BAP: PPP Bandwidth Allocation Protocol and

The Bandwidth Allocation Protocol (BAP) and the Bandwidth Allocation Control Protocol (BACP), provide Multilink PPP peers with the ability to manage link utilization and bandwidth on demand. Once connection between peers is successfully negotiated using BACP, peer nodes can use the Bandwidth Allocation Protocol (BAP) to negotiate bandwidth allocation.

BACP can operate over any physical interface that is PPP multilink capable and has a dial capability. Initially, BACP supports ISDN and asynchronous serial interfaces. BACP allows multilink implementations to interoperate by providing call control through the use of link types, speeds, and telephone numbers, and links being brought up and removed quickly. BACP informs both ends of the link when links are added or removed from a multilink bundle.

BAP defines packets, parameters and negotiation procedures to allow two endpoints to negotiate adding and dropping links from a multilink bundle, which allows dynamic bandwidth allocation. BAP also specifys which peer is responsible for various decisions regarding managing bandwidth during a multi-link connection. After BACP reaches the opened state, either peer MAY request another link be added to the bundle by sending a BAP Call- or Callback-Request packet. A Call-Request packet is sent if the implementation wishes to originate the call for the new link, and a Callback-Request packet is sent if the implementation wishes its peer to originate the call for the new link. The implementation receiving a Call- or Callback-Request MUST respond with a Call- or Callback-Response with a valid Response Code. The removal of a link is controlled by a link drop message in BAP.

Protocol Structure 

BAP Packet structure:

8	16bit	Variable
Type	Length	Data

• Type - Indicates the type of the BAP Datagram Option. This field is binary coded Hexadecimal.
• Length - Length of the BAP packet.

BACP packet structure:

• Code - Decimal value which indicates the type of BACP packet.
• Identifier - Decimal value which aids in matching requests and replies.
• Length - Length of the BACP packet, including the Code, Identifier, Length and Data fields.
• Data - Variable length field which may contain one or more configuration options.

BAP and BACP are defined by IETF (http://www.ietf.org ).

http://www.javvin.com/protocol/rfc2125.pdf : The PPP Bandwidth Allocation Protocol (BAP) / The PPP Bandwidth Allocation Control Protocol (BACP).