NE80E is connected to the router R at edge of national backbone network through 2.5G POS, and to other NE80Es through 2XGE. Also, it accesses the equipments including SMS10000 and S8016 at convergence layer through GE; it establishes EBGP neighbor with national backbone router, and IBGP neighbor with other NE80Es. OSPF serves as IGP for NE80E and other equipments in MAN. Both NE80E-1 and NE80-2 receive the summary routes and default routes advertised by R1 and R2, and they broadcast the default route in the local AS in a non-forced mode. After cutover, it is found that the traffic from SMS10000 only passes over NE80E-1, and there is nothing over the link with NE80E-2. Check the routing table of SMS10000, and only one default route to NE80E-1 is found.
According to checkup for configurations of link and interface, no problem is found, and equipments could ping to each other. Check the configuration of OSPF, and it is normal. OSPF neighbor is in FULL state, and NE80E-2 is configured correctly. The routing tables of both NE80E-1 and NE80E-2 are consistent. Check the routing table of S8016, and it contains two default route to two NE80E. Moreover, after checkup for two uplink interfaces of S8016, the traffic is even. Therefore, we could know that both route setting and link are normal. After careful checkup for configurations of SMS10000, REDBACK engineer finds that although route is configured correctly, the command ip maximum paths=2 for multiple uplinks of the equipment to take effect is not configured. After adding the command, check the routing table, and it displays two default route to both NE80E. Check the traffic over two uplink interfaces, and the traffic over both links do equal.
With the help of REDBACK engineer, we find that REDBACK SMS10000 has a unique feature: multiple uplinks need to configure a command as ip maximum paths=n to make them take effect, in which n is the number of uplinks.
The following possibiliteis cause that there is no traffic over uplink:
1. Link fails, including problem in configuration of port.
2. OSPF configuration is false.
3. NE80E-2 learns the false route.
4. SMS10000 is configured falsely.
In preparations for cutover, it is advisable to communicate with engineers of relevant manufacturers so as to master the unique features of products, avoiding that failure occurs to cutover because of problem of other equipments.