Tim, you are right that SONET and ATM are different mechanisms. Because of the short cells of ATM, it can be easily implemented by hardware including its routing decisions. ATM sits in the middle of packet switching and circuit switching and, most often, uses SONET as the underlying transport mechanism even though SONET does not care about what it is transporting. Due to the high price of ATM and its 10%+ overhead for the 5+48 octets cells, however, new protocols such as packet-over-SONET (POS) and even packet over DWDM are introduced to skip ATM.
In my opinion, the quality of service (QoS) offered by ATM should justify the 10%+ overhead in the long run, particularly when bandwidth is becoming cheaper and cheaper, but the high cost of ATM switches and the complexity of the technology may still be a factor for its applications. In reality, ATM probably will remain a popular choice for both WAN and enterprise backbones for years to come.
We've seen PMCS expand its product lines from PHY to SAR of ATM and other higher level devices. I certainly appreciate the contributions, particularly for the product-specific information, to this board by everyone, and hope our discussion will benefit investors by providing a better view and understanding to the stocks.
And best of all, PMCS and VTSS are up in tandem. |
