Can't Etherchannel Cisco 3660 router with Catalyst 2950 switch

[kgbroce]

I have configured "port-channels" on a Cisco 3660 router (IOS 12.4-5a) and a Catalyst 2950 switch (IOS 12.1-19).

I reset the configs to factory defaults and then applied just the commands to form an etherchannel between the two devices. The result is that neither device can ping the other.

For some reason, the CLI on the 3660 will only let me enter "channel-group <number>". It will not let me enter "mode", "auto", "desirable", etc. I can only assume that this means PAGP and LACP are not supported and that the above channel-group command is equivalent to "channel-group <number> mode on".

I temporarily removed the port-channels and defined an IP address directly on one of the router interfaces, and I was able to ping between the devices. This rules out an interface or cable issue.

Listed below are my device configs. Both devices report the port-channel as "up and up". My goal is to simply be able to ping between the devices.

Any help would be most appreciated!


Catalyst 2950

version 12.1
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Switch
!
no logging console
!
ip subnet-zero
!
!
spanning-tree mode pvst
no spanning-tree optimize bpdu transmission
spanning-tree extend system-id
!
!
interface Port-channel1
no ip address
duplex full
!
interface FastEthernet0/1
no ip address
duplex full
speed 100
channel-group 1 mode on
!
interface FastEthernet0/2
no ip address
duplex full
speed 100
channel-group 1 mode on
!
interface FastEthernet0/3
no ip address
!

<Config Truncated>

!
interface Vlan1
ip address 10.0.18.103 255.255.255.0
no ip route-cache
!
ip http server
!
!
line con 0
line vty 5 15
!
end


Cisco 3660

version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Router
!
boot-start-marker
boot-end-marker
!
logging buffered 16000 debugging
no logging console
!
no aaa new-model
!
resource policy
!
ip cef
no ip domain lookup
!
!
interface Port-channel1
ip address 10.0.18.100 255.255.255.0
full-duplex
hold-queue 0 in
!
interface FastEthernet0/0
no ip address
speed 100
full-duplex
channel-group 1
!
interface FastEthernet0/1
no ip address
speed 100
full-duplex
channel-group 1
!
!
ip http server
no ip http secure-server
!
control-plane
!
line con 0
line aux 0
line vty 0 4
!
!
end

Switch#show interface port-channel 1
Port-channel1 is up, line protocol is up (connected)
Hardware is EtherChannel, address is 0011.218e.9d81 (bia 0011.218e.9d81)
MTU 1500 bytes, BW 200000 Kbit, DLY 1000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Full-duplex, 100Mb/s
input flow-control is off, output flow-control is off
Members in this channel: Fa0/1 Fa0/2
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output 00:00:01, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
34 packets input, 3328 bytes, 0 no buffer
Received 10 broadcasts (0 multicast)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 4 multicast, 0 pause input
0 input packets with dribble condition detected
115 packets output, 11050 bytes, 0 underruns
0 output errors, 0 collisions, 5 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 PAUSE output
0 output buffer failures, 0 output buffers swapped out



Router#show interface port-channel 1
Port-channel1 is up, line protocol is up
Hardware is FEChannel, address is 0002.162e.0000 (bia 0002.162e.0000)
Internet address is 10.0.18.100/24
MTU 1500 bytes, BW 200000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
ARP type: ARPA, ARP Timeout 04:00:00
No. of active members in this channel: 2
Member 0 : FastEthernet0/0 , Full-duplex, 100Mb/s
Member 1 : FastEthernet0/1 , Full-duplex, 100Mb/s
No. of Non-active members in this channel: 0
Last input 00:00:14, output never, output hang never
Last clearing of "show interface" counters never
Input queue: 0/150/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/80 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
0 packets input, 0 bytes
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog
0 input packets with dribble condition detected
20 packets output, 1319 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out



Switch#show etherchannel detail

Channel-group listing:
-----------------------

Group: 1
----------
Group state = L2
Ports: 2 Maxports = 8
Port-channels: 1 Max Port-channels = 1
Protocol: -
Ports in the group:
-------------------
Port: Fa0/1
------------

Port state = Up Mstr In-Bndl
Channel group = 1 Mode = On/FEC Gcchange = -
Port-channel = Po1 GC = - Pseudo port-channel = Po1
Port index = 0 Load = 0x00 Protocol = -

Age of the port in the current state: 00d:00h:04m:47s

Port: Fa0/2
------------

Port state = Up Mstr In-Bndl
Channel group = 1 Mode = On/FEC Gcchange = -
Port-channel = Po1 GC = - Pseudo port-channel = Po1
Port index = 0 Load = 0x00 Protocol = -

Age of the port in the current state: 00d:00h:04m:34s

Port-channels in the group:
----------------------

Port-channel: Po1
------------

Age of the Port-channel = 00d:00h:10m:49s
Logical slot/port = 1/0 Number of ports = 2
GC = 0x00000000 HotStandBy port = null
Port state = Port-channel Ag-Inuse
Protocol = -

Ports in the Port-channel:

Index Load Port EC state No of bits
------+------+------+------------------+-----------
0 00 Fa0/1 On/FEC 0
0 00 Fa0/2 On/FEC 0

Time since last port bundled: 00d:00h:04m:34s Fa0/2

Switch#
Switch#sho etherchannel port-channel ?
| Output modifiers
<cr>


Router#show etherchannel detail

Channel-group listing:
-----------------------

 

[Minue]

Hello
I am currently studying enterchannel,no expert.Try making the making the channel a trunk,could be a VLAN1 issue.Another troubleshooting step would be to put a workstation on a switch port to try the ping.
Regards

 

[Minue]

Hello
Just google this link,strangely it says the 3600 doesn't support etherchannel.Could be an old doc.In any case the document expains exactly what you are trying to achieve.
Regards

http://www.cisco.com/en/US/products...iguration_example09186a00800ef797.shtml#tbl-3

 

[kgbroce]

Minue:

I have been using the document you referenced. Adding VLAN trunking doesn't help, unfortunately. Link Aggregation (EtherChannel) and VLAN Trunking are completely separate concepts, so I didn't think it would help, but I will try anything at this point.

When attaching a workstation to the switch, the pings are successful. This is definitely an issue with the router. Although the document says the 3600 does not support EtherChannel, I think that was as of version 12.2. I am using version 12.4, and it reports the EtherChannel as "up and up", so I am guessing that it is supported. Either I am missing some additional configuration command or EtherChannel is actually unsupported or broken in this IOS version.

On the 2950, I changed port-channel 1 to be a trunk:

interface Port-channel1
switchport mode trunk
no ip address
duplex full
flowcontrol send off


On the 3660, I added a sub-interface to port-channel 1.
I also turned off cef and spanning-tree.

no ip cef
no spanning-tree vlan 1

interface Port-channel1
no ip address
full-duplex
hold-queue 0 in

interface Port-channel1.1
encapsulation dot1Q 1 native
ip address 10.0.18.104 255.255.255.0
no snmp trap link-status


These changes had no effect.

Thanks for replying.

 

[Minue]

Hello
If you can ping the router that mean the channel is working.The etherchannel is having problems speaking to VLAN1 (the swith management interface).As far as trunking goes,I have always seen etherchannels configure as trunks.Try making the layer 2 port on the switch trunks as well.
Regards

 

[vipergg]

The 3600 series does not support etherchannel . Unless you have the following installed it does not appear to support channeling . This is pulled from this doc.

http://www.cisco.com/en/US/products...s_configuration_example09186a00800ef797.shtml

An exception to EtherChannel support on Cisco 2600, 3600, and 3700 series routers is when you have installed either the NM-16ESW or NM-36ESW Ethernet Switch Network Module. Each of these modules supports a maximum of six EtherChannels, with up to eight ports in an EtherChannel bundle.

 

[kgbroce]

You do not have to configure VLAN Trunking to support EtherChannel. The IEEE defines two independent standards:

802.3ad - Link Aggregation ("EtherChannel")
802.1q - VLAN Tagging ("VLAN Trunking")

The confusion people have is with the term "trunk". When two or more physical interfaces are combined together as one (802.3ad), it is sometimes referred to as a "trunk". Taking multiple VLANs and pushing them through a single interface (802.1q) is also called trunking. This "single interface" does not have to be an EtherChannel although it can be.

Many times you do see the two combined, and I plan to do this once I am able to get EtherChannel working (if ever). I purposely removed the VLAN Trunking in my config to focus on where the issue was occurring. The issue exists with or without VLAN trunking enabled.

I cannot ping the router from the switch, and I cannot ping the switch from the router. Both devices report the port-channel interface as "up and up". I can ping the router port-channel interface from within the router itself. I did configure the switch port-channel interface in trunk mode but this did not fix anything.

I had reviewed this document previously:

http://www.cisco.com/en/US/products...s_configuration_example09186a00800ef797.shtml

It was specific to IOS version 12.2. Because the CLI allowed me to build the port-channel and reported it as "up and up", I assumed that as of IOS version 12.4 that perhaps EtherChannel was now supported on the 3600 (without requiring an NM-*ESW). This may have been a bad assumption on my part. Normally, the CLI warns you and prevents you from configuring something that is not supported which is the reason I am still unsure if I am just missing a configuration step.

Thanks again for the responses.

 

[Minue]

Hi Vipergg,
Remember that Cisco is very contradicting on some of their products.Recently it seems that they have added support via "Flexible PAgP" for EtherChannel 0n the 2651XM ,2811, and up,3660, 3725/45 and 3825/45.I haven't seen any configuration examples around.
Regards

 

[vipergg]

Cisco has a habit of leaving commands within the CLI even if its not supported on given platforms.

 

[Minue]

That make sense too!But the channel link is up and traffic is passing.
Regards

 

[vipergg]

Do you have the default gateway set in the 2950 ? Normally you should be able to ping it if it is directly attached to the router but its something to check. Didn't see it in the 2950 config. should be 10.0.18.100