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What's causes high output drops on HWIC-CABLE-D-2

robdawg01
Level 1
Level 1

I have an internet connection to comcast. When I look at the interface stats on my cable interface I see a lot of output drops. What could be causing this? Here is the results from a "sh int c0/0/0 from my router:

Robrouter#sh int c0/0/0
Cable-Modem0/0/0 is up, line protocol is up
  HFC state is OPERATIONAL, HFC MAC address is 0018.19b6.5de4
  Hardware is Cable modem, address is 0014.1cc1.8973 (bia 0014.1cc1.8973)
  Description: WAN - Internet
  Internet address is 75.75.32.157/22
  MTU 1500 bytes, BW 768 Kbit/sec, DLY 13020 usec,
     reliability 255/255, txload 1/255, rxload 3/255
  Encapsulation ARPA, loopback not set
  Keepalive not supported
  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: 0/75/5/0 (size/max/drops/flushes); Total output drops: 135577
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  1 minute input rate 12000 bits/sec, 15 packets/sec
  1 minute output rate 3000 bits/sec, 3 packets/sec
  HFC input: 0 errors, 0 discards, 0 unknown protocols 0 flow control discards
  HFC output: 0 errors, 135411 discards
     36280225 packets input, 4281026903 bytes, 75 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 2 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 input packets with dribble condition detected
     2186322 packets output, 1518696830 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 output buffer failures, 0 output buffers swapped out

Thanks in advance

1 Accepted Solution

Accepted Solutions

paolo bevilacqua
Hall of Fame
Hall of Fame

First of all, you do not have a very high drop rate, just about one in 200.

The reason is that transmit speed on cable interface is not very high, router is reporting 768 Kbps., consequently when you upload much data, it is normal that there the queue fills up and there are drops.

You can try increasing a little hold-queue out on the interface, however that will not prevent drops under continued upload.

View solution in original post

1 Reply 1

paolo bevilacqua
Hall of Fame
Hall of Fame

First of all, you do not have a very high drop rate, just about one in 200.

The reason is that transmit speed on cable interface is not very high, router is reporting 768 Kbps., consequently when you upload much data, it is normal that there the queue fills up and there are drops.

You can try increasing a little hold-queue out on the interface, however that will not prevent drops under continued upload.

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