Thanks Kings, so when asked to match BPDUs, its better to specify both "lsap 0xAAAA" and "lsap 0x4242" ?
Mark On Thu, Aug 11, 2011 at 10:46 PM, Kingsley Charles < [email protected]> wrote: > IEEE STP BPDUs (uses 803.2 with 802.2) are sent vlan 1 on trunk ports > (802.1q) irrespective of whether it is the native or non-native vlan. > It can be matched using "permit any any lsap 0x4242 0x0". > > PVST+ BPDUs (Uses 803.2 with SNAP) are sent on other vlans excluding vlan 1 > on trunk port (802.1q). It can be match using "permit any any lsap 0xAAAA > 0x0" or "permit any any 0x010B 0x0". > > > mac access-list extended BPDU > permit any any lsap 0xAAAA > > permit any any lsap 0x4242 > > or > > > mac access-list extended BPDU > permit any any 0x010B 0x0 > > permit any any lsap 0x4242 > > > I prefer first one as 0xAAAA also permits cdp, vtp etc along with PVST+ > BPDUs. > > > With regards > Kings > > On Fri, Aug 12, 2011 at 3:26 AM, Mark Senteza <[email protected]>wrote: > >> 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 >> >> >> >> _______________________________________________ >> For more information regarding industry leading CCIE Lab training, please >> visit www.ipexpert.com >> >> Are you a CCNP or CCIE and looking for a job? Check out >> www.PlatinumPlacement.com >> > >
_______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com
