5 ms·

Insofar as ATM vs. IP, IP "won". I had some ATM in Customer sites the late 90s as a LAN / backbone technology. By the early 2000s it was disappearing. IP over

Insofar as ATM vs. IP, IP "won". I had some ATM in Customer sites the late 90s as a LAN / backbone technology. By the early 2000s it was disappearing. IP over gigabit Ethernet and layer 3 switches with wire-speed routing replaced it everywhere I ever used it. ATM is still inside older DSL networks, but I haven't seen it used as a WAN technology in a long time. I don't know enough about the innards of fast IP routers to say, but my gut says that, given the differences between IP and ATM, there's probably not much in the way of legacy ATM hiding inside our modern gear. Insofar as the "Bellhead" vs. "Nethead" mentality, as another comment says, the majority of big "Nethead" ISPs have all been acquired by legacy telco interests (I wept inside when CenturyLink acquired Level 3, for example). In the service provider space, at least, I think that the "Bellheads" won.

twic 8y ago
There's a fossil of ATM surviving inside the ADSL protocol (although i suppose there aren't many people still using that) - ADSL has an ungodly stack of different protocols, but at some point, there's AAL5, an adaptation layer on top of ATM, which in turn sits above the physical layer. ATM cells are fixed-size and short, and AAL5 creates variable-sized long frames on top of them. PPP then uses that, and IP uses PPP. Although from what i remember, the physical layer doesn't carry actual ATM cells; there's some scheme for packing them into large bundles, eliminating the repeated header, for more efficient transmission. So ATM is a sort of fiction which helps translate PPP messages into ADSL frames. It's been a long, long time since i really understood ADSL, though.
- blattimwind 8y ago
  MPoA (you can guess what the A stands for) has replaced the older PPPoA for VDSL deployments.
  - twic 8y ago
    TIL! I see that MP = multi-protocol: http://cs.hadassah.ac.il/staff/martin/Seminar/MPOA/mpoa.pdf http://cs.hadassah.ac.il/staff/martin/Seminar/MPOA/mpoa.pdf
- kev009 8y ago
  Most GPON (fiber to the home) in the US uses ATM cells too
ggm 8y ago
ATM cell size and phone data packet size relationship? Lots of people still think "more smaller is better" e.g. considering pMTU problems in IPv6, sending shorter non-fragmented IP packets is way better than sending long ones causing end-to-end congestion (no intermediate frag in V6)

twic 8y ago

There's a fossil of ATM surviving inside the ADSL protocol (although i suppose there aren't many people still using that) - ADSL has an ungodly stack of different protocols, but at some point, there's AAL5, an adaptation layer on top of ATM, which in turn sits above the physical layer. ATM cells are fixed-size and short, and AAL5 creates variable-sized long frames on top of them. PPP then uses that, and IP uses PPP. Although from what i remember, the physical layer doesn't carry actual ATM cells; there's some scheme for packing them into large bundles, eliminating the repeated header, for more efficient transmission. So ATM is a sort of fiction which helps translate PPP messages into ADSL frames. It's been a long, long time since i really understood ADSL, though.

blattimwind 8y ago
MPoA (you can guess what the A stands for) has replaced the older PPPoA for VDSL deployments.
- twic 8y ago
  TIL! I see that MP = multi-protocol: http://cs.hadassah.ac.il/staff/martin/Seminar/MPOA/mpoa.pdf http://cs.hadassah.ac.il/staff/martin/Seminar/MPOA/mpoa.pdf
kev009 8y ago
Most GPON (fiber to the home) in the US uses ATM cells too

ggm 8y ago

ATM cell size and phone data packet size relationship? Lots of people still think "more smaller is better" e.g. considering pMTU problems in IPv6, sending shorter non-fragmented IP packets is way better than sending long ones causing end-to-end congestion (no intermediate frag in V6)