Frame Modification

Frame Modification
It is important to understand that this shortcut switching occurs at layer 3. The layer 2 frame
addresses (that are a part of the conversation) coming after the first frame are rewritten by the
switch. Normally, a router (layer 3 device) would rewrite the frame with the necessary information.
A rewrite consists of changing the VLAN assignment, the source and destination MAC
addresses, and the checksums. The MLS-SE can also modify the TTL, TOS, and encapsulation.
VLAN 10 VLAN 50
VLAN 10 VLAN 50
VLAN 10 VLAN 50
FE0/0.10
FE0/0
FE0/0.50
Candidate packet
Host A
Host B
Host C
Host D
Host E
Host F
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Chapter 18 
Multilayer Switching (MLS