есть линк между двумя cisco 6506 и 3560
линк порядка 40км. работает, ттт, нормально. сегодня, когда резко возрасла нагрузка на этот линк на 3560 начал моргать светодиод зеленый/рыжий
посмотрел из консоли - вот такая картина:

sh run int gi0/25
!
interface GigabitEthernet0/25
  switchport trunk encapsulation dot1q
  switchport trunk allowed vlan 11,19,20,23,26,41,99,150,220,255,293,314,401,439
  switchport trunk allowed vlan add 511,617,713,760,762,777,807,808,996,998
  switchport mode trunk
end

sh int gi0/25

GigabitEthernet0/25 is up, line protocol is up (connected)
    Hardware is Gigabit Ethernet, address is 001a.xxxx.xxxx (bia 001a.xxxx.xxxx)
    Description:
    MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
          reliability 255/255, txload 44/255, rxload 36/255
    Encapsulation ARPA, loopback not set
    Keepalive not set
    Full-duplex, 1000Mb/s, link type is auto, media type is 1000BaseZX SFP
    input flow-control is off, output flow-control is unsupported
    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 02:37:26
    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 144620000 bits/sec, 23126 packets/sec
    5 minute output rate 172589000 bits/sec, 26242 packets/sec
          185440207 packets input, 2198744922 bytes, 0 no buffer
          Received 49284 broadcasts (0 multicast)
          0 runts, 0 giants, 0 throttles
          5276 input errors, 24 CRC, 0 frame, 0 overrun, 0 ignored
          0 watchdog, 35324 multicast, 0 pause input
          0 input packets with dribble condition detected
          185403960 packets output, 805659311 bytes, 0 underruns
          0 output errors, 0 collisions, 0 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

с другой стороны ничего криминального

sh run int gi1/1
!
interface GigabitEthernet1/1
  switchport
  switchport trunk encapsulation dot1q
  switchport trunk allowed vlan 11,19,20,23,26,41,99,150,220,255,293,314,401,439
  switchport trunk allowed vlan add 511,617,713,760,762,777,807,808,996,998
  switchport mode trunk
  no ip address
end

sh int gi1/1
GigabitEthernet1/1 is up, line protocol is up (connected)
    Hardware is C6k 1000Mb 802.3, address is 0008.xxxx.xxxx (bia 0008.xxxx.xxxx)
    Description:
    MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
          reliability 255/255, txload 35/255, rxload 40/255
    Encapsulation ARPA, loopback not set
    Keepalive set (10 sec)
    Full-duplex, 1000Mb/s, media type is ZX
    input flow-control is off, output flow-control is off
    Clock mode is auto
    ARP type: ARPA, ARP Timeout 04:00:00
    Last input 00:00:53, output 00:00:51, output hang never
    Last clearing of "show interface" counters never
    Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0
    Queueing strategy: fifo
    Output queue: 0/40 (size/max)
    5 minute input rate 160639000 bits/sec, 23143 packets/sec
    5 minute output rate 138633000 bits/sec, 21086 packets/sec
          13555436745 packets input, 9742486258100 bytes, 0 no buffer
          Received 57194457 broadcasts (19907878 multicasts)
          0 runts, 0 giants, 0 throttles
          0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
          0 watchdog, 0 multicast, 0 pause input
          0 input packets with dribble condition detected
          14449041093 packets output, 14185855567550 bytes, 0 underruns
          0 output errors, 0 collisions, 5 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

подскажите как можно отдебажить это дело?