Fiber: single or multimode?

[thewireguys 3]

You can get 1G SFP mods for around $100 a pair.

 

For 200M and less yes.

 

For 2000M and less no.

[woodyads 0]

Guys,

 

Multimode went by the wayside years ago. I haven't installed multimode since 2007 and that's because I had a RAD serial to fibre multiplexor to support. As far as normal run of the mill IP gear goes no-one looks seriously at multimode. Single mode and multi mode cost around the same, Cost of burying fibre is usually the main expence. The ends supports can be more expensive but not as expensive as having to change from multi to single when no one supports it any more. There was a world wide shortage of single mode around 2005 that was because everyone was replacing their multi mode.

 

 

Multimode is going no where!

We put it in every day.

Government projects where money is no object are migrating to 50 micron and 50 micron laser optimized but short runs will be multimedia for a long time to come.

 

As a general rule Multimode is used from MDF to IDF closets and short run building to building.

 

 

Good points, I did put in a group switch for a PABX back in 2004 that was legacy multimode only at the time and I guess there is little reason for that to change, and I guess as individual devices may be multi mode, like fibre channel disk arrays and I have come across some radio units that run fibre back to their indoor units. My comments did say run of the mill IP devices, like switches etc. I guess there are some routers that will come with multimode only fibre cards. I did deal with several low end switches that supported multimode only, but I slowly replaced them with Cisco IP3000's as a standard and moved totaly single mode. I always had legacy runs of multimode around but all my new runs were single only. The Cisco IP3000 are industrial switches that are managable with the rest of the corportate network so I deployed Vlan, Spanning tree, Trunking and IGMP Protocols over them. I wouldn't get that level of (centralised) management from a cheap switch with inbuilt multimode. Also most of my runs were between 500 and 10km so multimode would have a capacity cost. Just another point is I ran an NVR site only so no analogue over fibre.

 

So I guess if you have legacy non IP gear around, PABX, Serial over fibre, or DCS systems then make sure you put in multimode + singlemode.

If you aren't consolidating your networks like I did, then cheap switches with multimode may be the best solution.

 

ssmith10pn, I am an end customer who does all my own intergration and am about to move jobs and consult on another installation. CCTV is only a very small part of the system, the rest is monitoring and distributed control systems in a mine. Can you give me any specifics where you have had to use multimode for IP video or any managable low end switches that have worked for you, I am always up for new ideas or changes in direction.

[ChrisH 0]

Guys,

 

Multimode went by the wayside years ago. I haven't installed multimode since 2007 and that's because I had a RAD serial to fibre multiplexor to support. As far as normal run of the mill IP gear goes no-one looks seriously at multimode. Single mode and multi mode cost around the same, Cost of burying fibre is usually the main expence. The ends supports can be more expensive but not as expensive as having to change from multi to single when no one supports it any more. There was a world wide shortage of single mode around 2005 that was because everyone was replacing their multi mode.

 

 

Multimode is going no where!

We put it in every day.

Government projects where money is no object are migrating to 50 micron and 50 micron laser optimized but short runs will be multimedia for a long time to come.

 

As a general rule Multimode is used from MDF to IDF closets and short run building to building.

 

I agree. This is what I see in my neck of the woods also. Multimode is the correct type of fiber for this install. You can get 1gig across 62.5 multi all day long at this distance. 10gig with 50 micron

 

As far as connectors, LC are just a smaller form factor, so if you have just a few stands, you don't need to worry about space. SC's are easier to work with to terminate due to the slightly larger size. It's really does not matter though.

[woodyads 0]

Sheriffa, just to help you understand why some installers are recommending single mode, and how much you should install

 

Multimode preceded Single mode from a commercial perspective. Single mode is faster and goes a greater distance. There are still some proprietary interfaces that only support multimode because they don't need the speed, they are low volume or legacy products not worth the investment in upgrading. Government and enterprise and larger medium size businesses started migrating to single mode away from multimode between 2000 and 2005. At this stage multimode fibre was only good for 100mb-s only since 2005 have we seen gigabit multimode. Working in a geographically distributed LAN environment there would be times where we would put in a low end multimode switch on to a small remote office with less than 10 computers, however we would always install both multimode and single-mode to that office. Larger buildings that already had multimode we would pull single-mode only. The view being that when budget allowed all the switches would be upgraded and the entire network would be single-mode.

 

The biggest drivers in the larger network space are Consolidation, Redundancy and Management.

 

Consolidation

Externally the cost of leased lines is formidable. So enterprise environments move to consolidate their networks to minimise their leased lines. Internally an enterprise site may have services like VOIP, access to process control systems from off-site vendors, onsite contractors networks CCTV the list goes on. These networks require fibre, very quickly using up spare fibres and or the room you have spare in your conduit. The answer is to moved to managed switches with VLANS, clustering or stacking the switches to increase the number of ports without requiring more fibre cable. Fibre itself is then trunked to optimise the bandwidth, so instead of having 2 x 48 port switches on their own separate fibre, the two switches are clustered and the they share the aggregate of the two fibre pairs which in turn provide redundancy through STP. This way if one switch is under more demand than the other, the load is shared across the fibre, reducing the amount of fibre you need.

 

Redundancy

Redundancy in an enterprise environment becomes a capacity issue, again consolidation is used to manage the fibre capacity. For redundancy you must have two fibre pairs running to each switch. Redundancy on separate switches is n x 2. On a group of stacked or clustered switches it is n + 1. So in the case of 4 switches separated they need 8 pair but consolidated they need 2 pair.

 

Management

Very similar to the notes for consolidation only to add the less points of management the better. So consolidation or clustering your switches to a single managed switch decreases the room for human error and makes a large network with many switches easier for the network administrator to get his head around.

 

This all sounds well and good but when you add routers, wireless LANs, firewalls into the picture management becomes quite complex. A single switch with the wrong configuration can cause problems across the whole network, I have seen a laptop plugged into a port only configured for phones bring down the entire phone system. At the moment I am sitting at a site with a several clusters of 10 or more switches. All trunked back the head office into a firewall, everything is virtual, LANs, firewall ports, routers, it all sits in clouds underneath the physical layer. It has taken 3 months to find and solve an asymmetrical routing issue between the virtual firewall and the wireless LAN. So there is some pain involved with the enterprise level of network management not to mention cost.

 

The other option, which is feasible in smaller networks, is to keep the networks physically separate, which means separate fibre, as services become available to smaller businesses you will need to provide managed converged networks or physically separated networks. This is plausible because of the cost and difficulty of network management which only becomes efficient at a large size.

 

So as an CCTV integrator you must be sensitive to the client’s needs. If you put in multimode and a network engineer comes through in 6 months time and tell your customer they need to re-pull single-mode fibre then you’re not going to be too popular.

 

Sherrifa, I hope this helps you understand why some people have recommended single mode while others have recommended multi-mode

The day is coming when 1gb will not be enough for your 64 x 100megapix cameras, the wireless LAN you have installed in your warehouse for the touch-books for your stock pickers, the IP based cordless phone systems or possible the mobile substation that allows your employees to use the local PABX when in range so there are no charges for their mobile phones when making internal calls and only land line charges when making external calls, the stock tag swiping system than is now entirely IP based, along with your wireless bridge to the warehouse you bought across the road as your business expanded. So before you get greased up you may want to consider your fibre count.

 

Your decision is one of risk vs return, multimode will get faster as Gbic technology improves, network management will become more out of the box and consolidating networks will become more feasible to smaller businesses and on lower cost hardware and single mode technology will come down in price. On the other hand the services you are going to deploy tomorrow will take you by surprise. So the question is not so much what you need today but what you need tomorrow and the net present value of your investment and the risk of under investing. My advice is, if you need to put fibre in the ground, investigate the cost of composite cable (single + multi) and plenty of it, include the cost of the pulling and be mindful of the capacity of the conduit. If you are going direct bury just put in lots. If the cost of pulling fibre is negligible, then you can go smaller fibre count multimode. If you’re installing in a larger environment then consider single-mode hardware that is management compatible with the existing hardware. If the environment you’re installing in is larger but has a ailing network then make sure you’re aware of the customers network plans for the future.

 

Hope that helps. (Sorry about the essay but I am using parts of it in a project submission)

[ssmith10pn 0]

There are still some proprietary interfaces that only support multimode because they don't need the speed, they are low volume or legacy products not worth the investment in upgrading.

 

 

 

woodyads,

 

No disrespect intended but you must not live on the same planet I do.

 

You keep using buzz words like Legacy when referring to Multimode fiber.

You keep insinuating with words like "Commercial", "Enterprise", "Lower End" that we are residential installers or just back woods hicks stuck in the 90s.

 

You sir are all wet.

 

We just completed a 1,000,000 dollar cat6 and fiber job on a renovation job of one of the key buildings at a local Air Force Base.

 

This building also houses US Government Spooks.

 

Fiber to the desktop. Guess what? Multimode

 

Main feed entering the building: 1 OSP cable with 24 strands (2 buffer tubes) single mode and 24 strands 50 micron multi mode terminated in the MDF.

6 more IDF closets connected to the MDF with guess what? 62.5 Multimode.

 

I think I have a clue about fiber since it involves about 20 hours of my week splicing, repairing, terminating, and troubleshooting. I'm trained and certified by Corning, Systamax, AFL, Noyes, and others.

I use a Fugikura 60-S fusion splicer, Noyes M-200 OTDR, and Noyes C860 Quad OTDR and Certifier.

I think I have a clue when I say the 62.5 Multimode is going no where and is still installed everyday on new and enterprise projects.

If you don't believe me would you like me to have a Corning Rep check in?