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CHAPTER 5: Protocol Overview
5. Protocol Overview
The EPS supports 4 major protocols: NetWare, TCP/IP, AppleTalk
(EtherTalk), and LAT. The 4 protocols provide varying support for printing,
and each is discussed below.
For all 4 protocols: On the EPS, the term “service” denotes a printing
resource that another node can access. Services must be attached to the EPS
before a network node can access the print devices. You can disable certain
protocols on a specific service. For example, you could prevent NetWare
users from using the parallel port service. By default, there are 2 services on
the EPS—one for the serial port and one for the parallel port. Normally, LAT
is disabled on both services, while AppleTalk is disabled on the parallel port
service. The explanations for these defaults are described in Sections 5.1
through 5.4.
TCP/IP is the only protocol that you need to configure with an explicit
address. AppleTalk chooses an address dynamically, and LAT and NetWare
use the server’s hardware address as the network address.
The protocols supported advertise themselves in different ways. For this
reason, you may see a protocol that you don’t use coming from the EPS.
For example, you might see a NetWare packet even though you only have
AppleTalk traffic on your network. That’s because the EPS needs to:
1. Find any other nodes that might happen to start operation, and
2. Alert any other nodes that it will service these various protocols.
The EPS will do this regardless of whether it recognizes any hosts of that
type on the network. In general, TCP/IP and AppleTalk will not generate any
extra traffic, and respond only to queries from other nodes. NetWare and
LAT will generate any occasional (every 10-120 seconds) packet to alert other
nodes of the EPS’s presence. Also, the EPS will send an occasional NetWare
broadcast to locate any other NetWare file servers. The EPS will also send a
broadcast for the MOP (DECnet) remote console. You can eliminate some
or all of these, since there will be no NetWare or LAT announcements if the
protocol is not enabled on any of the EPS’s services. You cannot disable the
MOP broadcasts, but they should only appear every 10 minutes.