1. Considerations on WDS Addressing Tricci So 7 May 2004 Prepared by

2. Why do we need to talk about WDS Addressing?
7 May 2004
IEEE ESS Mesh PAR
Scope:
To develop an IEEE Extended Service Set (ESS) Mesh* with an IEEE Wireless Distribution System (WDS) using the IEEE MAC/PHY layers that supports both broadcast/multicast and unicast delivery over self-configuring multi-hop topologies.
Purpose:
The IEEE (2003 edition) standard provides a four-address frame format for exchanging data packets between APs for the purpose of creating a Wireless Distribution System (WDS), but does not define how to configure or use a WDS. The purpose of the project is to provide a protocol for auto-configuring paths between APs over self-configuring multi-hop topologies in a WDS to support both broadcast/multicast and unicast traffic in an ESS Mesh using the four-address frame format or an extension.
Why do we need to talk about WDS Addressing?
Tricci So

3. Let’s Examine How WDS Addressing was Defined?
7 May 2004
Let’s Examine How WDS Addressing was Defined?
To/From DS Values
Meaning
To DS = 0
From DS = 0
A data frame direct from one STA to another STA within the same IBSS, as well as all management and control type frames
To DS = 1
Data frame destined for the DS.
From DS = 1
Data frame exiting the DS
Wireless distribution system (WDS) frame being distributed from one AP to another AP.
These fields are defined to indicate how the “four addresses” are used for packet forwarding decision using the Link Layer WDS Addressing.
Tricci So

4. However, DS is NOT ONLY Data Link Based ...
7 May 2004
However, DS is NOT ONLY Data Link Based ...
ANSI/IEEE Std , 1999 Edition, page 14 – 5.3: The IEEE architecture allows for the possibility that the DS may NOT be identical to an existing wired LAN. A DS may be created from many different technologies including current IEEE 802 wired LANs. IEEE does NOT constrain the DS to be either DATA or NETWORK layer based. Nor does IEEE constrain a DS to be either centralized or distributed in nature.
And, As You Know. . .
WDS =
Wireless DS
Tricci So

5. A Little History of OSI Model & IEEE 802.2
7 May 2004
A Little History of OSI Model & IEEE 802.2
OSI
Model
Network
Data
Link
Physical
IEEE
802
Model
Logical
Link
Control
MAC
Access
Physical
IEEE
802
Standards
802.2 LLC
CSMA/CD
CSMA/CA
Token Bus
Token Ring
802.4
Physical
802.11
802.3
802.5
IEEE’s 802 working committee separated Data Link Layer of the OSI into two sublayers:
=> Logical Link Control (LLC) & Medium Access Control (MAC)
The purpose of the LLC sublayer is to provide a consistent interface to Network Layer
=> ONE LLC sublayer to ALL 802 MAC sublayers
Tricci So

6. Protocol Stack Traversal . . . . .
7 May 2004
Protocol Stack Traversal
Network
Data
Link
Physical
EACH Layer
“IS” its own
Addressing
ORIGINATOR
as well as
TERMINATOR
Network
Header
Data
Network Layer Addressing
Link Layer Addressing
Data Link
Header
Network
Data
Physical
Header
Data Link
Network
Data
Packet Delivery Decision is
determined by the addressing
of the given infrastructure which
is operating at a particular layer
Tricci So

7. Network Layer WDS Addressing Considerations
7 May 2004
Network Layer WDS Addressing Considerations
Link Layer
WDS
Addressing
Network Layer
WDS
Addressing
confusing
Reuse SAME “T0-DS/From-DS”
Indicator for Network Layer WDS
Addressing would be confusing &
inappropriate?!
Tricci So

8. Recommendations Link-Layer Based WDS Network-Layer Based WDS
7 May 2004
Recommendations
Link-Layer Based WDS AP
MAC Layer
Addressing
Origination &
Termination
To DS = 1
From DS = 1
Network-Layer Based WDS AP
Network Layer
Addressing
Origination &
Termination
To DS = 1
From DS = 1
N/A
Tricci So

9. 7 May 2004
Backup Slide
Protocol Stack Communications
Tricci So

10. Protocol Stack Communications
7 May 2004
Protocol Stack Communications
Each layer is responsible for its own addressing to make packet processing, termination and forwarding decision.
Network
Data
Link
Physical
Logical
Control
MAC
Access
MAC
Access
Control
Physical
Tricci So