|AURP, AppleTalk Update-based Routing Protocol|
|Protocol suites:||Appletalk, TCP/IP.|
|Protocol type:||Application layer routing protocol.|
The AURP protocol provides wide area routing enhancements to the AppleTalk routing protocols and is fully compatible with AppleTalk Phase 2.
The three major components of AURP are:
RFC 1504, pages 1, 6 and 7:
AURP includes many optional features for the presentation of network information. You can implement many of these optional features on routers that use either AURP or RTMP (Routing Table Maintenance Protocol) for routing-information propagation.
Wide Area Routing Enhancements. AURP provides AppleTalk Phase 2-compatible routing for large wide area networks (WANs). Key wide area routing enhancements provided by AURP include:
- Tunneling through TCP/IP internets and other foreign network systems.
- Point-to-point tunneling.
- Basic security-including device hiding and network hiding.
- Remapping of remote network numbers to resolve numbering conflicts.
- Internet clustering to minimize routing traffic and routing- information storage requirements.
- Hop-count reduction to allow the creation of larger internets improved use of alternate paths through hop-count weighting and the designation of backup paths.
RFC 1504, page 7:
AppleTalk tunneling allows a network administrator to connect two or more native internets through a foreign network system to form a large wide area network (WAN). For example, an AppleTalk WAN might consist of two or more native AppleTalk internets connected through a tunnel built on a TCP/IP internet. In such an AppleTalk WAN, native internets use AppleTalk protocols, while the foreign network system uses a different protocol family.
A tunnel connecting AppleTalk internets functions as a single, virtual data link between the internets. A tunnel can be either a foreign network system or a point-to-point link.
There are two types of tunnels, dual endpoint tunnels and multiple endpoint tunnels.
AURP implements multipoint tunneling by providing mechanisms for data encapsulation and the propagation of routing information to specific routers.
RFC 1504, pages 17 and 18:
Generally, exterior routers use null domain identifiers on point-to- point links, because there is no IP address to be administrated and the opposite end of the tunnel is already uniquely identified. However, an exterior router may use other domain-identifier formats.
The Point-to-Point Protocol (PPP) is a data-link-layer protocol that provides a standard method of encapsulating and decapsulating network-layer protocol information, and transmitting that information over point-to-point links. PPP includes an extensible Link Control Protocol (LCP) and a suite of Network Control Protocols (NCPs) that configure, enable, and disable various network-layer protocols.
When using AURP for routing-information propagation, a half-router uses a specific PPP protocol type to identify AURP routing-information packets-that is, packets preceded by a domain header. PPP provides separate channels for AppleTalk data packets and AppleTalk routing-information packets. Thus, a half-router can use DDP encapsulation to send AppleTalk data packets without including their domain headers. When using AURP, a half-router should accept both AppleTalk data packets that are preceded by domain headers and DDP-encapsulated packets.
|MAC header||IP header||UDP header||AURP packet|
[RFC 1378] The PPP AppleTalk Control Protocol (ATCP).
[RFC 1504] Appletalk Update-Based Routing Protocol: Enhanced Appletalk Routing.