Fibre optic

[tonywhyte87]

Hi there,

Does anyone know if you can get fibre optic modules for Cisco 2821 series router. I can not find anything apart a SFP module which contains only one SFP port.

Thanks

Tony

[pjmonline]

HWIC-1GE-SFP is the part number you need.

[tonywhyte87]

Yeh thats the one I had already seen but for every module you only get one SFP port. The Cisco 2821 has 4 HWIC modular slots (correct me if I am wrong) so that means if I want to have two connections to the access layer and two to the redundant router then I would use all four SFP ports (all 4 HWIC slots) so I wouldn't be able to have any modular slots left for WAN connectivity.

[pjmonline]

Not sure if that will work or not.  According to the datasheet the 2821 only supports 1 module

http://www.cisco.com/en/US/prod/collateral/routers/ps5854/product_data_sheet0900aecd8016be8d_ps5949_Products_Data_Sheet.html

[tonywhyte87]

How does that work then? The Router says in the spec it has  4 HWIC slots, so whats the point in having 4 if one 1 can work at a time?

[Leo Laohoo]

How does that work then? The Router says in the spec it has  4 HWIC slots, so whats the point in having 4 if one 1 can work at a time?

Look at it at this point of view, just because the 2800 can support HWIC-1GE-SFP does not mean that the 2800 can push data at wire speed.  So there's really no point allowing the 2800 to have more than one HWIC-1GE-SFP when the entire chassis can't push more than 87.04 Mbps of HALF DUPLEX and non-encrypted traffic.

[tonywhyte87]

Why don't they just make them with one then?

Is it so that you can use 4 slightly less powerful interface cards?

[darren.g]

Tony Whyte wrote:
Why don't they just make them with one then?
Is it so that you can use 4 slightly less powerful interface cards?

Because 1 gig fibre ports aren't the only HWIC modules you can put into a 2821.

The 2821 supports one HWIC-1GE-SFP - but you can also put in, for example, a HWIC-1ADSL-M to connect a DSL service, or a HWIC-4ESW-POE for 4 POE switchports as well as the gigabit SFP port.

The backplane on the 2821 is limited in its bandwidth, so putting more fast ports won't necessarily work - the router simply can't move wire-rate on gigabit ports - the 2821 will only switch about 88 Mb/s in CEF mode, and much less in process mode, so if youw ant a lot of gigabit capable ports, then you need either a much bigger router, or a layer-3 capable switch.

Cheers

[Leo Laohoo]

Is it so that you can use 4 slightly less powerful interface cards?

I agree with Darren.  Fibre isn't THE only choice.  That's why it's "modular":  You can stick whatever you want BUT with moderation.

Check this link:

http://www.cisco.com/en/US/products/ps5854/products_relevant_interfaces_and_modules.html

[pjmonline]

We use a 3750g 12S which has 12 SPF slots. The newer model is a 3750x which has options for up to 24 SPF slots. You can have a fiber uplinks come to this and the have one connection to the router.

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