Switching

A major project to migrate to new Datacentres within the next 12-14 months has started, as part of it there are 9 x 1Gb links which are currently under 10km to become greater than 10km in distance.  There will also be 10Gb links but Juniper at least has 10Gb 40km & 70km SFP's available.

I have found out that Juniper don't make 1Gb SFP's greater than 10km, what would be a recommended third party SFP solution?  The other issue is that I have mixed Cisco/Juniper switching and in my reading the Cisco 1Gb SFP's(1000BASE-EX) require a 5db inline optical attenuator at each end which I will have some of but the other end of the link could be a Juniper switching solution, still waiting on quotes however as price in this case will determine the switching solution for the new primary datacentre it is still not fully determined. 

If Juniper does come out as most cost effective, one option was to run a VC across the fibre to the secondary DC as well as our head office as all three sites will have redundant geographically diverse fibre paths. Is there any gotcha's about running a VC across WAN links, currently my VC's are all local to the rack but if I do this then I can look at reducing spanning tree requirements, hopefully.

The 1Gb links are purely for end site connectivity which is currently in place as I stated but at the moment all distances are less than 10km, in many cases less than 5km.  I don't want to have to put in 10Gb links for an office of 3 people for example.  As I said many of these sites have Cisco switching in place therefore the connectivity between the Cisco & Juniper I am also concerned about being over the 10km mark with the requirements around the inline attenuators on the Cisco end and the lack of Juniper SFP's on the other(well assuming third party certified solutions could be available).

Thanks in advance....

John

John, #1 you should be having this discussion with your local Juniper partner and/or Juniper account team.  As far as attenuation is concerned, as long as received signal is within specs no attenuation should be needed.  I would expect over distance this should not be a concern.  Also for any standards based optic from any vendor the transmit hotness should also be within spec so that no attenuator is needed.

Not sure which exact Juniper EX (I assume) product you are using but VC across a WAN is fully supported.  Officially needs to have less 100 msec roundtrip delay.  Also generally VCP (VC over Ethernet) is spec'd to be at 10GE, although 1GE often works.  This is an area you should discuss with local folks before you implement.

Not sure how helpful this is to you, but good luck.  I'd start with #1 above if I was in your shoes.

Hi  icthis,

Regarding your first query related to the more than 10 KM 1G SFP requirement, its the first I've heard of this limitation and I've always known otherwise . I don't know what type of switch you're using; but there are plenty of 40 KM 1G SFP's for EX switches referenced here . Here are some samples :

EX-SFP-GE40KT13R15

EX-SFP-GE40KT15R13

EX-SFP-1GE-LX40K

And here are some that support more than 70 KM ( there are even those that support up to 80 KM ) :

EX-SFP-1GE-LH

EX-SFP-GE80KCW1470

EX-SFP-GE80KCW1490

And they all support virtual chassis. If there is some limitation I'm not aware of that restricts your use of these SFPs in your setup then you should check finisar for compatible SFPs as an alternative.

I finally got further information from pre-sales on this greater than 10km limitation, it is the switch model which is an EX4550 the EX4500 can do 1GB over 10km but not the EX4550 at least on 1GB anyway.

With regards to the second part of your question related to the configuration of virtual chassis over long distances the setup you are looking for is referred to as "Extended Virtual Chassis Configuration" . You'll find more details on it here in this virtual chassis best practices guide :

http://forums.juniper.net/jnet/attachments/jnet/switch/9816/1/VC-Bestpractice-guide.pdf

If you are configuring it on an EX 8200 Series switch ( with external route engines ), you'll need this :

http://www.juniper.net/documentation/en_US/junos12.3/topics/task/configuration/virtual-chassis-ex8200-long-distance-vcp.html