MMUSIC B. Stucker
Internet-Draft Unaffiliated
Intended status: Informational H. Tschofenig
Expires: July 14, 2013 Nokia Siemens Networks
G. Salgueiro
Cisco Systems
January 10, 2013
Analysis of Middlebox Interactions for Signaling
Protocol Communication along the Media Path
draft-ietf-mmusic-media-path-middleboxes-06.txt
Abstract
Middleboxes are defined as any intermediary box performing functions
apart from normal, standard functions of an IP router on the data
path between a source host and destination host. Two such functions
are network address translation and firewalling.
When Application Layer Gateways, such as SIP entities, interact with
NATs and firewalls, as described in the MIDCOM architecture, then
problems may occur in the transport of media traffic when signaling
protocol interaction takes place along the media path, as it is the
case for recent key exchange proposals (such as DTLS-SRTP). This
document highlights problems that may arise. Unfortunately, it is
difficult for the end points to detect or predict problematic
behavior and to determine whether the media path is reliably
available for packet exchange.
This document aims to summarize the various sources and effects of
NAT and firewall control, the reasons that they exist, and possible
means of improving their behavior to allow protocols that rely upon
signaling along the media path to operate effectively.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
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Internet-Draft Middlebox Interactions January 2013
material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 14, 2013.
Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Architecture . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Packet Filtering . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Protocol Interaction . . . . . . . . . . . . . . . . . . . 6
4.1.1. Single-Stage Commit . . . . . . . . . . . . . . . . . 6
4.1.2. Two-Stage Commit . . . . . . . . . . . . . . . . . . . 8
4.2. Further Reading . . . . . . . . . . . . . . . . . . . . . 10
5. NAT Traversal . . . . . . . . . . . . . . . . . . . . . . . . 11
5.1. Protocol Interaction . . . . . . . . . . . . . . . . . . . 12
5.2. Further Reading . . . . . . . . . . . . . . . . . . . . . 15
6. Interactions between Media Path Signaling and Middlebox
Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.1. Packet Filtering . . . . . . . . . . . . . . . . . . . . . 16
6.2. NAT Traversal . . . . . . . . . . . . . . . . . . . . . . 17
7. Preliminary Recommendations . . . . . . . . . . . . . . . . . 18
8. Security Considerations . . . . . . . . . . . . . . . . . . . 19
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