IBM Token-Ring networking allows you
to establish connections from your machine
to other machines in these ways:
on a local ring
A local ring is the Token-Ring physically attached to
to other rings using gateways
A TCP/IP gateway is created when you configure TCP/IP over more than
one Token-Ring adapter on the same machine. Those adapters
must be connected to different rings and have different
IP subnet addresses.
TCP/IP gateways connected to Token-Ring networks
in this manner will route TCP/IP traffic to the rings
without using Token-Ring source routing.
Similar gateways can be set up using the OSI and
to other networks using a Token-Ring bridge
A Token-Ring bridge is a dedicated piece of computer hardware
connected to several Token-Rings. The bridge routes frames
between the rings.
All Token-Rings connected via bridges will appear as a single
ring to each station on the network.
Token-Ring source routing allows
your adapter to route network traffic across Token-Ring bridges
regardless of the protocol stack used by any of the
If you intend to connect your machine to a network that
includes a bridge, and if you intend to send information
from your machine across the bridge,
you must use automatic Token-Ring source routing.
The Network Configuration Manager
offers you two Token-Ring source routing options:
These options are set for individual adapters; they are not
global to all Token-Ring adapters configured in your system.
Source routing is not enabled;
frames are not routed beyond the local ring.
Source routing is enabled; frames include source routing
information and the DLPI module performs
source routing on behalf of the protocol stack. This is the
These options take effect for all protocol stacks
using the specified adapter. It is possible for stacks
to override default source routing without
affecting the source routing mode used by other stacks.
In such cases, the source routing is said
to be in ``stack'' mode for the specific
For example, SCO TCP/IP and
IPX/SPX can be configured to use automatic source
routing of a Token-Ring adapter, while a third-party
SNA product can provide stack mode
routing when using the same adapter.
Protocol stacks provide stack mode routing
if the characteristics of the protocol
prevent it from working with
the general purpose SCO source routing facility,
or if a more specialized source routing
that is designed to work
optimally for a particular protocol is desired.
Although no SCO protocol stacks
currently provide stack mode source routing,
third-party networking products
might contain such functionality.
Source route optimization
© 2003 Caldera International, Inc. All rights reserved.
SCO OpenServer Release 5.0.7 -- 11 February 2003