nanog mailing list archives
Re: ATM (was Re: too many routes)
From: Michael Dillon <michael () priori net>
Date: Thu, 11 Sep 1997 20:06:01 -0700
Do you? When I mean voice, I mean true POTS. You present dialtone over IP ? (It could be done, btw), but POTS over ATM can exit right into the DEXX's. (DEXX = Big telco switch) Lets see you allocate an ESF B8ZS Clear Channel T1 over IP....
Are you sure you aren't referring to a DACS or DCS here? (Digital Access and Cross-connect System). It's not quite the same as what is usually referred to as a telco switch, i.e. 5ESS et al.
CBR in a "worse case scenario" ATM net, IS TDM, not SDM. NO variance against TAT allowed.
You missed CBR (Constant Bit Rate) in your definitions. CBR is an ATM service used to do circuit emulation, i.e. deliver the same bits that a TDM T1 would deliver.
TDM = Time Division Multiplexing SDM = Statistical Division Multiplexing.
Stat muxing also known as X.25, frame relay, IP, ATM, or packet switching. In other words rather than dividing the bitstream into fixed timeslots (TDM) which guarantees that bits will arrive at the other end in a known time interval, we try to avoid sending bits with no information content and let another bitstream use the wire therefore the arrival time is not known but is a statistical probability yadda yadda. TDM is DS3's divided into 28 DS1 timeslots which can each be divided into 24 DS0 timeslots.
when running BEYOND the SCR, I lost the extra BW, and received FECN's ...... Slowing up the Ip. SCR = Sustained Cell Rate
Sustainable Cell Rate. This is an average rate, not a sustained flow of cells. This is something like a frame CIR in that you can burst beyond the SCR up to the Peak Cell Rate. It is used in ATM's VBR (Variable Bit Rate) service.
FECN = Forward Explicit Congestion Notification BECN = Backwards Explicit Congestion Notification
These are used in Frame Relay. ATM has no BECN but has EFCI (Explicit Forward Congestion Notification) instead of FECN.
Ahhh.. We await the completion, and proper interaction of RM, ILMI, and OAM.
Like IPv4, ATM is also evolving. Which one will win the evolutionary race?
RM = Remote Management
Resource Management. Handled by special RM cells in the data stream.
ILMI = a link management interface for ATM
Integrated Local Management Interface based on SNMP running through a reserved VBR VC on the network. Try to remember that there are many people on the list who are not that familiar with ATM. And given that ATM switches can't route IP packets that is probably OK. Only a few companies need to give serious thought to the IP and ATM together. ******************************************************** Michael Dillon voice: +1-650-482-2840 Senior Systems Architect fax: +1-650-482-2844 PRIORI NETWORKS, INC. http://www.priori.net "The People You Know. The People You Trust." ********************************************************
Current thread:
- Re: too many routes, (continued)
- Re: too many routes Peter Lothberg (Sep 10)
- Re: too many routes Peter Lothberg (Sep 10)
- Re: too many routes Sean M. Doran (Sep 10)
- Re: too many routes Peter Lothberg (Sep 10)
- RE: too many routes Chris A. Icide (Sep 11)
- Re: too many routes Sean M. Doran (Sep 11)
- Re: too many routes Richard Irving (Sep 11)
- ATM (was Re: too many routes) Sean M. Doran (Sep 11)
- Re: ATM (was Re: too many routes) Vadim Antonov (Sep 11)
- Re: ATM (was Re: too many routes) Richard Irving (Sep 11)
- Re: ATM (was Re: too many routes) Michael Dillon (Sep 11)
- Re: ATM (was Re: too many routes) Vadim Antonov (Sep 11)
- Re: ATM (was Re: too many routes) Geoff Huston (Sep 14)
- Re: ATM (was Re: too many routes) Susan R. Harris (Sep 15)
- Re: ATM (was Re: too many routes) Ken Hays (Sep 15)
- Re: ATM (was Re: too many routes) Alec H. Peterson (Sep 15)
- Re: ATM (was Re: too many routes) Adrian Bool (Sep 15)
- Re: ATM (was Re: too many routes) Greg Shepherd (Sep 15)
- Re: ATM (was Re: too many routes) Rob Barron (Sep 15)
- Re: ATM (was Re: too many routes) Mark Kent (Sep 15)
- NANOG-PHYSICS (was Re: ATM (was Re: too many routes)) John A. Tamplin (Sep 15)
- Re: too many routes Sean M. Doran (Sep 11)