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I have a LACP bonded trunk link between 2 switches, the bond contains 4 interfaces; all interfaces work fine except one. Cisco says you have to have matching configurations on all interfaces.

The speed on the suspended interface was operating to auto-100, however, the bonded interfaces are operating at auto-1000. If I override this value with speed 1000, the link goes not connected

Switch 1

NON WORKING INTERFACE:
GigabitEthernet0/1 is up, line protocol is down (SUSPENDED)
  Hardware is Gigabit Ethernet, address is XXXX.XXXX.XXXX (bia XXX.XXXX.XXXX)
  MTU 9000 bytes, BW 100000 Kbit, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 100Mb/s, media type is 10/100/1000BaseTX
  input flow-control is off, output flow-control is unsupported
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 1d03h, output 1d04h, output hang never

WORKING INTERFACE ON SWITCH 1:
GigabitEthernet0/2 is up, line protocol is up (connected)
  Hardware is Gigabit Ethernet, address is XXXX.XXXX.XXXX (bia XXXX.XXXX.XXXX)
  MTU 9000 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 1000Mb/s, media type is 10/100/1000BaseTX
  input flow-control is off, output flow-control is unsupported
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:11, output 00:00:08, output hang never
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  • Hi CodeMagic... what model switch, what IOS, etc... on both sides of the link
    – Mike Pennington
    Feb 21, 2014 at 23:24
  • if you override it with speed 1000 you need to do it on both sides. Can you also provide output of show etherchannel detail?
    – Kveri
    Feb 24, 2014 at 23:18
  • I have the same issues, but with a 4500x VSS cluster, and only 10GBase-SR links. The other end is a Check Point VSX cluster, running R77.20. When rebooting the fwnodes, it is always the last one to reboot that will get a "suspended" state. Any clues?
    – user14651
    Mar 30, 2015 at 16:07
  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer.
    – Ron Maupin ♦
    Aug 10, 2017 at 3:02

4 Answers 4

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Assuming the other side of Gi 0/1 is also a GigabitEthernet, the most likely cause is a bad cable. You need a cable with all four pairs connected. 100M will work with only two pairs. That is probably why you negotiate to 100M.

For more info on how GE uses all four pairs, see: http://goo.gl/DMYkSM

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  • Thats what i thought, i changed the cable and got the same problem again, i think the port is physically broken.
    – CodeMagic
    Feb 21, 2014 at 22:32
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The issue is that the link speed of the suspended interface is not the same as the rest of the interfaces in the bundle.

Your working interfaces are operating at

BW 1000000 Kbit

Whereas, your suspended interfaces are working at

BW 100000 Kbit

The most common problem for interfaces that refuse to come up to auto-1000 are damaged cables. This assumption alone shouldn't disqualify the possibility of a configuration error, though. Verify both sides of the interface are set to autonegotiate the link speed to make sure that isn't why your link hasn't come up to 1Gb.

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If the links are trunked make sure you are not restricting the native VLAN with "trunk allowed" statement, also if you created a different type of port channel protocol make sure you delete the port-channel interface (I'm not 100% sure this is a problem), once I did this the LACP came up.

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Faced a similar issue and it was found that the new Vlans we were adding in to the network were not manually added in the port channel. Post adding the same the interfaces came up.

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