How many SFP ports needed for campus Ethernet Ring

[Shin Woo Paik]

Hi, I have a few simple qustions. I've looked through this site, other web sites, and books but cannot find the clear answers for these. I'd appreciate indeed if you can answer or give me any comments. Thanks.

1. When you connect the core switch in the MDF room to the access switches in IDF rooms in each floor, how many SFP ports do you need? It's for new office building and typical corporate tenants (FE/GE). I've always wondered why always 1 SFP needed regardless of the number of access ports (RJ-45) in the switch; I think it should be different depending on the active access ports to ensure the overall throuput of the fiber link back to the core switch. e.g. 24 ports of FE RJ-45 will need 2.4Gbps bandwidth of fiber link?? And 48 ports will need 4.8 Gbps??

2. For redundancy, I plan to put a distribution switch which is connected to the core switch. What connection do I need between these two switches? Distribution switch will reside different location. How many fiber strands do I need?

3. I have a ring topology around the campus to connect about 30 buildings. This Ethernet Ring will connect the core switches in the MDF rooms in each building. How many strands do I need to connect the core switches? And do I need to have MAN type switches (ME series) to support REP?? Or is it ok to run just RSTP for this Ethernet Ring?

4. Also, in the simple Ethernet Ring inside the building (8 small switches and dual ring), do I need 4 SFP ports for this?

Thanks in advance for you help/advise.

[vmiller · Accepted solution]

Shin,

Have you looked at this design guide?

http://www.cisco.com/en/US/docs/solutions/Enterprise/Campus/HA_campus_DG/hacampusdg.html

Generally uplinks from access to distribution layers are done in pairs to 2 distribuion layer switches.

links from distribution to core are done in pairs to a pair of core level switches.

of course all this assumes a budget!

I can't address item 3, you might consider posting that question on the optical forum. there are some sharp folks

that go there.

Item 4, I would consider looking at a CWDM solution.

[Shin Woo Paik]

vmiller,

Thanks a lot!! Glad I have a first comment on my first post!!

Let me look through the document. I'll look for WDM solutions also. Thanks a lot.

[vmiller]

You are most welcome.

i would encourage you to keep things as simple as possible, and use field tested designs. The campus design has been

around for a while, because it works.