3com S7906E 설치 설명서

 

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Hierarchy of VPLS (H-VPLS) can extend the VPLS access range of a service provider and reduce 

costs. 

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H-VPLS has lower requirements on the multi-tenant unit switch (MTU-s). It has distinct hierarchies 

which fulfill definite tasks. 

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H-VPLS reduces the logical complexity of the fully meshed network consisting of PEs and the 

configuration complexity. 

1)  H-VPLS LSP access 

Figure 1-3 H-VPLS LSP access 

 

 

As shown in 

, UPE functions as the convergence device MTU-s and establishes only a virtual 

link U-PW with NPE 1. It does not establish virtual links with any other peers. 

Data forwarding in H-VPLS LSP access mode is as follows: 

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Upon receiving a packet from a CE, UPE tags the packet with the MPLS label for the U-PW, 

namely the multiplex distinguishing flag, and then sends the packet to NPE 1. 

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When receiving the packet, NPE 1 determines which VSI the packet belongs to by the label and, 

based on the destination MAC address of the packet, tags the packet with the multiplex 

distinguishing flag for the N-PW, and forwards the packet. 

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Upon receiving the packet from the N-PW, NPE 1 tags the packet with the multiplex distinguishing 

flag for the U-PW and sends the packet to UPE, which forwards the packet to the CE. 

For packets to be exchanged between CE 1 and CE 2, UPE can forward them directly without NPE 1 

because it holds the bridging function by itself. For the first packet with an unknown destination MAC 

address or a broadcast packet, UPE broadcasts the packet to CE 2 through the bridging function and, at 

the same time, forwards it through U-PW to NPE 1, which replicates the packet and sends a copy to 

each peer CE. 

2)  H-VPLS QinQ access