3550 Layer 3 access-lists applied to layer 2 ports

From: Tim Last (packtmon@yahoo.com)
Date: Wed Apr 21 2004 - 11:05:34 GMT-3

Hi all,
 
The 3550 documentation seems to imply that it's OK to apply an access-list which looks at layer 3 or higher layer info inside the frame ( for example, mark all ip pkts from ip addr x with ip prec y) and apply it to layer 2 port ( vs a routed port).
 
1) Am I interpreting the documentation correctly ie there's no problem with doing that?
 
2) If that's OK, how does that work? Isn't it true that Ethernet switches, in general, only look at MAC headers and based on mac addresses make their switching decision?
 
3) Are there any restrictions or limitations in doing this? Can I create any access-list that would work on a routed interface, apply it to 3550 layer 2 port and expect that it will work?
 
4) For this to work, do I need to configure anything on the 3550 in addition to the commands that create the access-list and apply it to port? For example, mls qos?
 
Maybe someone can explain what's going on here.
 
Thanks in advance, Tim

                
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