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!
short answer is yes.
Here is what it looks like in an actual switch:
switchport mode access
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)
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)
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
*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#sh int trunk
Port Mode Encapsulation Status Native vlan
Po50 on 802.1q trunking 1
Port Vlans allowed on trunk
Port Vlans allowed and active in management domain
Port Vlans in spanning tree forwarding state and not pruned
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.