Futurity Media

Carrier Ethernet is a continuing hot topic in networks as it sweeps all before it. However, there is often some confusion about what it all means and how it is distinguished from traditional Ethernet. This article from Jim Theodoras, Chair of the Carrier Ethernet Subcommittee, Ethernet Alliance explains the some of the key issues about the Carrier Ethernet. His key points include:

• Carrier Ethernet has evolved to specifically carry disparate traffic from different subscribers. Each subscriber’s particular packets are therefore packaged up and transported undisturbed from one location to another, this provides traffic segregation and security;
• The first attempts to combine multiple subscribers Ethernet packets ran into all sorts of trouble because of inconsistent use of LAN addressing between different subscribers, in other words it was hard to identify who was what;
• Standardisation of hierarchical MAC addressing was required so that carriers could have their own addressing schemes, which were separate from their subscribers’
• Virtual LAN (VLAN) tagging allowed carriers to identify and separate traffic from different LANs. This has now expanded to allow double tagging to meet the needs of carriers for video traffic, etc.;
• Quality of service (QoS) is a key area of development. Simply marking a packet as a priority is not enough and Hierarchical QOS is helping carriers identify latency-sensitive traffic amongst a deluge of non-critical packets.

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