Which LACP negotiating mode is used by X-series?

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Article ID: 167807

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Updated On:

Products

XOS

Issue/Introduction

This article documents the LACP negotiating mode on X-series.This article documents the LACP negotiating mode on X-series together with an example for an LACP channel between X-series and Cisco switch.

Cause

LACP supports two link negotiating modes: active and passive. A device in active mode always sends LACP control frames, while a passive device waits on its neighbor to start the negotiation. 

At least one side of the channel must be acting in active mode to establish the aggregated link bundle.

Resolution

X-series chassis always forms LACP channel in active mode.

The peer device can be configured either in active or passive mode.


Below, there is an example of group interface 1/2 + 2/2 on X-series side (active mode) and Gi1/2 + Gi2/2 on Cisco side (passive mode):

1. X-series side output example:

CBS# show veth-stats
Reporting Module            vsxr65_1
    Load Balance State      Selected
    Slot/Port               1/2
    Circuit Name            DSVR
    Local Key               0x0200
    Partner Key             0x0007
    Partner Sys. Priority   32768
    Partner ID              00:21:55:38:2f:80
    TX State                Distributing
    RX State                Current
    Check Frequency         Slow Periodic
    Local Oper. State       LACP Activity, Aggregation, Synchronization, Collecting, Distributing
    Partner Oper. State     Aggregation, Synchronization, Collecting, Distributing
 
Reporting Module            vsxr65_1
    Load Balance State      Selected
    Slot/Port               2/2
    Circuit Name            DSVR
    Local Key               0x0200
    Partner Key             0x0007
    Partner Sys. Priority   32768
    Partner ID              00:21:55:38:2f:80
    TX State                Distributing
    RX State                Current
    Check Frequency         Slow Periodic
    Local Oper. State       LACP Activity, Aggregation, Synchronization, Collecting, Distributing
    Partner Oper. State     Aggregation, Synchronization, Collecting, Distributing

 
2. Cisco side output example:
 
show etherchannel 7 detail
Group state = L2
Ports: 2   Maxports = 16
Port-channels: 1 Max Port-channels = 16
Protocol:   LACP
Minimum Links: 0
                Ports in the group:
                -------------------
Port: Gi1/2
------------
 
Port state    = Up Mstr In-Bndl
Channel group = 7           Mode = Passive      Gcchange = -
Port-channel  = Po7         GC   =   -         Pseudo port-channel = Po7
Port index    = 1           Load = 0x55        Protocol =   LACP
 
Flags:  S - Device is sending Slow LACPDUs   F - Device is sending fast LACPDUs.
        A - Device is in active mode.        P - Device is in passive mode.
 
Local information:
                            LACP port     Admin     Oper    Port        Port
Port      Flags   State     Priority      Key       Key     Number      State
Gi1/2     SP      bndl      32768         0x7       0x7     0x102       0x3C
 
Partner's information:
          Partner Partner   LACP Partner  Partner   Partner  Partner     Partner
Port      Flags   State     Port Priority Admin Key Oper Key Port Number Port State
Gi1/2     SA      bndl      32768         0x0       0x200    0x22        0x3D
 
Port: Gi2/2
------------
 
Port state    = Up Mstr In-Bndl
Channel group = 7           Mode = Passive      Gcchange = -
Port-channel  = Po7         GC   =   -         Pseudo port-channel = Po7
Port index    = 0           Load = 0xAA        Protocol =   LACP
 
Flags:  S - Device is sending Slow LACPDUs   F - Device is sending fast LACPDUs.
        A - Device is in active mode.        P - Device is in passive mode.
 
Local information:
                            LACP port     Admin     Oper    Port        Port
Port      Flags   State     Priority      Key       Key     Number      State
Gi2/2     SP      bndl      32768         0x7       0x7     0x202       0x3C
 
Partner's information:
          Partner Partner   LACP Partner  Partner   Partner  Partner     Partner
Port      Flags   State     Port Priority Admin Key Oper Key Port Number Port State
Gi2/2     SA      bndl      32768         0x0       0x200    0x42        0x3D
 
                Port-channels in the group:
                ----------------------
Port-channel: Po7    (Primary Aggregator)
 
------------
 
Age of the Port-channel   = 1068d:19h:09m:32s
Logical slot/port   = 14/6          Number of ports = 2
Port state          = Port-channel Ag-Inuse
Protocol            =   LACP
 
Ports in the Port-channel:
 
Index   Load   Port     EC state        No of bits
------+------+------+------------------+-----------
  1          55     Gi1/2    Passive           4
  0          AA     Gi2/2    Passive           4

Workaround

N/A