Setting Med Attribute - Zte ZXR10 5900E Series User Manual

ZXR10 5900E Series User Manual (IPv4 Volume)
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1. Set the LOCAL_PREF attribute with the BGP default local-pr
eference command.
R3 configuration:
ZXR10_R3(config)#router bgp 256
ZXR10_R3(config-router)#neighbor 1.1.1.1 remote-as 100
ZXR10_R3(config-router)#neighbor 128.213.11.2 remote-as 256
ZXR10_R3(config-router)#bgp default local-preference 150
R4 configuration:
ZXR10_R4(config)#router bgp 256
ZXR10_R4(config-router)#neighbor 3.3.3.2 remote-as 300
ZXR10_R4(config-router)#neighbor 128.213.11.1 remote-as 256
ZXR10_R4(config-router)#bgp default local-preference 200
2. Set the LOCAL_PREF attribute with the route-mapcommand.
R4 configuration:
ZXR10_R4(config)#router bgp 256
ZXR10_R4(config-router)#neighbor 3.3.3.2 remote-as 300
ZXR10_R4(config-router)#neighbor 3.3.3.2 route-map setlocalin in
ZXR10_R4(config-router)#neighbor 128.213.11.1 remote-as 256
....
ZXR10_R4(config)#ip as-path access-list 7 permit ^300$
...
ZXR10_R4(config)#route-map setlocalin permit 10
ZXR10_R4(config-route-map)#match as-path 7
ZXR10_R4(config-route-map)#set local-preference 200
ZXR10_R4(config-route-map)#exit
ZXR10_R4(config)#route-map setlocalin permit 20
ZXR10_R4(config-route-map)#set local-preference 150

Setting MED Attribute

Metric attribute is also called the Multi_Exit_Discrimination at-
tribute (MED) .Router only compares the adjacent Metric value
of the BGP from the same AS by default. If comparing adjacent
Metric values of neighbors from different ASs, execute necessarily
the MED attribute command to forcefully compare them.
To configure the Metric values of neighbors from different As, use
the bgp always-compare-med command.
R1 synchronously receives the 180.10.0.0 update from R2, R3 and
R4. Only compare the Metric values of the adjacent R3 and R4
from the same AS by default.
Metric value of the R3 is smaller than that of the R4. Therefore,
for the 180.10.0.0 update, the R1 preferentially uses the R3. This
is shown in Figure 19.