Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucsd!rutgers!texbell!attctc!vector!telecom-gateway From: goldstein@delni.enet.dec.com Newsgroups: comp.dcom.telecom Subject: Re: TCP/IP over ISDN Basic Rate Message-ID: Date: 14 Nov 89 17:14:55 GMT Sender: news@vector.Dallas.TX.US Organization: Digital Equipment Corporation, Littleton MA USA Lines: 21 Approved: telecom-request@vector.dallas.tx.us X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@vector.dallas.tx.us X-TELECOM-Digest: volume 9, issue 511, message 2 of 9 This has degenerated into a "tastes filling/less great" kind of argument. ISDN is a candy mint/breath mint. Okay, have it your way. ISDN provides 8 kHz integrity, which means that it does guarantee octet accuracy for the 8 kHz services, including circuit mode data. You put in an octet, you get out an octet. Voice coders need that; HDLC doesn't. But HDLC does need bit sequence integrity, so (for example) if you have two separate 64 kbps channels, you can't simply combine them and expect all 16 bits to be delivered in sequence; each channel may have different delay characteristics. H channels maintain 8 kHz integrity. HDLC protocols are usually processed on the ISDN chip, so the 8-bit chip output is taken after bit-destuffing. You tell the chip if it's HDLC or not; if not, you get raw bits. But the network itself delivers raw bits with 8 kHz integrity, and it's your option to use a bit or byte protocols. DDCMP does have its advantages... fred