HP JetAdvantage Security Manager 10 Device E-LTU Instrukcja Użytkownika Pobierz pdf (Strona 81)

remained available as a Macintosh communications suite until 2009 when support was dropped due

to its diminishing usefulness on large enterprise networks. Using a very simplistic approach,

AppleTalk connected Macs together in small local area networks and automatically managed a name

based approach to host identification and network communication. Much of the Appletalk feature set

was later introduced in Bonjour and Universal Plug and Play. Appletalk contained several primary

protocols; Appletalk Address Resolution Protocol (AARP), Name Binding Protocol (NBP), Printer

Access Protocol (PAP), Routing Table Maintenance Protocol (RTMP) and Zone Information Protocol

(ZIP), just to name a few. AARP allowed hosts to generate their own addresses and NBP was a

dynamic system for mapping network addresses to user-readable names. PAP managed printer

connections and other servers, plus conveyed status and coordinate actual data transfer. RTMP

managed routing information over Appletalk networks and ZIP managed the relationship between

network numbers and zones.

The Appletalk protocol is available on many of HP’s existing installed base of legacy printing devices,

but has since been eliminated on newer Future Smart devices. On HP devices that support it,

Appletalk is enabled by default. At Appletalk startup, a socket is created and set to listen for any

print requests. Printer status and the printer’s ability to accept jobs is provided to the network at this

time. When a client request for print is received, a peripheral channel is locked for Printer Access

Protocol (PAP) exclusive use. Data is then forwarded to the printer and the printer establishes reverse

channel communication to complete the handshake. Synchronization between the client and printer

continues during the forwarding of data. The client then sends a “connection close” request when

data transfer is complete, signaling the peripheral to unlock the PAP channel for future use.

Security risks associated with Appletalk are minimal, although Denial of Service (DoS) attacks over

Appletalk networks have been recorded. For devices that still support Appletalk, disabling is

recommended unless the protocol is required in the print environment. Once again, it is important to

note that Appletalk is unsupported on Mac OS X v10.6 (2009) and later operating systems. Today, it

would be rare to find any Appletalk use in most enterprise print environments.

Data Link Control (DLC) / Logical

Data link control (DLC) and logical link control (LLC), which operate at the ISO link layer, are typically

used in smaller networks. DLC traffic, which uses the MAC address as its transport, can only be

routed within a single subnet.

Data Link Control (DLC) was originally developed for IBM mainframe communications. The term DLC

referred to a higher level API to the Logical Link Control (LLC) protocol that was defined by IBM. DLC

was designed as a protocol for sending data from a print server to an HP networked printer, not as a

general network communications protocol. Although there is no DLC interface present in JetDirect, the

LLC printing solution is historically referred to as DLC or DLC/LLC. LLC is a reliable, non-routable

protocol that is supported in legacy Jetdirect products.

1 2 ... 76 77 78 79 80 81 82 83 84 85 86 ... 115 116

Brak uwag

HP JetAdvantage Security Manager 10 Device E-LTU Instrukcja Użytkownika Strona 81