Hey
What values do you match when asked to filter STP BPDUs, for both 802.1q and
ISL trunks ?
I've read that IEEE STP BPDUs use 802.2 LLC encapsulation with SSAP/DSSP
values of 0x42 or LSAP value of 0x4242. The document further states that you
can also see STP packets sent across ISL trunks using the same LSAP value of
0x42.
PVST+ BPDUs use 802.2 SNAP encapsulation, with LSAP=0xAAAA. All
SNAP-encapsulated packets can be matched using an LSAP value of 0xAAAA.
So, my question is, in order to match STP BPDUs for both 802.1q and ISL
trunks, would I have to do the following:
mac access-list extended BPDU
permit any any 0xAAAA 0x0
permit any any lsap 0x4242
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