David,

>There are plenty of books describing how IP packets are encapsulated in
>Ethernet frames or ATM cells, or PPP frames. But I have not seen a book
>describe how IP packets be carried in DS1, Fractional DS1, DS3, Fractional
>DS3 signals. These signals are point to point, byte streams. I think IP
>packets should be directly put on those TDM time slots and send from one end
>point to the other. Can somebody answer my question or point out a book, web
>site, or a standard so I can find the answer.

Sorry if I'm stating the obvious, but you can't just carry IP packets over 
point-to-point links without some sort of framing, so you can tell where 
one packet ends and the next begins.  In addition to various 
vendor-proprietary framing methods for IP over serial links developed over 
the years, there have been two major methods standardized in the IETF to 
frame IP packets over point-to-point links, SLIP (RFC 1055) and PPP (RFCs 
1661 and 1662).  SLIP is actually a "non-standard standard" (see the RFC 
for more info).  PPP was developed to address SLIP's deficiencies, some of 
which are discussed in the SLIP RFC itself.

Cheers,
Andy

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