Telecommunications Essentials Chapter 9

Cost savings & revenue generation Logical rather than physical connections IPT – Telephony IPTV – Digital Television VPN Presence-aware communication Presence Over hyped QoS a serious obstacle

IPTIPT ~ VoIP ~ Internet TelephonyVoIP

Cost motivation 10% cost difference between Frame relay, ATM, & MPLS 25% difference with IPT & MPLS Application LAN – LAN or Enterprise Concerns 911 emergency services Law enforcement surveillance (decryption time)

Application – Infrastructure separation The most important paradigm shift – Golnienwski Potential involvement by: ITU EC FCC (IPT not covered by the Universal Services Fund) FCCUniversal Services Fund

Application Layer (or platform) Signaling Layer (or platform) Media Layer Video

Carrier grade Enable multimedia services over NextGen networks NextGen Connect circuit & packet switched networks Support Class 5 & 4 PSTN switches Note: Not to be confused with enterprise media gateways.enterprise media gateways

Carrier grade - resides in the central office Nortel Softswitch Enterprise grade Often decomposed to a Call Agent & Media Gateway No standard definition

Features: Voice mail Fax Conferencing Collaborative applications Replaces multiple standalone systems Open source IP PBX

Waveform Coders PCM: G.711, A-law & mu-lawG.711A-lawmu-law ADPCM G.722 Subband coder G.722 Transform coding Vocoder G.728 LD-CELP G.728 G.729 CELP G.729CELP

Comfort noise End to end delay Voice < 100 mSec Video < 80 mSec Games 30 – 50 mSec Jitter Fixed buffer – internet radio, fax Adaptive buffer – variable rate signal processing Error concealment Replay, interpolate, predict Layered coding – for multicast Layered coding

RTP – VoIP & real-time applications RTP RTCP – control packets, RTCP Flow & congestion control QoS measurements SRTP – encryption & authentication SRTP VoIP Privacy Requires XR (reporting extension) for diagnostics VoIP Software

H.324 – H.324 Voice, video & data over analog loops H.323 Audio visual communication on packet networks MGCP – Media Gateway Control Protocol MGCP Signaling & control over a distributed system SIP – Session Initiation Protocol SIP Call setup & tear down

Media Gateway Also called Call Agent Enable multimedia communication across networks Media Gateway Controller Also called a Softswitch Provides call processing functions Competing Protocols Megaco or H.248 Megaco MGCP - Cisco MGCP

Widespread industry support Peer-to-peer protocol OSI application & session layers Uses proxy servers or user agents Users are given a SIP address Sip addressed can be placed in web pages

Translates telephone numbers to URLs Based on DNS architecture Present service providers use their own address mapping

MPEG-2 TS MPEG-2TS Managed network (Possible) Bi-directional capability Can deliver high quality full screen content IGMP – Multicasting (not broadcasting) IGMP RTSP - VoD RTSPVoD

A concept A logical network on shared service provider facilities Internet based VPN Uses the public internet, limited QoS Multiple service providers User groups are defined by encryption Provisioned VPN (multiple protocols) Operated on service provider’s backbone Improved performance Frame relay or ATM IP VPN (single protocol) Operated on service provider’s backbone MPLS

CPE IPsec VPNIPsec OSI layer 3 Traffic is encrypted to run over the internet Transport mode IP payload encrypted Used between host & router Tunnel mode IP datagram is encrypted and given a new IP header Used between gateways Network IPsec VPN MPLS VPN

Combines Ethernet & MPLSEthernetMPLS Uses pseudo-wires to emulate a LANpseudo-wires Leverages existing technologies Lack of QoS Throw bandwidth at the problem

GRE Datagram based IP in IP L2TP GPRS PPTP PPPoE PPPoA Streaming base TLS SSH Tunneling requires three different protocols: 1.Carrier protocol - The protocol used by the network that the information is traveling over 2.Encapsulating protocol - The protocol (GRE, IPSec, L2F, PPTP, L2TP) that is wrapped around the original data 3.Passenger protocol - The original data (IPX, NetBeui, IP) being carried

Symmetric encryption Both parties use the same key DES IDEA & PGP IDEAPGP AES Asymmetric (public key) encryptionpublic key