Port-Channel

[krzysztofmaciejewskiit]

Hi, I am wondering why port-channel 3 works when I have 'access' at one end of Po3 and 'trunk' at the other end of Po3.

---Switch2---

interface Port-channel3

switchport mode access

!

interface FastEthernet0/23

switchport mode access

channel-group 3 mode passive

!

interface FastEthernet0/24

switchport mode access

channel-group 3 mode passive

---Switch3---

interface Port-channel3

switchport mode trunk

!

interface FastEthernet0/23

switchport mode trunk

channel-group 3 mode active

!

interface FastEthernet0/24

switchport mode trunk

channel-group 3 mode active

[MHM Cisco World]

Show interface status or show interface switchport check last mode of PO I think it access not trunk.

[krzysztofmaciejewskiit]

after executing the 'show interfaces status' command on the switch where I had previously set Po3 as 'switchport mode access' the only thing that changes is in the 'vlan' column from 'trunk' to '1', status, duplex, speed, type remain the same. So yes you are right, it is 'access' and not 'trunk' but I did it on purpose with the idea that it would fail, but however the port-channel works and it started me thinking.

[MHM Cisco World]

How you test PO? 

[Joseph W. Doherty]

"Hi, I am wondering why port-channel 3 works when I have 'access' at one end of Po3 and 'trunk' at the other end of Po3."

I would think for the same reason a non-Etherchannel access<>trunk would "work".  (It appears many believe cannot mix those port types, but, in the past, I've posted examples were it does "work", although with "issues".  My prior posts were not a recommendation to do this, but as teaching examples to better understand these port "kinds".)

[Gopinath_Pigili]

if you are doing with Cisco Packet tracer.....save the topology....close the program..

reopen the topology and check....port-channel is up/down...?

It may helpful....

[krzysztofmaciejewskiit]

After re-open the CPT, Po3 us ip.

[Gopinath_Pigili · Accepted solution]

from this what i understand  is it might problem with packet tracer......it self...

As we know clearly...we can establish port-channel between similar links...Both sides either Access/Trunk...

When we use dissimilar modes port-channel shouldn't  be up/establish...

I think it is the limitation/bug  in packet tracer...

Thanks

[Richard Burts]

I agree that most likely this is an issue with the emulator. But there is one possibility to consider: on the trunk the native vlan frames are forwarded without any tag. If that frame in the native vlan is received on the access port of the other switch it would be forwarded normally and "it works". However any frames in the other vlans on the trunk would not work. So "it works" would be only partially true.