MS425 1G backward compatibility

[MohitChauhan]

Hi all,

We have a requirement to deploy Meraki MS425-16. However we are not sure the fibre run connecting the MS250 switches (from different places) to this core can support 10G.

So in an event if we have to go back to 1G fibre connection, I was not sure about the following:

1. The MS425-16 supports 1G?
2. MA-SFP-10GB-LRM can run at 1G? I think we will have to use 1G SFP's.
3. The MS250’s uplink can support 1G Uplinks. 

If anyone has used the similar environment, can you please confirm if the above arrangement will work in 1G backbone?

Thanks,

Mohit

[ww]

There are only few fibre sfp that can set speed, i dont think meraki has one.. So if you want Gbit buy a Gbit SFP.  SFP can be used in the SFP+ slots

[MohitChauhan]

Thanks for your reply. In that case all we have to worry about is the SFP type, based on do we need 1G or 10G?

[PhilipDAth]

What grade of fibre have you got installed?  It should be written on the side wall of the fibre.

If you change to using MA-SFP-10GB-SR then OM3 can go about 300m at 10Gbe.  OM4 is good for 400m.  I hope you don't still have OM2 - but it can do around 82m.

I don't use MA-SFP-10GB-LRM with multimode fibre (OM3-4) - even thought it works, because you suffer a reduced range.  So I only use MA-SFP-10GB-LRM when customers have single mode fibre, such as OS1 or OS2 (and the range is 220m).

No optical SFP or SFP+ supports multiple speeds.  If you need to drop back to Gigabit then you should get something like MA-SFP-1GB-SX (assuming you are using multi-mode OM1[1-4]).  If you are using single mode (OS1 or OS2) then you would need to use the expensive MA-SFP-1GB-LX10.

This datasheet is a good guide.

https://meraki.cisco.com/lib/pdf/meraki_datasheet_sfp.pdf

[MohitChauhan]

Thanks for taking out time in replying Philip.

We have to check the fibre run specs but apparently it is a very old infrastructure. So I am suspecting it will be OM1 as the patch leads I looked are mostly orange colours which used to be with the OM1 environment if I am not mistaken?

With that in mind, going by the SFP datasheet, shouldn;t the LRM's be the best bet as they can stretch upto 220m on OM1 compared 26m on MA-SFP-10GB-SR?

And in regards to switch side, are you suggesting we should be safe with 425-16? Those 10G slots are good to run on 1G if we use MA-SFP-1GB-SX?? And the same goes with the MS250 uplink module? 

Thanks.

[PhilipDAth · Accepted solution]

The spec sheet says both MA-SFP-10GB-LRM and MA-SFP-1GB-SX go 220m on OM1.  So you might as well go MA-SFP-10GB-LRM.

Yes, you can use MA-SFP-1GB-SX in both a 425-16 and an MS250 and they will talk to each other just fine.

[MerakiDave]

@PhilipDAth is correct and remember that if you do have legacy OM1/OM2 62.5 multimode and you're going to use the 10G LRM optics, don't forget to order the appropriate (with respect to length and connector type) mode conditioning patch cables on both ends between your switch/SFP and patch panel.