HP 200 Series Services And Applications page 9

Features of HP Routers
Routing Services and Protocols
N o t e s
However, HP routers do not transparently bridge from a token ring to a
token ring (only between Ethernet/802.3 LANs); source-routing bridging
is used for this function. Also note that the source-routing bridging func-
tion does not provide communication between a source-routing system
on one ring and a non-source-routing system on another ring.
For details on the various types of bridging, refer to the "Bridging Service"
note later in this manual.
HP routers provide source-routing end-node support for the IP, IPX,
AppleTalk, and XNS routing services (described in the following sections).
These routing services are users of the underlying physical and data-link
layers, which allow them to route packets in token ring and mixed-media
environments.
IP Routing
The Internet Protocol (IP) is the network layer of the TCP/IP de facto
standard. It is supported by most major computer vendors and used
extensively in large networks such as the "Internet".
Generally, each corporation or similar entity sets up an internal network
composed of a number of routers and computers. Within this network, IP
allows the creation of subnets. Subnets usually reflect the organizational and
geographic structure of the entity. Communication between subnets can
optionally be enabled or disabled based on subnet address. This capability
simplifies traffic control and enhances network security.
Within the entity's internal network, IP routers exchange network informa-
tion using an interior gateway protocol (IGP). HP routers support two IGPs:
Routing Information Protocol (RIP) and Open Shortest Path First (OSPF)
protocol.
RIP is widely accepted as a standard router-to-router protocol for IP
networks. RIP selects network routes based on the lowest number of hops
required to traverse the network between subnets. In addition to RIP's stand-
ard features, HP routers allow users to adjust the hop count for a particular
network link to reflect lower link speed, higher delay, or other factors. This
feature allows RIP to be tuned to avoid network bottlenecks.
OSPF is another IGP standard that is better suited to larger, more complex
networks than RIP. OSPF provides more security with an option for pass-
word authentication on routing update messages. OSPF increases network
efficiency by using multicast addresses for update messages, sending
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