Trashtone

Q: Local ping problems between C3750G and Xserve G5

I have an old XServe X5 box with two separate 1GE links to a local Cisco C3750G switch (and ~2m Cat6 cables in between). The interfaces are not bonded, so each interface has a unique IP address. Things should be immaculate, but for some reason I'm getting packet loss when pinging from the switch to the XServe. I also observe intermittent packet loss when accessing the box from the internet. This is how it looks:

 

switch#pi 10.0.0.2 rep 1000 so vl10

 

Type escape sequence to abort.

Sending 100, 100-byte ICMP Echos to 10.0.0.2, timeout is 2 seconds:

Packet sent with a source address of 10.0.0.1

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!

Success rate is 99 percent (997/1000), round-trip min/avg/max = 1/1/9 ms

 

Interface MTU on both ends are set at 1500 bytes so no discrepancies there. Any idea why this is happening?

Posted on Apr 18, 2016 3:24 AM

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Q: Local ping problems between C3750G and Xserve G5

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  • by Trashtone,

    Trashtone Trashtone Apr 18, 2016 3:47 AM in response to Trashtone
    Level 1 (4 points)
    Servers Enterprise
    Apr 18, 2016 3:47 AM in response to Trashtone

    Slight update:

     

    - OSX Server version is 10.5.8

    - Ping loss happens if I ping either interface so it's not a matter of which interface is in use.

    - Switchports to other devices (Several linux boxes) work perfectly, no ping loss observed therein.

    - Physical interfaces on the switch are not collecting errors. Not pasting both interfaces stats since the other interface is as clean as this one, but this is how it looks on one of the ports:

     

    GigabitEthernet1/0/3 is up, line protocol is up (connected)

      Hardware is Gigabit Ethernet, address is xxxx.yyyy.zzzz (bia xxxx.yyyy.zzzz)

      Description: titanium en0 (xserve)

      MTU 1500 bytes, BW 1000000 Kbit, 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 2d22h, output 00:00:01, output hang never

      Last clearing of "show interface" counters 8w5d

      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 20000 bits/sec, 13 packets/sec

      5 minute output rate 6000 bits/sec, 4 packets/sec

         8466649 packets input, 874724018 bytes, 0 no buffer

         Received 8395983 broadcasts (0 multicasts)

         0 runts, 0 giants, 0 throttles

         0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

         0 watchdog, 5069446 multicast, 0 pause input

         0 input packets with dribble condition detected

         1462700 packets output, 124006536 bytes, 0 underruns

         0 output errors, 0 collisions, 3 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

  • by Camelot,

    Camelot Camelot Apr 19, 2016 3:13 PM in response to Trashtone
    Level 8 (47,243 points)
    Mac OS X
    Apr 19, 2016 3:13 PM in response to Trashtone

    The switch reports 3 interface resets. Does that coincide with the three dropped packets reported in the ping?

     

    FWIW, MTU wouldn't affect ping since each ping packet is less than the MTU, so that's not a concern.

     

    I'd also want to see the interface statistics from the Mac's side. Does the Mac see all the pings? That would tell you whether it's the ping or the ack that's getting lost (run tcpdump on the Mac while the switch is pinging and look at the output).

     

    Do you see the same problem if you ping from the Mac to the switch?

     

    Finally - and I maybe should have asked this first - you say you have two non-bonded interfaces, each with their own IP address... are they in the same subnet? or different subnets. If the same subnet (red flag), why not bond the interfaces?