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Internet Printing Protocol tested in Bake-Off No. 3

Nov 01, 2000, 07:52 (3 Talkback[s])
(Other stories by Kurt Pfeifle)

[ Thanks to Kurt Pfeifle for this report: ]

The Printer Working Group (PWG) has finished the third Bake-Off to test the interoperability of different implementations for IPP-enabled products. The IPP (Internet Printing Protocol) has been designed by the PWG and has the approval of the IETF (Internet Engineering Task Force) in a set of RFCs (Request For Comments) which rate the IPP to be in an "experimental" status for the time being.

The IPP, now in version 1.1 is supposed to become the successor of the venerable LPR/LPD Protocol for network printing. LPR/LPD is often thought of being based on RFC 1179. But in reality it never was a formal standard. RFC-1179 itself describes its own contents as "informational" only. In real life it nevertheless became a de-facto standard, but was deviated from very soon by all its implementers, almost beyond recognition and certainly beyond smooth interoperability. As its shortcomings became felt more and more in recent years, the vendors of printing hard- and software decided to go for a new shot. And all the Big Birds of the industry joined in, as you can see from a quick look into the PWG minutes.

IPP is designed to be based on and serve as an extension of HTTP 1.1 using its bi-directional abilities for GET-ting and POST-ing data between a client and a server. This was no bad decision at all from different points of view:

  • HTTP 1.1 is a robust and proved protocol working in LAN and WAN, through firewalls (or not), across continents and routers, gateways;
  • vendor engineers have already quite a bit of experience with HTTP as most of their network printers have an embedded webserver inside already;
  • HTTP 1.1 will nicely be plugging into other internet standards such as LDAP (for directory services) or SSL/TLS (for data encryption).

The Common UNIX Printing System (CUPS) which was selected by MandrakSoft to form the basis of a new printing aera in their new 7.2 edition is exactly based on this IPP. Also easyLinux 2.2 have adopted CUPS and many more vendors will be stepping in soon...

At the Bake-Off there were 18 vendors present (Axent, Canon, EfI, Epson, IBM, i-data, JCI, McAfee, Microsoft, Netreon, NETsilicon, Novell, Oak, QualityLogic, Ricoh, SEH und Xerox), who in between them had 17 IPP-printers, 9 IPP-clients and 2 HTTP-proxies. Out of possible 153 combinations for a pair of client and printer there were 151 tested.

In the PWG's Bake-Off summary report they don't tell you names of vendors or products, they only give you tables. The overall success rate was 93 % for any client/printer combination. It was 100 % in the case of 1.0 version clients and 1.1 version printers and a mere 31 % if a 1.1 client was served by a 1.0 printer. This is not the least dissapointing as some printer implementations explicitly dissallow that combination.

It seems there were quite a few new products present at this test field whereas on the other hand there were a few "proved ones" missing: names as AXxis, Lexmark, HP, Minolta or Easy Software Products (CUPS) are missing on the list of participants. Those vendors are named on the PWG home page to contribute to the number of around 150 IPP-products available so far.

A very positive balance sheet is drawn from the first-ever testings of the IPP-security features:

  • there was not a single failure with SSL3 (Secure Socket Layer) and TLS (Transport Layer Security);
  • Basic Authentification worked 93% (here an implementation error on the part of different vendors was recognised, caused by a "HTTP 100 continue" message);
  • Digest Authetification rated weakest with only 68% success;
  • Firewalls did work as expected: block or let traffic pass according to configuration, and also they processed the clients authentifications with no problems;
  • HTTP proxies - switched in between an IPP client and an IPP printer - worked without a flaw even if security was enabled

Now, do you have to be cautious if you come across that brand-new "IPP inside" sticker when you unpack your next network printer>? No, most IPP-enabled printers will still be supporting the old-fashioned LPR/LPD thingy for years to come. But I hope, Grant Taylor's (Linux Printing HOWTO) new-born Crusade for the Death of LPD will succeed way before that...

And Mandrake 7.2 and easyLinux 2.2 gim-me hope!