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LoopProtect and MSTP

LoopProtect and MSTP

jeronimo
Contributor III

‎04-09-2016 03:58 PM

Hi,

I've been reading up on Spanning Tree and LoopProtect. In the 7100 v8.41 Configuration Guide on page 338 there is a note that says:

The Loop Protect enable/disable settings for an MSTI port should match those for the CIST port.
What exactly does this mean? What does this statement require us to be vigilant about in our configs?

Does it mean that if you "set spantree lp ge.1.2 enable sid 1" you should also "set spantree lp ge.1.2 enable" (sid 0) etc. for all other SIDs? Why?

Bye,

Marki

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8 REPLIES 8

Erik_Auerswald
Contributor II
In response to jeronimo

‎04-23-2016 05:20 PM

That is what I would expect, but I never actually tested this.

Once I had to use several MSTP regions of significant size each to overcome the hop count limit inside a region. But that has been the only time STP hop count has been a concern for me.
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jeronimo
Contributor III
In response to jeronimo

‎04-23-2016 05:20 PM

Nope, we did not. Are you saying that RSTP would work equally well as MSTP in case you don't need the individual instances that MSTP provides?
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Erik_Auerswald
Contributor II
In response to jeronimo

‎04-23-2016 05:20 PM

Hello Marki,

did you test and verify an RSTP hop limit of 7?

Erik
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Allen_George
Extreme Employee

‎04-22-2016 02:34 PM

Hello,

"The Loop Protect enable/disable settings for an MSTI port should match those for the CIST port."
Answer: The MSTI port is the port in which the MSTP Instance is configured but the CIST port in this case will be the underlying SID 0. So when you configure SID 1 and 2 and align VLAN 5,15 to SID 1 and then VLAN 10,20 to SID 2. You will then configure 'set spantree lp ge.x.x sid 1' on all ports that belong to that VLAN and the same goes for SID 2 for any port that belongs to those correlating VLANs. But that is only configuring for the MSTI, to match the CIST port, you must also configure Loop Protect on SID 0 for all of these same ports to ensure proper operation in MSTP.

So in a way this does require you to be very specific about how you prepare and apply your configuration or you may be unknown results if done improperly.

Please let me know if that answers your question.

Thank you and have a great day!

Regards,
Allen George
Technical Support Engineer, GTAC / Extreme Networks
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