Jim Gogan on Appletalk at UNC-CH

 

In fact, we STRONGLY, STRONGLY, STRONGLY (can I say that louder?)

recommend that folks using AppleTalk-based services look at IP

alternatives. Apple now provides (as indicated below) printing over IP,

and with AppleShareIP alternatives, there are file sharing approaches

using IP as well. There are three basic (although I could easily add to

this list) reasons why we make this recommendation:

 

(1) AppleTalk (the protocol) does not scale well; it was designed for

small workgroup networks. The dynamic mechanism of choosing node

addresses, the 10 second broadcast interval of RTMP packets, the impact

of the AppleTalk Echo Protocol, the inability for zone information to be

dynamically propagated across routers, the kludge known as "extended

network" addresses all are indications of that.

 

(2) AppleTalk (the protocol) is inherently slower than IP; even Apple

has published findings that with the same hardware doing the same things

over the same switched 10 Mb/sec Ethernet, what can generate 9.3 Mb/sec

with IP can only do 7 Mb/sec. On a 100 Mb/sec connection, AppleTalk can

only generate AT MOST 35 Mb/sec. The reasons for this: the AppleTalk

ATP retry-acknolwedgement algorithm is nowhere near as efficient or as

effective as TCP and its congestion control/flow control mechanisms, and

Datagram Delivery Protocol (DDP) in AppleTalk only uses datagram packets

no larger than 586 bytes, even though an Ethernet frame can be 1500

bytes in length.

 

(3) A larger number of vendors (old and newer startups) are not

supporting AppleTalk in the next generation of Layer 4 gigabit speed

switches. Some are not even supporting IPX. The networking world is

becoming an IP world -- we will need to be ready for it.

 

-- Jim Gogan

Director, ATN Networking and Communications