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Bronze

etherchannel

Hi every body!

Let say we have a etherchannel named port-channel p01.

Po1 has three ports in access mode.

My question is is it possible to configure po1 as trunk which in turn set the components ports in etherchannel as trunk?

thanks a lot!

1 ACCEPTED SOLUTION

Accepted Solutions

Re: etherchannel

short answer is yes.

Here is what it looks like in an actual switch:

interface Port-channel50

switchport

switchport mode access

load-interval 30

end

c6509#sh int port 50

Port-channel50 is up, line protocol is up (connected)

Hardware is EtherChannel, address is

MTU 1500 bytes, BW 2000000 Kbit, DLY 10 usec,

reliability 255/255, txload 0/255, rxload 0/255

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Full-duplex, 1000Mb/s

input flow-control is off, output flow-control is on

Members in this channel: Gi4/45 Gi4/46

ARP type: ARPA, ARP Timeout 04:00:00

Last input never, output never, output hang never

Last clearing of "show interface" counters never

Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo

Output queue: 0/40 (size/max)

30 second input rate 0 bits/sec, 0 packets/sec

30 second output rate 0 bits/sec, 0 packets/sec

14591 packets input, 2170794 bytes, 0 no buffer

Received 14591 broadcasts (14579 multicasts)

0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

0 watchdog, 0 multicast, 0 pause input

0 input packets with dribble condition detected

c6509#sh etherc sum

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

------+-------------+-----------+-----------------------------------------------

50 Po50(SU) PAgP Gi4/45(P) Gi4/46(P)

c6509#conf t

Enter configuration commands, one per line. End with CNTL/Z.

c6509(config)#int port 50

c6509(config-if)#switch mode trunk

Command rejected: An interface whose trunk encapsulation is "Auto" can not be configured to "trunk" mode.

c6509-E(config-if)#switch trunk encap dot1q

c6509-E(config-if)#switch mode trunk

c6509-E(config-if)#end

c6509-E#

*Jan 9 04:14:53.197: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet4/45, changed state to down

*Jan 9 04:14:53.205: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet4/46, changed state to down

*Jan 9 04:14:53.205: %EC-SP-5-UNBUNDLE: Interface GigabitEthernet4/45 left the port-channel Port-channel50

*Jan 9 04:14:53.213: %EC-SP-5-UNBUNDLE: Interface GigabitEthernet4/46 left the port-channel Port-channel50

*Jan 9 04:14:54.701: %SYS-5-CONFIG_I: Configured from console by console

*Jan 9 04:14:56.704: %DTP-SP-5-TRUNKPORTON: Port Gi4/45-Gi4/46 has become dot1q trunk

*Jan 9 04:14:58.937: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet4/45, changed state to up

*Jan 9 04:14:59.073: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet4/46, changed state to up

*Jan 9 04:14:58.907: %EC-SP-5-BUNDLE: Interface GigabitEthernet4/45 joined port-channel Port-channel50

*Jan 9 04:14:59.058: %EC-SP-5-BUNDLE: Interface GigabitEthernet4/46 joined port-channel Port-channel50

c6509-E#

c6509-E#sh int trunk

Port Mode Encapsulation Status Native vlan

Po50 on 802.1q trunking 1

Port Vlans allowed on trunk

Po50 1-4094

Port Vlans allowed and active in management domain

Po50 1,10,55-57,200,601-605,999

Port Vlans in spanning tree forwarding state and not pruned

Po50 none

c6509-E#

4/45 and 4/46 were initially both access ports as you can see the port-channel 50 that resulted in putting both 4/45 and 4/46 to channel-group 50. Upon making the port-channel 50 a trunk channel the physical interfaces also became trunks.

This answers your question.

10 REPLIES
Cisco Employee

Re: etherchannel

Hi Sarah,

All ports in an etherchannel needs to have identical configuration.

HTH,

jerry

Re: etherchannel

short answer is yes.

Here is what it looks like in an actual switch:

interface Port-channel50

switchport

switchport mode access

load-interval 30

end

c6509#sh int port 50

Port-channel50 is up, line protocol is up (connected)

Hardware is EtherChannel, address is

MTU 1500 bytes, BW 2000000 Kbit, DLY 10 usec,

reliability 255/255, txload 0/255, rxload 0/255

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Full-duplex, 1000Mb/s

input flow-control is off, output flow-control is on

Members in this channel: Gi4/45 Gi4/46

ARP type: ARPA, ARP Timeout 04:00:00

Last input never, output never, output hang never

Last clearing of "show interface" counters never

Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo

Output queue: 0/40 (size/max)

30 second input rate 0 bits/sec, 0 packets/sec

30 second output rate 0 bits/sec, 0 packets/sec

14591 packets input, 2170794 bytes, 0 no buffer

Received 14591 broadcasts (14579 multicasts)

0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

0 watchdog, 0 multicast, 0 pause input

0 input packets with dribble condition detected

c6509#sh etherc sum

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

------+-------------+-----------+-----------------------------------------------

50 Po50(SU) PAgP Gi4/45(P) Gi4/46(P)

c6509#conf t

Enter configuration commands, one per line. End with CNTL/Z.

c6509(config)#int port 50

c6509(config-if)#switch mode trunk

Command rejected: An interface whose trunk encapsulation is "Auto" can not be configured to "trunk" mode.

c6509-E(config-if)#switch trunk encap dot1q

c6509-E(config-if)#switch mode trunk

c6509-E(config-if)#end

c6509-E#

*Jan 9 04:14:53.197: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet4/45, changed state to down

*Jan 9 04:14:53.205: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet4/46, changed state to down

*Jan 9 04:14:53.205: %EC-SP-5-UNBUNDLE: Interface GigabitEthernet4/45 left the port-channel Port-channel50

*Jan 9 04:14:53.213: %EC-SP-5-UNBUNDLE: Interface GigabitEthernet4/46 left the port-channel Port-channel50

*Jan 9 04:14:54.701: %SYS-5-CONFIG_I: Configured from console by console

*Jan 9 04:14:56.704: %DTP-SP-5-TRUNKPORTON: Port Gi4/45-Gi4/46 has become dot1q trunk

*Jan 9 04:14:58.937: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet4/45, changed state to up

*Jan 9 04:14:59.073: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet4/46, changed state to up

*Jan 9 04:14:58.907: %EC-SP-5-BUNDLE: Interface GigabitEthernet4/45 joined port-channel Port-channel50

*Jan 9 04:14:59.058: %EC-SP-5-BUNDLE: Interface GigabitEthernet4/46 joined port-channel Port-channel50

c6509-E#

c6509-E#sh int trunk

Port Mode Encapsulation Status Native vlan

Po50 on 802.1q trunking 1

Port Vlans allowed on trunk

Po50 1-4094

Port Vlans allowed and active in management domain

Po50 1,10,55-57,200,601-605,999

Port Vlans in spanning tree forwarding state and not pruned

Po50 none

c6509-E#

4/45 and 4/46 were initially both access ports as you can see the port-channel 50 that resulted in putting both 4/45 and 4/46 to channel-group 50. Upon making the port-channel 50 a trunk channel the physical interfaces also became trunks.

This answers your question.

Bronze

Re: etherchannel

Thanks a lot Bosalaza !

I really appreciate your help.

Community Member

Re: etherchannel

Hi, I've been tasked with implementing VLAN pruning and ran across this. Will this same scnerio work if - once I enable pruning on the server switch if I could manually enable pruning on the port-channels and let it propagate to the low end devices? I seen that adding the trunk in the ether-channel did work, this seems like the same type of thing? Thanks,

Hall of Fame Super Blue

Re: etherchannel

Ted

You don't need to enable VTP pruning on the individual port channels. Just enable VTP pruning on the VTP server in global configuration mode and this will then propogate to all your client switches.

Jon

Community Member

Re: etherchannel

I have devices with max stp instance currently on them and can not add another vlan to them with our a core melt down. I understand that I need to add VTP pruning on the VTP server. But on my low end switches is where I want to free up STP instances. I need to manually do this. These low end blade switches connect to my core via port-channel and they are trunks as well. Thanks, Ted

Hall of Fame Super Blue

Re: etherchannel

Ted

If you are trying to free up STP instances then don't use VTP pruning. Instead use the "switchport trunk vlan allowed ....." command. If you don't allow a vlan on a trunk link then an instance of STP does not run across it.

With VTP pruning it still runs an STP instance.

Jon

Community Member

Re: etherchannel

Ok, I was misinformed then, I thought manual creation of vtp pruning would free up stp instances - only the aut0matic enabling of vtp pruning kept the intstances. Ok so will adding the switchport trunk allowed vlan #'s to the port-channel work? Also I do still need to delete some of the VLAN's allowed still. If you know of a good document plese send it my way. Thanks for your help.

Hall of Fame Super Blue

Re: etherchannel

Ted

Sincere apologies, but you may well be right actually. What you have just said rings a bell. I was assuming you were looking to do automatic VTP pruning but that was my misunderstanding.

In fact i have just found one of my old posts confirming that if you use the "switchport trunk pruning" command at the interface level.

So yes you should be able to add this to this to the individual interfaces on your port-channel and it should works as you intend.

Jon

Community Member

Re: etherchannel

Ok super because I need to fix this issue in a timely manner and have a lot of low end switches with a number of trunks connected. By being able to add this to the port-channel will help with the some of the actual ports i need to touch. Would you happen to know the best method for deleting unused VLANs on some of these trunks that are set to be pruned? Thanks again, Ted

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