elecommunications protocol over Internet packets, have no reference or relationship to any clocking, timing, or basic synchronizing intelligence. They are just out there somewhere in the Ether. T1/E1, PPP/HDLC, ATM, and Ethernet all have clocking and synchronizing information embedded in the stream. Packet switching is nothing more than switching and/or routing at packet borders, or between packets after the details in the packet header have been opened and read. Only after the entity has been opened and read can it be routed or switched to a second port. Many times the mail system is used as a metaphor for packet switching. It's a pretty good metaphor, but with some subtle differ- ences. First, the packet entity must be opened and read. It does not have an outside and an inside unless the payload has been en- crypted, or otherwise sealed and secured in some way. One of the fundamental flaws in the Internet everyone knows about and experi- ences every day is simple courtesy and security. In addition to the payload and addressing information, there are other significant details inside the packet entity exposed for any and everyone to see and do with as they please. These other details have to do with all kinds of fun things that can muck up the overall machinery such as administrative control of the routing machines. A view that says the Internet has evolved from prior well-known methods and technology wouldn't be difficult to contend, but would PRACTICAL IP AND TELECOM FOR BROADCAST ENGINEERING AND OPERATIONS likely be more difficult to defend. Many modern IP network design- ers seem blissfully unaware that the Internet is critically dependent on an underlying transmission infrastructure they simply refer to as the network layer. Very few of them have a clue about the importance of network clocking and timing. Many think packet over SONET/ SDH isn't a big deal because it's done all the time (over PDH), which for the most part goes over SONET/SDH any way. Very few realize that HDLC, or PPP framing, is as rigid and