Contents. Network Topology. Common Network Topology. Chain Network. Protection Mode. Ring with Chain Network, страница 7

Since services are allocated among NEs equably, the service on the ring adopts MSP, the service from ring to chain or from chain to ring adopts SNCP and the service on chain has no protection.

For the configuration of MSP protection, refer to section 2.3.2 “Protection Mode”.

This section describes the flow and protection of services transmitted over ring and chain.

There are 32 x E1 services between NE A and NE E, the service flow is shown in Figure 2-17.

Figure 2-17 Active service flow between NE A and NE E

Table 2-7 Service flow between NE A and NE E and the configuration of NE D

Service flow	Active route	NE D configuration
E®A	NE E (tributary) ®NE E (chain: west) ®NE D (chain: west) ®NE D (ring: east) ®NE A (ring: west) ®NE A (tributary)	Configure active route service on NE D. NE D (chain: west)®NE D (ring: east) NE D (chain: west)®NE D (ring: west)
A®E	NE A (tributary) ®NE A (ring: west) ®NE D (ring: east) ®NE D (chain: west) ®NE E (chain: west) ®NE E (tributary )	Configure active route service on NE D. NE D (ring: east)®NE D (chain: west)

If the fiber between NE A and NE D breaks, the active service will be switched. In this case, the service from NE A to NE E can be protected by MSP and the service will be selected in NE D. While the service from NE E to NE A will be transmitted though other connection in NE D, as shown in Figure 2-18

Figure 2-18 Switching of service from NE A to NE C

If the NE D is not configured as SNCP node, the service from chain to ring cannot be protected.

n  Typical NE configuration

Take the interconnecting node NE D as an example to introduce the typical configuration of ring with chain networks.

On the line, NE D configures two SL16 boards for east and west lines respectively and configures one SL4 for the chain. On the tributary, it configures two PQ1 boards to add/drop 2 x 32 x E1 services and configures one PL3 board to add/drop 3 x E3 services. Figure 2-19 shows the typical NE configuration.

Figure 2-19 Board configuration of NE D

2.  SNCP with 1+1 Protection Chain

n  Configuration plan

In Figure 2-20, NEs A, B, C and D form an STM-16 ring and NE D and NE E form an STM-16 chain.

Figure 2-20  Typical ring with chain network

Table 2-8 lists the service allocation among the nodes in the network.

Table 2-8 Service between nodes

Node	A	B	C	D	E
A	-	32 x E1	32 x E1	32 x E1	32 x E1
B	32 x E1	-	-	-	-
C	32 x E1	-	-	-	-
D	32 x E1	-	-	-	3 x E3
E	32 x E1	-	-	3 x E3	-

n  Configuration description

Since traffic is centralized to NE A and the service between the ring and chain needs protection. SNCP is adopted to protect the service on the ring and between the ring and chain. The service on chain adopts 1+1 linear MSP.

The services on the ring are transmitted through the whole ring over different routes when SNCP is adopted. For services added/dropped at a station, configure the active and standby service routes. While for services not added/dropped at this station, configure them as bidirectional pass-through services.

Here shows the services transmitted between the ring and the chain.

There are 32 x E1 services between NE A and NE E, the service flow is shown in Figure 2-21.