All,
Trying to understand the proctor guide thoroughly, I'm now struggling
with an explanation in the proctor guide. It says that PVST+ is using an
LSAP with value 0xAA. I have no clue what an LSAP is, but seeing the
value it is presumably the concatenation of the DSAP and the SSAP.
However, permitting frames with LSAP 0xAA simply permits all frames that
have a SNAP LLC header. Should there not be additional filtering to
allow ONLY spanning tree traffic frames?
Finally, something completely unrelated just to satisfy my curiosity; in
the Cisco manual the mac filter is described as:
{ deny | permit} {any | host src-MAC-addr | src-MAC-addr mask} {any |
host dst-MAC-addr | dst-MAC-addr mask} [type mask | aarp | amber | cos
cos | dec-spanning | decnet-iv | diagnostic | dsm | etype-6000 |
etype-8042 | lat | lavc-sca | lsap lsap mask |mop-console | mop-dump |
msdos | mumps | netbios | vines-echo | vines-ip | xns-idp]
Question: why do they have a specific option for etype-6000 and
etype-8042, that in my opinion could be written as:
permit any any 0x6000 0x0000 and permit any any 0x8042 0x0000
Once again kind regards,
Frank
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