Huawei AR1200 Series Configuration Manual - Mpls page 31

Huawei AR1200 Series Enterprise Routers
Configuration Guide - MPLS
Table 2-1 Timers for a local LDP session
LDP Timers
Link Hello send
timer
Link Hello hold
timer
KeepAlive send
timer
KeepAlive hold
timer
Exponential
backoff timer
Using default values of these timers are recommended.
Issue 01 (2011-12-30)
Description
Used to send Hello messages
periodically to notify a peer LSR
of the local LSR's presence and
establish a Hello adjacency. The
Hello send timer of LDP remote
session is called Target Hello
send timer.
Used to exchange Hello
messages periodically between
two LDP peers to maintain the
Hello adjacency. If no Hello
message is received after the link
Hello hold timer expires, the
Hello adjacency is torn down.
The Hello hold timer of LDP
remote session is called Target
Hello hold timer.
Used to send KeepAlive
messages periodically,
maintaining the local LDP
session.
Used to send LDP PDUs over an
LDP session, maintaining the
local LDP session. If no LDP
PDU is received after the
KeepAlive hold timer expires,
the TCP connection is closed and
the local LDP session is
terminated.
Started by an LSR that plays an
active role after an LDP
Initialization message sent by
the LSR to another LSR that
plays a passive role fails to be
processed or parameters carried
in the message are rejected. The
LSP that plays the active role
periodically resends an LDP
Initialization message to initiate
an LDP session before the
Exponential backoff timer
expires.
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2 MPLS LDP Configuration
Suggestion
On an unstable network, decrease the
value of a link Hello send timer,
speeding up network fault detection.
On a network with unstable links or a
large number of packets, increase the
value of the link Hello hold timer,
preventing a local LDP session from
being torn down and set up frequently.
On an unstable network, set a smaller
value for a KeepAlive send timer,
speeding up network fault detection.
On a network with unstable links,
increase the value of the KeepAlive
hold timer, preventing the local LDP
session from flapping.
l When a device is upgraded, prolong
the period for the active role to retry
setting up a session. In this case, you
can set larger initial and maximum
values for the Exponential backoff
timer.
l When a device that bears services
tends to alternate between Up and
Down, shorten the period for the
active role to retry setting up a
session. In this case, you can set
smaller initial and maximum values
for the Exponential backoff timer.
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