推荐给好友

打印

加入收藏

更新于2008-06-25 21:44:09

5.3 Logical service interfaces

• A DS may be created from many different technologies including current IEEE 802 wired LANs. IEEE Std 802.11 does not constrain the DS to be either data link or network layer based. Nor does IEEE Std 802.11 constrain a DS to be either centralized or distributed in nature.
•  IEEE Std 802.11 explicitly does not specify the details of DS implementations. Instead, IEEE Std 802.11 specifies services. The services are associated with different components of the architecture. There are two categories of IEEE 802.11 service—the station service (SS) and the distribution system service (DSS). Both categories of service are used by the IEEE 802.11 MAC sublayer.
• The complete set of IEEE 802.11 architectural services are as follows:
  a) Authentication
  b) Association
  c) Deauthentication
  d) Disassociation
  e) Distribution
  f) Integration
  g) Data confidentiality
  h) Reassociation
  i) MSDU delivery
  j) DFS
  k) TPC
  l) Higher layer timer synchronization (QoS facility only)
  m) QoS traffic scheduling (QoS facility only)
• This set of services is divided into two groups: the SS and the DSS. The SS are part of every STA. The DSS are provided by the DS.

5.3.1 SS

• The service provided by STAs is known as the SS.
• The SS is present in every IEEE 802.11 STA (including APs, as APs include STA functionality). The SS isspecified for use by MAC sublayer entities. All conformant STAs provide SS.
• The SS is as follows:
  a) Authentication
  b) Deauthentication
  c) Data confidentiality
  d) MSDU delivery
  e) DFS
  f) TPC
  g) Higher layer timer synchronization (QoS facility only)
  h) QoS traffic scheduling (QoS facility only)

5.3.2 DSS

• The service provided by the DS is known as the DSS.
• This service is represented in the IEEE 802.11 architecture by arrows within the APs, indicating that theservice is used to cross media and possibly address space logical boundaries. An AP is a logical entity, andthe functions described may be shared by one or more physical entities.
• The services that comprise the DSS are as follows:
  a) Association
  b) Disassociation
  c) Distribution
  d) Integration
  e) Reassociation
  f) QoS traffic scheduling (QoS facility only)
• DSSs are specified for use by MAC sublayer entities.
• Figure 5-7 combines the components from previous figures with both types of services to show the completeIEEE 802.11 architecture.

<<PREV NEXT>>