pros and cons of ethernet wan delivery handoff

Answered Question

I have been asked to put forth the pro & cons of a link when delivered as traditional SDH (OC3) and as ethernet services. Here ethernet would mean only the last handoff and the SP backend would still be SDH


I cannot think of any advantage except for the cost savings in buying a OC3 module if i go with ethernet option


are there any other risk and qos factors that i might need to consider


Ambi

we have used Enet over SDH a lot for various links (at 10, 100 and Gig speeds), and it is pretty good in general - the pipes are usually wire speed or close, and the kit benefits from SDH reliability.


couple of points:


if you get Enet over SDH for the pipe, then you probably get VC based bandwidth - you need to know what you have so you can limit your traffic to stay inside the rate unless the pipe is "qos aware" - a lot of the SDH GFP kit doesnt seem to be, or the SP doesnt turn that on.


you probably want to know if the SDH is on 1 or more paths, and what happens under fault conditions - you might lose maybe 50% of the capacity.


1 advantage is that it is Ethernet - you can use a switch rather than a software based router at the end of the link.


We had some problems with 100 Mbps as using SDH it is often set up as 2 VC-3s, giving only 97 Mbps. If you overdrive the Ethernet link, then since the SDH doesnt understand QoS that gives some problems. Rate limit the end points and it works very well.

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ted.kelley Thu, 12/20/2007 - 15:15
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am I to understand that we are talking about the "local loop" being delivered as MetroE versus POS?


if I not confused and this is what you are talking about then the major drawback we have seen in the ethernet handoff is the lack of QoS offerings from the SPs on ME that we are getting from the same SPs on our POS interfaces.

ted.kelley Thu, 12/20/2007 - 15:26
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am I to understand that we are talking about the "local loop" being delivered as MetroE versus POS?


if I not confused and this is what you are talking about then the major drawback we have seen in the ethernet handoff is the lack of QoS offerings from the SPs on ME that we are getting from the same SPs on our POS interfaces.

ted.kelley Thu, 12/20/2007 - 16:19
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oopps, meant for this to be in the last message.


Under the heading of "DUH", MetroE as a local loop handoff allows us to scale up bandwidth as needed without the typical long provisioning cycle/process by the SP and without the additional of new cards, routers, network redesign, etc everytime we need a BW upgrade...Major reason we deploy MetroE as our access....

Our service is more of a ethernet over SDH.


The provider has installed a mux in our premises and runs a fiber SDH backbone. But he gives us a ethernet handoff to connect to our router. So anytime we need an upgrade the provider needs to provision the circuit but the only thing that is not needed is the interface cards on our routers


Ambi


Correct Answer

we have used Enet over SDH a lot for various links (at 10, 100 and Gig speeds), and it is pretty good in general - the pipes are usually wire speed or close, and the kit benefits from SDH reliability.


couple of points:


if you get Enet over SDH for the pipe, then you probably get VC based bandwidth - you need to know what you have so you can limit your traffic to stay inside the rate unless the pipe is "qos aware" - a lot of the SDH GFP kit doesnt seem to be, or the SP doesnt turn that on.


you probably want to know if the SDH is on 1 or more paths, and what happens under fault conditions - you might lose maybe 50% of the capacity.


1 advantage is that it is Ethernet - you can use a switch rather than a software based router at the end of the link.


We had some problems with 100 Mbps as using SDH it is often set up as 2 VC-3s, giving only 97 Mbps. If you overdrive the Ethernet link, then since the SDH doesnt understand QoS that gives some problems. Rate limit the end points and it works very well.

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