System information

The Network Layer
Book Title
13-290
The Network Layer
VINES uses the VINES Internetwork Protocol (VIP) to perform Layer 3 activities (including
internetwork routing). VINES also supports its own Address Resolution Protocol (ARP), its own
version of the Routing Information Protocol (RIP) called the Routing Table Protocol (RTP), and the
Internet Control Protocol (ICP), which provides exception handling and special routing cost
information. ARP, ICP, and RTP packets are encapsulated in a VIP header.
VIP
VINES network-layer addresses are 48-bit entities subdivided into network (32 bits) and subnetwork
(16 bits) portions. The network number is better described as a server number because it is derived
directly from the server’s key (a hardware module that identifies a unique number and the software
options for that server). The subnetwork portion of a VINES address is better described as a host
number because it is used to identify hosts on VINES networks. Figure 13-2 illustrates the VINES
address format.
Figure 13-2 The VINES Address Format
The network number identifies a VINES logical network, which is represented as a two-level tree
with the root at a service node. Service nodes, which are usually servers, provide address resolution
and routing services to clients, which represent the leaves of the tree. The service node assigns VIP
addresses to clients.
When a client is powered on, it broadcasts a request for servers. All servers that hear the request
respond. The client chooses the first response and requests a subnetwork (host) address from that
server. The server responds with an address consisting of its own network address (derived from its
key), concatenated with a subnetwork (host) address of its own choosing. Client subnetwork
addresses are typically assigned sequentially, starting with 8001H. Server subnetwork addresses are
always 1. The VINES address selection process is shown in Figure 13-3.
Network number
1323348
Subnet number
(Server number) (Host number)