User guide

A-30 Cisco 2500 Series Access Server User Guide
Desktop Protocols
IPX Directory Services
Novell servers advertise their presence throughout the IPX internetwork with the Service
Advertisement Protocol (SAP). Novell servers include file servers, print servers, and
directory servers. Each type of server is advertised by a SAP type number as well as its IPX
address.
SAP works like a distance vector routing protocol. Access servers and routers running IPX
build server tables based on the SAPs they have received, and they advertise the servers they
know to others with SAPs. Enter the command show ipx servers to see the server table in
an access server running Cisco IOS software.
When an IPX client starts up, it sends a Get Nearest Server (GNS) request on its connected
data link to locate the nearest Novell server. If there are no Novell servers on that data link,
the access server responds with the best available server (based on cost) in its server table.
Cisco IOS software has many features to control SAP overhead and GNS functionality. No
special configuration is required for standard SAP and GNS support.
IPX Data Link Encapsulations
Novell has defined four distinct encapsulations, or formats, for placing frames on a data link
such as Ethernet. In order for two or more IPX devices on a data link to communicate, they
must use the same encapsulation. Encapsulation on distinct data links do not have to agree
in order to maintain connectivity. You must determine the encapsulation that will be used
on each data link and network.
Table A-5 shows the four kinds of encapsulation available on Ethernet networks.
Table A-5 Ethernet Encapsulation Keywords
Novell Term Cisco Term Common Term
Ethernet_II arpa Ethernet
Ethernet_802.3 novell-ether raw
Ethernet_802.2 sap 802.2
Ethernet_SNAP snap snap