User Manual V2IU 4350 Converged Network Appliance
applied to traffic in both the upstream (LAN to WAN) and downstream (WAN to LAN) direction. Each direction is independent of the other and can support different size priority queues.
Classifying
High priority voice and video traffic generated by endpoint devices is automatically identified by the V2IU’s VoIP Application Layer Gateway. Other VoIP devices (not making use of the ALG) can be defined as
As the 4350 processes packets they are identified as either high or low priority based on this configuration. Packets identified as high priority are marked as such in the TOS bits of their IP header, allowing prioritization by downstream routers. The TOS field is set to 12 hexadecimal “minimize delay and maximize throughput.” This value overwrites any prior value.
Upstream Traffic Management
The 4350 appliance uses a combination of Class Based Queuing and simple classless queuing to send data in the upstream direction. The Class Based Queue (CBQ) consists of two priority classes (high and low), a scheduler to decide when packets need to be sent, and a traffic shaper to
Priority classes
Voice and video traffic is placed in the
Scheduler
High priority data is polled before lower priority data to reduce overall latency for voice traffic.
Traffic shaper
To smooth bursts from high speed data links (typically from the LAN Ethernet heading to the WAN) the 4350 appliance uses a buffer that clocks data out at rates not exceeding
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