RE: Ethernet Line Tuning

Rick ... This is interesting. We were having severe slowdowns when running
FTP over our 100MB Ethernet connection and actually discovered that when we
changed out line configuration to *AUTO and removed a hub between the AS/400
and a CISCO switch, our throughput went up by a factor of 10!


Kenneth

-----Original Message-----
From: Rick Nardone [mailto:rick@midtel.net]
Sent: Thursday, August 08, 2002 11:41 AM
To: midrange-l@midrange.com
Subject: Ethernet Line Tuning


I tried something without success today, and thought I would pass this by
the group.  I searched IBM and midrange-l archives for specific information
but found none.

Getting some errors on Ethernet and an occasional slowness and attempted to
properly take advantage of 100MB/Full Duplex allowed on our 2838-001
Feature(9406 170 v5r1).  Ethernet cable line tested ok, no interference,
etc.  Both the Cisco and the iSeries Ethernet card had been auto negotiating
speed of 100M and duplex of half.  Read a tech doc that auto is not all it
is cracked up/trusted to be.
so....
- I Ended TCP and varied off ETHLIND
- I set speed to 100 and duplex to full on the Cisco switch port.
- I changed ETHLIND "Line Speed" to 100M(was *auto) and "duplex" to
*full(was *auto).  "Link Speed" was already set to 100M.  This is a bit
confusing why link speed AND line speed?
- At vary on of ETHLIND it errored off and had to return to half duplex.

Should I have attempted to change "Line Speed" or should I have left that at
*auto?
Also, my frame size is 1496.. Is that the most efficient size?  I read
somewhere that 1492 was efficient size.

Thanks,

Rick Nardone
Middleburgh Telephone



As a result of above not working, I forced 100MB/Half duplex on both the
switch and the 2838..again staying away for *auto.

Current Stats
-------------
FastEthernet0/12 is up, line protocol is up
  Hardware is Fast Ethernet, address is 0090.b1a5.ae4c (bia 0090.b1a5.ae4c)
  Description: qs1032cpm
  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec, rely 255/255, load 1/255
  Encapsulation ARPA, loopback not set, keepalive not set
  Half-duplex, 100Mb/s, 100BaseTX/FX
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input never, output 00:00:01, output hang never
  Last clearing of "show interface" counters 04:23:11
  Queueing strategy: fifo
  Output queue 0/40, 0 drops; input queue 0/75, 0 drops
  5 minute input rate 2000 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 2 packets/sec
     40366 packets input, 19671692 bytes, 0 no buffer
     Received 307 broadcasts, 2 runts, 0 giants, 0 throttles
     10 input errors, 0 CRC, 7 frame, 0 overrun, 0 ignored, 0 abort
     0 watchdog, 0 multicast
     0 input packets with dribble condition detected
     37209 packets output, 13481977 bytes, 0 underruns
     0 output errors, 4 collisions, 0 interface resets
     0 babbles, 0 late collision, 1062 deferred
     0 lost carrier, 0 no carrier
     0 output buffer failures, 0 output buffers swapped out

Current ETHLIND
---------------
Ethernet standard  . . . . . . . . :   *ALL
Line speed . . . . . . . . . . . . :   *AUTO
Current line speed . . . . . . . . :   100M
Duplex . . . . . . . . . . . . . . :   *HALF
Current duplex . . . . . . . . . . :   *HALF
Maximum frame size . . . . . . . . :   1496

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