Transmode's evolving packet optical technology mix

• Transmode adds MPLS-TP, Carrier Ethernet 2.0 and OTN 
• The three protocols make packet transport more mesh-like and service-aware
• The 'native' in Native Packet Optical 2.0 refers to native Ethernet  

Transmode has enhanced its metro and regional network equipment to address the operators' need for more efficient and cost-effective packet transport.

“Native Packet Optical 2.0 extends what the infrastructure can do, with operators having the option to use MPLS-TP, Carrier Ethernet 2.0 and OTN, making the network much more service-aware”

Jon Baldry, Transmode

Three new technologies have been added to create what Transmode calls Native Packet Optical 2.0 (NPO2.0). Multiprotocol Label Switching - Transport Profile (MPLS-TP) was launched in June 2012 to which has now been added the Metro Ethernet Forum's (MEF) latest Carrier Ethernet 2.0 (CE2.0) standard. The company will also have line cards that support Optical Transport Network (OTN) functionality from April 2013. 

Until several years ago operators had distinct layer 2 and layer 1 networks. “The first stage of the evolution was to collapse those two layers together,” says Jon Baldry, technical marketing director at Transmode. “NPO2.0 extends what the infrastructure can do, with operators having the option to use MPLS-TP, CE2.0 and OTN, making the network much more service-aware.”

By adopting the enhanced capabilities of NPO2.0, operators can use the same network for multiple services. “A ROADM based optical layer with native packet optical at the wavelength layer,” says Baldry. “That could be a switched video distribution network or a mobile backhaul network; doing many different things but all based on the same stuff.”

Transmode uses native Ethernet in the metro and OTN for efficient traffic aggregation. “We are using native Ethernet frames as the payload in the metro,” says Baldry. “A 10 Gig LAN PHY frame that is moved from node to node, once it is aggregated from Gigabit Ethernet to 10 Gig Ethernet; we are not doing Ethernet over SONET/SDH or Ethernet over OTN.”

Shown are the options as to how layer 2 services can be transported and interfaced to multiple core networks. The Ethernet muxponder supports MPLS-TP, native Ethernet and the option for OTN, all over a ROADM-based optical layer. “It is not just a case of interfacing to three core network types, we can be aware of what is going on in these networks and switch traffic between types,” says Transmode's Jon Baldry. Note: EXMP is the Ethernet muxponder. Source: Transmode.

Once the operator no longer needs to touch the Ethernet traffic, it is then wrapped in an OTN frame for aggregation and transport. This, says Baldry, means that unnecessary wrapping and unwrapping of OTN frames is avoided, with OTN being used only where needed.

There are economical advantages in adopting NPO2.0 for an operator delivering layer 2 services. There are also considerable operational advantages in terms of the way the network can be run using MPLS-TP, the service types offered with CE2.0, and how the metro network interworks with the core network, says Baldry.

MPLS-TP and Carrier Ethernet 2.0

Introducing MPLS-TP and the latest CE2.0 standard benefits transport and services in several ways, says Baldry.

MPLS-TP provides better traffic engineering as well as working practices similar to SONET/SDH that operators are familiar with. “MPLS-TP creates a transport-like way of dealing with Ethernet which is good for operators having to move from a layer-1-only world to a packet world,” says Baldry. MPLS-TP is also claimed to have a lower total cost of ownership compared to IP/MPLS when used in the metro.

The protocol is also more suited to the underlying infrastructure. “Quite a lot of the networks we are deploying have MPLS-TP running on top of a ROADM network, which is naturally mesh-like,” says Baldry.

In contrast Ethernet provides mainly point-to-point and ring-based network protection mechanisms; there is no support for mesh-based restoration. This resiliency option is supported by MPLS-TP with its support of mesh-styled ‘tunnelling’. A MPLS-TP tunnel creates a service layer path over which traffic is sent.

“You can build tunnels and restoration paths through a network in a way that is more suited to the underlying [ROADM-based] infrastructure, thereby adding resiliency when a fibre cut occurs,” says Baldry.

MPLS-TP also benefits service scalability. It is much easier to create a tunnel and its protection scheme and define the services at the end points than to create many individual circuits across the network, each time defining the route and the protection scheme.

“Because MPLS-TP is software-based, we can mix and match MPLS-TP and Ethernet on any port,” says Baldry. “You can use MPLS-TP as much or as little as you like over particular parts of the network.”

The second new technology, the MEF’s Carrier Ethernet 2.0, benefits services. The MEF has extended the range of services available, from three to eight with CE2.0, while improving class-of-service handling and management features.

Transmode says its equipment is CE2.0 compliant and suggests its systems will become CE2.0-certified in the new year.

Hardware

The packet-optical products of Transmode comprise the TM-Series transport platforms and Ethernet demarcation units.

The company's single and double slot cards - Ethernet muxponders – fit into the TM-Series transport platforms. The single-slot Ethernet muxponder has ten, 1 Gigabit Ethernet (GbE) and 2x10GbE interfaces while the double-slot card supports 22, 1GbE and 2x10GbE interfaces. Transmode also offers 10GbE only cards: the single slot is 4x10GbE and the double-slot has 8x10GbE interfaces. These cards are software upgradable to support MPLS-TP and the MEF’s CE2.0.

“In early 2013, we are introducing a couple of new cards – enhanced Ethernet muxponders – with more gutsy processors and optional hardware support for OTN on 10 Gigabit lines,” says Baldry.

The Ethernet demarcation unit, also known as a network interface device (NID), is a relatively small unit that resides for example at a cell site. The unit undertakes such tasks as defining an Ethernet service and performance monitoring. The box or rack mounted units have Gigabit Ethernet uplinks and interface to Transmode’s platforms.

Baldry cites the UK mobile operator, Virgin Media, which is using its platforms for mobile backhaul. Here, the Ethernet demarcation units reside at the cell sites, and at the first aggregation point the10- or 22-port GbE card is used. These Ethernet muxponder cards then feed 10GbE pipes to the 4- or 8-port 10GbE cards. 

“For the first few thousand cell sites there are hundreds of these aggregation points,” says Baldry. “And those aggregation points go back to Virgin Media’s 50-odd main sites and it is at those points we put the 8x 10GbE cards.”  Thus the traffic is backhauled from the edge of the network and aggregated before being handed over as a 10GbE circuit to Virgin Media’s various radio network controller (RNC) sites.

Transmode says that half of it customers use its existing native packet optical cards in their networks. Since MPLS-TP and CE2.0 are software options, these customers can embrace these features once they are required.

However, operators will only likely start deploying CE2.0-based services once Transmode’s offering becomes certified. 

Further reading:

Detailed NPO2.0 application note, click here