OECG – Chapter 17

698 Words. Plan about 2 minute(s) to read this.

AIS – Alarm Indication Signal – sending a bunch of 1s down a T1 as a response to a problem. Helps recover synchronization and framing.

AMI – alternate mark inversion – serial line encoding, layer 1. 3mV = 1, 0Mv = 0

B8ZS – bipolar 8 zero substitution. Uses Bipolar Violations during 8 consecutive binary 0s. Helps maintain line synchronization.

BPV – bipolar violation – when consecutive signals are of the same polarity.

CDPCP – CDP control protocol; used by PPP for CDP support.

CHAP – challenge handshake authentication protocol. A PPP authentication method, supports hashing and a 3-way handshake.

CTS – clear to send. “yes, you may” And also a Cadillac.

D4 framing – an aka for Superframe (SF)

DCD – data carrier detect – “yup, the line is working”

DS0 – 64Kbps – digital signal level 0.

DS1 – 24 DS0s for a T1 or 30 DS0s for an E1

DS3 – 28 DS1s for a T3 or 16 DS1s for an E3

DSR – data set ready

DTR – data terminal ready

E1 – a DS1 inside Europe

E3 – a DS3 inside Europe

encoding – layer 1. Using electrical signal to make those all important 0s and 1s.

ESF – extended superframe – a T1 framing method, successor to SF

framing – how to tell what’s overhead bits and what fits into specific subchannels.

HDB3 – high-density binary 3, like B8ZS, but does a BPV on 4 consecutive 0s instead of 8.

IPCP – IP control protocol – a PPP negotiation protocol for IP features running across a PPP link

Layer 2 payload compression – taking a L2 frame and compressing it before shoving it across a link

LCP – link control protocol – PPP negotiation that isn’t specific to a L3 protocol

LFI – link fragmentation and interleaving – QoS over MLPPP. Allows small frame fragments to be interleaved with large frame fragments so as to avoid small fragment latency issues.

line coding – same as encoding

LOF – loss of frame – can’t identify the frame consistently anymore

LOS – loss of signal – don’t see any polarity changes for quite a while

MLP – multilink PPP – bundling multiple parallel serial links, and then fragmenting each frame, one fragment per serial line, before transmitting the frame

MLP LFI – same as LFI. Duh.

NCP – network control protocol – PPP L3 negotiation that’s specific for each L3 protocol riding PPP

OAM – operation, administration and maintenance – the bits needed to manage TDM circuits

OOF – what you say when you get punched in the gut. Out of Frame – like LOF. The receiver can’t consistently identify the frame.

PAP – password authentication protocol – uses cleartext and a two way handshake to authenticate over PPP

PCM – pulse code modulation – encodes analog voice as a digital signal, requires 64Kbps.

PPP – point to point protocol – a serial data link protocol, supported on sync and async. Provides framing, link negotiation, L3 interface features and more.

Red Alarm – the state a T1 end point is in while experiencing an AIS/LOF/OOF condition. Will send a yellow alarm to the other end.

RTP header compression – compressing the IP/UDP/RTP headers of a packet before shoving that packet down a link

RTS – ready to send “mother, may I?”

SF – superframe – a T1 framing method, succeeded by ESF.

T1 – DS1s inside of North America

T3 – DS3s inside of North America

TCP header compression – compressing the IP and TCP headers of a packet before shoving that packet down a link
TDM – time division multiplexing – combining multiple synchronized input signals over a single medium by giving each signal its own time slot. Then breaking out the signals.

TDM hierarchy – the structure inside the original digital circuit build-out of the telcos in the mid 1900’s. It was based on TDM, and used to take smaller DS levels and combine them into larger levels, and vice-versa.

Yellow Alarm – a T1 endpoint is in a yellow alarm state when he receives a yellow alarm from the other end of the link. This means that the other end is in a Red Alarm state.

Ethan Banks writes & podcasts about IT, new media, and personal tech.
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