Настройка QoS для RTP пакетов на роутере

[amper]

Имеем два SHDSL роутера Telindus 1421, между WAN интерфейсами 2.3мбита, интерфейсы в режиме PPP (routing).

 

Задача, приоретизировать на этих интерфейсах пересылку RTP пакетов, по которым бегает VoIP трафик. Насколько я знаю, каждая софтина, генерящая VoIP трафик, должна изменять DSCP в заголовке пакета, вопрос в том, как это сделать на роутере, мануал предлагает следующие вариации на тему:

 

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telindus1421Router/router/trafficPolicy[ ]/method

Use this attribute to choose an IP traffic policy method. This IP traffic policy is then used to …

• determine, on traffic overload conditions, how and which queues are filled with the “excess” data.

• do policy based routing.

• filter data on an interface.

 

Собственно методы:

 

1) tosDiffServ The data is redirected to the queues based on DiffServ regarding class and drop precedence.

This means that, depending on their DSCP field in the TOS byte, some packets are moved to other queues and/or dropped sooner than other packets in case the queue is full.

 

The highest 3 bits of the DSCP field are mapped as follows:

The next 2 bits of the DSCP field define the drop levels:

 

telindus1421Router/router/trafficPolicy[ ]/dropLevels

Use this attribute to define for each user configurable queue, how many

packets may be queued before they are dropped.

The dropLevels table contains the following elements:

 

Element & Description

dropLevel1 - Use this element to set the maximum length (drop level 1), in packets, of each user configurable queue.

dropLevel2 - Use this element to set the maximum length (droplevel 2), in packets, of each user configurable queue.

dropLevel3 - Use this element to set the maximum length (droplevel 3), in packets, of each user configurable queue.

 

2) tosMapped In tos2QueueMapping table specify which data has to be redirected to which queue. If an overload condition occurs, then a packet is redirected to the specified queue when the criteria as specified in the

tos2QueueMapping table are met.

 

Element & Description

startTos - Use these elements to set the TOS byte value. Packets that have a TOS byte value within the specified range are redirected to the targetQueue.

 

endTos - targetQueue Use this element to set the destination queue. The targetQueue element has the following values:

Queue1, Queue2, Queue3, Queue4, Queue5, lowDelayQueue.

 

interface - Use this element to set the destination interface for a packet matching an entry in the tos2QueueMapping

table. This is policy based routing. Type the name of the interface in the interface element, e.g. lan.

 

gateway - Use this element to set the gateway for a packet matching an entry in the tos2QueueMapping table. This

is policy based routing.

 

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Как я понимаю, достаточно варианта tosDiffServ, но какие величины указывать в dropLevels? Кроме того, в таблице dropLevers еще 5 уровней:

 

Их назначение мануал не объясняет.