RE: [ethmac] how about VLAN?

["Illan Glasner" <iglasner@zumanetworks.com>]

   Hi,

         I'm not sure I follow what you try to say when you write special aritmetic, but basicly when you get a packet and want to remove/change the vlan while you remove the vlan your crc checker will check the original packet before the remove/change and NOT after.

and when sending packet if you insert/change a vlan you recalculate the crc on the fly while sending it away and just override the old crc with the new one.

Notice that 64-67 byte packet with vlan that you decide to remove the vlan you need to pad to prevent the packet to become less than 64.

have a nice day

   Illan


-----Original Message-----
From: jcwh@sina.com [mailto:jcwh@sina.com]
Sent: Thursday, April 04, 2002 1:52 AM
To: ethmac@opencores.org
Subject: [ethmac] how about VLAN?


Is someone going to implement VLAN tag insertion and extraction in this 
mac controller?

when inserting /extracting the VLAN tag, CRC should be calculated once 
more.

Can we just change the old crc on some kind of spcial arithmetic ,while 
not "crc through" the whole frame?

does someone here know this kind of arithmetic?

thanks

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