Cisco 4500 MTU size (Jumbo) 1

[VinceWhirlwind]

Let's say I have the following on a 4500 switch:

Int Gi1/1
sw mo access
sw access VLAN 100
mtu 9198
Int Gi1/2
sw mo access
sw access VLAN 100
mtu 9198
int vlan 100
no ip address

Now, according to the IOS guide:
"the packet size of ingress frames is checked. If the packet is larger than the configured MTU, it is dropped."
and
"The Catalyst 4500 series switch does not compare the packet size with the MTU at the egress port, but jumbo frames are dropped in ports that do not support them."
and
"The MTU of a packet is not checked on the ingress side for an SVI; it is checked on the egress side of an SVI. If the MTU of a packet is larger than the MTU of the egress SVI, the packet will be sent to the CPU for fragmentation processing."

With the configuration I have above, if a jumbo frame is received on Gi1/1 and has to go out Gi1/2, both switchports are configured for jumbo frames, so the frame will be OK for the switchports. The bit I'm not clear on is the SVI - if the packet is going between two switchports on the same VLAN, is it in fact using "the egress side of the SVI", or, is "the egress side of the SVI" only used on a layer3 switch when being L3 switched to another VLAN?

 

[dgrizzard]

Correct, since they are in the same VLAN they would not hit the SVI. Going between VLANs would be the case where the egress SVI would come into play.