Category: Protocols

Encapsulting Protocols

Secure Shell (SSH )Encapsulating protocols at Network LayerIP in IP Multiprotocol Label Switching (MPLS) ESP (Encapsulating Security Payload)Encapsulating protocols at Transport Layer TLS and Datagram Transport Layer Security (DTLS)Generic Routing Encapsulation (GRE)QUIC TCP encapsulationSubtle points of using encapsulationPath MTU and fragmentationMigration of inner payload from one to another protocolPrioritization and congestion post encapsulationMisordering Loss of ECN … Continue reading Encapsulting Protocols

Multihoming protocols and mobility

Low Layer Multihoming Layer 3 Network Layer multihomingLayer 4 Transport layer multihoming Higher Layer Multihoming techniquesBest Path Selection among multiple pathsFIFO or Round RobinWeights ( predetermined or dynamically allocated)Prioritization algorithmsMultiPath protocol designService discovery Unique Identifiers Path / Route and Network identifiers Header metadata Pre - Registration Handover / Failover from one path to another without … Continue reading Multihoming protocols and mobility

HTTP/2 – offer/answer signaling for WebRTC call

HTTP ( Hyper Text Transfer Protocol ) is the top application layer protocol atop the Tarnsport layer ( TCP ) and the Network layer ( IP ). HTTP/1.1 HTTP/1.1 was released in 1997. HTTP/1 allowed only 1 req at a time. But HTTP/1.1 allows one one outstanding connection on a TCP session but allowed request … Continue reading HTTP/2 – offer/answer signaling for WebRTC call

Websockets as VOIP signal transport medium

Web resources are usually build on request/response paradigm such as HTTP , SIP messages . This means that server responds only when a client requests it to. This made web intercations very slow and unsuited for VOIP signalling Long Poll involved repeated polling checks to load new server resources by itself instead of client made … Continue reading Websockets as VOIP signal transport medium

PJSIP

SIP stack written in C. Available under GPL pjsip dev guide architecture diagram PJSip user agent Attributes: local_info+tag, local_contact, call_id Operations: pj_status_t pjsip_ua_init(endpt, param); pj_status_t pjsip_ua_destroy(void); pjsip_module* pjsip_ua_instance(void); pjsip_endpoint* pjsip_ua_get_endpt(ua); PJSip dialog Attributes: state, session_counter, initial_cseq, local_cseq, remote_cseq, route_set, local_info+tag, local_contact, remote_info+tag, remote_contact, next_set Operations: pj_status_t pjsip_dlg_create_uac(ua, local_uri, contact, …); pj_status_t pjsip_dlg_create_uas(ua, rdata, contact, &dlg); … Continue reading PJSIP

XMPP server with JavaScript XMPP clients ( Converse.js)

The setps to install , configure and test a Openfire XMPP server was discussed in my previous blog . It also contained the java client code to interact with the XMPP server like connect , send presence , get and send message etc . This article will describe the process of making a web based … Continue reading XMPP server with JavaScript XMPP clients ( Converse.js)

H 323

International standard for multimedia communication ( real-time voice, video, and data communication) over packet-switched networks includes the standards H.323, H.225.0, H.245, the H.450-series documents, and the H.460-series. T.120 for data collaboration and file transfer. Ability to utilize network services for address resolution, including ENUM, LDAP, and DNS an provide various supplementary services Call transfer , … Continue reading H 323