I seem to recall some Cisco switches that would perform cut-through switching until a configurable number of CRC's are detected and would switch to store-and-forward until errors cleared.
Dave Priscilla Oppenheimer wrote: > > 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 -- David Madland Sr. Network Engineer CCIE# 2016 Qwest Communications Int. Inc. [EMAIL PROTECTED] 612-664-3367 "Emotion should reflect reason not guide it" Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=48336&t=48316 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
