Ethernet CRC and Alignment Errors

From: Thomas Blaney (trb811_at_HOTMAIL.COM)
Date: 06/04/03

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    Date:         Wed, 4 Jun 2003 15:34:59 -0400
    To: aix-l@Princeton.EDU
    
    

    I'm experiencing some problems with poor network performance between 2 B50
    servers on the same lan segment/subnet. They are both fixed at 100FD and
    are connected via a Nortel Networks BayStack 450-24T Switch. They both also
    have the same type of ethernet adapter installed -- IBM 10/100 Mbps Ethernet
    PCI Adapter (23100020). No problems are showing up in either server's error
    log.

    entstat on one of the servers is showing increasing error counts for both
    "CRC" and "Alignment"

    # entstat -d ent0 | grep Errors
    Transmit Errors: 0 Receive Errors: 0
    No Carrier Sense: 0 CRC Errors: 970
    Lost CTS Errors: 0 Alignment Errors: 414
    Max Collision Errors: 0 No Resource Errors: 0
    Late Collision Errors: 0 Receive Collision Errors: 0
    Deferred: 0 Packet Too Short Errors: 0
    SQE Test: 0 Packet Too Long Errors: 0
    Timeout Errors: 0 Packets Discarded by Adapter:
    0
    No mbuf Errors: 0
    No Receive Pool Buffer Errors: 0

    How do I reduce/eliminate these errors? Is there a way to tell whether they
    are hardware and/or software related?

    The odm settings I have on each adapter are identical:
    # lsattr -l ent0 -EH
    attribute value description
    busio 0xbfe800 Bus I/O address
    busintr 6 Bus interrupt level
    intr_priority 3 Interrupt priority
    tx_que_size 16384 TRANSMIT queue size
    rx_que_size 256 RECEIVE queue size
    rxbuf_pool_size 2048 RECEIVE buffer pool size
    media_speed 100_Full_Duplex Media Speed
    use_alt_addr no Enable ALTERNATE ETHERNET address
    alt_addr 0x000000000000 ALTERNATE ETHERNET address
    ip_gap 96 Inter-Packet Gap
    poll_link no Enable Link Polling
    poll_link_timer 500 Time interval for Link Polling

    The network settings on each server are identical as well:
    # no -a |egrep "sb_max|tcp_"
                       sb_max = 1310720
                   tcp_ndebug = 100
                      tcp_ttl = 60
                tcp_sendspace = 221184
                tcp_recvspace = 221184
                tcp_keepintvl = 150
                 tcp_keepidle = 14400
                  tcp_mssdflt = 512
                 tcp_keepinit = 150
            tcp_pmtu_discover = 1
                 tcp_timewait = 1
            tcp_ephemeral_low = 32768
           tcp_ephemeral_high = 65535
                  tcp_newreno = 0
              tcp_nagle_limit = 65535

    Any suggestions would be appreciated.
    Thanks.

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