RAF - Resource Allocation Frames

Synchronous Bandwidth Allocation

Guaranteed transmission time respectively some kind of committed information rate can be assigned to FDDI adapters via synchronous bandwidth allocation (SBA). There are three SBA commands:

1 = request

2 = report

3 = change

RAF Request

Param.

Type RAF Request: Allocation Request

====== =====================================================================

0x0015 ResourceType

Always set to 'synchronous bandwidth':

0x00000001.

0x0016 SBACommand

0x00000001 = request allocation.

0x0017 SBAPayloadRequest

Request for bandwidth for user data transmission (number of bytes

per 125 µs).

0x0018 SBAOverheadRequest

Request for bandwidth for transmission of necessary protocol

overhead (number of bytes per token rotation: T_Neg).

0x0019 AllocationAddress

MAC source address of requesting station; has to be repeated

by the response frame. This address may also be a group address.

0x001A Category

Category of requested or assigned synchronous bandwidth.

0x001B MaxTNeg

Maximum T_Neg value acceptable for transmission of synchronous data.

0x001C MinSegment

Minimum synchronous data rate (bytes per frame) acceptable.

0x320B PathType

Designates the path synchronous bandwidth is requested for

(primary or secondary). All following parameters refer to this

path.

0x320F CurrentSBAPayload

Current bandwidth assigned for user data transmission (bytes

per 125 µs).

0x3210 CurrentSBAOverhead

Current bandwidth assigned for transmission of necessary

protocol overhead (bytes per token rotation: T_Neg).

Param.

Type RAF Request: Allocation Response

====== =====================================================================

0x0012 ReasonCode

Code of (un)successfull operation completion.

0x0015 ResourceType

Always set to 'synchronous bandwidth':

0x00000001.

0x0016 SBACommand

0x00000001 = request allocation.

0x0019 AllocationAddress

MAC source address of requesting station; has to be repeated

by the response frame. This address may also be a group address.

0x001A Category

Category of requested or assigned synchronous bandwidth.

0x001D SBAAllocatable

Remaining non-synchronous bandwidth.

0x320B PathType

Designates the path synchronous bandwidth is requested for

(primary or secondary). All following parameters refer to this

path.

0x320F CurrentSBAPayload

Current bandwidth assigned for user data transmission (bytes

per 125 µs).

0x3210 CurrentSBAOverhead

Current bandwidth assigned for transmission of necessary

protocol overhead (bytes per token rotation: T_Neg).

RAF Report

Param.

Type RAF Report: Allocation Request

====== =====================================================================

0x0015 ResourceType

Always set to 'synchronous bandwidth':

0x00000001.

0x0016 SBACommand

0x00000002 = report allocation.

Param.

Type RAF Report: Allocation Response

====== =====================================================================

0x0015 ResourceType

Always set to 'synchronous bandwidth':

0x00000001.

0x0016 SBACommand

0x00000002 = report allocation.

0x320B PathType

Designates the path synchronous bandwidth is requested for

(primary or secondary). All following parameters refer to this

path.

0x320F CurrentSBAPayload

Current bandwidth assigned for user data transmission (bytes

per 125 µs).

0x3210 CurrentSBAOverhead

Current bandwidth assigned for transmission of necessary

protocol overhead (bytes per token rotation: T_Neg).

Optional with data transmission on secondary ring:

0x320B PathType

Designates the path synchronous bandwidth is requested for

(primary or secondary). All following parameters refer to this

path.

0x320F CurrentSBAPayload

Current bandwidth assigned for user data transmission (bytes

per 125 µs).

0x3210 CurrentSBAOverhead

Current bandwidth assigned for transmission of necessary

protocol overhead (bytes per token rotation: T_Neg).

RAF Change

Param.

Type RAF Change: Allocation Request

====== =====================================================================

0x0015 ResourceType

Always set to 'synchronous Bandwidth':

0x00000001.

0x0016 SBACommand

0x00000003 = change allocation.

0x320B PathType

Designates the path synchronous bandwidth is requested for

(primary or secondary). All following parameters refer to this

path.

0x320F CurrentSBAPayload

Current bandwidth assigned for user data transmission (bytes

per 125 µs).

0x3210 CurrentSBAOverhead

Current bandwidth assigned for transmission of necessary

protocol overhead (bytes per token rotation: T_Neg).

0x001A Category

Category of requested or assigned synchronous bandwidth.

Param.

Type RAF Change: Allocation Response

====== =====================================================================

0x0015 ResourceType

Always set to 'Synchronous Bandwidth':

0x00000001.

0x0016 SBACommand

0x00000003 = change allocation.

0x320B PathType

Designates the path synchronous bandwidth is requested for

(primary or secondary). All following parameters refer to this

path.

0x320F CurrentSBAPayload

Current bandwidth assigned for user data transmission (bytes

per 125 µs).

0x3210 CurrentSBAOverhead

Current bandwidth assigned for transmission of necessary

protocol overhead (bytes per token rotation: T_Neg).

0x001A Category

Category of requested or assigned synchronous bandwidth.

Optional with data transmission on secondary ring:

0x320B PathType

Designates the path synchronous bandwidth is requested for

(primary or secondary). All following parameters refer to this

path.

0x320F CurrentSBAPayload

Current bandwidth assigned for user data transmission (bytes

per 125 µs).

0x3210 CurrentSBAOverhead

Current bandwidth assigned for transmission of necessary

protocol overhead (bytes per token rotation: T_Neg).

0x001A Category

Category of requested or assigned synchronous bandwidth.