Creating a Ring with Ethernet?? Rate Limiting

[ee99ee2]

This is a two question topic. I am in an office building and I want to provide ISP services to people throughout the building. I have 5 2900XL switches with fiber gigabit ports for uplinking to each other. I will put one switch in each floor for clients to plug into, and run fiber from floor to floor.

Using the equiptment I have (i.e. -- not special SONET equiptment or anything), how can I create a redudant ring so that if the fiber is broken traffic will flow in the other direction? I know SONET will do this, but I don't want to buy special equiptment for that.

Also, please remember this will need to be at layer-2 since these are only layer-2 switches, so using dynamic routing to handle the redudancy is not an option.

Finally, each client will be put in their own VLAN. How can I rate limit the outbound traffic? For example, I may want to sell a 6Mbps service and charge more for it than a 3Mbps service.

Is there any way I can use what I have to do what I need? If not, what additional equiptment do I need to buy?

[Bobby Thekkekandam]

Hi,

You can certainly daisy chain them into a ring type topology, and Spanning Tree Protocol will block one of the redundant links to prevent a loop.

A better, (but more costly design) would be to have two additional switches and dual home all of the 2900xl switches to the "core switches." That will give you redundancy as well as keeping traffic flow such that the 2900 switches aren't used as "transit" switches for devices communicating between non-contiguous switches. However, for 5 switches, this may be overkill :-)

As for rate limiting, the 2900XL series switches do not provide rate-limiting or policing features. They are fairly dumb Layer 2 devices and will not give you the option to limit the bandwidth on any port. The lowest-end switch that we currently sell that can do rate-limiting is the 2960.

HTH,

Bobby

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[ee99ee2]

Will Spanning Tree Protocol enable the redudant link when the one that is in use goes down?

Also, since each customer will be in their own VLAN, and all the switches will be in the same VLAN group, could I not use one smarter switch for that on the main uplink to the rest of our network?

What protocol/feature does the rate limiting anyway? I'd like to research it some...

[Bobby Thekkekandam]

Yes, Spanning tree will enable the redundant link if the active interface goes down.

Also, you can certainly use one smarter switch to uplink the rest of the switches as well -- it all depends on how much redundancy you require.

The feature that does rate limiting is a part of QoS called Policing.

Here's a doc on policing for the 3550. The same principles will apply to most of the 3xxx series switches.

HTH,

Bobby

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