[K12OSN] Network Question

"Terrell Prudé, Jr." microman at cmosnetworks.com
Sat Feb 12 03:43:46 UTC 2005

Jim Christiansen wrote:

> Hello,  Our technician was in the building pulling cat5 and after he 
> left this am, my librarian came to me to inform me that the clients 
> were running at 1/2 speed.
> I just thought to run ifconfig and I see carrier:14197 and 
> overruns:12141....   Great.  I know this isn't good.
> Does anyone know what this means?  Thanks,  Jim
> Here is my complete ifconfig:
> [root at linux-thin1 ~]# ifconfig
> eth0      Link encap:Ethernet  HWaddr 00:E0:81:28:27:52
>          inet addr:  Bcast:  Mask:
>          inet6 addr: fe80::2e0:81ff:fe28:2752/64 Scope:Link
>          RX packets:126270015 errors:0 dropped:0 overruns:12141 frame:0
>          TX packets:153628098 errors:0 dropped:0 overruns:0 carrier:14197
>          collisions:0 txqueuelen:1000
>          RX bytes:1069418867 (1019.8 MiB)  TX bytes:652818974 (622.5 MiB)
>          Interrupt:169 Base address:0x2000
> lo        Link encap:Local Loopback
>          inet addr:  Mask:
>          inet6 addr: ::1/128 Scope:Host
>          UP LOOPBACK RUNNING  MTU:16436  Metric:1
>          RX packets:315878 errors:0 dropped:0 overruns:0 frame:0
>          TX packets:315878 errors:0 dropped:0 overruns:0 carrier:0
>          collisions:0 txqueuelen:0
>          RX bytes:204548481 (195.0 MiB)  TX bytes:204548481 (195.0 MiB)

What kind of gear are these drops plugged into?  Hubs, switches, and at 
what speed?  If they're hubs, you're going to see a reduction in 
throughput.  If they're half-duplex switches, it won't be as bad.  
Optimum is full duplex.  If you're using 100Mbps/FDX switches, you might 
check to see if your autonegotiation is 1.) turned on <they usually are 
by default>, and 2.) actually working right.

Also, did he perform a full cabling test, and if so, did he give you a 
copy of the results?  Wiring contractors are supposed to do that.


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