Recommendations For End-To-End Qos; Diffserv - Avaya Application Solutions Deployment Manual

Recommendations for end-to-end QoS

When end-to-end QoS is desired, Avaya recommends using DiffServ, a Layer 3 CoS method.
Modern can map DiffServ Code Points (DSCP) to 802.1p priority values, so 802.1p tags can be
recreated on each Ethernet link. This functionality is supported in Avaya Layer 3 switches, and
the X330 WAN module.
IEEE 802.1p states a standard according to which these bits are used for CoS. The precedence
is listed in Table 73: IEEE 802.1 precedence and service
Table 73: IEEE 802.1 precedence and service mapping
User priority
000
001
010
011
100
101
110
111

DiffServ

The Differentiated Services (DiffServ) prioritization scheme redefines the existing TOS byte in
the IP header (Figure 83: Differentiated Services (DiffServ) TOS byte
combining the first 6 bits into 64 possible combinations. This use of the TOS byte is still
evolving, but can be used now by Communication Manager, IP Telephones, and other network
elements such as routers and switches in the LAN and WAN.
Service mapping
Default, assumed to be best effort
Reserved, less than best effort
Reserved
Reserved
Delay sensitive, no bound
Delay sensitive, 100 ms bound
Delay sensitive, 10 ms bound
Network control
mapping.
on page 318) by
Issue 3.4.1 June 2005
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