Native TDM and Ethernet TDM

[rm77]

hi;
Please is there someone who can explan me what is the circuit emulation in the new generation of transmission equipment supporting IP ,and if it has any impact on the voice quality (delay).
which is the better thing ? hybride equipement or those which can carry the native TDM and Ethernet TDM separately.
hope someone can cleared this for me, i'm a little bit confused.
thanks in advance.

[rm77]

please read native TDM and native Ethernet .

[byja]

There are some radios that utilize circuit emulation over packet, such as CESoP(SN), or SAToP, or similar PWE3 methods. Suggest you take a look at http://en.wikipedia.org/wiki/Pseudo-wire first, and then maybe read following documents:

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Anyway, don't have any hands-on experience with this yet, only 2nd hand experience based on customers who used our eth MW links to carry PWE3 but over dedicated equipment. CESoPSN looks promising cause it can carry low capacity E1s (where only few TSs are used) and you don't have to map whole E1 so you can save on bandwidth in the backbone part for some low cap base stations.

I guess you're interested in this for a possible swap scenario. I've done two major network swaps, both for Telenor, and I know that they didn't want their E1s carried over MW radio which don't transport this in a native way. That's why for example NSN's Flexi Packet radio was not considered. Every swap is similar, first you swap backbone network (MW or other), then agg links and then you swap RAN cluster and access links. But till that last swap you have bunch of old base stations connected over E1s, and customer likes some good old field-proven native TDM radios to carry this traffic. In the end they end up with pseudowires, anyway.

You can find it everywhere that circuit emulation quality depends on packet delay and packet delay variation, but haven't seen any of such problems simply because new links were usually overprovisioning, with utilization well below 10-20 %, so both PD and PDV were kept to a minimum.

[rm77]

hi ;:)
first i want to thanks you for this nice explanation;
really this is our deal because as i know some new MW equipements like MPR can't carry the TDM trafic as native way ,it provide only the circuit emulation solution that is why i'm wondering about the delay and his impact on the quality for the voice services.
Anyway thanks and please if you find some useful DOC to share it .

[byja]

Here's one document, don't know how useful it is. It gives no conclusion to the question, but then again, there is no simple answer to a complex question.

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[Wizeguy]

My advice here is.
If you have a TDM network up and running and plan to migrate towards a packet based network, you should use a hybrid solution.
Some vendors equipment can support a seamless migration from TDM to packet, simply by configuring the µW-hops to use part of the bandwidth for native TDM remaining for native Ethernet. When you migrate your traffic from TDM, it is possible to reconfigure TDM in steps of E1/DS1 to become native Ethernet without traffic disturbance.

If do not run TDM or if you expand your network without need for TDM or TDM at low BW, you should use a packet solution with CES as a complement when needed for small amounts of TDM.
Working with lots and lots of TDM E1/DS1 over pseudowire (CES) is not recommended.

Future seem to be all packet, make sure to have your system ready for migration if you do not already run it.

[rm77]

thanks too much ..... ;)
hi ;
this forum has a button called thanks, you can pushed it when see that post is useful ,like byja support.