ZyXEL P-2602HW-D3A User Guide - Page 162

Quality of Service QoS

Page 162 highlights

P-2602H(W)(L)-DxA Series User's Guide Table 55 VoIP > SIP Settings > Advanced LABEL Back Apply Cancel DESCRIPTION Click this to return to the SIP Settings screen without saving your changes. Click this to save your changes and to apply them to the ZyXEL Device. Click this to set every field in this screen to its last-saved value. 11.10 Quality of Service (QoS) Quality of Service (QoS) refers to both a network's ability to deliver data with minimum delay, and the networking methods used to provide bandwidth for real-time multimedia applications. 11.10.1 Type Of Service (ToS) Network traffic can be classified by setting the ToS (Type Of Service) values at the data source (for example, at the ZyXEL Device) so a server can decide the best method of delivery, that is the least cost, fastest route and so on. 11.10.2 DiffServ DiffServ is a class of service (CoS) model that marks packets so that they receive specific perhop treatment at DiffServ-compliant network devices along the route based on the application types and traffic flow. Packets are marked with DiffServ Code Points (DSCPs) indicating the level of service desired. This allows the intermediary DiffServ-compliant network devices to handle the packets differently depending on the code points without the need to negotiate paths or remember state information for every flow. In addition, applications do not have to request a particular service or give advanced notice of where the traffic is going.1 11.10.2.1 DSCP and Per-Hop Behavior DiffServ defines a new DS (Differentiated Services) field to replace the Type of Service (TOS) field in the IP header. The DS field contains a 2-bit unused field and a 6-bit DSCP field which can define up to 64 service levels. The following figure illustrates the DS field. DSCP is backward compatible with the three precedence bits in the ToS octet so that nonDiffServ compliant, ToS-enabled network device will not conflict with the DSCP mapping. Figure 89 DiffServ: Differentiated Service Field DSCP (6-bit) Unused (2-bit) 1. The ZyXEL Device does not support DiffServ at the time of writing. 162 Chapter 11 Voice

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P-2602H(W)(L)-DxA Series User’s Guide
162
Chapter 11 Voice
11.10
Quality of Service (QoS)
Quality of Service (QoS) refers to both a network's ability to deliver data with minimum delay,
and the networking methods used to provide bandwidth for real-time multimedia applications.
11.10.1
Type Of Service (ToS)
Network traffic can be classified by setting the ToS (Type Of Service) values at the data
source (for example, at the ZyXEL Device) so a server can decide the best method of delivery,
that is the least cost, fastest route and so on.
11.10.2
DiffServ
DiffServ is a class of service (CoS) model that marks packets so that they receive specific per-
hop treatment at DiffServ-compliant network devices along the route based on the application
types and traffic flow. Packets are marked with DiffServ Code Points (DSCPs) indicating the
level of service desired. This allows the intermediary DiffServ-compliant network devices to
handle the packets differently depending on the code points without the need to negotiate
paths or remember state information for every flow. In addition, applications do not have to
request a particular service or give advanced notice of where the traffic is going.
1
11.10.2.1
DSCP and Per-Hop Behavior
DiffServ defines a new DS (Differentiated Services) field to replace the Type of Service
(TOS) field in the IP header. The DS field contains a 2-bit unused field and a 6-bit DSCP field
which can define up to 64 service levels. The following figure illustrates the DS field.
DSCP is backward compatible with the three precedence bits in the ToS octet so that non-
DiffServ compliant, ToS-enabled network device will not conflict with the DSCP mapping.
Figure 89
DiffServ: Differentiated Service Field
Back
Click this to return to the
SIP Settings
screen without saving your changes.
Apply
Click this to save your changes and to apply them to the ZyXEL Device.
Cancel
Click this to set every field in this screen to its last-saved value.
Table 55
VoIP > SIP Settings > Advanced
LABEL
DESCRIPTION
1.
The ZyXEL Device does not support DiffServ at the time of writing.
DSCP
(6-bit)
Unused
(2-bit)