Zte ZXR10 GER - MPLS VPN Maintenance and Diagnosis

Chapter 19 MPLS Configuration
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 Last two bytes indicate the internal label space ID of the LSR.
For the label space per platform, the last two bytes are
always “0”.
Rules for selecting the router ID of an LDP on ZXR10 GER
Routers are as follows:
 If mpls ldp router-id command is used to designate the
address of an interface as the router ID, and also the
interface has an IP address and is in UP status, the interface
will serve as the router ID.
 If there are loopback interfaces configured with an IP
address, maximum IP address among the IP addresses of all
the loopback interfaces will serve as the router ID.
 Maximum one among the IP addresses of interfaces
configured with IP addresses in UP status is selected as the
router ID.
An LSR sends LDP hello messages periodically, indicating that it
hopes to advertise label binding to find LDP peers. A Hello
message contains the LDP ID of the label space that the LSR
wants to advertise. The LDP uses UDP as a transmission protocol
to send the Hello message, with the port ID of 646.
When an LSR receives a Hello message from another LSR, it will
“think” that it has found an LSR and its special label space. If
two LSRs find each other, they will start to set up an LDP session.
LDP defines two types of discovery mechanisms. At present,
ZXR10 GER router supports basic discovery mechanism, used to
discover directly-connected peers. Hello message in basic
discovery mechanism is sent on all interfaces configured with
LDP, with multicast addresses of “all routers on the subnet” as
the destination addresses.
The procedure for setting up an LDP session between two LSRs
is as follows.
1. Open a TCP connection used for label distribution.
On ZXR10 GER, by default, router ID of LDP serves as the
transport address of the TCP connection. Alternatively, in
interface configuration mode, mpls ldp discovery
transport-address command can be used to designate an
IP address or source IP address for sending Hello messages
can serve as the transport address of the TCP connection.
NOTE: To set up a TCP connection, an LSR should have a
route to TCP transport address of another LSR.
2. Negotiate LDP session parameters
Parameters to be negotiated are label distribution mode
(independent downstream label distribution/downstream
label distribution on demand) and other parameters.
After the LDP session is set up, the LDP can start label
distribution.
Rules for
selecting
router ID
LDP hello
messages
Procedure