D-Link DGS-6600-48TS Configuration Guide - Page 301

Comparing MED for Paths from Neighbors in Different Autonomous Systems, LEVEL, AS-NUMBER, IP-ADDRESS

Page 301 highlights

Volume 4-Layer 3 Configurations / Chapter 30-Border Gateway Protocol (BGP) BGP Configuration commands You must specify a unique router ID within the network. This command will reset all active BGP peering sessions. It is recommended to configure a loopback interface, since the physical interface link may be up/ down/removed for some reason. Command enable [privilege LEVEL] configure terminal router bgp AS-NUMBER bgp router-id IP-ADDRESS Explanation Enter privileged EXEC mode. Enter Global configuration mode. Enter the following information to configure BGP routing process and enter into BGP configuration mode. Enter the following command to configure a fixed router ID for the local BGP routing process. Configuration Example To change the router ID to 192.168.1.1 for the local BGP routing process: dgs-6600:2>enable dgs-6600:15#configure terminal dgs-6600:15(config)#router bgp 65100 dgs-6600:15(config-router)#bgp router-id 192.168.1.1 dgs-6600:15(config-router)# Comparing (MED) for Paths from Neighbors in Different Autonomous Systems Use the bgp always-compare-med command to compare the Multi Exit Discriminator (MED) for paths from neighbors in different autonomous systems. The MED, as stated in RFC 1771, is an optional non-transitive attribute that is a four octet non-negative integer. The value of this attribute may be used by the BGP best path selection process to discriminate among multiple exit points to a neighboring autonomous system. The MED is one of the parameters that is considered when selecting the best path among many alternative paths. The path with a lower MED is preferred over a path with a higher MED. During the best-path selection process, MED comparison is done only among paths from the same autonomous system. The bgp always-compare-med command is used to change this behavior by enforcing MED comparison between all paths, regardless of the autonomous system from which the paths are received. The bgp deterministic-med command can be configured to enforce deterministic comparison of the MED value between all paths received from within the same autonomous system. DGS-6600 Configuration Guide 301

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Volume 4-Layer 3 Configurations / Chapter 30-Border Gateway Protocol (BGP)
BGP Configuration commands
DGS-6600 Configuration Guide
301
You must specify a unique router ID within the network.
This command will reset all active BGP peering sessions.
It is recommended to configure a loopback interface, since the physical interface link may be up/
down/removed for some reason.
Configuration Example
To change the router ID to 192.168.1.1 for the local BGP routing process:
Comparing (MED) for Paths from Neighbors in Different Autonomous Systems
Use the
bgp always-compare-med
command to compare the Multi Exit Discriminator (MED) for paths from
neighbors in different autonomous systems.
The MED, as stated in RFC 1771, is an optional non-transitive attribute that is a four octet non-negative integer. The
value of this attribute may be used by the BGP best path selection process to discriminate among multiple exit points
to a neighboring autonomous system.
The MED is one of the parameters that is considered when selecting the best path among many alternative paths.
The path with a lower MED is preferred over a path with a higher MED. During the best-path selection process, MED
comparison is done only among paths from the same autonomous system. The
bgp always-compare-med
command is used to change this behavior by enforcing MED comparison between all paths, regardless of the
autonomous system from which the paths are received.
The
bgp deterministic-med
command can be configured to enforce deterministic comparison of the MED value
between all paths received from within the same autonomous system.
Command
Explanation
enable [privilege
LEVEL
]
Enter privileged EXEC mode.
configure terminal
Enter Global configuration mode.
router bgp
AS-NUMBER
Enter the following information to configure BGP
routing process and enter into BGP configuration
mode.
bgp router-id
IP-ADDRESS
Enter the following command to configure a fixed
router ID for the local BGP routing process.
dgs-6600:2>enable
dgs-6600:15#configure terminal
dgs-6600:15(config)#router bgp 65100
dgs-6600:15(config-router)#bgp router-id 192.168.1.1
dgs-6600:15(config-router)#