Problems with Etherchannel

[spalislam]

I can't get the Etherchannel to work on my 3550 <--> 2950.

Everything is configured properly, but still etherchannel sometimes brings both of the interfaces up and sometimes shuts one of them down, for no reason. Cables are same, configs same, everything exactly same. I already looked up the error message talking something about balun cable. I am not sure what kind of cable is balun, but I used normal CAT5 crossover cables between switches. Please if anyone has any suggestions, I would really appreciated.

2950 is configured through PO1 (on fa0/23, fa0/24) to PO8 on 3550 (on fa0/44, fa0/43)

Here is the configs:

3550:

!##################################

! Created by Senad P. on May 2003

!##################################

!

! Last configuration change at 10:19:08 MST Thu May 15 2003

!

version 12.1

no service single-slot-reload-enable

no service pad

service timestamps debug datetime

service timestamps log datetime

service password-encryption

!

hostname D2-2001

!

clock timezone MST -7

!

vlan 233

!

vlan 234

!

vtp domain wb

vtp mode transparent

!

interface Port-channel1

switchport trunk encapsulation dot1q

switchport mode trunk

no ip address

interface Port-channel8

switchport trunk encapsulation dot1q

switchport mode trunk

no ip address

!

... SHORTENED BECAUSE OF CHARRACTER LIMITATION

interface Port-channel9

switchport trunk encapsulation dot1q

switchport mode trunk

no ip address

!

interface Port-channel10

switchport trunk encapsulation dot1q

switchport mode trunk

no ip address

!

interface FastEthernet0/1

switchport access vlan dynamic

no ip address

no logging event link-status

speed 100

duplex full

no snmp trap link-status

storm-control broadcast level 70.00

storm-control multicast level 70.00

storm-control unicast level 85.00

spanning-tree portfast trunk

!

interface FastEthernet0/2

switchport access vlan dynamic

no ip address

no logging event link-status

speed 100

duplex full

no snmp trap link-status

storm-control broadcast level 70.00

storm-control multicast level 70.00

storm-control unicast level 85.00

spanning-tree portfast trunk

!

SHORTENED BECASUE OF CHARACTER LIMITATION

!

interface FastEthernet0/44

switchport trunk encapsulation dot1q

switchport mode trunk

no ip address

speed 100

duplex full

channel-group 8 mode on

!

interface FastEthernet0/45

switchport trunk encapsulation dot1q

switchport mode trunk

no ip address

speed 100

duplex full

channel-group 9 mode on

!

interface FastEthernet0/46

switchport trunk encapsulation dot1q

switchport mode trunk

no ip address

speed 100

duplex full

channel-group 9 mode on

!

interface FastEthernet0/47

switchport trunk encapsulation dot1q

switchport mode trunk

no ip address

speed 100

duplex full

channel-group 10 mode on

!

interface FastEthernet0/48

switchport trunk encapsulation dot1q

switchport mode trunk

no ip address

speed 100

duplex full

channel-group 10 mode on

!

interface GigabitEthernet0/1

description "UPLINK TO CAT6509"

switchport trunk encapsulation dot1q

switchport mode trunk

no ip address

!

interface GigabitEthernet0/2

no ip address

!

!

interface Vlan1

no ip address

no ip route-cache

shutdown

!

interface Vlan234

ip address 137.190.x.x 255.255.x.x

no ip route-cache

!

ip default-gateway 137.190.x.x

ip classless

no ip http server

!

2950:

sh run

Building configuration...

vlan 234

!

vlan 243

!

vtp domain wb

vtp version 2

vtp mode transparent

!

vmps server 137.190.

!

interface FastEthernet0/1

switchport access vlan dynamic

no ip address

no logging event link-status

speed 100

duplex full

no snmp trap link-status

storm-control broadcast level 70.00

storm-control multicast level 70.00

storm-control unicast level 85.00

storm-control action trap

spanning-tree portfast trunk

!

interface FastEthernet0/2

switchport access vlan dynamic

no ip address

no logging event link-status

speed 100

duplex full

no snmp trap link-status

storm-control broadcast level 70.00

storm-control multicast level 70.00

storm-control unicast level 85.00

storm-control action trap

spanning-tree portfast

!

SHORTENED BECAUSE OF CHARACTER LIMITATION

!

interface FastEthernet0/23

description "UPLINK TO 3550"

switchport mode trunk

no ip address

speed 100

duplex full

channel-group 1 mode on

!

interface FastEthernet0/24

description "UPLINK TO 3550"

switchport mode trunk

no ip address

speed 100

duplex full

channel-group 1 mode on

!

interface Vlan1

no ip address

no ip route-cache

shutdown

!

interface Vlan234

ip address 137.190. 255.255.

no ip route-cache

!

ip default-gateway 137.190.

D2-2003#

#

#%ETHCNTR-3-LOOP_BACK_DETECTED

#

Here is the DEBUG LOG from 2950:

May 21 20:27:57: FEC: pagp_switch_find_master: group 1

May 21 20:27:57: FEC: fec_bundle: Fa0/24

May 21 20:27:57: FEC: add port (Fa0/24) to agport (Po1)

May 21 20:27:57: FEC: fec_set_agport_macaddr: Po1 Fa0/24 (add)

May 21 20:27:57: FEC: pagp_switch_add_port_to_agport: msg to PM to bundle port Fa0/24 with Po1

May 21 20:27:57: FEC: pagp_switch_want_to_bundle: Bndl msg to PM for port Fa0/24 to Agport Po1

May 21 20:27:57: FEC: pagp_switch_hotstandby: for agport Po1

May 21 20:27:57: FEC: pagp_switch_hotstandby: PAgP not enabled on agport Po1

May 21 20:27:57: FEC: pagp_switch_reset_load_index: reading load-index for port Po1

May 21 20:27:58: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/24, changed state to up

May 21 20:27:59: %LINK-3-UPDOWN: Interface FastEthernet0/23, changed state to up

May 21 20:27:59: %LINK-3-UPDOWN: Interface Port-channel1, changed state to up

May 21 20:28:00: FEC: pagp_switch_port_up: Fa0/23

May 21 20:28:00: FEC: pagp_switch_invoke_port_up: Fa0/23

May 21 20:28:00: FEC: pagp_switch_agc_compatable: comparing GC values of Fa0/23 Fa0/24 flag = 1 1

--More-- May 21 20:28:00: FEC: pagp_switch_port_attrib_diff: Fa0/23 Fa0/24 same

May 21 20:28:00: FEC: pagp_switch_agc_compatable: GC values are compatable

May 21 20:28:00: FEC: fec_bundle: Fa0/23

May 21 20:28:00: FEC: add port (Fa0/23) to agport (Po1)

May 21 20:28:00: FEC: fec_set_agport_macaddr: Po1 Fa0/23 (add)

May 21 20:28:00: FEC: pagp_switch_add_port_to_agport: msg to PM to bundle port Fa0/23 with Po1

May 21 20:28:00: FEC: pagp_switch_want_to_bundle: Bndl msg to PM for port Fa0/23 to Agport Po1

May 21 20:28:00: FEC: pagp_switch_hotstandby: for agport Po1

May 21 20:28:00: FEC: pagp_switch_hotstandby: PAgP not enabled on agport Po1

May 21 20:28:00: FEC: pagp_switch_reset_load_index: reading load-index for port Po1

May 21 20:28:00: %LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel1, changed state to up

May 21 20:28:01: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/23, changed state to up

May 21 20:28:55: %ETHCNTR-3-LOOP_BACK_DETECTED: Loop-back detected on FastEthernet0/24. The port is forced to linkdown.

May 21 20:28:55: FEC: pagp_switch_hotstandby: for agport Po1

May 21 20:28:55: FEC: pagp_switch_hotstandby: PAgP not enabled on agport Po1

May 21 20:28:55: FEC: pagp_switch_port_down: Fa0/24

May 21 20:28:55: FEC: pagp_switch_invoke_port_down: Fa0/24

--More-- May 21 20:28:55: FEC: fec_unbundle: Fa0/24

May 21 20:28:55: FEC: pagp_switch_delete_port_from_agport: delete_port_from_agport: for port Fa0/24

May 21 20:28:55: FEC: delete port (Fa0/24) from agport (Po1)

May 21 20:28:55: FEC: pagp_switch_remove_from_bundle: Un-Bndl msg NOT send to PM for port Fa0/24 from Po1

May 21 20:28:55: FEC: pagp_switch_reset_load_index: reading load-index for port Po1

May 21 20:28:55: FEC: fec_set_agport_macaddr: Po1 Fa0/24 (remove)

May 21 20:28:56: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/24, changed state to down

May 21 20:31:21: %LINK-3-UPDOWN: Interface FastEthernet0/24, changed state to up

May 21 20:31:22: FEC: pagp_switch_port_up: Fa0/24

May 21 20:31:22: FEC: pagp_switch_invoke_port_up: Fa0/24

May 21 20:31:22: FEC: pagp_switch_agc_compatable: comparing GC values of Fa0/24 Fa0/23 flag = 1 1

May 21 20:31:22: FEC: pagp_switch_port_attrib_diff: Fa0/24 Fa0/23 same

May 21 20:31:22: FEC: pagp_switch_agc_compatable: GC values are compatable

May 21 20:31:22: FEC: fec_bundle: Fa0/24

May 21 20:31:22: FEC: add port (Fa0/24) to agport (Po1)

May 21 20:31:22: FEC: fec_set_agport_macaddr: Po1 Fa0/24 (add)

May 21 20:31:22: FEC: pagp_switch_add_port_to_agport: msg to PM to bundle port Fa0/24 with Po1

--More-- May 21 20:31:22: FEC: pagp_switch_want_to_bundle: Bndl msg to PM for port Fa0/24 to Agport Po1

May 21 20:31:22: FEC: pagp_switch_hotstandby: for agport Po1

May 21 20:31:22: FEC: pagp_switch_hotstandby: PAgP not enabled on agport Po1

May 21 20:31:22: FEC: pagp_switch_reset_load_index: reading load-index for port Po1

May 21 20:31:23: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/24, changed state to up

D2-3003#

[lgijssel]

Hello,

When looking at your configs I get the idea that the channel numbers are not the same on both devices. This is a requirement while the channel-group nr is communicated between them.

When you attach the 2950 to channel-group 10 on the 3550, you MUST configure channel-group 10 on the 2950, even if there is only one channel.

Regards,

Leo

[spalislam]

Leo,

Thanks for the info. And please forgive me, I am not doubting your knowledge, just wanted to make sure about it. However, are you sure that channel numbers are supposed to be same? If that is the case, 2950 supports only up to 6 channels, and 3550 I think about 24 if I remember correctly. So what happens when I configure more then a 6 channels of 2950s into 3550. Next channel after six-th one would be 7, 8 and so on. However, I cannot configure channel # higher then 6 on 2950. With this, I am limiting 3550 to only 6 channels.

Now, I have not got experience in doing ether-channels. However, I was thinking logicly and thoughed that Cisco would not limit 3550s to 2950 limitation.

Please advise.

Thanks

[hnorvik]

Hi,

I hope you fixed your issue since this is 1 1/2 year ago.

The port numbering may be different on the two sides of the etherchannel like you have; Po1 to Po8.

However looking at your log and config, I woudl suggest that you use PAgP on two devices that can talk PAgP. Use channel-group 1 mode desirable instead of mode on.

show etherchannel and show pagp will then help you find the error.