I have read more than just some introductory articles. At least I have downloaded the standard protocol document and read more than the overview part :)
Some protocols have participated in the development of commercial products;
Some are just some of the implementations of open source code;
Some, just look at it and understand the design ideas of the Protocol.
Instant messaging (IM)
(Once circulated on the InternetJabber technical White PaperAndProtocol OverviewBut Peter Saint-Andre, the author of the two documents, said they have been outdated for a long time. To learn about the jabber/XMPP technology, see XMPP rfcs)
Rfc3920 extensible messaging and presence protocol (XMPP)-Core
Rfc3921 XMPP-instant messaging and presence.txt
XMPP extension (P2P)
XEP-0166 (jingle)
Jingle RTP sessions XEP-0167
XEP-0176 jingle ICE-UDP Transport Method
XEP-0177 jingle raw UDP Transport Method
NAT traversal
Draft-ietf-behave-turn-09
Draft-ietf-mmusic-ice-19-interactive connectivity establishment (ICE) A protocol for network address translator (NAT) traversal for offer-Answer protocols
Draft-ietf-behave-rfc3489bis-15-session traversal utilities for (NAT) (Stun)
SS7
Q.700 introduction to CCITT Signalling System No. 7
Q.701 functional description of the message transfer part (MTP) of Signalling System No. 7
Q.702-signalling Data Link
Q.703-signalling Link
Q.704 signalling network functions and messages
VoIP, media transmission/RTP
Rfc3550 standard 64, RTP-a transport protocol for real-time applications
Rfc3551 RTP profile for audio and video conferences
Rfc2736 guidelines for writers of RTP payload format specifications
Rfc2038 RTP payload format for MPEG1-MPEG2 video
Draft-ietf-codec-requirements-00
GSM/GPRS/UMTS
3GPP ts 23.003 numbering, addressing and Identification
3GPP ts 22.060 General Packet Radio Service (GPRS); service description; Stage 1
3GPP ts 23.060 General Packet Radio Service (GPRS); service description; Stage 2.
3GPP ts 29.232 media gateway controller (MGC)-Media Gateway (MGW) interface Stage 3
H.248.1 Gateway Control Protocol: Version 3
3GPP tr23.930 IU principles
3GPP ts 25.410 UTRAN Iu interface general aspects and principles
3GPP ts 32.401 telecommunication management; performance management (PM); concept and requirements
IMS
3GPP ts 22.228-a00 service requirements for the Internet Protocol (IP) multimedia core network subsystem (IMS); Stage 1.doc
Rfc3261 sip-Session Initiation Protocol
LTE (4G)
(Simplified LTE network architecture)
3GPP ts 36.401 evolved universal Terrestrial Radio Access Network (E-UTRAN); architecture description
Layer 2 (data link layer)
Rfc1661 The Point-to-Point Protocol (ppp;.txt
Rfc1662 PPP in HDLC-like framing.txt
Q.920 ISDN User-network interface data link layer-General aspects.pdf
rfc826 An Ethernet Address Resolution Protocol
Transport Layer
Rfc793 Transmission Control Protocol
Rfc2581 TCP congestion control
RFC 768 user datateprotocol (simple UDP Protocol)
Draft-gg-udt-02.txt (a reliable data transmission protocol based on UDP, It is said Baidu Hi has used it)
RFC 3828 the lightweight user datateprotocol (UDP-lite) (a part of the tolerable packet is corrupted and may be used as a substitute for UDP in specific applications. Linux Kernel 2.6.20 already contains UDP-lite)
Application Layer
(For the differences between http1.1 and 1.0, seeThis article,
Questions about http on the csdn Forum:HTTP FAQ)
Rfc2616 Hypertext Transfer Protocol -- HTTP-1.1.txt
Spdy protocol-Draft 1 (Google's HTTP improvement test)
Security/AAA
Rfc3588 diameter Base protocol