HP 200 Series Services And Applications page 63

Routing in Token Ring and Mixed-Media
Environments
The IP, IPX, XNS, and AppleTalk routing services provide support for
networks containing source-routing bridges. Source-routing support has not
been provided for DECnet. Therefore, the following discussion of routing
applies only to IP, IPX, XNS, and AppleTalk.
Source routing may be enabled or disabled for each routing service on each
interface. The routing services act as end systems (the PC or the mainframe
in figure 3), from a source-routing perspective. This is what is meant by
support for source-routing bridges. The routing services never function as
source-routing bridges.
The routing services are users of the underlying physical and data-link
layers. Thus, the routing services do not modify data-link-layer headers
(source and destination station addresses, source-routing information, etc.).
Since the routing services' operations are independent of the data-link layer,
there are no media-dependent, topological restrictions on the use of routers
in large mixed-media networks. The network topology shown in figure 4
illustrates this point. Each computer in the network is able to communicate
with any other computer. This assumes that all systems communicate using
routable protocols supported on token rings (IP, IPX, XNS, and AppleTalk),
and that the routers are configured to route (not bridge) these protocols.
On HP routers, the bridging service as well as the routing services listed
above all support networks with token rings and mixed media. Routing is
generally better at handling them than bridging, so give preference to routing
if you can. However, the following two conditions will require you to use
bridging instead of routing.
Non-routable protocols (such as SNA, NetBIOS, 3270) are used on
the network.
The network is not sermented properly to allow routing.
Most of the rest of this bridging note describes how the bridging service
handles source routing and mixed media.
Bridging Service
Token Ring Solutions
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