RFC 4850

RFC 4850: Declarative Public Extension Key for Internet Small Computer Systems Interface (iSCSI) Node Architecture ✨

Okay bestie, welcome to RFC 4850 🎀 This one came out of the Network Working Group and was written by D. Wysochanski at Network Appliance, Inc. 💅 It's a Standards Track document, dated April 2007, and it updates RFC 3720 🔥 The header doesn't list anything it obsoletes. Its whole job is to add a little public key to iSCSI so nodes can share what they're made of during login, which makes debugging and support way less painful 🧚

Status of This Memo

This document is an Internet standards track protocol for the Internet community, and it's basically asking everyone to talk about it and suggest improvements 🦋 For the current standardization state and status of this protocol, check the current edition of the "Internet Official Protocol Standards" (STD 1). Distribution of this memo is unlimited 🌈

Copyright Notice

Copyright (C) The IETF Trust (2007). 💜

Abstract ✨

So iSCSI, described in RFC 3720, lets you add extension items in the form of Private or Public Extension Keys 🌸 This doc is about a Public Extension Key that helps with supportability 🫶 The key lets iSCSI nodes share their architecture details during the iSCSI login sequence, and then the receiving node can use that info for better logging and support 📝

The other big thing: this document updates RFC 3720 so that iSCSI extension items can be defined by standards track RFCs and experimental RFCs too, not just informational RFCs 💅 Iconic glow-up 👑

1. Introduction ✨

1.1. Overview

Okay so this doc describes a declarative Public Extension Key, the kind defined in Section 12.22 of RFC 3720 [2] 💖 It's used to share extra iSCSI node info with the peer node in a session 🧚 This info has been super useful in real iSCSI customer environments, because initiator and target vendors team up to fix technical issues and understand how their iSCSI implementations interact 🤝

The key is modeled on the HTTP "Server" and "User-Agent" header fields from Sections 14.38 and 14.43 of RFC 2616 [3] 🎀 The text-value(s) of the key are roughly the same as the Product Tokens in Section 3.8 of RFC 2616 [3]. Heads up though, the text-value(s) in the key's list-of-values MUST conform to the Text Format in Section 5.1 of RFC 3720 [2] ⚠️

The key gets sent during operational parameter negotiation in an iSCSI session's login phase 🌈 The whole point is better logging and support, plus collecting iSCSI implementation and usage info 💜

⚠️ Quick reminder: the Text Format from Section 5.1 of RFC 3720 [2] is non-negotiable for those list-of-values. No cap 🧢

1.2. Terminology

Here's the vibe check on the key words 🦋 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are read the way RFC 2119 [1] describes ✨

2. Definition

The key's definition is written to match Sections 11 and 12 of RFC 3720 [2], and the example list-of-values follow Section 5.1 of RFC 3720 [2] 💅

Here's the tea: the key uses "LO", which makes it a Leading Only key 💖 It doesn't change Sections 11 or 12 of RFC 3720 [2] at all. So the key MUST only be sent on the leading connection, MUST NOT be changed after the leading connection login, and MUST only be sent after the security negotiation login stage is done (during the operational negotiation login stage) 🔥 It may be sent during normal or discovery sessions too 🌸

2.1. X#NodeArchitecture

Here's the key's header info, all cute and tidy 🎀

Use: LO, Declarative
Senders: Initiator and Target
Scope: SW

The syntax is:

X#NodeArchitecture=<list-of-values>

Some examples, because examples are everything 🧚

X#NodeArchitecture=ExampleOS/v1234,ExampleInc_SW_Initiator/1.05a
X#NodeArchitecture=ExampleInc_HW_Initiator/4010,Firmware/2.0.0.5
X#NodeArchitecture=ExampleInc_SW_Initiator/2.1,CPU_Arch/i686

The initiator or target uses this key to tell the remote endpoint the details of its iSCSI node architecture 💜 Those details can include (but aren't limited to!) the iSCSI vendor's software, firmware, or hardware versions, the OS version, or the hardware architecture 🌈

The length of the key value (that's the total length of the list-of-values) MUST NOT be greater than 255 bytes 📏 Also, X#NodeArchitecture MUST NOT be redeclared 🙅‍♀️

3. Implementation ✨

Functional behavior of the iSCSI node is totally separate from this key 🫶 That includes the iSCSI protocol logic (the SCSI, iSCSI, and TCP/IP protocols). That behavior MUST NOT depend on the presence, absence, or content of the key 🦋 Nodes MUST NOT use the key for interoperability or for excluding other nodes either 🙅‍♀️ To keep things proper, key values SHOULD be set by the node itself, and there SHOULD NOT be provisions for key values to contain user-defined text 💅

Nodes that implement this key MUST pick one of these options:

• only transmit the key,
• only log the key values received from other nodes, or
• both transmit and log the key values.

Any node that chooses to transmit key values MUST be ready to handle the reply from RFC 3720 [2] compliant nodes that don't understand the key 😭 RFC 3720 [2] says compliant nodes MUST respond with X#NodeArchitecture=NotUnderstood.

Nodes that transmit and/or log key values can also add administrative mechanisms that turn off or change the logging and transmission detail (see Security Considerations) 🔐 So a totally valid behavior for this key is for a node to be completely silent: it doesn't transmit any key value, and it just discards any key values it gets without sending a NotUnderstood response 🤫🌸

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to be continued in part 2 🦋✨

Appendix A. Acknowledgments 🎀

Okay bestie, the IP Storage (ips) Working Group in the Transport Area of the IETF is the crew that actually defined the iSCSI protocol ✨, along with a whole bunch of other IP Storage protocols. The author gives a shoutout to the entire working group for their contributions 🫶.

The following individuals directly helped out by spotting issues and/or suggesting fixes for the issues in this document 💅: David Black, Mallikarjun Chadalapaka, Paul Koning, Julian Satran, John Hufferd, Claire Kraft, Ranga Sankar, Joseph Pittman, Greg Berg, John Forte, Jim Yuill, William Studenmund, and Ken Sandars. The document benefited from all of them 💖.

Finally, the author thanks Network Appliance, Inc. for sponsorship and support while this work was being developed 🌸.

Author's Address 🦋

Dave Wysochanski 8311 Brier Creek Parkway Suite 105-296 Raleigh, NC 27617 US

Phone: +1 919 696 8130 EMail: wysochanski@pobox.com

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Copyright (C) The IETF Trust (2007).

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