ETHERCHANNEL: UNDERSTANDING TOPOLOGY


How to check Port channels & associated physical ports with their status ?

core_1#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 – in use      f – failed to allocate aggregator

u – unsuitable for bundling
Number of channel-groups in use: 28
Number of aggregators:           28

Group  Port-channel  Protocol    Ports
——+————-+———–+———————————
1      Po1(RU)         LACP      Gi6/5(D)   Gi11/1(P)  Gi13/42(P)
2      Po2(RD)         LACP      Gi6/6(D)   Gi11/2(D)

 

How to check which protocols are running on Ether channels?

core_1#sh etherchannel protocol

Group: 1

Protocol: LACP

Group: 2

Protocol: LACP

 

How to check if Etherchannel is a Layer 2 or Layer 3 Etherchannel ?

core_1#sh etherchannel   < etherchannel no.>   de

Example

core_1#sh etherchannel 1 de

Group state = L3

core_1#sh etherchannel 19 de

Group state = L2

 

How to check when last time any physical port was bundled or unbundled?

Example

core_1#sh etherchannel 19 de | i Time

Time since last port bundled:   487d:12h:09m:15s   Gi4/33

Time since last port Un-bundled: 487d:13h:13m:38s   Gi4/33

 

How to check if there is any port in the suspended state?

core_1#sh int status | i suspended

Port     Name               Status       Vlan       Duplex Speed Type

Gi2/6     Trunk             suspended   trunk       full   1000 1000BaseSX

 

When Physical Port in a Port Channel goes into Suspended State, Example Logs Generated?

Mar 1 00:29:22: %EC-5-CANNOT_BUNDLE2: Fa0/13 is not compatible with Fa0/14 and will be suspended (trunk encap of Fa0/13 is dot1q, Fa0/14 is isl)

/ This shows Encapsulation mismatch /

 

How to check LACP or PAgP packets sent or received OR,

How to check for any LACP or PAgP error packet?

core_1#sh lacp counters

LACPDUs         Marker     Marker Response   LACPDUs

Port       Sent   Recv     Sent   Recv     Sent   Recv     Pkts Err


Channel group: 1

Gi6/5         0     0       0     0       0     0         0

Gi11/1     620092 620104   0     0       0     0         0

Gi13/42   620022 620152   0     0       0     0         0

 

core_1#sh pagp counters

Information         Flush       PAgP

Port     Sent   Recv     Sent   Recv   Err Pkts


Channel group: 21

Gi3/45   620089   620163   0       0       0

Gi3/46   620064   620192   0       0       0

 

How to check LACP or PAgP Port priority?

core_1#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

Gi6/5     SA     down     32768         0x1       0x0     0x605       0x45

Gi11/1   SA     bndl     32768        0x1       0x1     0xB01       0x3D

 

core_1#sh pagp internal

Flags: S – Device is sending Slow hello. C – Device is in Consistent state.

A – Device is in Auto mode.       d – PAgP is down

Timers: H – Hello timer is running.       Q – Quit timer is running.

S – Switching timer is running.   I – Interface timer is running.

Channel group 21

Hello   Partner PAgP     Learning Group

Port     Flags State   Timers Interval Count   Priority   Method Ifindex

Gi3/45   SC   U6/S7           30s     1       128       Any     506

Gi3/46   SC   U6/S7           30s     1       128       Any     506

 

How to check LACP neighbor parameters ?

core_1#sh lacp neighbor

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 neighbors

Partner’s information:

Partner Partner   LACP Partner Partner   Partner Partner     Partner

Port     Flags   State     Port Priority Admin Key Oper Key Port Number Port Stat

Gi6/5     SP     down     0             0x0       0x0     0x0         0x0

Gi11/1   SA     bndl     32768         0x0       0x2     0xF         0x3D

Gi13/42   SA     bndl     32768         0x0       0x2     0xE         0x3D

 

 

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