H3C Technologies H3C S5560 Series Switches - Manual (Page 257)

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Tuning and optimizing BGP networks
This section describes how to tune and optimize BGP networks.
Configuring the keepalive interval and hold time
BGP sends keepalive messages at a specific interval to keep the BGP session between two routers.
If a router receives no keepalive or update message from a peer within the hold time, it tears down the
session.
You can configure the keepalive interval and hold time globally or for a specific peer or peer group. The
individual settings take precedence over the global settings.
The actual keepalive interval and hold time are determined as follows:
• If the hold time settings on the local and peer routers are different, the smaller setting is used. If the
hold time is 0, BGP does not send keepalive messages to its peers and never tears down the
session.
• If the keepalive interval is 0 and the negotiated hold time is not 0, the actual keepalive interval
equals 1/3 of the hold time. If the keepalive interval is not 0, the actual keepalive interval is the
smaller one between 1/3 of the hold time and the keepalive interval.
To configure the keepalive interval and hold time (IPv4):
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter BGP view or BGP-VPN
instance view.
• Enter BGP view:
bgp as-number
• Enter BGP-VPN instance view:
a. bgp as-number
b. ip vpn-instance
vpn-instance-name
N/A
3. Configure the keepalive
interval and hold time.
• Configure the global keepalive
interval and hold time:
timer keepalive keepalive hold
holdtime
• Configure the keepalive
interval and hold time for a
peer or peer group:
peer { group-name | ip-address
[ mask-length ] } timer
keepalive keepalive hold
holdtime
Use at least one method.
By default, the keepalive interval is
60 seconds, and hold time is 180
seconds.
The timer command takes effect for
new BGP sessions and does not
affect existing sessions.
If you modify the timers with the
peer timer command, BGP
immediately closes the existing
BGP session and creates a new
session to the peer by using the
new settings.
The holdtime must be at least three
times the keepalive interval.
To configure the keepalive interval and hold time (IPv6):