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RE: [Fwd: Re: 20 MHz clock oscillator]



The frame counter counts the number of alignment errors. 
An alignment error occurs when an uneven number of nibbles
have been received. As far as I can understand tt least 
two things can cause this to occur:

1. The packaet contains an uneven number of nibbles
(as interpreted by the receiver).2
2. A collision occurs at an uneven nibble boundary when
receiving.

So for a half-duplex network with > 2 nodes it is completely
normal to get alignment errors (because collisions do happen
at uneven nibbles).

I will check more with the ASIC guys about this.

/Mikael

-----Original Message-----
From: owner-dev-etrax@xxxxxxx.com">mailto:owner-dev-etrax@xxxxxxx.com] On Behalf Of girerd
Sent: Friday, July 02, 2004 5:46 PM
To: dev-etrax
Subject: [Fwd: Re: 20 MHz clock oscillator]


  Hi,

We use a MCM2+8 in our design and we observed that frame counter
(field frame in the status return by ifconfig) increases
during data transfer betwwen a PC and our device. 

here is a sample of result of ifconfig :

ifconfig
eth0      Link encap:Ethernet  HWaddr 00:40:8C:00:00:C3  
          inet addr:172.16.5.255  Bcast:172.16.255.255  Mask:255.255.0.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:724 errors:0 dropped:0 overruns:0 frame:2
          TX packets:277 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100 
          RX bytes:729894 (712.7 kb)  TX bytes:30094 (29.3 kb)
          Interrupt:17 DMA chan:1 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:35 errors:0 dropped:0 overruns:0 frame:0
          TX packets:35 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:3804 (3.7 kb)  TX bytes:3804 (3.7 kb)


What is the exact meaning of the field frame in the status return by ifconfig ?

Does someone has any idea about the possible reasons of this value of frame ?


Thank you

Claude




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