One, the current PTN network, the second layer uses PW redundancy protection, the normal situation, the business flow is as follows:

In the current LTE network, the existence of the following scenarios will lead to the carrying business one-way interruption
1.1 for the L2/L3 equipment is not the same room
(1), the following figure, 6, 7 interrupted at the same time, to the L3-1 LTE site data L2 layer Business switch to the standby node, and VPNFRR did not trigger the switch, the downlink data did not switch, resulting in the downlink data interruption, the uplink data is normal. At this time to county L2/L3-1 mainly used LTE base station interruption. Similarly, when the 6/8 interruption, the county L2/L3-2 mainly used for the LTE base station interruption, so 6 and 7 and 6 and 8 can not be the same route.

(2), the following figure, 4/6/10 at the same time interrupt, to county L2/l3-1 LTE site data downlink VPNFRR trigger switch, L2 layer business did not trigger the switch, resulting in the uplink data interruption, the downlink data is normal. At this time to county L2/3-1 mainly used LTE base station interruption. Similarly, when there is 5/6/9 interruption, the county L2/L3-2 mainly used for the LTE base station interruption, so 4/6/10 and 5/6/9 can not be the same route.

(3), the following figure, 3/4 at the same time interrupt, L3vpn the uplink trigger VPNFRR switch, and uni side down (IPFRR) did not occur switching, The downlink data that led to the L3-1 of the new building was interrupted and the uplink data switched. At this time the LTE to EPC A Route interruption, similarly, when 10/11 simultaneous interruption, to EPC B Route interrupted. Therefore 3/4 and 10/11 can not be the same route.

(4), the following figure, 1/3 at the same time interrupt, triggering ipfrr protection switch, L3VPN uplink did not trigger the switch, at this time. At this time the LTE to EPC A Route interruption, similarly, when 11/12 simultaneous interruption, to EPC B Route interrupted. Therefore, 1/3 and 11/12 can not be the same route, L3 equipment Interconnect fiber (3/11) and L2/L3 Equipment Interconnect fiber (6) for the protection of switching plays a very important role, can not be with other fiber-like routes.

(5), the following figure, 4/5 or 9/10 simultaneous interruption, resulting in a plane S1 link total resistance. So 4/5 and 9/10 cannot be routed.

(6), the following figure, 7/8 interrupt at the same time, resulting in two-tier link main standby interrupt, so 7/8 can not be the same route.

1.2 If the two turn three equipment in the same room, then need to cross-linked tail fiber and other tail fiber can not be in the same tail fiber channel.