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Beginner

Congestion causing Output drops

Hello All.  I may be trying to fix something that isn't broke, but here goes :

I have 2 access switches, both 6500's - Sup 720's, connected by gig fiber, trunked.  Switch A is our LAN switch, while Switch B is in our server room.  A is connected to the router and the rest of the world.  Switch A's interface to the server room is seeing quite a few output drops.  I guess saying the phrase "quite a few" is a misnomer, as the total amount of drops rarely ever rises over .009%, but it is still no zero :

Switch A

GigabitEthernet6/2 is up, line protocol is up (connected)
  Hardware is C6k 1000Mb 802.3, address is 0014.a982.2ddd (bia 0014.a982.2ddd)
  Description: Downlink to Server Room
  MTU 9216 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 18/255, rxload 115/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 1000Mb/s, media type is SX
  Media-type configured as SFP connector
  input flow-control is off, output flow-control is off
  Clock mode is auto
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:56, output 00:00:26, output hang never
  Last clearing of "show interface" counters 06:42:56
  Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 20857
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 451178000 bits/sec, 41116 packets/sec
  5 minute output rate 71836000 bits/sec, 17933 packets/sec
     770120728 packets input, 1009314634174 bytes, 0 no buffer
     Received 152334 broadcasts (32024 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
     426544861 packets output, 288985375916 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

Switch B

GigabitEthernet6/1 is up, line protocol is up (connected)
  Hardware is C6k 1000Mb 802.3, address is 001a.a22d.77a4 (bia 001a.a22d.77a4)
  Description: Uplink to 6509
  MTU 9216 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 80/255, rxload 19/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 1000Mb/s, media type is SX
  input flow-control is off, output flow-control is off
  Clock mode is auto
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:04, output 00:00:00, output hang never
  Last clearing of "show interface" counters 06:52:10
  Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 45630
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 77422000 bits/sec, 15313 packets/sec
  5 minute output rate 316287000 bits/sec, 29672 packets/sec
     433879867 packets input, 293048152751 bytes, 0 no buffer
     Received 279794 broadcasts (171938 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
     786365110 packets output, 1031587587444 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

None of the scientific data in the vlans is real-time/time sensitive that passes over the trunk.  We don't have any extra fiber to create an etherchannel between them, but that is coming.  Should I worry about the congestion?  I ask because we will start to ramp it up in about 3 months.  Are there any tuning suggestions anyone wishes to point me to?  If it isn't broke, I won't try and fix it.

Thanks

Poirot

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Hall of Fame Master

Re: Congestion causing Output drops

You don't have to worry about it, and if the traffic is all equally important, there is nothing that you can do about it, except upgrading to 10 Gb.

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Beginner

Re: Congestion causing Output drops

Thanks for the response.  We are planning on implementing 10G at some point (more or less when they fork over the cash).    We have a small presence of 10G in the server room in the form on an HP switch (not mine).  It is part of a cluster that is segergated from the rest of the network.  There will be a large presence of 10G when we move our main datacentrer to some new digs.

Thanks

Poirot

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