Issue with PowerEdge 1850 network connectivity

JackHammer19 jackhammer19 at gmail.com
Sun Apr 30 21:14:32 CDT 2006


I have a Dell PowerEdge 1850 web server with dual Intel PRO/1000
network interfaces built into the motherboard.  The operating system is
CentOS 4.2 (identical to Red Hat Enterprise Linux AS 4.2 - built from
Red Hat sources).  I am running the latest kernel ( 2.6.9-34.ELsmp).
The lspci output reports the interfaces as Intel 82541GI/PI.

The system has the latest patches applied.

The e1000 driver information, as reported by modinfo, is:

-----------------------------------------------------------------------------
$ /sbin/modinfo e1000
filename:       /lib/modules/2.6.9-34.ELsmp
/kernel/drivers/net/e1000/e1000.ko
parm:           debug:Debug level (0=none,...,16=all)
version:        6.1.16-k3-NAPI 4BCC06D27AAC4C711223CC9
license:        GPL
description:    Intel(R) PRO/1000 Network Driver
author:         Intel Corporation, <linux.nics at intel.com>
parm:           InterruptThrottleRate:Interrupt Throttling Rate
parm:           RxAbsIntDelay:Receive Absolute Interrupt Delay
parm:           RxIntDelay:Receive Interrupt Delay
parm:           TxAbsIntDelay:Transmit Absolute Interrupt Delay
parm:           TxIntDelay:Transmit Interrupt Delay
parm:           XsumRX:Disable or enable Receive Checksum offload
parm:           FlowControl:Flow Control setting
parm:           AutoNeg:Advertised auto-negotiation setting
parm:           Duplex:Duplex setting
parm:           Speed:Speed setting
parm:           RxDescriptors:Number of receive descriptors
parm:           TxDescriptors:Number of transmit descriptors
alias:          pci:v00008086d000010B5sv*sd*bc*sc*i*
alias:          pci:v00008086d0000109Asv*sd*bc*sc*i*
alias:          pci:v00008086d00001099sv*sd*bc*sc*i*
alias:          pci:v00008086d0000108Csv*sd*bc*sc*i*
alias:          pci:v00008086d0000108Bsv*sd*bc*sc*i*
alias:          pci:v00008086d0000108Asv*sd*bc*sc*i*
alias:          pci:v00008086d0000107Fsv*sd*bc*sc*i*
alias:          pci:v00008086d0000107Esv*sd*bc*sc*i*
alias:          pci:v00008086d0000107Dsv*sd*bc*sc*i*
alias:          pci:v00008086d0000107Csv*sd*bc*sc*i*
alias:          pci:v00008086d0000107Bsv*sd*bc*sc*i*
alias:          pci:v00008086d0000107Asv*sd*bc*sc*i*
alias:          pci:v00008086d00001079sv*sd*bc*sc*i*
alias:          pci:v00008086d00001078sv*sd*bc*sc*i*
alias:          pci:v00008086d00001077sv*sd*bc*sc*i*
alias:          pci:v00008086d00001076sv*sd*bc*sc*i*
alias:          pci:v00008086d00001075sv*sd*bc*sc*i*
alias:          pci:v00008086d00001060sv*sd*bc*sc*i*
alias:          pci:v00008086d0000105Fsv*sd*bc*sc*i*
alias:          pci:v00008086d0000105Esv*sd*bc*sc*i*
alias:          pci:v00008086d00001028sv*sd*bc*sc*i*
alias:          pci:v00008086d00001027sv*sd*bc*sc*i*
alias:          pci:v00008086d00001026sv*sd*bc*sc*i*
alias:          pci:v00008086d0000101Esv*sd*bc*sc*i*
alias:          pci:v00008086d0000101Dsv*sd*bc*sc*i*
alias:          pci:v00008086d0000101Asv*sd*bc*sc*i*
alias:          pci:v00008086d00001019sv*sd*bc*sc*i*
alias:          pci:v00008086d00001018sv*sd*bc*sc*i*
alias:          pci:v00008086d00001017sv*sd*bc*sc*i*
alias:          pci:v00008086d00001016sv*sd*bc*sc*i*
alias:          pci:v00008086d00001015sv*sd*bc*sc*i*
alias:          pci:v00008086d00001014sv*sd*bc*sc*i*
alias:          pci:v00008086d00001013sv*sd*bc*sc*i*
alias:          pci:v00008086d00001012sv*sd*bc*sc*i*
alias:          pci:v00008086d00001011sv*sd*bc*sc*i*
alias:          pci:v00008086d00001010sv*sd*bc*sc*i*
alias:          pci:v00008086d0000100Fsv*sd*bc*sc*i*
alias:          pci:v00008086d0000100Esv*sd*bc*sc*i*
alias:          pci:v00008086d0000100Dsv*sd*bc*sc*i*
alias:          pci:v00008086d0000100Csv*sd*bc*sc*i*
alias:          pci:v00008086d00001009sv*sd*bc*sc*i*
alias:          pci:v00008086d00001008sv*sd*bc*sc*i*
alias:          pci:v00008086d00001004sv*sd*bc*sc*i*
alias:          pci:v00008086d00001001sv*sd*bc*sc*i*
alias:          pci:v00008086d00001000sv*sd*bc*sc*i*
depends:
vermagic:       2.6.9-34.ELsmp SMP gcc-3.4
-----------------------------------------------------------------------

The internal Ethernet interface is connected to a Dell 2708 Gigabit
switch which has two other hosts with gigabit interfaces attached, one
host with a 100 Mbps full duplex LAN card and an uplink to a 3Com
SuperStack3 10/100 Mbps full duplex switch.

The external interface connects to another 3Com SuperStack3 10/100 Mbps
full duplex switch which also has a Cisco 1720 router attached through a
100 Mbps full duplex interface.  The Cisco 1720's external serial
interface connects to a MCI T1 line that provides internet connectivity
to the web server.  The server's default route is set to the T1 gateway.
The 3Com switch also has another Cisco 827 router connected to it on
another totally different IP subnet, which provides Internet
connectivity to a different set of hosts.

The PE 1850 runs smoothly when it is the only host connected to the
Cisco router/ T1 line.  However, when I attach another host to the
Cisco router/ T1 line, the web server exhibits huge delays in serving web
pages.
The internal interface is unaffected.  However external clients experience
huge delays
and frequent timeouts and CGI processes accumulate on the web server,
increasing server load till it eventually crashes.

I have tried several methods of fixing this, including moving the T1
line to a separate Cisco Catalyst 1900 switch, changing the router (I
first had a Cisco 1605R installed with a 10 Mbps half duplex port which
was then upgraded to a Cisco 1720 with a 100 Mbps full duplex port) etc.
I next tried adjusting the e1000 driver settings for the external
interface (eth1) including the following:

* Interrupt Throttle Rate set to figures between 3000 to 7000
* Interrupt Throttle Rate set to 70,000
* Interrupt Throttle Rate turned off (0)
* Tx and Rx delays and absolute delays set to 0
* TCP segment offload turned off

in various combinations.  Nothing seems to work though, with the web
server seizing up whenever another host is attached.  I still seem to
be able to ping out to the world when logged into the affected system
through the affected external interface though.

Any advice or suggestions would be welcome.

TIA,

JH
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