Stacks of protocol stacks
Tinniam V Ganesh 270004Y158 Visits (1965)
Communication protocols like any other technology arrive on the scene to solve a particular problem. Some protocols endure while many perish. The last 60 years or so have seen a true proliferation of protocols in various domains.
So what is a protocol?
In my opinion a protocol is any pre-defined set of communication rules. For e.g. consider the exchange between me and you
Me: “Thank You”
You: “You’re welcome”.
A more complex exchange could be
You: “How are you doing today?”
Me:”Fine. And yourself?”
These are “protocols of courtesy or decorum”. There are many such protocols in daily use so there is little wonder that the technological world is full of protocols.
A couple of decades back there were 3 main standard bodies that came up with protocols namely IEEE (for LANs), IETF for the internet and ITU-T for telecom. Now there are many more bodies for e.g. CableLabs for cable television, WiMAX forum for WiMAX, NFC Forum etc.
Also protocols exist both for wired and the wireless domain. The protocols differ based on the distance for which the protocol will apply. This post will try to take a look at the some of most important in this. Certainly many will slip through the cracks, so beware!
Near Field Communication (NFC): This is a wireless protocol of the order of a few centimeters primarily for contactless data transfers. Its primary use is for mobile payment. As opposed to Bluetooth there will be no necessity for device pairing. The NFC standards are maintained by the NFC Forum.
Bluetooth: This is another wireless protocol and uses the 2.4- 2.48 GHz band for data exchange and is commonly used in mobile phones, TVs, and other devices. This protocol requires pairing of devices prior to data transfer. The Bluetooth details are maintained in Bluetooth Special Interest Group.
Zigbee: Zigbee is a low powered, low cost wireless protocol that will connect devices within residential homes. Zigbee has a data rate of 250 kbps and is based on the IEEE 802 standard for Personal Area Network (PAN) or Home Area Network (HAN). Zigbee will be protocol of choice in the Smart Home which will be part of Smart Grid concept. More details can be found at the Zigbee Alliance.
LAN protocols: LAN protocols are wired protocols. The main 3 LAN protocols are IEEE 802.3 (Ethernet), IEEE 802.4 (Token Bus) & IEEE (Token Ring) are used in enterprises, schools or small buildings of the order of a few 100 meters. LAN protocols ensure transmission speeds of the order of 10 Mbps – 40 Mbps.
WiFi: WiFi provides wireless access in residential homes, airports, cafes at a distance of 20 meters with speeds of 2 Mbps – 8 Mbps (802.11a/b/e/g). Wireless hotspots use WiFi protocols
Super WiFi/Whitespaces: Whitespaces refers to using abandoned TV frequency bands for wireless data transmission around the 700 MHz range. Whitespaces can travel larger distances typically around 100 km and through trees and walls. This is nascent technology and is based on IEEE 802.22 protocol. A new forum for taking this technology forward is the Whitespace Alliance.
ISDN: This protocol is governed by the Q.931 standards and was supposed to carry high speed data (64 kbps???) from residential homes, This protocol went into relative obscurity soon.
Wired Trunk protocols: There are several trunk protocols that connect digital exchanges (digital switches) for e.g. ISUP (Q.763), BTUP, TUP. These protocols exchange messages between central offices and are used for setting up, maintaining and release of STD voice calls.
The predominant protocol of the internet is TCP/IP (RFC 793). There are several other protocols that work in the internet. A few of them
Exterior Gateway Protocol (EGP)
OSPF Open Shortest Path First protocol
Interior Gateway Protocol (IGP)
RSVP & DiffServ
WAN protocols: There is a variety of protocols to handle communication between regions or across a large metropolitan area. The most common among these are
MPLS: Multi-protocol Label System.
ATM : Asynchronous Transfer Mode
Protocols that are exist in both the Internet & Telecom domain
A number of protocols work in concert to setup, maintain and release multi-media sessions
SIP/SDP: Session Initiation Protocol (RFC 3261 et al) /Session Description Protocol (RFC 2327)
SCTP/RTP/RTSP: Session Control Transport Protocol/Real Time Protocol/Real Time Secure Protocol – These protocols are used to send and control media packets.
MGCP/Megaco: This is a protocol used to control the Softswitch.or the Media Gateway Controller (MGC)
WiMAX: (Worldwide Interoperability for Microwave Access) is a technology for wirelessly delivering high-speed Internet service to large geographical areas. WiMAX offers data speeds in the range of 40 Mbps – 70 Mbps. This is an IEEE 802.16 family of protocols. Details about WiMAX can be obtained at WiMAX Forum.
DOCSIS: DOCSIS is the protocol that is used in cable TV and uses hybrid fiber co-axial cables for transmission. This protocol is also used these days for internet access. More details regarding the DOCSIS protocol can be found at CableLabs.