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Shock horror: IP networks 100x more faulty than SDH?

By Mark Lum, independent telecoms consultant

I’m here at Packet Transport Networks in Vienna, and a good conference turnout reflects the growing importance of packet transport. I’m sure there’ll be much of interest over the next few days.

But in my first blog post for fibresystems.org, I’m startled by a statistic from Huawei comparing a national mobile operator’s IP network layer with its SDH layer. We are told that:

• 95% of network element failures are down to the IP equipment, with just 5% from SDH;
• 66% of network failures derive from the IP layer, with 33% from SDH.

It’s hardly a happy comparison, but we are further told that the SDH layer had three times as much equipment supporting 30 times more connections. It seems that the fault incidence from IP is out of all proportion to its deployment volume, not to mention the increased opex and staff costs.

Several possible conclusions occur to me (I’m happy to consider other suggestions!)…

• we expect this type of anti-IP propaganda from the dumb-pipe transport people!
• this is just a one-off extreme outlying example;
• the operator must be using the wrong brand of router;
• the IP technicians are not properly certified and need more training;
• the operator should transform its network with a new architecture;
• IP/MPLS is still a new technology and can only improve in the future;
• there’s nothing we can do: IP is more complex by definition — get with the program!

No-one is suggesting that SDH and IP are interchangeable, neither as technology nor in function. But as bandwidth consumption continues to grow — both packet and (still) TDM-based — we need to figure out the best way to provide lower cost packetised networks by an order of magnitude.

There’s lots of discussion here about MPLS-TP, even as IETF and ITU-T try to decide exactly what that is with heated opinions. Based on this datapoint, I think they have their work cut out to define a packet transport technology that will improve carriers’ economics, rather than make them worse.

Posted by Pauline Rigby on April 28, 2009 4:01 PM | Permalink