Ethernet access switch chip boosts service support

The Serval-2 architecture. Source: Vitesse

Vitesse Semiconductor has detailed its latest Carrier Ethernet access switch for mobile backhaul, cloud and enterprise services. 

The Serval-2 chip broadens Vitesse's access switch offerings, adding 10 Gigabit Ethernet (GbE) ports while near-tripling the switching capacity to 32 Gigabit;  the Serval-2 has 2x10 GbE and 12 1GbE ports.

The device features Vitesse's service aware architecture (ViSAA) that supports Carrier Ethernet 2.0 (CE 2.0). "We have built a hardware layer into the Ethernet itself which understands and can provision services," says Uday Mudoi, product marketing director at Vitesse.

CE 2.0, developed by the Metro Ethernet Forum (MEF), is designed to address evolving service requirements. First equipment supporting the technology was certified in January 2013. What CE 2.0 does not do is detail how services are implemented, says Mudoi. Such implementations are the work of the ITU, IETF and IEEE standard bodies with protocols such as Muti-Protocol Label Switching (MPLS)/ MPLS-Transport Profile (MPLS-TP) and provider bridging (Q-in-Q). "There is a full set of Carrier Ethernet networking protocols which comes on top of CE 2.0," says Mudoi.

Serval-2 switch

The Serval-2 switch features include 256 Ethernet virtual connections, hierarchical quality of service (QoS), provider bridging, and MPLS/ MPLS-TP.

An Ethernet Virtual Connection (EVC) is a logical representation of an Ethernet service, says Vitesse, a connection that an enterprise, data center or cell site uses to send traffic over the WAN.

Multiple EVCs can run on the same physical interface and can be point-to-point, point-to-multipoint, or multipoint-to-multipoint. Each EVC can have a bandwidth profile that specifies the committed information rate (CIR) and excess information rate (EIR) of the traffic transmitted to, or received from, the Ethernet service provider’s network.

The EVC also supports one or more classes of service and measurable QoS performance metrics. Such metrics include frame delay - latency - and frame loss to meet a particular application performance requirements.

The Serval-2 supports 256x8 class of service (CoS) EVCs, equivalent to over 4,000 bi-directional Ethernet services, says Mudoi.

The Serval-2 also supports per-EVC hierarchical queuing. It allows for 256 bi-directional EVCs with policing, statistics, and QoS guarantees for each CoS and EVC. Hierarchical QoS also enables a mix of any strict or byte-accurate weighting within the EVC, and supports the MEF's dual leaky bucket (DLB) algorithm that shapes traffic per-EVC and per-port.

"Service providers guarantee QoS to subscribers for the services that they buy," says Mudoi. "If each subscriber's traffic - even different applications per-subscriber - is treated using separate queues, then one subscriber's behavior does not impact the QoS of another."  Supporting thousands of queues allows service providers to offer thousands of services, each with its own QoS.

Q-in-Q, defined in IEEE 802.1ad, allows for multiple VLAN headers - tags - to be inserted into a frame, says Mudoi, enabling service provider tags and customer tags.

Meanwhile, MPLS/ MPLS-TP direct data from one network node to the next based on shortest path labels rather than on long network addresses, thereby avoiding complex routing table look-ups. The labels identify virtual links between distant nodes rather than endpoints.

MPLS can encapsulate packets of various network protocols. Serval-2's MPLS-TP supports Label Edge Router (LER) with Ethernet pseudo-wires, Label Switch Router (LSR), and H-VPLS edge functions.

Q-in-Q in considered a basic networking function for enterprise and carrier networks, says Mudoi, while MPLS-TP is a more complex protocol.

Serval-2 also supports service activation and Vitesse's implementation of the  IEEE 1588v2 timing standard, dubbed VeriTime.

"Before you provision a service, you need to run a test to make sure that once your service is provisioned, the user gets the required service level agreement," says Mudoi. Serval-2 supports the latest ITU-T Y.1564 service activation standard.

IEEE 1588v2 establishes accurate timing across a packet-based network and is used for such applications as mobile. The Serval-2 also benefits from Intellisec, Vitesse's MACsec Layer 2 security standard implementation (see Vitesse's Intellisec ).

"Both [Vitesse's VeriTime IEEE 1588v2 and Intellisec technologies] highly complement what we are doing in ViSAA," says Mudoi.

Availability 

Serval-2 samples will be available in the third quarter of 2013. Vitesse expects it will take six months for system qualification such that Ethernet access devices using the chip and carrying live traffic are expected in the first half of 2014.