Specifications

mpls ldp discovery
MP-213
Cisco IOS Multiprotocol Label Switching Command Reference
January 2010
Usage Guidelines The discovery hold time is set to the smaller of the following: the locally proposed hold time or the hold
time proposed by the neighbor. The hello interval is selected so that within the hello hold time period at
least three hellos messages are sent for a link hello and at least nine hello messages are sent for a targeted
hello.
When the discovery hold time elapses for a neighbor discovered on an interface or for a neighbor
d
iscovered by means of a targeted hello message, the record associating the neighbor with that interface
or the targeted hello message source is discarded. If an LDP session exists with a neighbor, but a
discovery record no longer exists for that neighbor, the LDP session is terminated.
Setting the hold time too high causes LDP to be slow in detecting link outages; setting the hold time too
lo
w might cause LDP to terminate sessions when a hello message is dropped during traffic bursts on a
link.
The exchange of targeted hello messages between two nondirectly connected neighbors (N1 and N2)
ma
y occur in the following ways:
• N1 may initiate the transmission of targeted hello messages to N2, and N2 may send targeted hello
messages in response. In this situation, N1 is considered to be active and N2 is considered to be
passive.
N1 targeted hello messages carry a request that N2 send targeted hello messages in response. To
re
spond, N2 configuration must permit it to respond to N1. The mpls ldp discovery targeted-hello
accept command is used to configure whether N1 must respond to requests for targeted hello
messages.
• Both N1 and N2 may be configured to initiate the transmission of targeted hello messages to each
other. In this situation, both are active.
Both, one, or neither of N1 and N2 may be passive, depending on whether they have been configured
t
o respond to requests for targeted hello messages from the other.
12.0(14)ST This command was integrated into Cisco IOS Release 12.0(14)ST.
12.1(2)T This command was integrated into Cisco IOS Release 12.1(2)T.
12.1(8a)E This command was integrated into Cisco IOS Release 12.1(8a)E.
12.2(2)T This command was integrated into Cisco IOS Release 12.2(2)T.
12.2(4)T This command was integrated into Cisco IOS Release 12.2(4)T.
12.2(8)T This command was integrated into Cisco IOS Release 12.2(8)T.
12.0(21)ST This command was integrated into Cisco IOS Release 12.0(21)ST.
12.0(22)S This command was integrated into Cisco IOS Release 12.0(22)S.
12.0(23)S This command was integrated into Cisco IOS Release 12.0(23)S. Default
v
alues for the holdtime and interval keywords were changed.
12.2(14)S This command was integrated into Cisco IOS Release 12.2(14)S.
12.2(13)T This command was integrated into Cisco IOS Release 12.2(13)T.
12.2(33)SRA This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2SX This command is supported in the Cisco IOS Release 12.2SX train. Support
i
n a specific 12.2SX release of this train depends on your feature set,
platform, and platform hardware.
12.2(33)SCA This command was integrated into Cisco IOS Release 12.2(33)SCA.
Release Modification