MSTP and regions

[Marki]

Hi,

I'm about to separate our MSTP setup into different regions.

The reason is simple: Most VLANs are only needed at the core, and
recomputations of those should not affect the entire "cloud" (and vice-versa).

For now, I have configured ONE additional region to the existing one.

So in fact we now have two regions, the one shown in orange, as well as the
rest of the drawing: Loading Image...

Now I find that drawing a setup with multiple regions in topology manager
does not seem to really work out, or there is some config issue.

Here's some output from the switches

G3 -> show spantree stats sid 1
Spanning tree status - enabled
Spanning tree instance - 1
Designated Root MacAddr - 00:1F:45:aa:xx:58
Designated Root Port - 0
Designated Root Priority - 32768
Designated Root Cost - 0
Root Max Age - 20
Root Hello Time - 2
Root Forward Delay - 15
Bridge ID MAC Address - 00:1F:45:aa:xx:58
Bridge ID Priority - 32768
Bridge Max Age - 20
Bridge Hello Time - 2
Bridge Forward Delay - 15
Topology Change Count - 65
Time Since Top Change - 6 days 5:15:37
Max Hops - 20


B5 -> show spantree stats sid 1
Spanning tree status - enabled
Spanning tree instance - 1
Designated Root MacAddr - 00:1F:45:aa:xx:58
Designated Root Port - ge.1.48
Designated Root Priority - 32768
Designated Root Cost - 20000
Root Max Age - 20
Root Hello Time - 2
Root Forward Delay - 15
Bridge ID MAC Address - 20:B3:99:bb:yy:DC
Bridge ID Priority - 32768
Bridge Max Age - 20
Bridge Hello Time - 2
Bridge Forward Delay - 15
Topology Change Count - 2
Time Since Top Change - 19 days 3:53:19
Max Hops - 20

The B5 seems to have accepted the G3 correctly as its STP root.

But why are the links in (and out of the region) in topology manager dotted?

The MST Configuration Identifier is identical on the switches supposed to
form the region.

"show spantree mstmap" and "show spantree vlanlist" show the same thing on
all those switches.

What is a "designated root" as shown in the diagram? Does it mean the CIST Root?

BTW Neither do I find much on the CLI which would point me toward the
correctness of my setup. On Ciscos you see boundary ports and MACs of CIST
regional roots, is there some similar output here somewhere?

And what does it mean when the CLI says during "show spantree mstmap":

Vlan 1 is mapped to Sid CST

Yeah there is no setting mapping it to an instance right. But even when I
have only one region it still talks about CST, although in my understanding
the CST only really exists when there are multiple regions. So what does
this mean?


This is Netsight 4.4 by the way, and the most recent FWs on the respective
switches.

Best regards,
Marki




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[Erik Auerswald]

Hi,

I cannot say much about the Topology Manager, but have some remarks
regarding MSTP:

- Both configuration name and configuration revision must match in addition
to the VLAN mapping for several switches to form an MST region.

- In the default configuration every switch forms its own MST region.

- In the default configuration the one existing VLAN 1 is mapped to MST
instance 0, the common spanning tree (CST). Unless you change this
mapping by assigning VLAN 1 to a different MST instance (SID) you will
get the "Vlan 1 is mapped to Sid CST" output.

To see which ports are participating in STP use the "show spantree stats
active" command (you can add "sid 1" to show the ports active in MST
instance 1).

To verify your configuration you can use:

show spantree version
show spantree mstilist
show spantree mstmap
show spantree vlanlist
show spantree mstcfgid

HTH,
Erik
--
Dipl.-Inform. Erik Auerswald http://www.fg-networking.de/
***@fg-networking.de T:[phone] M:[phone]

Gesellschaft für Fundamental Generic Networking mbH
Geschäftsführung: Volker Bauer, Jörg Mayer
Gerichtsstand: Amtsgericht Kaiserslautern - HRB: 3630

Post by Marki
Hi,
I'm about to separate our MSTP setup into different regions.
The reason is simple: Most VLANs are only needed at the core, and
recomputations of those should not affect the entire "cloud" (and vice-versa).
For now, I have configured ONE additional region to the existing one.
So in fact we now have two regions, the one shown in orange, as well as the
rest of the drawing: http://i57.tinypic.com/2557yix.png
Now I find that drawing a setup with multiple regions in topology manager
does not seem to really work out, or there is some config issue.
Here's some output from the switches
G3 -> show spantree stats sid 1
Spanning tree status - enabled
Spanning tree instance - 1
Designated Root MacAddr - 00:1F:45:aa:xx:58
Designated Root Port - 0
Designated Root Priority - 32768
Designated Root Cost - 0
Root Max Age - 20
Root Hello Time - 2
Root Forward Delay - 15
Bridge ID MAC Address - 00:1F:45:aa:xx:58
Bridge ID Priority - 32768
Bridge Max Age - 20
Bridge Hello Time - 2
Bridge Forward Delay - 15
Topology Change Count - 65
Time Since Top Change - 6 days 5:15:37
Max Hops - 20
B5 -> show spantree stats sid 1
Spanning tree status - enabled
Spanning tree instance - 1
Designated Root MacAddr - 00:1F:45:aa:xx:58
Designated Root Port - ge.1.48
Designated Root Priority - 32768
Designated Root Cost - 20000
Root Max Age - 20
Root Hello Time - 2
Root Forward Delay - 15
Bridge ID MAC Address - 20:B3:99:bb:yy:DC
Bridge ID Priority - 32768
Bridge Max Age - 20
Bridge Hello Time - 2
Bridge Forward Delay - 15
Topology Change Count - 2
Time Since Top Change - 19 days 3:53:19
Max Hops - 20
The B5 seems to have accepted the G3 correctly as its STP root.
But why are the links in (and out of the region) in topology manager dotted?
The MST Configuration Identifier is identical on the switches supposed to
form the region.
"show spantree mstmap" and "show spantree vlanlist" show the same thing on
all those switches.
What is a "designated root" as shown in the diagram? Does it mean the CIST Root?
BTW Neither do I find much on the CLI which would point me toward the
correctness of my setup. On Ciscos you see boundary ports and MACs of CIST
regional roots, is there some similar output here somewhere?
Vlan 1 is mapped to Sid CST
Yeah there is no setting mapping it to an instance right. But even when I
have only one region it still talks about CST, although in my understanding
the CST only really exists when there are multiple regions. So what does
this mean?
This is Netsight 4.4 by the way, and the most recent FWs on the respective
switches.
Best regards,
Marki

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[Darrin Green]

Marki,

Here is a production configuration we have between two N7 switches (names
have been changed to protect the innocent):

*Switch 1*
set spantree msti sid 1 create
set spantree msti sid 2 create
set spantree mstcfgid cfgname mst-region
set spantree mstmap 10,30,50 sid 1
set spantree mstmap 20,40,60 sid 2

*Switch 2*
set spantree msti sid 1 create
set spantree msti sid 2 create
set spantree mstcfgid cfgname mst-region
set spantree mstmap 10,30,50 sid 1
set spantree mstmap 20,40,60 sid 2

Post by Marki
Hi,
I'm about to separate our MSTP setup into different regions.
The reason is simple: Most VLANs are only needed at the core, and
recomputations of those should not affect the entire "cloud" (and
vice-versa).
For now, I have configured ONE additional region to the existing one.
So in fact we now have two regions, the one shown in orange, as well as the
rest of the drawing: http://i57.tinypic.com/2557yix.png
Now I find that drawing a setup with multiple regions in topology manager
does not seem to really work out, or there is some config issue.
Here's some output from the switches
G3 -> show spantree stats sid 1
Spanning tree status - enabled
Spanning tree instance - 1
Designated Root MacAddr - 00:1F:45:aa:xx:58
Designated Root Port - 0
Designated Root Priority - 32768
Designated Root Cost - 0
Root Max Age - 20
Root Hello Time - 2
Root Forward Delay - 15
Bridge ID MAC Address - 00:1F:45:aa:xx:58
Bridge ID Priority - 32768
Bridge Max Age - 20
Bridge Hello Time - 2
Bridge Forward Delay - 15
Topology Change Count - 65
Time Since Top Change - 6 days 5:15:37
Max Hops - 20
B5 -> show spantree stats sid 1
Spanning tree status - enabled
Spanning tree instance - 1
Designated Root MacAddr - 00:1F:45:aa:xx:58
Designated Root Port - ge.1.48
Designated Root Priority - 32768
Designated Root Cost - 20000
Root Max Age - 20
Root Hello Time - 2
Root Forward Delay - 15
Bridge ID MAC Address - 20:B3:99:bb:yy:DC
Bridge ID Priority - 32768
Bridge Max Age - 20
Bridge Hello Time - 2
Bridge Forward Delay - 15
Topology Change Count - 2
Time Since Top Change - 19 days 3:53:19
Max Hops - 20
The B5 seems to have accepted the G3 correctly as its STP root.
But why are the links in (and out of the region) in topology manager
dotted?
The MST Configuration Identifier is identical on the switches supposed to
form the region.
"show spantree mstmap" and "show spantree vlanlist" show the same thing on
all those switches.
What is a "designated root" as shown in the diagram? Does it mean the CIST
Root?
BTW Neither do I find much on the CLI which would point me toward the
correctness of my setup. On Ciscos you see boundary ports and MACs of CIST
regional roots, is there some similar output here somewhere?
Vlan 1 is mapped to Sid CST
Yeah there is no setting mapping it to an instance right. But even when I
have only one region it still talks about CST, although in my understanding
the CST only really exists when there are multiple regions. So what does
this mean?
This is Netsight 4.4 by the way, and the most recent FWs on the respective
switches.
Best regards,
Marki
---

--
Darrin E. Green
Senior Technical Support Specialist
Dallas Area Rapid Transit
1401 Pacific Avenue
Dallas, Texas 75202
Ph 214-749-3173
Fax [phone]
Email ***@dart.org

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[Marki]

Meanwhile I have made progress.

But from the start: An MSTP region is defined as:
* Format Selector
* Configuration Name
* Revision ID
* VLAN <-> SID hash

Consequently, I thought modifying one of those parameters was enough for a
new region to be created. While that seems true as far as MSTP itself is
concerned, Netsight Topology Manager does not seem to like it when you only
change the VLAN<->SID mapping but leave the rest untouched, i.e. same
configuration name and everything. It will show you two bridges that are
both CIST region root as well as designated root in one diagram.

If you indeed give the new region another configuration name, then you can
select the region+instance you wish to view from the dialog that shows when
you select "multiple spanning tree" from the menu.

All that does not belong to that region is then shown with dotted lines.


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