Configuring Services Interfaces for Voice Services
You define voice service properties such as compression by configuring statements and values for a voice services interface, specified by the interface type lsq-. You can include the following statements:
You can include these statements at the following hierarchy levels:
- [edit interfaces (lsq | ls)-fpc/pic/port unit logical-unit-number]
- [edit logical-systems logical-system-name interfaces (lsq | ls)-fpc/pic/port unit logical-unit-number]
The following sections provide detailed instructions for configuring for voice services on services interfaces:
Configuring the Logical Interface Address for the MLPPP Bundle
To configure the logical address for the MLPPP bundle, include the address statement:
You can configure this statement at the following hierarchy levels:
- [edit interfaces (lsq | ls)-fpc/pic/port unit logical-unit-number family inet]
- [edit logical-systems logical-system-name interfaces (lsq | ls)-fpc/pic/port unit logical-unit-number family inet]
address specifies an IP address for the interface. AS and Multiservices PICs support only IP version 4 (IPv4) addresses, which are therefore configured under the family inet statement.
For information on other addressing properties you can configure that are not specific to service interfaces, see the Junos® OS Network Interfaces.
Configuring Compression of Voice Traffic
You can specify how a services interface handles voice traffic compression by including the compression statement:
You can include this statement at the following hierarchy levels:
- [edit interfaces (lsq | ls)-fpc/pic/port unit logical-unit-number]
- [edit logical-systems logical-system-name interfaces (lsq | ls)-fpc/pic/port unit logical-unit-number]
The following statements configure the indicated compression properties:
- f-max-period number—Sets the maximum number of compressed packets to insert between the transmission of full headers. If you do not include the statement, the default is 255 packets.
- maximum-contexts number <force>—Specifies the maximum number of RTP contexts to accept during negotiation. The optional force statement requires the PIC to use the value specified for maximum RTP contexts, regardless of the negotiated value. This option enables interoperation with Junos OS Releases that base the RTP context value on link speed.
- port, minimum port-number, and maximum port-number—Specify the lower and upper boundaries for a range of UDP destination port values on which RTP compression takes effect. Values for port-number can range from 0 through 65,535. RTP compression is applied to traffic transiting the ports within the specified range.
- queues [ queue-numbers ]—Specifies one or more of queues q0, q1, q2, and q3 . RTP compression is applied to the traffic
in the specified queues.
Note: If you specify both a port range and one or more queues, compression takes place if either condition is met.
Configuring Delay-Sensitive Packet Interleaving
When you configure CRTP, the software automatically enables link fragmentation and interleaving (LFI). LFI reduces excessive delays by fragmenting long packets into smaller packets and interleaving them with real-time frames. This allows real-time and non-real-time data frames to be carried together on lower-speed links without causing excessive delays to the real-time traffic. When the peer interface receives the smaller fragments, it reassembles the fragments into their original packet. For example, short delay-sensitive packets, such as packetized voice, can race ahead of larger delay-insensitive packets, such as common data packets.
By default, LFI is always active when you include the compression rtp statement at the [edit interfaces interface-name unit logical-unit-number] hierarchy level. You control the operation of LFI indirectly by setting the fragment-threshold statement on the same logical interface. For example, if you include the fragment-threshold 256 statement at the [edit interfaces interface-name unit logical-unit-number] hierarchy level, all IP packets larger than 256 bytes are fragmented.
Example: Configuring Compression of Voice Traffic
Configure compression on a T1 interface with MLPPP encapsulation. Configure fragmentation for all IP packets larger than 128 bytes.
