You found 3000 of what? At 06:21 PM 7/9/2002 +0000, Alejandro Acosta Alamo wrote: >Hello again, > Priscilla, you have said that an ethernet frame must be at least 64 bytes, >right?. I have just placed an sniffer on my LAN and I found over 3000 out of >15.000 packets. Does this mean that 20% of those packets are illegal? > >Thanks > >Alejandro Acosta > >----- Original Message ----- >From: "Priscilla Oppenheimer" >To: >Sent: Monday, July 08, 2002 1:08 PM >Subject: RE: Cut-through vs Store & Forward [7:48316] > > > > Alejandro Acosta Alamo wrote: > > > > > > Hello, > > > I understand the differences between Cut-through and Store & > > > Forward. My > > > question is: How do you decide with method to use?, in whch > > > situation have > > > you change the switching method?. > > > > > > Thanks > > > > > > Alejandro Acosta > > > > > > > > A lot of switches support only one method, so you don't have a choice. If > > you do have a choice, the decision is based on the number of errors on >your > > network. Cut-through doesn't do any error checking and in fact forwards > > frames that have a bad CRC or are too short. Ethernet says that frames >must > > be at least 64 bytes. Anything less is considered a fragment and is >illegal. > > Cut-through forwards fragments that have an entire destination address >that > > can be looked up to get a port number. > > > > If your switch connects many shared networks, then CRC errors and >fragments > > due to collisions are normal. But why waste bandwidth forwarding these to > > other ports on the LAN? In this case, you might want to go with > > store-and-forward which does not forward errored frames or fragments. > > > > If your switch connects single devices all using full-duplex, then it's > > unlikely that you are experiencing many CRC or fragments. So, cut-through > > makes the most sense. > > > > > > Priscilla Oppenheimer > > http://www.priscilla.com
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