Shiro ADSL 2/2+ Ethernet Modem manual Quality of Service QoS

User Manual

Quality of Service (QoS)

Quality of service allows network administrators to configure the routers to meet the real time requirements for voice and video.

Different networks use different QoS markings like:

ToS network: ToS bits in the IP header

VLAN network: priority bits in the VLAN header

DSCP network: uses only 5 bits of the CoS

WLAN: WLAN QoS header.

The QoS framework is supported on all the above domains. How do you make them talk to each other? How can you make sure the priority from one network is carried over to another network? Class of service (CoS) is introduced as the common language for the QoS mappings. When QoS is enabled, the router has full control over packets from the time they enter the router till they leave the router.

This is how it works: The domain mapping (ToS bits, priority bits, etc.) of a packet needs to be translated to CoS when the packet enters the router, and vice versa, the CoS of a packet needs to be translated back to the domain mapping when the packet leaves the router.

There are 6 types of CoS (in descending priority):

CoS1

CoS2

CoS3

CoS4

CoS5

CoS6

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