AudioCodes MediaPack MP-201B, User Manual, Page: 76 / 270

MP-20x Telephone Adapter 76 Document #: LTRT-50609
User's Manual
Parameter Description
Policy The class policy determines the policy of routing packets inside the class:
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Priority: Priority queuing utilizes multiple queues so that traf fi c is dis-
tributed among queues based on priority. This priority is de fi ned
according to packet priority, which can be de fi ned explicitly, by a DSCP
value, or by a 802.1p value.
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FIFO: First In First Out. This priority queue ignores any previously-
marked priority that packets may have.
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Fairness: The fairness algorithm ensures no starvation by granting all
packets a certain level of priority.
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RED: Random Early Detection. Utilizes statistical methods to drop
packets in a ‘probabilistic’ way before queues over fl ow. Dropping
packets in this way slows a source down enough to keep the queue
steady and reduces the number of packets that would be lost when a
queue over
fl ows and a host is transmitting at a high rate.
Schedule: By default, the class is always active. However, you can con fi gure
scheduler rules to de fi ne time segments during which the class may be
active.
8.2.2.1 Class Rules
Class rules de fi ne which packets belong to the class. They must be de fi ned to associate
packets that meet them with the shaping class. Without class rules, the shaping class has
no effect whatsoever. Each class can have outbound and/or inbound rules, for outgoing
and incoming traf
fi c respectively. For example, you can de fi ne that all outgoing packets
from computer A in your LAN belong to your VoIP class. These packets are limited to the
class settings (bandwidth, schedule, etc.). In addition, you can de
fi ne the traf fi c protocol
and priority for each rule (this is not mandatory as in Traf fi c Priority rules).
8.2.2.1.1 Inbound and Outbound Data
MP-20x can control outgoing data easily. It can queue packets, delay them, give
precedence to other packets, or drop them. This helps in resolving upload (Tx) traf
fi c
bottlenecks and in most cases is suf fi cient. However, in the case of download (Rx) traf fi c
bottlenecks, the ability to control the fl ow is much more limited. MP-20x cannot queue
packets, since in most cases the LAN is much faster then the WAN, and when MP-20x
receives a packet from the WAN, it passes it immediately to the LAN.
QoS for ingress data has the following limitations, which do not exist for outgoing data:
„ QoS can only be applied to TCP streams (UDP streams cannot be delayed).
„ No borrowing mechanism.
„ When reserving Rx bandwidth, it is strictly taken from the bandwidth of all other
classes.