Maximum nodes in a REP segment?

[dstehle]

What is the maximum IE-3000-4TC switches that can be used in a REP segment?

Thanks,

David

[Matthew Blanshard · Accepted solution]

Hello David,

Our development testing has tested 32 nodes in our scalability/performance testing.  That being said we have several customers who have upwards of 100 devices in a ring without issue.  There's no hard/fast rule on exactly what is fully supported versus not supported.  More switches in the ring is going to equal slower convergence time and response to a failure.  Even with 100 devices in a ring though convergence time is still significantly improved over RSTP.

-Matt Blanshard

Cisco TAC - Lan Switching

[dstehle]

Matt,

Thanks for the quick reply. My engineer passed along this information:

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"Let’s see if he can confirm that this design should work fine  and not cause any loops in the system. I think it will control loops without issues if my  understanding of REP is correct.  But we have no control of how the fiber is  being laid out so I’m making sure how I configure the network will work with  this physical layout. This is a small sample design but the idea is the same no  matter how many IE3000’s there are in each segment. Just will take a little  longer (ms) to converge based on how many switches.

If  this won’t work by using segment 2 then I’ll just have to run RSTP on that part  of the ring and deal with the results of how many switches there are and hope  RSTP doesn’t get angry.

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I've attached his example of the network. Could you take a look at it and let us know what your thoughts are?

Thanks,

David

[Matthew Blanshard]

Hello David,

I have looked through your design and it looks good to me.  By using the two segments like you are this guarantees no loops are possible.  Your list of concerns with how offices link to each other are exactly the same ones I would have (last bullet point).

-Matt

[dstehle]

Matt,

Again, thank you very much for your assistance. We'll set it up in the lab and give it a try.

Yours,

David

[spoofneted]

Matthew/Cisco Experts,

Is this answer of 32 still valid? I've read a Technical Presentation recently which stated that 16 Nodes were advised, but that 32 had been tested.

Is there a revised "Advisory Level" (referring to the 16 Nodes), given that time has elapsed and REP has been developed since your original answer was posted?

Are you effectively saying there is no hard limit, other than the REP Segment restoration time being acceptable to us - so assuming higher REP Segment size can mean a higher REP Heal/Restoration time than the 50 - 250ms advisory figures?

Thanks in advance.