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Contributor
Eng_Ahmad
Posts: 24
Registered: ‎12-24-2009
0

MSTP configuration and digest number

[ Edited ]

Hello,

 

In the MSTP configuration I faced some strange thing. :robotsurprised:

 

When you create MSTIs you assign a list of vlans to each MSTI, and this list MUST be identical on each switch in the region even if it doesn't have some of the listed vlans.

 

And if you tried to add or remove even a single vlan from a switch it will be out of the zone and MSTI will not be working on this switch. It will still exist but deals with the switch as if it's on a different region even it has the same region name and revision-level.

 

This is because the calculation of the digest number depends on the configuration of the MSTIs and the list of vlans on each MSTI.

 

 

I don't see that this is a flexible way of implementation. I just can't force customers to change all the MSTIs configuration on all edge switches if they add a vlan into the MSTI configuration on the core for example.

 

I think this issue should be solved soon, and In my opinion i see that the digest number should depend only on the region name and the "revision-level", which will be much logical and flexible.

 

 

 

 

Please provide any related information.

 

Thanks

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Professionalism Is built on Problems .. So if you don't face problems, you will learn nothing.
Distinguished Expert
mikep
Posts: 483
Registered: ‎06-30-2009
0

Re: MSTP configuration and digest number

Hi,

 

well it is how IEEE standard defines it and I do not think it will be ever changed.

 

Kind Regards

Michael Pergament

Contributor
Eng_Ahmad
Posts: 24
Registered: ‎12-24-2009
0

Re: MSTP configuration and digest number

Hello mikep,

 

Thank you for your reply, it was very convenient to me.

 

Thanks and regards

 

 

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Professionalism Is built on Problems .. So if you don't face problems, you will learn nothing.
Contributor
aeroplane
Posts: 724
Registered: ‎06-30-2009
0

Re: MSTP configuration and digest number

Hi

 

It means that if 100 VLANS on core switch configured you have to define 100 VLANS also on access switches so that MSTI instance is same for core and access switches? OR we dont need to define these additional VLAN on access switches but we can define in MST instance?

Contributor
Eng_Ahmad
Posts: 24
Registered: ‎12-24-2009

Re: MSTP configuration and digest number

Hi aeroplane

 

No you don't have to create the 100 vlans on the access switches, you only will need to include them in the MSTI configuration of all access switches even if there are some vlans are not created on the switch, just to make the MSTI configurations identical on core and access switches.

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Professionalism Is built on Problems .. So if you don't face problems, you will learn nothing.
Contributor
aeroplane
Posts: 724
Registered: ‎06-30-2009
0

Re: MSTP configuration and digest number

Thanks Dear. Also if you can guide me, regarding the MSTP confiugration:

 

-There is configuration to define uplink ports are point to point under MSTP configuration? why we do this configuration?

-I want to put all access ports are edge ports except the uplink port? how I can do this?

 

Thanks

Recognized Expert
wimclend
Posts: 275
Registered: ‎04-03-2009
0

Re: MSTP configuration and digest number

one thing that (I don't think) isn't very well documented is that I believe you can define a range of VLANs for the MSTP config -- ie vlan 200-500

 

at first I thought you had to define each one separately like vlan [ 51 52 53  ... ] but I don't think that is the case.

 

Perhaps that will make MSTP look a little more attractive?

 

good luck,

 

will

Contributor
Locki
Posts: 25
Registered: ‎06-22-2010
0

Re: MSTP configuration and digest number

[ Edited ]

Well, I've just tested it on my EX 4200, and it's working for a VLANs range in mstp configuration:

 

set protocols mstp msti 3 vlan 3500-4000

 

MSTP information
MSTI     Member VLANs
   0 0-3499,4001-4094
   3 3500-4000

Trusted Contributor
BuckWeet
Posts: 159
Registered: ‎08-29-2008
0

Re: MSTP configuration and digest number

This is a big reason we've never switched to MST.. We're primarily a Cisco shop and its easier for us to to integrate via VSTP than it is MST. I feel that this configuration headache with MST opens up possibilities for causing outages. 

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