HP 5920 Series Command Reference Manual page 281

Default
Load balancing is not enabled.
Views
BGP IPv4 unicast address family view, BGP-VPN IPv4 unicast address family view, BGP IPv6 unicast
address family view, BGP-VPN IPv6 unicast address family view
Predefined user roles
network-admin
Parameters
number: Specifies the maximum number of BGP ECMP routes for load balancing. When it is set to 1,
load balancing is disabled.
Usage guidelines
Unlike IGP, BGP has no explicit metric for making load balancing decision. Instead, it implements load
balancing by modifying route selection rules. If multiple BGP routes destined for a network meet the
following conditions, the device selects the specified number of routes from these routes for load
balancing:
The routes have the same AS_PATH, ORIGIN, LOCAL_PREF, and MED attributes. (The balance
•
as-path-neglect command enables BGP to implement load balancing over routes with different
AS_PATH attributes. Before using that command, make sure it does not cause any routing loops.)
All the routes are reflected by a route reflector, or none of the routes is reflected by a route reflector.
•
The value range for the number argument depends on the max-ecmp-num command. If you set the
maximum number of ECMP routes to m by using the max-ecmp-num command and reboot the device,
the number argument in the balance command is in the range of 1 to m.
Examples
# In BGP IPv4 unicast address family view, enable load balancing and specify the maximum number of
BGP ECMP routes used for load balancing as 2.
<Sysname> system-view
[Sysname] bgp 100
[Sysname-bgp] address-family ipv4 unicast
[Sysname-bgp-ipv4] balance 2
# In BGP-VPN IPv6 unicast address family view, enable load balancing and specify the maximum
number of BGP ECMP routes for load balancing as 2.
<Sysname> system-view
[Sysname] bgp 100
[Sysname-bgp] ip vpn-instance vpn1
[Sysname-bgp-vpn1] address-family ipv6 unicast
[Sysname-bgp-ipv6-vpn1] balance 2
Related commands
max-ecmp-num
•
balance as-path-neglect
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