

        M - not in use, minimum links not met
        u - unsuitable for bundling
        w - waiting to be aggregated
        d - default port


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

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
1      Po1(SU)         LACP      Gi1/0/1(P)  Gi1/0/27(P) 

WS-C3750G-24TS#

Does lacp port-priority not work on Cisco Catalyst 3750 series? Or am I doing something wrong?

1
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can provide your own answer and accept it. – Ron Maupin Aug 7 '17 at 14:01
3

This looks normal to me. I think you may have a misunderstanding about the nature of this command.

This should help, from Cisco documentation:

The lacp port-priority interface configuration command determines which ports are bundled and which ports are put in hot-standby mode when there are more than eight ports in an LACP channel group.

3
  • Thanks! Does IOS support a similar functionality to bundle maximum-active links available in IOS XR? – Martin Jun 10 '15 at 7:30
  • That sounds like it would be a great start for another question (feel free to reference this one if you like). Without looking into it more, I do not recall such a command but I also have never come across the need to limit the size of the link aggregation group...if the links are there, why not use them? – YLearn Jun 10 '15 at 12:51
  • One use-case that I see is if the port-channel is created solely for redundancy purpose over two completely separate WAN links with different RTT(for example 30ms VS 60ms). IMHO in such situation it would make sense to use one or another connection and not to load-balance traffic over two links. – Martin Jun 11 '15 at 10:43

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.