I have a Cisco 3825 with redundant upstream connections to the datacenter border router. I noticed that there are a large number of "collisions" on the two interfaces. I've read elsewhere that that can be caused by having the interface set to Half-Duplex, but they are both definitely set to Full-Duplex. I'm also certain that the upstream connection is also 1Gbps. There are no issues reaching outside networks, but there are frequent bouts of unusual network slowness where the router is only pushing 30Mbps or so, but everything is crawling. Any idea on resolving these collisions?
c3825# sh run interface GigabitEthernet0/0 description Link to Border10 ip address XX.XX.239.118 255.255.255.252 ip flow ingress ip flow egress duplex full speed 1000 media-type rj45 no mop enabled ! interface GigabitEthernet0/1 description Link to Border11 ip address XX.XX.239.122 255.255.255.252 ip flow ingress ip flow egress duplex full speed 1000 media-type rj45 !
c3825#sh int GigabitEthernet 0/0 GigabitEthernet0/0 is up, line protocol is up Hardware is BCM1125 Internal MAC, address is 001d.7039.1140 (bia 001d.7039.1140) Description: Link to Border10 Internet address is XX.XX.239.118/30 MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec, reliability 255/255, txload 5/255, rxload 1/255 Encapsulation ARPA, loopback not set Keepalive set (10 sec) Full Duplex, 1Gbps, media type is RJ45 output flow-control is XON, input flow-control is XON 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: 0/75/0/127 (size/max/drops/flushes); Total output drops: 0 Queueing strategy: fifo Output queue: 0/40 (size/max) 5 minute input rate 7225000 bits/sec, 2287 packets/sec 5 minute output rate 21278000 bits/sec, 2918 packets/sec 2031411499 packets input, 281305862 bytes, 0 no buffer Received 4 broadcasts (0 IP multicasts) 0 runts, 0 giants, 0 throttles 1789 input errors, 0 CRC, 0 frame, 1789 overrun, 0 ignored 0 watchdog, 4294868991 multicast, 0 pause input 2351846464 packets output, 3281062849 bytes, 0 underruns 308 output errors, 4286578687 collisions, 3 interface resets 0 unknown protocol drops 0 babbles, 4294950911 late collision, 0 deferred 310 lost carrier, 0 no carrier, 0 pause output 0 output buffer failures, 0 output buffers swapped out c3825#sh int GigabitEthernet0/1 GigabitEthernet0/1 is up, line protocol is up Hardware is BCM1125 Internal MAC, address is 001d.7039.1141 (bia 001d.7039.1141) Description: Link to Internap Border11 Internet address is XX.XX.239.122/30 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, 1Gbps, media type is RJ45 output flow-control is XON, input flow-control is XON ARP type: ARPA, ARP Timeout 04:00:00 Last input 00:00:19, output 00:00:01, output hang never Last clearing of "show interface" counters never Input queue: 0/75/0/2 (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 188601 packets input, 34900616 bytes, 0 no buffer Received 0 broadcasts (0 IP multicasts) 0 runts, 0 giants, 0 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored 0 watchdog, 2650799615 multicast, 0 pause input 135889 packets output, 13672869 bytes, 0 underruns 0 output errors, 4293852927 collisions, 3 interface resets 0 unknown protocol drops 0 babbles, 4150263791 late collision, 0 deferred 2 lost carrier, 0 no carrier, 0 pause output 0 output buffer failures, 0 output buffers swapped out