MCR LANCP SHOW DEVICE /ALL /COUNT -> Data overruns

[Art Wiens]

Alpha ES47 with two, DE602-BB using only one port on each card, VMS v7.3-2 all patched up.

I am noticing "choppy" response in a Telnet session (TCPware v5.7-2 all patched up). Issuing the above command, the only "problem" I see is Data overruns. I also see Data overruns logged against the NCP lines, nothing against the circuits.

Absolutely confirmed that both the switch ports and the SRM variables are set to 100/Full.

Can anyone provide some insight as to what might be causing "Data overruns"?

Cheers,
Art

[EdgarZamora]

This is usually a mismatch between the switch port and the NIC. You may have checked the switch port and the console variable but did you check LANCP? Can you post output of LANCP SHOW DEV /CH ?

[Art Wiens]

Here you go. I did not include EIB0 and EID0, they are not plugged in. It would sure seem like "everyone" is in agreement the interfaces are 100/Full. I sat with the network guy and watched him show the switch ports - 100/Full. I have also included the SRM variables for the two ports in the attachment.

Cheers
Art

[EdgarZamora]

Sure seems like it, although your LANCP output seems a little different from what I get on a fully patched 7.3-2 system (I can't put a finger on it yet because I don't have access right now). What changed? Did this use to work fine? Is the network heavily utilized? The buffers may need increasing.

[Bill Hall]

Art,

I believe data overruns are a count of the number of times the NIC lost an incoming packet. Which would lead to a retransmit(s), which could look choppy.

I've heard the DE602 did not perform as well as the DE500, maybe it can't keep up with the switch port... Are any other LANCP counters increasing on these NICs? Does MONITOR MODES show an extremely high interrupt rate?

I'm running some ES47s with 4 DEGX2-TA (dual Gigabit Ethernet) in each, no jumbo frames, 5 of the 8 ports active (3 LL devices and two EW devices dedicated to SCA traffic) and I see no data overruns.

Bill

[Art Wiens]

I had this system built for a few months in test mode, I didn't notice a performance issue so I can't say that I ever looked at the LANCP counters.

This week I blew it all away as the SAN allocations had to be redone and started the production build "for real".

The system itself is idle, I see the data overruns start incrementing immediately after a reboot. The switches are "busy" but not with this system.

BTW, the DE602's are plugged into:

"Cisco WS-C3750G-24TS-S

Software version: c3750-ipbasek9-mz.122-25.SEB4

2 Switches in the stack (cluster)"

One NIC is plugged into each switch in the stack.

Art

[Volker Halle]

Art,

did you have a look at LANCP> SHOW DEVICE/INTERNAL_COUNTERS ? Maybe there is some more information available. Could you post the counters in a .TXT atttachment ?

Volker.

[Art Wiens]

Edgar:
"Is the network heavily utilized? The buffers may need increasing."

It's a busy network and it's in a busy switch, but the ES47 is idle. I look this morning and each interface has ~10,000 data overruns.

Which buffers do you propose increasing?

Bill:
"I believe data overruns are a count of the number of times the NIC lost an incoming packet."

If we can believe the LANCP counters both interfaces say:

1 Link up transitions ( 7-NOV-2007 13:02:30.40)
0 Link down transitions

NCP circuit says:

0 Circuit down
0 Initialization failure
0 Adjacency down
1 Peak adjacencies

"Does MONITOR MODES show an extremely high interrupt rate?"

No, the system is "idle". I'm only at the point of having upgraded VMS and TCPware so far.

Cheers,
Art

[Art Wiens]

Attached are the /internal_counters.

Art

[Volker Halle]

Art,

this may be related to:

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=1129303

What's the image ident and link time of your SYS$EIDRIVER ?

Volker.