Although I don't think this is necessarily the cause of your dropouts as you
put it, one must understand the way autonegotiation and manual speed and duplex
work between network gear.
For autonegotiation to work, BOTH devices must support autonegotiation, OR both
devices must be set to the same speed and duplex setting. If one only supports
auto and the other does not, you must NOT set the device that you can manually
configure to full duplex. The auto device will never negotiate at full duplex
and fall back to half when autonegotiation fails, causing a duplex mismatch and
horrible network performance and loss.
A very rough set of rules of thumb (YMMV):
When connecting to an unmanaged switch, use auto. If your host doesn't support
auto, set it to half-duplex.
When connecting to a managed switch, make sure the port is set to auto and set
your system to auto, otherwise force both the switch port and your host to the
same settings. This is required especially if the host doesn't support auto
negotiation and you want to run at full duplex.
When connecting to a managed switch, enable portfast or the equivalent
spanning-tree command on the switch port your host is connected to so it
forwards traffic immediately when getting link.
So to sum it up, auto only works if both sides speak auto. Auto negotiation
failure falls back to half-duplex!
Of course there are all the horror stories where auto negotiation is evil and
that different vendor's implementations don't play nice or are just completely
broken, so always set things to manual or you and your family will suffer an
untimely death... There are so many of these stories that one would think there
has to be some truth to it. In my own experience, I have never had an issue
with auto negotiation in some ten years of working with a dozen different
vendors' networking gear so I guess I'm lucky... or I just understand how it
interacts with other devices and their capabilities. I still don't know which
exactly.
Hope this helps! :)
Dimuthu Parussalla wrote:
Hi All,
Apart from random dropout from the network. Our IBM X236 server suffers slow
network performance. I've changed the server from CISCO switch to a netgear
switch on a test platform. Also tried 1000m full-duplex setup with no auto
negotionation on both ends. Still after few days (3-4) server drops the
connection. And while its working I get 90KBps upload/download with ftp
transfers.
I have treid changing BGE network cards to EM (intel 100/1000) still the
same result. Any idea's to nail this problem?
/etc/sysctl.conf
kern.ipc.maxsockbuf=8388608
kern.ipc.somaxconn=2048
net.inet.tcp.sendspace=3217968
net.inet.tcp.recvspace=3217968
net.inet.tcp.rfc1323=1
#net.inet.tcp.rfc3042=0
net.inet.ip.portrange.hilast=65535
net.inet.ip.portrange.hifirst=49152
net.inet.ip.portrange.last=65535
net.inet.ip.portrange.first=1024
net.inet.tcp.inflight.enable=0
/boot/loader.conf
kern.ipc.nmbclusters=32768
Interfaces:
em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=b<RXCSUM,TXCSUM,VLAN_MTU>
inet 192.168.1.12 netmask 0xffffff00 broadcast 192.168.1.255
ether 00:0e:0c:d0:73:3c
media: Ethernet 1000baseTX <full-duplex>
status: active
em1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=b<RXCSUM,TXCSUM,VLAN_MTU>
inet 6x.xx.xx.xx netmask 0xffffffc0 broadcast xxx.xxx.xxx.255
ether 00:0e:0c:9f:f4:5e
media: Ethernet 100baseTX <full-duplex>
status: active
Regards
Dimuthu Parussalla
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