Telecom Networking

Carrier Ethernet (CE) is a hot topic for the last several years. We have seen a lot of media hype, significant technical work done in industry forums and standards committees, and marketing activities sponsored by various industry players. Originally named Metro Ethernet, the repositioning of the technology to support the whole carrier network changed its name to be Carrier Ethernet. It was expected that CE would be replacing the legacy infrastructure of carriers, with the promise of an all-packet, unified transport solution, delivering all services for all purposes.
But hey, doesn’t that sound familiar? If we replace in the last sentence the “CE” for ATM and the “packet” for “cell”, wouldn’t it be exactly like the message ATM supporters conveyed back in the 1990s? ATM took a leading position in core data networks and thanks to the ADSL-standard adopting it, in the access DSLAMs, but it had never been able to overcome the complexity and cost barriers and become the single, unified transports its proponents so desired. So if ATM could not make it with all the efforts and money spent on it, why do we feel so comfortable that CE could do it?
I think the difference lies in the two critical factors mentioned above, cost and complexity (maybe we should brand these as CO2…). My years of experience in this industry have taught me that these are two of the most critical factors in any decision making process in the service providers’ market. ATM was simply too complex to carry multiple services, compared to the simple SONET alternative. Since at that time most of the traffic (including data) was still based on the T-carrier system, SONET was much more cost-optimized and simple compared to the adaptation layer required for ATM transport. Yes, timing is everything…
Now let’s apply the above lessons to our current environment. We all recognize the growth in data services that are based on Ethernet/IP. Legacy TDM services are declining and are headed towards extinction (though it will take quite a few years of course). The data bandwidth far exceeds the real “TDM” traffic, SONET/SDH can no longer meet the demand and need for a packet-based network is evident. However, as for the choice of the right packet technology, we need to turn back to the textbooks and read the chapter about CO2 (I knew this phrase would catch up). We have two relevant technologies to choose from: Ethernet, ubiquitously deployed in the enterprise and growing in popularity in the provider access networks, and IP/MPLS that is often found in core networks. Service providers have now two options to choose from: Carrier Ethernet, natively simple and cost effective, or MPLS, already existing in their network core and promised to be cost reduced and somewhat simplified to enable widespread proliferation.
At the end of the day, as coined by Bill Clinton in the previous millennium – “it’s the economy, stupid”. The cost is the key factor, especially in our current economical downturn. Complexity is also translated to cost – training existing technical staff, recruiting new staff, spending time and effort due to long learning curves etc. Ethernet provides a solution that is similar to today’s data access networks, and with the appropriate management approach, also resemble legacy SONET/SDH. It is surely going to play an important role in the transition of our networks to the all-packet dream.