note: one of the other names of ATM is broadband ISDN.
ATM tries to overcome the limitations of the 64 kbps channels of ISDN that are a problem for data networks (also without considering billing).
ATM uses the FR concepts of VCs (logical circuits):
a single access link can be used to reach different destinations using different PVCs or SVCs: each one has a different VPI/VCI value that is unique on the link between the ATM DTE (router atm interface) and the ATM DCE (ATM switch port).
ATM uses small fixed size frames called cells (53 bytes in size with a 5 byte header) and concentrate on switching these cells inside the ATM cloud along pre-established paths (Permanent VCs) or via on demand paths (SVCs that need to be setup before traffic can flow).
ATM provides extensive QoS support and needs to provide AAL services= capacity to take an IP packet for example to encapsulate it inside an AAL PDU, then to segment it on cells that are sent to the other side where the AAL PDU is reassambled and the IP packet can be reassembled and de-encapsulated to be fowarded towards destination as needed.
Actually ATM is most used with PVCs then with SVCs but it has the potential for a call and ATM NSAP addresses can be seen as similar to E.164 phone numbers.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...