Peppe
ATM and IP networks are different, so the description of 'intelligence' needs to be different too.
Router intelligence is basically a big table lookup.
Each packet coming through an IP router is a 'new' packet. No memory of previous packets for the same customer is recorded. The router looks at the destination address, checks in its table, finds the port leading on to the destination, and sends the packet on its way. As networks become more complex, the routing tables get longer and longer, thus scalability is in question for IP networks.
BGP4 and OSPF are ways that each router contacts its neighbor routers to update any routes which may have gone bad since the last update. These IGPs and EGPs are not used to route individual user packets.
ATM on the other hand, is a connection oriented transport protocol. The first few packets coming for a customer contain destination routing information. These packets 'set up a connection' for following packets. This connection uses a quicky routing scheme which does not require the ATM switches along the route to dig through long routing tables, only shorter tables for each of its ports and each of the virtual connections it is handling at the moment. The last few cells of a connection contain information which allows the connection to be torn down and the memory and table space to be used by new connections.
Since ATM connection setup packets contain information about the QoS requirements and the bandwidth requirements for that connection, those aspects can be supported.
Telephone connection packets slide onto the ATM networks with appropriate specs so that telephone connections are clear and do not contain sporadic pops, clicks, and pauses.
IP data packets move through a MPOA (or other) stage at the edge of the ATM network where appropriate ATM specs are added to create a virtual connection for those packets. Since data packets usually do not require a timely delivery, IP traffic can be bumped to allow cells with higher QoS specs (and higher revenue) through the ATM network.
IP packets containing telephone conversations are problematic.
As telcos learn how to control their IP traffic better, I would imagine that IP packets containing telephone conversations will become more erratic (data packets do not have to be delivered at a particular rate..), thus that area of telco competition will be relegated to the 'back of the bus', or required to pay a bit more for timely delivery along contracted virtual pathways. ATM is the future.
Regards
fumble |
