Duplex mode diffs btw. host NIC & switch

[Ralph Grothe]

Hello Networkers,

on one of our hosts we experience dead slow DSM/TSM storage backup rates.

In the dsmerror.log we get repeatedly this error message, which seems to indicate a network problem:

06/20/02 20:44:46 sessRecvVerb: Error -50 from call to 'readRtn'.

I suspect the cause to lie in incompatibilies as far as operational modes (viz. half duplex vs. full duplex vs. auto negotiation) between the host's NIC and the switch's port to wich the host is connected is concerned.
So far I haven't been able to speak to our netadmin responsible for the switch.
Thus I cannot tell offhand how it might be configuered.
I can only have the nic's mibstats queried.
(the nic the host's IP address is bound to is lan6)

# lanadmin -g mibstats 6|grep -i duplex
Description = lan6 Hewlett-Packard 10/100Base-TX Half-Duplex
Hw Rev 0

Having read the manpages of lanadmin and ndd I couldn't find out if the mode is configurable at all, or is it a hardware imposed fixum?

As this is only my naive suspicion, can anyone maybe give me a hint what else to employ to further trace the problem?
Would packet sniffing shed more light?
(usage of nettl?)

Regards
Ralph

[Stefan Farrelly · Accepted solution]

Weve seen many problems before with slow backups, slow ftp's etc. In almost all cases we fixed the problem by hard setting both the NIC on the HP and the port on the hub/switch they connect to to 100/HD. No autonegotation. The autonegotation seems to be the culprit.

You can get your network team to set it on the hub/switch, and for your 100Mb NIC's on the HP you can set it in /etc/rc.config.d/hpbase100conf

(see this file, it has comments at the top on how to set it).

[Ian Dennison_1]

Configurable - yes.

All recommendations I have seen state that Duplex Mode and Speed should be set manually on both the Network Port at the Switch, and on the NIC.

To modify the NIC, use SAM - networking and Communications - network Interface Cards - select card and modify.
You can enter the speed and Duplex Mode here.

You can also modify this using a conf file (I forget which one).

Your network 'propellor heads' should be able to configure the switch end of the connection for you.

Share and Enjoy! Ian

[Ralph Grothe]

Stefan,

glad to hear that someone else encountered the same.
So manually fixing settings on both end sounds promissing.
Many thanks for letting me know which config file to edit.
But I will not be able to have it fixed today.
Either everyone is watching footbal (it's Germany vs. USA at the moment), or people already started their weekend.

Ian,

I already discovered the submenu in SAM where to configure the device.
Unfortunately before I posted I hadn't noticed that you have to toggle the "Autoneg" field to "no" in order to be able to tab to "Duplex Mode" field.
So I was mistaken to believe that the hardware wouldn't allow such thing, which seemed strange to me anyway.