Adaptive services interfaces include a voice services feature that allows you to specify interface type lsq-fpc/pic/port to accommodate voice over IP (VoIP) traffic. This interface uses compressed RTP (CRTP), which is defined in RFC 2508, Compressing IP/UDP/RTP Headers for Low-Speed Serial Links.
CRTP enables VoIP traffic to use low-speed links more effectively, by compressing the 40-byte IP/UDP/RTP header down to 2 to 4 bytes in most cases.
Voice services on the AS and MultiServices PICs support single-link PPP-encapsulated IPv4 traffic over the following physical interface types: ATM2, DS3, E1, E3, OC3, OC12, STM1, and T1, including the channelized versions of these interfaces.
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NOTE: On J-series Services Routers, you can configure CRTP with MLPPP or PPP logical interface encapsulation on link services ( |
Voice services do not require a separate service rules configuration.
Voice services also support LFI on M-series routers, except the M320 router. For more information about configuring voice services, see Voice Services Configuration Guidelines.
For link services IQ interfaces (lsq) only, you can configure CRTP with multiclass MLPPP (MCML). MCML greatly simplifies packet ordering issues that occur when multiple links are used. Without MCML, all voice traffic belonging to a single flow is hashed to a single link in order to avoid packet ordering issues. With MCML, you can assign voice traffic to a high-priority class, and you can use multiple links. For more information about MCML support on link services IQ interfaces, see Configuring Link Services and CoS.