Tuesday, March 15, 2011

EVC: Ethernet Virtual Circuits – Part 2

As we saw the basic of EVC in my earlier post EVC: Ethernet Virtual Circuits – Part 1 & here we will dig some more to know about EVC.

1] What is Ethernet Flow point (EPF)? : - EPF is a Service Instance which classifies frames
     belongs to particular Ethernet service & also defines & applies feature,behavior & forwarding action.

2] Ethernet Virtual Circuit (EVC): - EVC is management plane containers which represents
    globally & also do 1-toMany mapping for EVC to EPF.

3] Bridge Domain (BD): - BD is a broadcast domain local to that device.

EVC Bridge Domain: EVC bridges decouple VLAN from broadcast domain.
  • VLAN are treated as encapsulation on a wire.
  • VLAN on a wire are mapped to internal bridge domain.
  • Result : Per – Port VLAN Significance.

Flexible Service Mapping
  • Service Instance construct Layer 2 Flow on Ethernet Interface
  • Single Tagged
  • Double Tagged
  • Header / Payload
Service Instance Mapping is specified by following command :

Encap do1q 100 : match any frame with Outer Tag equal to 100

Encap dot1q 100 sec 200 : match any frame with outer tag as 100 and second tag as 200

Encap Default : Service Instance with default encapsulation matches all frame otherwise unmatched by any other S-I on the same port.

Advance Frame Manipulation or VLAN Tag Manipulation
  • PUSH Operation : Add one VLAN Tag or Two VLAN Tag
  • POP Operation : Remove One VLAN Tag or Two VLAN Tag
  • Translation Operation :
         1:1 VLAN Translation
         1:2 VLAN Translation
         2:1 VLAN Translation
         2:2 VLAN Translation

The Biggest advantage on EVC is to support multiple services per physical port . That means you can have multiple service under one physical port.
  • Local Connect
  • EoMPLS ( xconnect)
  • L2 Multipoint Bridge
  • L2 Multipoint Bridge ( VPLS , SVI-Based EoMPLS)
  • L2 Point to multipoint bridge
  • L3 Termination

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