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This document describes MPLS configurations supported by the switch, including the principle and configuration procedures of static LSPs, MPLS LDP, MPLS QoS, MPLS TE, and MPLS common features, and provides configuration examples.
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(Optional) Configuring Timers for LDP Session
(Optional) Configuring Timers for LDP Session
Context
Table 4-9 describes
the timers for an LDP session.
Table 4-9 Timers for an LDP session
LDP Timer
Description
Suggestion
Hello send timer:
Link-Hello send timer (for only local LDP sessions)
Target-Hello send timer (for only remote LDP sessions)
Used to send Hello messages periodically to notify a peer
LSR of the local LSR's presence and establish a Hello adjacency.
On an unstable network, decrease the value of a Hello send
timer, speeding up network fault detection.
Hello hold timer:
Link-Hello hold timer (for only local LDP sessions)
Target-Hello hold timer (for only remote LDP sessions)
Used to exchange Hello messages periodically between two
LDP peers to maintain the Hello adjacency. If no Hello message is
received after the Hello hold timer expires, the Hello adjacency is
torn down.
On a network with unstable links or a large number of packets,
increase the value of the Hello hold timer, preventing the LDP session
from being torn down and set up frequently.
Keepalive send timer
Used to send Keepalive messages periodically, maintaining
the LDP sessions.
On an unstable network, set a smaller value for a Keepalive
send timer, speeding up network fault detection.
Keepalive hold timer
Used to send LDP PDUs over an LDP session, maintaining the
LDP session. If no LDP PDU is received after the Keepalive hold timer
expires, the TCP connection is closed and the LDP session is terminated.
On a network with unstable links, increase the value of
the Keepalive hold timer, preventing the LDP session from flapping.
Exponential backoff timer
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 LSR that plays the active role periodically
resends an LDP Initialization message to initiate an LDP session before
the Exponential backoff timer expires.
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.
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.
When local and remote LDP sessions coexist,
the timeout interval of the Keepalive hold timer of the local and
remote LDP sessions must be the same.
Procedure
Configuring timers for
a local LDP session
Run system-view
The system view is displayed.
Run interfaceinterface-typeinterface-number
The view of an interface on which an LDP session is to be established
is displayed.
(Optional) On an Ethernet interface,
run undo portswitch
The interface is switched to Layer 3 mode.
By default,
an Ethernet interface works in Layer 2 mode.
Only
the S5720HI, S5720EI,
S6720EI, and S6720S-EI support
switching between Layer 2 and Layer 3 modes.
Run mpls ldp timer hello-sendinterval
A link Hello send
timer is configured.
The default value of a link Hello send
timer is one third of the value of a link Hello hold timer.
Effective value of a link Hello send timer = Min {Configured value
of the link Hello send timer, one third of the value of the link Hello
hold timer}
Run mpls ldp timer hello-holdinterval
A link Hello hold
timer is configured.
The default value of a link Hello hold
timer is 15, in seconds.
The smaller value between two configured
link Hello hold timers on both ends of the LDP session takes effect.
Run mpls ldp timer keepalive-sendinterval
A Keepalive send timer
is configured.
The default value of a Keepalive send timer is
one third of the value of the Keepalive hold timer.
Effective
value of a Keepalive send timer = Min { Configured value of the Keepalive
send timer, one third of the value of the Keepalive hold timer }
If more than one LDP-enabled links connect two
LSRs, the values of Keepalive send timers for all links must be the
same. Otherwise, LDP sessions become unstable or fail to be set up.
If there is only one link between two LSRs and
both local and remote sessions are configured, the local and remote
sessions must have the same Keepalive send timer value. Otherwise,
LDP sessions become unstable or fail to be set up.
Run mpls ldp timer keepalive-holdinterval
A Keepalive hold timer
is configured.
The default value of a Keepalive hold timer is
45, in seconds.
The smaller value between two configured Keepalive
hold timers on both ends of the LDP session takes effect.
If more than one LDP-enabled links connect two LSRs,
the values of Keepalive hold timers for all links must be the same.
Otherwise, LDP sessions become unstable or fail to be set up.
If there is only one link between two LSRs and both
local and remote sessions are configured, the local and remote sessions
must have the same Keepalive hold timer value. Otherwise, LDP sessions
become unstable or fail to be set up.
Changing
the Keepalive hold timer value in an instance will interrupt the MPLS
service in the instance because the LDP session must be reestablished.
Configure an Exponential backoff timer.
Run quit
The system view is displayed.
Run mpls ldp
The MPLS LDP view is displayed.
Run backoff timerinitmax
An Exponential backoff
timer is configured.
By default, the initial value is 15 and
the maximum value is 120, in seconds. Setting the initial value of
the Exponential backoff timer to be greater than or equal to 15s and
the maximum value to be greater than or equal to 120s is recommended.
Configuring timers for
a remote LDP session
Run system-view
The system view is displayed.
Run mpls ldp remote-peerremote-peer-name
The remote
MPLS LDP peer view is displayed.
Run mpls ldp timer hello-sendinterval
The target Hello send
timer is configured.
The default value of the target Hello send
timer is one third of the value of a target Hello hold timer that
takes effect.
Effective value of a target Hello send timer =
Min { Configured value of the target Hello send timer, One third of
the value of the target Hello hold timer }
Run mpls ldp timer hello-holdinterval
The target Hello hold
timer is configured.
The default value of the target Hello hold
timer is 45, in seconds.
The smaller value between two configured
target Hello hold timers on both ends of the LDP session takes effect.
Run mpls ldp timer keepalive-sendinterval
A Keepalive send timer
is configured.
The default value of a Keepalive send timer is
one third of the value of the Keepalive hold timer.
Effective
value of a Keepalive send timer = Min { Configured value of the Keepalive
send timer, one third of the value of the Keepalive hold timer }
If more than one LDP-enabled links connect two
LSRs, the values of Keepalive send timers for all links must be the
same. Otherwise, LDP sessions become unstable or fail to be set up.
If there is only one link between two LSRs and
both local and remote sessions are configured, the local and remote
sessions must have the same Keepalive send timer value. Otherwise,
LDP sessions become unstable or fail to be set up.
Run mpls ldp timer keepalive-holdinterval
A Keepalive hold timer
is configured.
The default value of a Keepalive hold timer is
45, in seconds.
The smaller value between two configured Keepalive
hold timers on both ends of the LDP session takes effect.
If more than one LDP-enabled links connect two LSRs,
the values of Keepalive hold timers for all links must be the same.
Otherwise, LDP sessions become unstable or fail to be set up.
If there is only one link between two LSRs and both
local and remote sessions are configured, the local and remote sessions
must have the same Keepalive hold timer value. Otherwise, LDP sessions
become unstable or fail to be set up.
Changing
the Keepalive hold timer value in an instance may interrupt the MPLS
service in the instance because the LDP session must be reestablished.
Configure an Exponential backoff timer.
Run quit
The system view is displayed.
Run mpls ldp
The MPLS LDP view is displayed.
Run backoff timerinitmax
An Exponential backoff
timer is configured.
By default, the initial value is 15 and
the maximum value is 120, in seconds. Setting the initial value of
the Exponential backoff timer to be greater than or equal to 15s and
the maximum value to be greater than or equal to 120s is recommended.
