Addressing
Regardless of what is happening at the upper layers, the IPX addressing scheme is an integral part of routing. NetWare is a software router. The routing table consists of unique internal (server) and external (wire) IPX numbers. The internal network number is internal to the file server and always ends in 0000.0000.0001. It is a logical network that routes packets to the physical networks to which a server is attached. Think of it like a loopback interface on a Cisco router. The external network number is the wire ID analogous to a subnet in IP. Periodic broadcasts are sent out on the wire, and the network and encapsulation numbers must match (as you saw in the chapter scenario).
You viewed the router routing table with show ipx route and the services table with show ipx servers. You can even see the server list from the client with slist/nlist. You viewed the Novell routing table on the server with display networks and the Novell SAP table with display servers.
NetWare addresses consist of an 80-bit network.host hex number. The network number is 32 bits—an 8-digit hex number where the leading 0s are suppressed. The host (node) number is 48 bits, or a 6-digit hex number. Because the MAC address is the node address, there is no need for ARP in an IPX environment. Hexadecimal is Base16, where the digits 0 to 9 and the letters A to F are available. The following Cisco commands are quite helpful for addressing:
show ipx interface brief
show ipx interface interface
show protocols
NOTE
Novell offers the Novell Network Registry, which is a service to assign and track IPX network addresses and organization names. The Registry assigns a contiguous block of addresses unique to your organization. This way when companies merge or want to interconnect, the numbers are ensured to be unique. Send an e-mail to [email protected] or call 408 577-7506 to receive a copy of the Novell Network Registry if you are still using IPX.
How do you determine the network number? You could ask someone, use Cisco Discovery Protocol (CDP), or use the NetWare config command at the file server console.
You have certainly witnessed practical examples of where you need to know addressing. Another example is an access list. Unlike IP, IPX standard access lists (800 to 899) include both source and destination addresses. Therefore, many things can be accomplished with either a standard ACL or a SAP filter (1000 to 1099). If you need extended protocol or socket capabilities, extended IPX ACLs (900 to 999) provide that.