Your understanding is correct -- Setting LSAP to 0xAAAA (DSAP = 0xAA, SSAP = 0xAA) only tells us that there is indeed another SNAP header that follows. However, the switch does not let us get that detailed. There is no way to match the individual SNAP PID that I know of.
On Wed, Jan 20, 2010 at 3:10 PM, Frank <[email protected]> wrote: > > 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 > > > > > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > -- Regards, Joe Astorino CCIE #24347 (R&S) Sr. Technical Instructor - IPexpert Mailto: [email protected] Telephone: +1.810.326.1444 Live Assistance, Please visit: www.ipexpert.com/chat eFax: +1.810.454.0130 IPexpert is a premier provider of Classroom and Self-Study Cisco CCNA (R&S, Voice & Security), CCNP, CCVP, CCSP and CCIE (R&S, Voice, Security & Service Provider) Certification Training with locations throughout the United States, Europe and Australia. Be sure to check out our online communities at www.ipexpert.com/communities and our public website at www.ipexpert.com _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
