The proper maximum interval at which Keepalive messages are sent is one third the
holdtime and is not less than one second. If the holdtime is not set to 0, it is 3s at least.
By default, the
keepalive-time
value is 60s and the
hold-time
value is 180s.
NOTE
Setting the Keepalive time to 20s is recommended. If the Keepalive time is smaller than 20s,
sessions between peers may be closed.
When setting values of
keepalive-time
and
hold-time
, note the following points:
–
The
keepalive-time
and
hold-time
values cannot be both set to 0. Otherwise, the
BGP timers become invalid, meaning that BGP will not send Keepalive messages
to detect connection status.
–
The
hold-time
value cannot be much greater than the
keepalive-time
value. For
example,
keepalive-time
cannot be set to 1 while
hold-time
is set to 65535. If the
hold-time
value is too large, BGP cannot detect connection status in time.
After a connection is established between peers, the
keepalive-time
and
hold-time
values are negotiated by the peers. The smaller one of the
hold-time
values carried by
Open messages of both peers is taken as the
hold-time
value. The smaller of one third
of the
hold-time
value and the locally configured
keepalive-time
value is taken as the
keepalive-time
value.
If the local device establishes BGP peer relationships with many devices, it needs to
process huge BGP messages. If
hold-time
negotiated among BGP peers is small, the
timer may expire before the local device processes the Keepalive messages sent from
other BGP peers. The peer relationships are then interrupted, and routes flap. To solve
the preceding problem, you can configure an appropriate value for
min-holdtime
min-
holdtime
based on the CPU processing capability of the local device.
If the value of
min-holdtime
is changed, but the values of
keepalive-time
and
hold-
time
negotiated between two BGP peers remain unchanged, the established peer
relationship is not affected. Only when the local device attempts to re-establish a
relationship with a remote device, the value of
min-holdtime
configured on the local
device takes effect. The local device compares
min-holdtime
with
hold-time
sent from
the remote device. If the value of
min-holdtime
exceeds that of
hold-time
,
hold-time
negotiation fails, and the peer relationship fails to be established.
NOTE
If
min-holdtime
is configured on the local device, and the value of
hold-time
sent from the
remote device is 0,
hold-time
negotiation between the two devices succeeds. The negotiated
value of
hold-time
is 0, and the peer relationship is established. The value 0 of
hold-time
indicates that the peer relationship never expires.
l
Configure timers for a specific peer or peer group.
1.
Run:
system-view
The system view is displayed.
2.
Run:
bgp
{
as-number-plain
|
as-number-dot
}
The BGP view is displayed.
3.
Run:
peer
{
ipv6-address
|
group-name
}
timer
keepalive
keepalive-time
hold
hold-time
[
min-holdtime
min-holdtime
]
HUAWEI NetEngine80E/40E Router
Configuration Guide - IP Routing
9 BGP4+ Configuration
Issue 02 (2014-09-30)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
1074
