so says the market speak. in terms of how things really work, it makes not one whit of difference how the forwarding cache is constructed. look at bits C through D to determine the MAC or bits A through B to determine the IP address. The processor can do either one about as fast. The layer three header still has to be stripped before placing the packet on the local wire, which operates at the MAC layer anyway.
so my cache can say that MAC aaaa.aaaa.aaaa is out port 4 or it can say 192.168.1.1 is out port 4. no difference. I'm guessing the gains here are in that a separate lookup or process does not have to be involved, meaning there is a performance enhancement if "layer 3" switching is used. as far as placing the packet onto the local wire, it shouldn't matter. Chuck -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of ndabarasa michel Sent: Thursday, December 06, 2001 11:39 AM To: [EMAIL PROTECTED] Subject: Re: What's the critical difference between level 3 switching [7:28315] hello, the difference between layer3 and layer2 switching is that: *for layer2 switching the switching box use the info in the second layer of the OSI model(datalink layer) to choose where to forward the frame while.the info used is the MAC address ab:34:fe:bla:blabla:blablabla *while for layer3 switching the box uses the info in the third layer of the OSI model to make forwarding decisions.the info in layer3 is the IP address 210.12.x.x On Thu, 6 Dec 2001 12:57:43 -0500 "c.h.ip" wrote: > hi all, > > It seems that both is looking for level 3 header > information (like > destination IP address) to make decision of packet > forwarding. > > Just can't get into the concepts between them. > > Any hint is appreciated. > > Regards, > c.h.Ip > [EMAIL PROTECTED] /'^ ^'\ ((o)-(o)) |----oOOO--(_)--OOOo--------------|-|- | Ndabarasa Michel............... | | CCNA,CCAI...................... | | National University of Rwanda.. | | Computing Centre............... | | voice.......................... | | office (+250)530666............ | | cell (+250)08510951.......... | |==== .oooO | |.... ( ) Oooo. | |-------\ (--- ( )---------------|-| \_) ) / |-| (_/ ---------------------------------------------- FREE! The Best in Rwanda Email Address @mail.rw Reserve your name right now at http://mail.rw Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=28335&t=28335 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
