Comments on: MSTP Tutorial Part II: Outside a Region

By: @pnee

@pnee — Wed, 16 Feb 2011 20:05:23 +0000

when the external root path cost is same to the CIST root bridge from REGION234, how did SW2 can become the root?. Since the external path cost is same, the tiebreaker should be the sender bridge id, right. Since SW4 has a lower sender bid, shouldn’t SW4 be the Regional Root Bridge for REGION 234?.

By: Petr Lapukhov, 4xCCIE/CCDE

Petr Lapukhov, 4xCCIE/CCDE — Fri, 03 Dec 2010 17:17:09 +0000

@jusegi

Yes you can add 80 switches provided that you change the Hop Count for the network. However, such large network is most likely to be very unstable due to count to infinity problem and huge broadcast domains.

By: jusegi

jusegi — Fri, 03 Dec 2010 15:38:03 +0000

Excellent work !!!!, thanks for this great work.

But I still have a question: There is some limit of switches within a region? Can I join 80 switches in a region 1 for example?

I´ll appreciate your comments.

By: Dustin Cardoza

Dustin Cardoza — Thu, 02 Dec 2010 05:55:09 +0000

Another great STP article! This is the BEST explaination of MSTP/PVST+ interop that I’ve seen to date.

By: Dani Petrov

Dani Petrov — Fri, 12 Nov 2010 19:52:09 +0000

I just wanted to say that I have never read such a good explanation of this technology. It’s quite, much better even than Cisco’s explanation (which is kinda scant).

Best regards for all of you guys and two thumbs up for all these posts, which you’re digging for a people who are getting bored while reading all these drily written RFC’s or vendor’s interpretation attempts.

Best regards,
Dani

By: Blog Post Catalogue | CCIE Blog

Blog Post Catalogue | CCIE Blog — Fri, 24 Sep 2010 14:07:54 +0000

[...] MSTP Tutorial Part 2: Outside a Region [...]

By: Andry Scan

Andry Scan — Wed, 07 Jul 2010 08:40:42 +0000

Petr, thanks for the article!
It helped me when I migrate from PVST to MSTP

By: Rik

Rik — Sat, 15 May 2010 09:56:48 +0000

Ok
I have read the show you post before and its right that the output show P2p Bound(RSTP) because is a boundary switch
But if the 3Com had the RSTP instead of MSTP what might be show the cisco output?

By: Rik

Rik — Fri, 14 May 2010 20:34:19 +0000

Ok I’have read the show you post UP and its right that the output show p2p Bound(RSTP) because it is a boundary port

If the 3Com had RSTP instead of MSTP what might show the output?

By: Rik

Rik — Fri, 14 May 2010 19:42:06 +0000

Hi Peter
thanks for the excellent explanation
I have a question on MSTP
I have Cisco with MSTP connected to a 3Com with MSTP too but in different region
On Cisco output why there is Bound (RSTP) and not p2p?
Its right or wrong?
It seems that Cisco see an RSTP peer not a MSTP peer

SF-A#sh spanning-tree mst

…………………………………………………
—————- —- — ——— ——– ——————————–
Gi3/1 Root FWD 20000 128.129 P2p Bound(RSTP)

Thank