1

Some help required please.

I have a stack which contains two access switches, and an interface from switch 1 has a successful link to the core.

However, when I try adding a secondary link on switch 2 back to the core, the interface is in a suspended state.

Access Stack

switchport mode trunk
 switchport nonegotiate
 channel-protocol lacp
 channel-group 1 mode active

Core Switch

switchport trunk encapsulation dot1q
 switchport trunk allowed vlan 100,120,200,300-302,400-403,700,900-902
 switchport mode trunk
 no keepalive
 channel-protocol lacp
 channel-group 1 mode active

Access Stack Interface

GigabitEthernet3/0/47 is up, line protocol is down (suspended)
  Hardware is Gigabit Ethernet, address is 40a6.e851.bb2f (bia 40a6.e851.bb2f)
  MTU 1500 bytes, BW 1000000 Kbit/sec, 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 never, output never, 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
     82 packets input, 5248 bytes, 0 no buffer
     Received 82 broadcasts (82 multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 82 multicast, 0 pause input
     0 input packets with dribble condition detected
     0 packets output, 0 bytes, 0 underruns
     0 output errors, 0 collisions, 2 interface resets
     0 unknown protocol drops
     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

Core Switch Interface

GigabitEthernet0/42 is up, line protocol is down (suspended)
  Hardware is Gigabit Ethernet, address is 3c08.f63a.16aa (bia 3c08.f63a.16aa)
  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive not set
  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 00:44:02, output 00:00:28, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 68
  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
     34339 packets input, 7966960 bytes, 0 no buffer
     Received 5778 broadcasts (2018 multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 2018 multicast, 0 pause input
     0 input packets with dribble condition detected
     59283 packets output, 44210435 bytes, 0 underruns
     0 output errors, 0 collisions, 2 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

Is there something wrong with my config that's causing this?

EDIT: On both interfaces from the core and the access stack, there is a stationary amber light which usually indicates STP has suspended the port to avoid a loop.

Port Channel 1 (Access Stack)

Port-channel1 is up, line protocol is up (connected)
  Hardware is EtherChannel, address is 40a6.e8ba.a530 (bia 40a6.e8ba.a530)
  MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
     reliability 255/255, txload 2/255, rxload 20/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 100Mb/s, link type is auto, media type is unknown
  input flow-control is off, output flow-control is unsupported
  Members in this channel: Gi1/0/48
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:00, output 00:00:00, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 3151
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 8118000 bits/sec, 1396 packets/sec
  5 minute output rate 1141000 bits/sec, 939 packets/sec
     7569694044 packets input, 3273308277235 bytes, 0 no buffer
     Received 3873169150 broadcasts (2541283760 multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 2541283760 multicast, 0 pause input
     0 input packets with dribble condition detected
     2240014676 packets output, 349722616455 bytes, 0 underruns
     0 output errors, 0 collisions, 1 interface resets
     0 unknown protocol drops
     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

Port Channel 1 (Core Switch)

Port-channel1 is up, line protocol is up (connected)
  Hardware is EtherChannel, address is 3c08.f63a.1682 (bia 3c08.f63a.1682)
  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
     reliability 255/255, txload 21/255, rxload 3/255
  Encapsulation ARPA, loopback not set
  Keepalive not set
  Full-duplex, 100Mb/s, link type is auto, media type is unknown
  input flow-control is off, output flow-control is unsupported
  Members in this channel: Gi0/2
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:00, output 00:00:00, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 430857
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 1200000 bits/sec, 984 packets/sec
  5 minute output rate 8536000 bits/sec, 1472 packets/sec
     5529865138 packets input, 817634236496 bytes, 0 no buffer
     Received 115285777 broadcasts (109549995 multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 109549995 multicast, 0 pause input
     0 input packets with dribble condition detected
     17791035271 packets output, 7051584854682 bytes, 0 underruns
     0 output errors, 0 collisions, 2 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

Etherchannel Summary (Core)

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
1      Po1(SU)         LACP      Gi0/2(P)    Gi0/3(w)    Gi0/42(s)
2      Po2(SU)         LACP      Gi0/47(P)   Gi0/48(P)
3      Po3(SU)         LACP      Te1/1(P)    Te1/2(P)

Etherchannel Summary (Stack)

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
1      Po1(SU)         LACP      Gi1/0/48(P) Gi2/0/48(D) Gi3/0/47(s)
18
  • Typically you can see in the log of the switches, what the reason is for the suspension. Maybe it's because the access switch is trunk nonegotiate, you could try to remove it. When working with port-channels everything typically needs to be configured exactly the same in both ends and on both port-channel and interface.
    – user36472
    Oct 18 '17 at 9:11
  • How would I check the logs? I've basically mirrored the first link to the core with the exact same config, and it's not working, so it could be a switching loop.
    – BabyPython
    Oct 18 '17 at 9:19
  • @BabyPython Can you please post the configuration of Po1 interface on Access and Core as well?
    – Hung Tran
    Oct 18 '17 at 9:26
  • @BabyPython show logging on the device.
    – user36472
    Oct 18 '17 at 9:34
  • @HungTran I've updated this information in the question for review. You will see that he interfaces are different because the interfaces I'm trying to use for this port channel are not currently members, even though I've entered channel-group 1 mode active on both interfaces
    – BabyPython
    Oct 18 '17 at 9:45
2

Hi I haven't got a reputation score of 50 yet so can't add to the comments... But following on from what @Cown was saying here are the guidelines from Cisco:

All ports must be identical: - Same speed & duplex - Cannot mix Fast Ethernet & Gigabit Ethernet - Cannot mix PAgP & LACP - Must all be VLAN trunk or nontrunk operational status - All VLANs and allowed VLANs must match - All links must be L2 or L3 in a single channel group - All trunk links are in the same mode ISL or Dot1Q

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