Cisco – Interface suspended when linking access to core

ciscoetherchannelstacking

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)

Best Answer

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