Etherchannel on 3745 chassis interfaces

[svallet]

Hi,

I'm currently trying to enable etherchannel on the built-in FastEthernet interfaces. The router is a c3745, running IOS 12.3, connected to a 3550 catalyst.

Everything seems to run fine, a sh int port-channel 2 shows the link is up on both sides, but there is no way to ping between the 2 devices. By looking at ARP tables, you can see that the switch is receiving requests from the router, and replying, but the router does not seem to receive anything ; more, a sh etherchannel 2 detail on the 3745 does not show any information.

So here's the question : is it at all possible to get an etherchannel working using the built-in FaE interfaces from a 3745 ? I could not find any doc on the subject, be it on cisco's website or using Google.

Any hint is appreciated

Thanks,
Simon

 

[IPKONFIG]

You should be able to etherchannel on the 3745. Why don't you post your config so we can see if there is an issue there.

"I can picture a world without war. A world without hate. A world without fear. And I can picture us attacking that world, because they'd never expect it."
- Jack Handey, Deep Thoughts

 

[svallet]

OK, here's the relevant config

c3745, IOS 12.3(12) Fa 0/0 and 0/1 are chassis interfaces:
[...]
!
interface Port-channel2
no ip address
full-duplex
no cdp enable
!
interface Port-channel2.103
encapsulation dot1Q 15 native
ip address 192.168.103.249 255.255.255.0
no snmp trap link-status
no cdp enable
!
[...]
!
interface FastEthernet0/1
no ip address
speed 100
full-duplex
channel-group 2
no cdp enable


c3550, IOS 12.1(22)EA2
[...]
!
interface Port-channel2
switchport access vlan 15
switchport trunk encapsulation dot1q
switchport trunk native vlan 15
switchport mode trunk
!
[...]
!
interface FastEthernet0/2
switchport access vlan 15
switchport trunk encapsulation dot1q
switchport trunk native vlan 15
switchport mode trunk
speed 100
duplex full
channel-group 2 mode on
!
[...]
!
interface Vlan15
ip address 192.168.103.254 255.255.255.0
!


on the switch :
# sh int port 2
Port-channel2 is up, line protocol is up (connected)
Hardware is EtherChannel, address is 000e.830d.b302 (bia 000e.830d.b302)
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Full-duplex, 100Mb/s, media type is unknown media type
input flow-control is off, output flow-control is unsupported
Members in this channel: 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)
[...]

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

Port state = Up Mstr In-Bndl
Channel group = 2 Mode = On/FEC Gcchange = -
Port-channel = Po2 GC = - Pseudo port-channel = Po2
Port index = 0 Load = 0x00 Protocol = -

Age of the port in the current state: 0d:20h:11m:29s

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

Port-channel: Po2
------------

Age of the Port-channel = 0d:20h:11m:38s
Logical slot/port = 1/0 Number of ports = 1
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 Fa0/2 On/FEC 0

Time since last port bundled: 0d:20h:11m:30s Fa0/2

On the router:
# sh int port 2.103
Port-channel2.103 is up, line protocol is up
Hardware is FEChannel, address is 0011.9328.0201 (bia 0011.9328.0200)
Internet address is 192.168.103.249/24
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation 802.1Q Virtual LAN, Vlan ID 15.
ARP type: ARPA, ARP Timeout 04:00:00
Last clearing of "show interface" counters never

# sh ether 2 detail
(empty)

# sh int port 2 etherchannel
Etherchnl not enabled on this port

... and there is no way to ping between those two interfaces ; using "debug arp" I can see arp requests from the router on the switch, I can see the switch replying to those requests, but I can't see anything on the router

 

[chieftan999]

I can only see the one FA port that is assigned to the Etherchannel.

You will need to have more than 1 port to set up a correct etherchannel (at least I would assume so).

The port assigned is FA0/2 - althogh FA0/1 stipulates channel-group2 it is not switched on.

Look at the difference between the configuration of fa0/1 and fa0/2 and you will see the obvious.

You can also see from your sh port commands that the only true assigned active port to channel-group2 is fa0/2.

 

[IPKONFIG]

Chieftan is right...I noticed that it only shows one interface in your channel. Both interfaces should have the same channel group.

"I can picture a world without war. A world without hate. A world without fear. And I can picture us attacking that world, because they'd never expect it."
- Jack Handey, Deep Thoughts

 

[chieftan999]

Also note thatbwhen setting up an 802.1q encapsulated etherchannel, both ends of the link MUST be identical or it will not function correctly.

Reamin positive. The affect on those around you will amaze.

 

[svallet]

Hi all,

thanks for your suggestions: the source of the problem may be that there isn't a second interface in the channel. However, the other router/switch link, on Fa0/0 is currently in production, and I can't disable it just to see if that works.

Besides, the Catalyst seems to be fine having just one interface in the channel, and trying to assign another Fa interface (on an etherwitch NM plugged into the router) to the port-channel does seem to be functional, i.e. the corresponding "sh ether 2 detail" does produce output. That's why I specifically mentionned the built-in interfaces.

I think I'll finally have to rewire this, sadly.