6509 drops legitimate traffic - free up buffer

Unanswered Question
Oct 12th, 2007

Hi

I have a 6509 switch that shows high counters on ifOutDiscards. Cisco Interpretent tool says that reason for discarding such a packet can be to free up buffer

space.

DRAM FLASH NVRAM

Module Total Used Free Total Used Free Total Used Free

------ ------- ------- ------- ------- ------- ------- ----- ----- -----

1 65408K 43673K 21735K 16384K 9913K 6471K 512K 285K 227K

This shows that i still have unused DRAM

show counter 1/1

64 bit counters

0 rxHCTotalPkts = 6861779

1 txHCTotalPkts = 8077616

2 rxHCUnicastPkts = 6279025

3 txHCUnicastPkts = 7818555

4 rxHCMulticastPkts = 516192

5 txHCMulticastPkts = 191800

6 rxHCBroadcastPkts = 66551

7 txHCBroadcastPkts = 67261

16 txHCTrunkFrames = 8056140

17 rxHCTrunkFrames = 6785673

18 rxHCDropEvents = 0

32 bit counters

0 rxCRCAlignErrors = 0

1 rxUndersizedPkts = 0

2 rxOversizedPkts = 0

3 rxFragmentPkts = 0

4 rxJabbers = 0

5 txCollisions = 0

6 ifInErrors = 0

7 ifOutErrors = 0

8 ifInDiscards = 0

9 ifInUnknownProtos = 0

10 ifOutDiscards = 49145

11 txDelayExceededDiscards = 0

12 txCRC = 0

13 linkChange = 0

14 wrongEncapFrames = 0

0 dot3StatsAlignmentErrors = 0

1 dot3StatsFCSErrors = 0

2 dot3StatsSingleColFrames = 0

3 dot3StatsMultiColFrames = 0

4 dot3StatsSQETestErrors = 0

5 dot3StatsDeferredTransmisions = 0

6 dot3StatsLateCollisions = 0

7 dot3StatsExcessiveCollisions = 0

8 dot3StatsInternalMacTransmitErrors = 0

9 dot3StatsCarrierSenseErrors = 0

10 dot3StatsFrameTooLongs = 0

11 dot3StatsInternalMacReceiveErrors = 0

0 txPause = 0

1 rxPause = 0

0 rxTotalDrops = 11

1 rxFIFOFull = 0

2 rxBadCode = 0

Last-Time-Cleared

--------------------------

Thu Oct 11 2007, 07:33:47 (yesterday)

CPU is at 4-5%

ifOutDiscards increas, 3-4 per second.

Another error msg I got is:

%SYS-4-SUPERVISOR_ERR:Forwarding engine IP checksum error counter = 3529994

Indicates that the

switch forwarding engine has received an IP packet that is less than the minimum

length allowed for IP-packets

show counters supervisor

Forwarding Engine Error Stats Counters

======================================

IP len against Physical length err = 2

IP min. length check error = 0

IP pkts with cksum error = 49618

IPX len against Physical length err = 0

IPX min. length check error = 0

I dont know if these two errors are related. The first error says its problem is with memory and the second says its not a problem on the switch itself only on incoming traffic. Hope someone has a clue.

I have this problem too.
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jsivulka Thu, 10/18/2007 - 07:17

You could change the flowcontrol settings back to their defaults: off for Rx and disired for Tx. At these settings, the switch will ignore any pause frames sent by the server and just continue to send traffic. If the server is capable of "digesting" the frames at the rate they are coming out of the switch then this will solve the problem. If the server is not able to handle the traffic, then all

this will do is move the drops from the switch to the server.

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