The egress traffics of the two core egress devices are unbanlanced in multiple cities. In some cities, one of the two core egress devices is Huawei NE5000E and the other one is CRS1XXXX from company C. In some sities, the two core egress devices are NE5000Es. However, the network structures in these cities are the same. This case takes city A as an example.
Traffics of ports on an NE5000E in city A are listed as follows:
Pos3/0/0 up up 27% 34% 1352435561 0
Pos4/0/0 up up 28% 34% 278424347 0
The egress traffic of the two ports is about 6.8 Gbit/s.
Traffics of CRS related ports in city A:
A-CR12-MB01#show int pos 4/0/0
5 minute output rate 1266791000 bits/sec, 267328 packets/sec
A-CR12-MB01#show int pos 14/0
5 minute output rate 1279011000 bits/sec, 265380 packets/sec
The egress traffic of the two ports is about 2.4 Gbit/s.
The symptom is caused by the difference of BGP route selection policies in different versions:
The BGP route selection policy of V300R005 (city A)
1. The locally originated route with a low preference value is preferred
2. The next hop unattainable route is firstly discarded.
3. The IPv4 route with labels is preferred unconditionally.
BGP route queried on the NE5000E in city A and NE5000E in city G are as follows:NE5000E in city A: