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End-to-End EtherChannel problem with Cisco 7200 Routers

Posted on 2004-09-13
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Last Modified: 2013-11-29
Hi,
I have 2 x 7200VXR (both at different locations) connected to each other via a pair of 100Mb/s 'Lan Extension' ccts provided by COLT Telecom.
Int FA2/0 on router 1 is connected to Int FA2/0 on router 2. Similarly, INT FA2/1 on router 1 is connected to INT FA2/1 on router 2.
INT FA2/0 and FA2/1 on each router are combined into a FastEtherChannel (int portchannel 1), which works OK.
However, when I disconnect int FA2/0 on router 1 to take that interface out of the EtherChannel, INT FA2/0 on router 2 (on the other end of the LES cct) does  
not leave it's own Etherchannel, causing connectivity between the  2 routers to stop.
I believe this is happening because the LES cct terminating equipment provides a local Ethernet link, so the remote end in this case (router 2), still believes that the cct is up.
What mechanism can I use to ensure an end-to-end keepalive, which will take the interface at the other end of a LES cct out of the EtherChannel if the local  end goes down? Is PAgP an option on the 7200? - I am running IOS 12.3(1a)
Any Ideas?
Thanks!
-Chris
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Question by:chrisdixon
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Expert Comment

by:celsmk
ID: 12043045
Chris,
There is a few things to check:
1) The portchannel interface is the routed interface: do not assign L3 addressing to your fastethernet ports, neither do assign bridge-group to physical interfaces. Spanning tree should be disabled.
2) In show interface portchannel1, fa2/0 and 2/1 on either router, check if keepalives are set. They must be set, otherwise, router will not detect remote interface problems.

With regards to PAgP, there are just a few routers and interfaces supporting this protocol. 7200 seems not to be in this short list.

Regards,

Celsmk
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Author Comment

by:chrisdixon
ID: 12043703
Hi Celsmk,
Here is the output from the 'sh int portchannel' command on both routers. Keepalives are enabled on both sides.
Should router2 be able to detect that int fa2/0 has gone down on router1?
-Chris

Router 1 - FA2/0 Disconnected, FA2/1 connected

Port-channel1 is up, line protocol is up
  Hardware is FEChannel, address is 0011.bb32.5638 (bia 0011.bb32.561b)
  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  1., loopback not set
  Keepalive set (10 sec)
  ARP type: ARPA, ARP Timeout 04:00:00
    No. of active members in this channel: 1
        Member 0 : FastEthernet2/1 , Full-duplex, 100Mb/s
    No. of Non-active members in this channel: 1
        Member 0 : FastEthernet2/0 , Full-duplex, 100Mb/s
  Last input 00:07:02, output never, output hang never
  Last clearing of "show interface" counters 00:00:20
  Input queue: 0/75/4294967294/0 (size/max/drops/flushes); Total output drops: 4294967215
  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
     0 packets input, 0 bytes
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     4294967295 input errors, 4294967295 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog
     0 input packets with dribble condition detected
     5 packets output, 770 bytes, 0 underruns
     4294967290 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

Router 2 - FA2/0 Disconnected, FA2/1 connected

St-Andrews-Hill-7200#sh interfaces port-channel 1
Port-channel1 is up, line protocol is up
  Hardware is FEChannel, address is 000f.2437.6238 (bia 000f.2437.621b)
  MTU 1500 bytes, BW 200000 Kbit, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation 802.1Q Virtual LAN, Vlan ID  1., 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 : FastEthernet2/0 , Full-duplex, 100Mb/s
        Member 1 : FastEthernet2/1 , Full-duplex, 100Mb/s
    No. of Non-active members in this channel: 0
  Last input 00:31:06, output never, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/150/1/0 (size/max/drops/flushes); Total output drops: 258097
  Queueing strategy: fifo
  Output queue: 0/80 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 2000 bits/sec, 0 packets/sec
     505791 packets input, 112539686 bytes
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     1 input errors, 1 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog
     0 input packets with dribble condition detected
     1097141 packets output, 765909515 bytes, 0 underruns
     0 output errors, 1 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
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Accepted Solution

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celsmk earned 250 total points
ID: 12049199
Chris,

Yes, the routers should exchange keepalives in order to see whether the other party is functioning.

What are the show interface fast 2/0 and 2/1 from both routers? The physical interfaces should have keepalives enabled.

Celsmk
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Author Comment

by:chrisdixon
ID: 12116760
I've done some testing, and it seems that the keepalives are only local, between the FastEthernet interfaces and the LES CCT NTEs.
I just have to hope that the NTEs take their Ethernet interfaces down if the cct goes down!
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