topic Re: Create all NNI's as an MLT? in ExtremeSwitching (VSP/Fabric Engine)

Create all NNI's as an MLT?

Anonymous — Thu, 20 May 2021 18:56:36 GMT

Hi,

Very simple question, just testing the idea of putting every single link NNI into an MLT. My theory is that with ISIS being a P2P protocol, it might be good practise to do this as it would be easy to add another link if required.

That seem like a logical idea?

Just testing the water in case there is some component that I am missing.

Only downside I see is that you are adding another protocol layer to a single link that doesn’t necessarily need it, but is generally very stable.

When I label the MLT’s I am using the port number i.e. slot 1 port 45 is MLT145, slot 3 port 12 is MLT 312, if using LACP I am also using that number as the key. If IST I am using 501.

If more then one port is on same switch in an MLT I use the first port.

Obviously doesn’t work for an 8600 has MLT numbering is 1-512, but generally works. Makes it very quick and easy to see what ports belong to an MLT without searching for it, and has a general rule to follow that works.

Anyway, see what anyone else might do?

Many thanks in advance

Re: Create all NNI's as an MLT?

EXTR_Paul — Thu, 20 May 2021 19:41:04 GMT

This will work. The only issue is that you will have all your MLTs in an error state, all the time.

When I build fabrics with customers, when its a single NNI its a point-to-point NNI. If its an MLT/NNI then we create the group and enabled it as an NNI.

Re: Create all NNI's as an MLT?

Anonymous — Thu, 20 May 2021 19:52:49 GMT

Hi Paul,

Thanks for posting back.

Just to clarify, I’m not clear on why the MLT’s would show an error state. In terms of creating the group and enable it as an NNI, is this the type of configuration you would expect to see:

mlt 501 enable name "MLT to xxxx"
mlt 501 member 1/18
mlt 501 encapsulation dot1q

interface mlt 501
isis
isis spbm 1
isis enable
exit

Many thanks

Re: Create all NNI's as an MLT?

EXTR_Paul — Thu, 20 May 2021 20:03:12 GMT

Martin.

Sorry….you are correct!!!! This will only show being in Error state if its an SMLT.

IMHO adding unnecessary configurations when not required is just something else to troubleshoot when something goes wrong.

Someone from the TME or Engineering group can chime in, but this is likely not a tested and validated design.

But I did do this in the early 2000s with ERS8600s Cores and ERS5500 edge. We made all the MLT/SMLT links 4 to 8 ports, but only used one. With the idea “Hey, if we ever need more links we can just add them later”. Well, 8 years later no one ever returned to add more links.

Re: Create all NNI's as an MLT?

Anonymous — Thu, 20 May 2021 20:08:11 GMT

No problem, thanks Paul, appreciate the opinion.

Probably not then the norm, will go for more simplicity I think as a better principle on design and perhaps skip adding MLT’s to all the NNI’s, unless something comes up that provides a compelling reason.

Cheers.

Re: Create all NNI's as an MLT?

EXTR_Paul — Thu, 20 May 2021 20:17:10 GMT

The nice thing with a Fabric, as long as you have redundant paths you can do this Move, Add, Change with no disruption.

Re: Create all NNI's as an MLT?

Roger_Lapuh — Tue, 25 May 2021 17:40:37 GMT

I don’t see any reason why this would not be supported. As for “additional protocol”: As long as you are not using LACP, there is no additional protocol running. You are using more configuration steps, but other than that there is no additional CPU involvement when running static MLTs.

Roger