G.8032 Gains Momentum

CEN Feature (Apr 5 2011)

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   Deployments of Ethernet rings based on the ITU G.8032 standard have been rising steadily since the standard was finalized in 2008. Initially the province of smaller alternative carriers, G.8032 more recently has begun to find its way into Tier 1 incumbent carrier networks.

   G.8032 brings SONET/SDH-like deterministic switching to Ethernet local aggregation infrastructure, explains Scott Knox, director of solutions development for Overture Networks. “No matter how many nodes there are, it will switch the same way every time,” he says.

   The G.8032 standard also requires self-restoration capabilities akin to that of SONET/SDH. In creating the standard, developers set a performance benchmark of restoration times of 50 milliseconds or less on a ring with 16 nodes and 1200 kilometers of fiber, says Knox.

    “G.8032 is very attractive to people who have been deploying SONET/SDH,” comments Knox. “They like the architecture, the speed and the diverse route protection. What they didn’t like about SONET/SDH was the price tag and the fact that it was not optimized for Ethernet and IP services.”

   Other architectures for Ethernet aggregation networks required a greater departure from traditional SONET/SDH practices and procedures. Spanning tree protocols, for example, generally take longer to switch. “There are rapid spanning tree solutions that can get to 50 millisecond restoration under very controlled circumstances, but they’re much less deterministic,” Knox says.

   And while many carriers are using MPLS in the core of their Ethernet service networks, MPLS tends to be overkill in the local Ethernet aggregation network. “MPLS has a couple of challenges,” comments Knox. “It’s more complex, the equipment is more expensive and the control plane is more complex.”

   The complexity of MPLS is what drove the development initially of PBB-TE and later MPLS-TP. But PBB-TE lost steam when Nortel, its chief advocate, went bankrupt. And the approval process for MPLS-TP has stalled over disagreements about its control plane.  [See earlier article in CEN]

   Ultimately, Knox believes some carriers will want their whole network to be MPLS and will use MPLS-TP at the edge. But those who prefer the cost and simplicity of a pure Carrier Ethernet approach are more likely to use G.8032 at the edge, he says.

   The original version of the G.8032 standard focused on stand-alone rings, but Version 2, finalized in 2010, allows for a network of multiple concatenated rings that can support end-to-end services, Knox explains. Alternatively, operators can use a combination of G.8032 at the edge and MPLS at the core.

   Currently most G.8032 deployments have been at 1 Gb/s data rates, says Knox. But some 10 Gb/s deployments also have been made—and speeds of 10 Gb/s or higher will probably be increasingly popular as more Tier 1 operators adopt G.8032.

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