Technical Documentation

Configuring Compressed RTP on J Series Routers

On J Series routers link services interfaces (ls), you can configure the compressed Real-Time Transport Protocol (CRTP) with either MLPPP or PPP encapsulation.

You can also configure CRTP with MLPPP on link services IQ (lsq-) interfaces and voice services interfaces. When you configure CRTP with MLPPP, the configuration syntax for J Series routers is the same as the syntax you use on the AS or MultiServices PIC. The only difference is that you use the ls- interface descriptor for J Series routers, and you use the lsq- interface descriptor for the AS or MultiServices PIC. For more information, see Configuring Services Interfaces for Voice Services.

All CRTP traffic is sent on the LFI queue (q2). We recommend that the incoming voice traffic be classified to the appropriate queue.

The configuration syntax for CRTP with PPP encapsulation is much like the syntax you use when you configure CRTP with MLPPP.

To configure CRTP with PPP encapsulation, perform the following steps:

  1. On the logical T1 or E1 constituent link, configure the link services interface used for compression by including the compression-device statement:
    compression-device interface-name;

    The interface name is the link services interface on which the T1 or E1 constituent link is bundled.

    You can include this statement at the following hierarchy levels:

    • [edit interfaces interface-name unit logical-unit-number]
    • [edit logical-systems logical-system-name interfaces interface-name unit logical-unit-number]
  2. Specify how the link services interface handles voice traffic compression by including the following statements:
    compression {
    rtp {
    f-max-period number;
    queues [ queue-numbers ];
    port {
    minimum port-number;
    maximum port-number;
    }
    }
    }

    You can include these statements at the following hierarchy levels:

    • [edit interfaces interface-name unit logical-unit-number]
    • [edit logical-systems logical-system-name interfaces interface-name unit logical-unit-number]

    For detailed information about these statements, see Configuring Services Interfaces for Voice Services.

Example: Configuring Compressed RTP with MLPPP Encapsulation

Configure compression on a J Series T1 interface with MLPPP encapsulation. Configure fragmentation for all IP packets larger than 128 bytes.

For detailed information about these configuration statements, see Configuring Services Interfaces for Voice Services.

[edit interfaces]
t1-1/0/0 {
unit 0 {
family mlppp {
bundle ls-1/1/0.1;
}
}
}
ls-1/1/0 {
unit 1 {
compression {
rtp {
port minimum 16384 maximum 32768;
}
}
encapsulation multilink-ppp;
family inet {
address 30.1.1.2/24;
}
fragment-threshold 128;
}
}

Example: Configuring Compressed RTP with PPP Encapsulation

Configure compression on a J Series T1 interface with PPP encapsulation. Configure fragmentation for all IP packets larger than 128 bytes.

[edit interfaces]
t1-1/0/0 {
encapsulation ppp;
unit 0 {
compression-device ls-0/0/0.1
}
}
ls-0/0/0.1 {
compression {
rtp {
port minimum 16384 maximum 32768;
}
}
family inet {
address 10.0.2.3;
# Other IPv4 parameters here.
}
}

Published: 2009-07-20