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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Why doesn't BGP... -Reply
Larry J. Plato <[email protected]> wrote: >Connectionless and Connection oriented both refer to packet switched >technologies, whereas the phone company uses circuit switched technology. Yes, this is absolutely correct. >Circuit switched means that the same wires/timeslots are dedicated to >a call from the time it starts until the time it finishes.If you do >not speak, the wires are idle/wasted. I am sure you understand packet >switching. In a packet switched network, connectionless means that each >packet has no state information, and stands alone, in the IP world we call >this UDP. Connection oriented would be the equivalent of telnet or >some other TCP service. This is a terminological question. Here the talk was about connectionless and connection-oriented _network_ layer; not the transport layer. The connection-oriented packet routing network is a generalized case of circuit switching -- you can multiplex connections differently. The fundamental difference between connectionless and connection-oriented networks is the amount of state necessarily kept by gateways in order to perform forwarding of the bits. A gateway of a connectionless network has only to keep the traffic-independent topological information (this definition is more generic than just next-hop routing; it includes source-based routing, semi-flows, etc). A gateway of a connection-oriented network has to keep the topological information (in order to be able to route connections) and the traffic-dependent table of connections. BTW, by that definition an IP network which supports RSVP _is_ a connection oriented network. If gateway has state which is modified by traffic, that state must necessarily grow with the traffic; in Internet case, exponentially and at the rate far exceeding Moore law's. >SS7 (Signalling System 7) is a connectionless packet switched technology >used to control the setup and teardown of circuit switched calls. >Originally is was used as a database query technology to make 800 >numbers portable across carriers. If this did not make sense I can descibe >it in a little mnore detail offline. At least that telcos got right. --vadim - - - - - - - - - - - - - - - - -
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