Reliant Octel 300 Spezifikationen PDF herunterladen (Seite 137)

IP Office Product Description

IP Office 4.2

Page 137

Issue 18.b.- (08 July 2008)

IP Packet Flow Control

While a high-performance switch forwards data packets at full wire speed to and from its ports simultaneously,

there may be times when a switch port may not be able to accept packets at the rate it is receiving them.

For example, the switch port may be receiving packets from multiple ports at the same time, or the switch

port may be receiving packets from a port operating at a faster speed. For instance, the sending port might be

operating at 100 Mbps, while the receiving port operates at 10 Mbps; or the sending port might operate at

1000 Mbps, while the receiving port operates at 100 or 10 Mbps. If data packets arrive for a port that is

saturated with other packets, the packets may overflow the port’s buffer, resulting in dropped packets and lost

data.

Flow control is a congestion-control mechanism that prevents data loss at congested ports. Flow control

prevents packet loss by controlling the flow of data from the transmitting device to ensure that the receiving

device can handle all of the incoming data.

IEEE 802.3 flow control is used on Avaya IP telephones operating in full-duplex mode. If the receiving device

becomes congested, it sends a pause frame to the transmitting device. The pause frame instructs the

transmitting device to stop sending packets for a specific period of time. The transmitting device waits the

requested time before sending more data.

VoIP Standards Supported

IP Office supports the following protocols and standards:

· H.323 V2 (1998), Packet-based multimedia communications systems.

· Q.931, ISDN user-network interface layer 3 specification for basic call control.

· H.225.0 (1998), Call signaling protocols and media stream packetization for packet-based multimedia

communication systems.

· H.245 (1998), Control protocol for multimedia communication.

· Session Initiation Protocol.

· Audio CODECs:

· G.711 A-law/U-law.

· G.723.1 MP-MLQ.

· G.729 Annex A – CS-ACELP.

· Silence Suppression.

· Fax Relay (IP Office to IP Office Fax Transport over IP).

· Local End Echo Cancellation 25ms.

· Out of band DTMF.

· Jitter buffer, 5 frames of jitter buffer.

· Internet Standards/Specification (in addition to TCP/UDP/IP).

· RFC 1889 – RTP/RTCP, Real Time and Real Time Control Protocol.

· RFC 2507, 2508, 2509 – Header Compression.

· RFC 2474 – DiffServ, Type of Service field configurable.

· RFC 1990 - PPP Fragmentation.

· RFC 1490 - Encapsulation for Frame Relay.

· RFC 2686 - Multiclass Extensions to Multilink PPP.

· RFC 3261 - Session Initiation Protocol (SIP).

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