Hi Friends,
Today, data traffic is eclipsing voice traffic in volume, and demand by both business and consumers for a wide array of interactive services is growing.
That advantage derives from a fundamental difference between IP and ATM: IP technology can distinguish between various services and make per-hop routing, aggregation, traffic shaping and priority decisions, while ATM technology can only distinguish between virtual circuits .
ATM transports voice and data traffic in fixed-size, 53-byte cells. In the ATM world, all cells, and therefore all traffic, look the same, and an ATM-optimized DSLAM cannot discriminate between one kind of traffic and another. IP works with Internet packets, which are larger than ATM cells and distinguishable by type of service and destination. An IP-based concentrator can see these packets in their entirety, and discriminate between different kinds of traffic and between traffic from different subscribers.
Like, for example, a DSL service provider that signs up 100 subscribers for a full menu of services, including QoS VoDSL. To provision 10 voice calls for 10 subscribers with an ATM-optimized DSLAM, this provider must set up and manage 100 PVCs. In contrast, a DSL service provider that standardizes on DSLAMs with IP service intelligence can aggregate all voice subscribers into one low-delay path through the entire network. Where the ATM-centric provider must set up 100 PVCs to provision 10 calls for 10 subscribers, the IP-based provider can provision the same number of calls with only one network path.
Br.//
Rishabh Mittal.
Today, data traffic is eclipsing voice traffic in volume, and demand by both business and consumers for a wide array of interactive services is growing.
That advantage derives from a fundamental difference between IP and ATM: IP technology can distinguish between various services and make per-hop routing, aggregation, traffic shaping and priority decisions, while ATM technology can only distinguish between virtual circuits .
ATM transports voice and data traffic in fixed-size, 53-byte cells. In the ATM world, all cells, and therefore all traffic, look the same, and an ATM-optimized DSLAM cannot discriminate between one kind of traffic and another. IP works with Internet packets, which are larger than ATM cells and distinguishable by type of service and destination. An IP-based concentrator can see these packets in their entirety, and discriminate between different kinds of traffic and between traffic from different subscribers.
Like, for example, a DSL service provider that signs up 100 subscribers for a full menu of services, including QoS VoDSL. To provision 10 voice calls for 10 subscribers with an ATM-optimized DSLAM, this provider must set up and manage 100 PVCs. In contrast, a DSL service provider that standardizes on DSLAMs with IP service intelligence can aggregate all voice subscribers into one low-delay path through the entire network. Where the ATM-centric provider must set up 100 PVCs to provision 10 calls for 10 subscribers, the IP-based provider can provision the same number of calls with only one network path.
Br.//
Rishabh Mittal.
Can you comment on the QOS..since it will not only talk about GBR but also rest of the traffic types.. Is the IP QOS enough.. Or do we need better QOS integration with ATM??
ReplyDeleteHi Soumya,
ReplyDeleteIp is not qos enough as we have only only dscp bits in the ip header which are not sufficient to have good qos differentiation when we have large number of services. Now a days we have number of applications at application level with every new days we have one new application. Ip is providing us the platform and differentiation between these services in terms of application.
To met the requirement of these real time and time application level protocols service provider are now deploying Ethernet backbones in the WAN which is previously limited to LAN side only. We are using encapsulation as ethernet in the data link to have different QOS for different service as ethernet can provide us dereference at Service and customer level in terms of VLAN and right now new standard of ethernet is also going to be launched in some time which will provide more qos options for application services.
QOS implemenation in ATM is not possible as per the present senerio due to following reasons-
1. ATM is connection oriented service which require end to end to connection between the clients which create trouble sometimes.
2. ATM have right now only three services as CBR,UBR and UBR+ so permutation and combinations is very tough here.
3. Also overhead factor in ATM is also on the higher side (10%).
:)
Thanks Rishabh. Very informative.
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