
DiffServ
Recommendations for end-to-end QoS
When
IEEE 802.1p states a standard according to which these bits are used for CoS. The precedence is listed in Table 54: IEEE 802.1 precedence and service mapping.
Table 54: IEEE 802.1 precedence and service mapping
User priority | Service mapping |
|
|
000 | Default, assumed to be best effort |
|
|
001 | Reserved, less than best effort |
|
|
010 | Reserved |
|
|
011 | Reserved |
|
|
100 | Delay sensitive, no bound |
|
|
101 | Delay sensitive, 100 ms bound |
|
|
110 | Delay sensitive, 10 ms bound |
|
|
111 | Network control |
|
|
DiffServ
The Differentiated Services (DiffServ) prioritization scheme redefines the existing TOS byte in the IP header (Figure 90: Differentiated Services (DiffServ) TOS byte on page 322) by 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.