RE: protocol number ISL pvst

From: Alex Steer (alex.steer@eison.co.uk)
Date: Sat Nov 17 2007 - 11:02:58 ART


Nice one Joe,

I knew there would be some output you could use to find out what it is
without having to remember! (I had tried debugging but couldn't spot
anything useful) A quick double take at the difference and it's all
making sense!

Cheers

At which point do I receive the bill for your time?

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Joseph Brunner
Sent: 17 November 2007 13:50
To: Alex Steer; 'Cisco certification'
Subject: RE: protocol number ISL pvst

0x4242 is for ISL trunks (PVST)

Lsap 0x4242 for pvst (isl)

Lsap 0xaaaa for pvst+ (dot1q)

Just remember it this way, if you were going to be around, and not be
phased
out, what would your credit rating be? AAAA or 4242? LOL

You can also do "debug spanning-tree bpdu receive" to get the lsap type
you
need

(see this line regarding stp ENC)

5d14h: STP: enc 01 80 C2 00 00 00 00 15 2B 2C 7E 8E 00 26 42 42 03

In this debug message

5d14h: STP: VLAN0101 Po12:0000 00 00 00 606500152B2C7E80 00000000
606500152B2C7E80 8090 0000 1400 0200 0F00
5d14h: STP(101) port Po12 supersedes 0
5d14h: STP: VLAN0001 rx BPDU: config protocol = ieee, packet from
Port-channel12 , linktype IEEE_SPANNING , enctype 2, encsize 17
5d14h: STP: enc 01 80 C2 00 00 00 00 15 2B 2C 7E 8E 00 26 42 42 03
5d14h: STP: Data
0000000000600100152B2C7E8000000000600100152B2C7E8080900000140002

Of course this is an ISL trunk switch to Pvst+ (802.1q)

So I re-config'd po12 (member interfaces f0/13-14) to dot1q on both
sides,
and look now

5d14h: STP: VLAN0101 rx BPDU: config protocol = ieee, packet from
Port-channel12 , linktype SSTP , enctype 3, encsize 22
5d14h: STP: enc 01 00 0C CC CC CD 00 15 2B 2C 7E 8E 00 32 AA AA 03 00 00
0C
01 0B
5d14h: STP: Data
0000000001606500152B2C7E8000000000606500152B2C7E8080900000140002000F00

(see the AA AA)!!!

LOL, you only have "what you take in with you" and that is in your head
and
the CLI interface.

-Joe

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Alex
Steer
Sent: Saturday, November 17, 2007 7:11 AM
To: Cisco certification
Subject: protocol number ISL pvst

Hi

Does anyone know the protocol number for pvst over an isl trunk?

I can't seem to get spanning-tree to work with the following
configuration, fa0/8 is a trunk to another switch. The configuration
works fine if I change the a isl trunk into a dot1q trunk

mac access-list extended pvst

 permit any any lsap 0xAAAA 0x0

mac access-list extended arp

 permit any any 0x806 0x0

spanning-tree mode pvst

!

vlan access-map filter56 10

 action forward

 match ip address filter56

vlan access-map filter56 20

 action forward

 match mac address arp

vlan access-map filter56 30

 action forward

 match mac address pvst

vlan access-map filter56 40

 action drop

!

vlan filter filter56 vlan-list 56

int fa0/8

swi trunk encap isl



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