Contents. Network Topology. Common Network Topology. Chain Network. Protection Mode. Ring with Chain Network, страница 3

Figure 2-3 Board configuration of NE D

NE B is an MADM, the ADM selects two SL16 boards as the line boards, and TM selects SL4 board as the line board and three PQ1 boards as the tributary boards to add/drop 158 x E1 (63 x E1 + 63 x E1 + 32 x E1) services. Figure 2-4 shows the typical configuration.

Figure 2-4 Board configuration of NE B

2.  Self-Healing Chain

In a self-healing chain network, the service can be protected, that is, use a chain to protect the rest chains in the network. We define the chain carrying services as the active chain, while the chain to protect services as the slave or standby chain.

The typical protection mode in a self-healing chain network is linear multiplex section protection, including linear 1+1 protection and 1:N (1£N£14) protection. Usually, we adopt 1:N protection to transmit extra traffic on the standby route and thus to improve the network utilization; and adopt 1+1 protection to restore the switched service as soon as possible.

Compared with the non-protection chain network, this network needs to add a pair of fibers.

n  Configuration plan

As shown in Figure 2-5, a 1+1 chain network is composed of three NEs: A, B and C. There are four fibers between adjacent NEs.

Figure 2-5 Typical self-healing chain network

Table 2-3 shows the services allocation between adjacent NEs.

Table 2-3 Service allocation of NEs

NE name	A	B	C
A	-	63 x E1	-
B	63 x E1	-	63 x E1
C	-	63 x E1	-

NE A and NE C only transmit services in one direction, they can be respectively configured as a TM with the rate of STM-16 considering the tributary service requirement and future expansion.

NE B transmits services in two directions, it can be configured as an ADM with the rate of STM-16.

n  Configuration description

In a self-healing 1+1 network, you need to configure the service on the active chain and standby chain in transmitting direction. In the receiving direction, you only need to configure the service on the active chain, because the service on the standby chain will be generated by the system according to the active chain service.

The service configuration on the active chain is the same with that in a non-protection chain network.

n  Typical NE configuration

NE A and NE C share the same board configuration, with two SL16 as the line boards (one for active chain, the other for standby chain) and PQ1 as the tributary board to add/drop 63 x E1 services. Figure 2-6 shows the NE configuration.

Figure 2-6 Board configuration of NE A and NE C

NE B configures two SL16 for east and west lines respectively, one for the active chain and the other for the standby chain, and configures two PQ1 to add/drop 126 x E1 services. Figure 2-7 shows the NE configuration.

Figure 2-7 Board configuration of NE B

2.3  Ring Network

2.3.1  Application

Connect the nodes in a network (for example, a chain network) end to end, and you will get a ring.

The ring network is a basic network topology that provides powerful self-healing capability to guarantee the operating and maintenance of equipment. If possible, the ring network is preferred.

A single ring is the basic ring network topology, as well as the element of complex networks. Here introduces the feature, protection mode and typical NE configuration of a single ring network.