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2960G High Output Drops only on Gigabit

Matthew Scheele
Level 1
Level 1

I just got a Cisco 2960G 24-port gigabit switch so that our HP servers can have a Gigabit connection to the network. I moved 2 servers to it (HP Proliant DL380's)  but they don't actually seem to be able to achieve even close to 1000Gbps. I ran same some LAN bandwidth tests and it was showing only around 200-300 Mbps between all of them. I also ran a network stress test utility, LAN Tornado, and it was showing packet loss as high as 60% when on gigabit, and only .07% when on 100Mbps.

-Both the NIC's and the switch ports are set to 1000/Full

-Currently using Cat5e cabling no more than 25Ft in length (I know Cat6 would be better but Cat5e is supposed to support Gigabit)

-All servers are on the same VLAN

Here are the port statistics when running just a stress test @ 10Mbps that had a 45% packet loss. What's odd though is when I set the servers and switches to 100Mbps, I get less than 1% packet loss.

GigabitEthernet1/0/16 is up, line protocol is up (connected)

  Hardware is Gigabit Ethernet, address is 203a.07ff.7e90 (bia 203a.07ff.7e90)

  MTU 9000 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 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: 73910

  Queueing strategy: fifo

  Output queue: 0/40 (size/max)

  5 minute input rate 2298000 bits/sec, 201 packets/sec

  5 minute output rate 18000 bits/sec, 16 packets/sec

     252169491 packets input, 359391822515 bytes, 0 no buffer

     Received 11797 broadcasts (0 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

     81726145 packets output, 14926084698 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

2960-Bldg1-Servers#show interf gi1/0/18

GigabitEthernet1/0/18 is up, line protocol is up (connected)

  Hardware is Gigabit Ethernet, address is 203a.07ff.7e92 (bia 203a.07ff.7e92)

  MTU 9000 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 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: 41350

  Queueing strategy: fifo

  Output queue: 0/40 (size/max)

  5 minute input rate 5000 bits/sec, 2 packets/sec

  5 minute output rate 2555000 bits/sec, 230 packets/sec

     51764985 packets input, 76065117441 bytes, 0 no buffer

     Received 101907 broadcasts (0 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

     39414582 packets output, 5203629330 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

Also, here is the CPU history

2960-Bldg1-Servers#show process cpu history

      111222221111111111111111111111111111111111122222111111111111
      888111118888888888888888888888888999998888811111999999999999
  100
   90
   80
   70
   60
   50
   40
   30
   20 **********************************************************
   10 **********************************************************
     0....5....1....1....2....2....3....3....4....4....5....5....6
               0    5    0    5    0    5    0    5    0    5    0
               CPU% per second (last 60 seconds)


      222222222222222222222222222222222224222222222222222222222222
      111112111131131134113311431112111214242211111171222121121113
  100
   90
   80
   70
   60
   50
   40                                    *
   30                                    *          *
   20 ##########################################################
   10 ##########################################################
     0....5....1....1....2....2....3....3....4....4....5....5....6
               0    5    0    5    0    5    0    5    0    5    0
               CPU% per minute (last 60 minutes)
              * = maximum CPU%   # = average CPU%


      554454446555555435434435544453544445434434434464364645534555443454444545
      501795365028647542356340194928271820852645593802411861894367299713220606
  100
   90
   80
   70         *                                          *
   60 *   *   *  ** *                               *  * *  *   **         *
   50 ** *** ********* *  *  *** ** ** * **  * **  **  * ****  *** * **    *
   40 **************** ***** ***************** ******* *********************
   30 **********************************************************************
   20 ######################################################################
   10 ######################################################################
     0....5....1....1....2....2....3....3....4....4....5....5....6....6....7..
               0    5    0    5    0    5    0    5    0    5    0    5    0
                   CPU% per hour (last 72 hours)
                  * = maximum CPU%   # = average CPU%

2 Replies 2

paolo bevilacqua
Hall of Fame
Hall of Fame

Do you have any QoS config? If so, try removing it.

Matthew Scheele
Level 1
Level 1

No. I have no QoS configured on those ports. Here is the port configuration:

interface GigabitEthernet1/0/18
switchport access vlan 100
no logging event link-status
speed 1000
duplex full
no snmp trap link-status
spanning-tree portfast
end

!
interface GigabitEthernet1/0/16
switchport access vlan 100
no logging event link-status
speed 1000
duplex full
no snmp trap link-status
spanning-tree portfast
end

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