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Limitations of REP protocol?

Joris Syen
Level 1
Level 1

Hello,

I can see the Cisco REP protocol will allow fast convergence in a ring.

But I cannot find the exact number, nor the number of switches that can be in the ring, nor the number of devices that can be interconnected to the ring (via another switch or directly). Is there any documentation on this?

Another question I have is:

"There can be a maximum of 22 REP segments per router."What does this mean? I have a REP ring that contains 1 layer3 switch that is used for routing.

In this Ring I got 150 VLANs and the Router also has 150 VLANs.

Does this mean I can only have 22 VLANs on the router or what is that "REP segments"?

Or does this mean I can only connect 22 Rings to this router?

Thank you, I really need this

Joris                  

3 Replies 3

InayathUlla Sharieff
Cisco Employee
Cisco Employee

Hi Joris,

I usually refer the following link for any issues on REP. This gives you complete information requried on REP.

http://www.cisco.com/en/US/docs/ios-xml/ios/lanswitch/configuration/xe-3s/lsw-cfg-rep.html

http://www.cisco.com/en/US/docs/ios-xml/ios/lanswitch/configuration/xe-3s/lsw-cfg-rep.html#GUID-4723E88F-09FB-471D-97DD-DE1973C044F9

HTH

Regards

Inayath

*Plz rate if this is helpfull.

Hi Inayath,

Thank you for your reply.

The only information about convergence times in a ring I found in the links was this:

"In the ring network topology, REP might fail to converge the traffic within 50 ms. For example, if the topology is made of copper cable, REP might fail to converge the traffic due to hardware limitations of the copper interface. In such a scenario, a remote end can take up to 700 ms to detect shutdown failure of a local port."

I have no idea what will happen if a create a ring of 40 switches, connected with fiber.

But it feels like it would be better to create 5 rings above each other, so that it would only be 8 switches for each ring.

Best Regards,

Joris

Hi Joris,

I have come across your old post regarding REP and wondered how you got on with your deployment, and have similar questions to yours which I have yet to find the answers such as;

- How many REP Rings/Segments are supported on a single switch?

- How many VLANs are supported across all the REP rings?

 

My customer use case requires four (4) rings all aggregated on a pair of IE4010 switches.  And I need to carry four (4) VLANs across all the rings (Profinet Access, Card Reader Access, Network Mgmt, RSPAN).

 

We also need 100ms convergence which should be fine as have a maximum of 40 nodes across all the rings - roughly 10 nodes per ring.

 

Would love to know if there are any pitfalls with the above.

 

Thanks

Aaron

 

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