H3C Technologies H3C S10500 Series Switches - Manual (Page 260)

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Configuring the AS-PATH attributes
In general, MBGP checks whether the AS-PATH attribute of a route from a peer contains the local AS
number. If it does, it discards the route to avoid routing loops.
Follow these steps to configure the AS-PATH attributes:
To do… Use the command… Remarks
Enter system view system-view —
Enter BGP view bgp as-number —
Enter IPv4 MBGP address family
view
ipv4-family multicast —
Allow the local AS number to
appear in the AS-PATH of routes
from a peer or a peer group and
specify the number of times that the
local AS number can appear in the
AS-PATH of routes from the peer or
the peer group
peer { group-name | ip-address }
allow-as-loop [ number ]
Optional
By default, the local AS number
can not appear in routes from a
peer or a peer group.
Disable BGP from considering the
AS_PATH during best route
selection
bestroute as-path-neglect
Optional
By default, BGP considers
AS_PATH during best route
selection.
Configure updates to a peer or a
peer group not to keep private AS
numbers
peer { group-name | ip-address }
public-as-only
Optional
By default, BGP updates carry
private AS numbers.
Tuning and optimizing MBGP networks
This task involves resetting MBGP connections and configuring load balancing.
Prerequisites
You need to configure BGP basic functions before configuring this task.
Configuring MBGP soft reset
After modifying a route selection policy, you have to reset MBGP connections to make it take effect.
The current MBGP implementation supports the route refresh feature that enables dynamic route refresh
without terminating MBGP connections.
However, if a peer that does not support route refresh exists in the network, you must configure the peer
keep-all-routes command to save all routes from the peer. When the routing policy is changed, the
system updates the MBGP routing table and applies the new policy.
Performing soft reset through route refresh
If the peer is enabled with route refresh, when the MBGP route selection policy is modified on a router,
the router advertises a route-refresh message to its MBGP peers, which resend their routing information