Pure Ethernet MANs

A pure Ethernet MAN uses only layer 2 switches for all of its internal structure. This allows for a very simple and cheap design, and also for a relatively simple initial configuration. The original Ethernet technology was not well suited for service provider applications; as a shared-media network, it was impossible to keep traffic isolated, which made implementation of private circuits impossible.

Ethernet MANs became feasible in the late 90s due to the development of new techniques to allow transparent tunneling of traffic through the use of Virtual LANs as "point to point" or "multipoint to multipoint" circuits.

Combined with new features such as VLAN Stacking (also known as VLAN Tunneling), and VLAN Translation, it became possible to isolate the customers' traffic from each other and from the core network internal signaling traffic. However, Ethernet is constantly evolving and has now carrier class features with the recent addition of IEEE 802.1ad (Provider Bridges)(also known as QinQ or stacked VLANs) and IEEE 802.1ah (Provider Backbone Bridges) (also known as MAC in MAC or PBB) and IEEE 802.1Qay (Provider Backbone Transport) (also known as PBT or PBB-TE). Spanning-tree, broadcast packets and dynamic MAC learning are disabled and sub 50ms failover features are introduced.

December 16, 2011

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