Creating a low bandwidth channel within a high bandwidth packet stream
View Patent ↗Creating a low-bandwidth channel in a high-bandwidth channel. By taking advantage of extra bandwidth in a high-bandwidth channel, a low-bandwidth channel is created by inserting extra packets. When an inter-packet gap of the proper duration is detected, the extra packet is inserted and any incoming packets on the high-bandwidth channel are stored in an elastic buffer. Observing inter-packet gaps, minimal latency is introduced in the high-bandwidth channel when there is no extra packet in the process of being sent, and the effects of sending a packet on the low-bandwidth channel are absorbed and distributed among other passing traffic.
1. A method for creating a low-bandwidth channel in a high-bandwidth channel, comprising:
converting an input serial datastream, from the high-bandwidth channel, to a high-bandwidth parallel datastream;
holding an extra packet, for the low-bandwidth channel, in a first memory;
examining the high-bandwidth parallel datastream to sense an appropriate time for transmitting the extra packet;
routing the extra packet for transmission at the appropriate time;
routing the high-bandwidth parallel datastream for transmission when the extra packet is not routed for transmission;
holding the high-bandwidth parallel datastream in a second memory when the extra packet is routed for transmission; and
converting the high-bandwidth parallel datastream, forming the high-bandwidth channel, and the extra packet, forming the low-bandwidth channel, to an output serial datastream for transmission.
2. A method as in claim 1 , wherein routing the high-bandwidth parallel datastream for transmission comprises:
minimizing inter-packet gaps in the high-bandwidth parallel datastream.
3. A method as in claim 1 , further comprising:
waiting a minimum hold time prior to routing a subsequent extra packet, for the low-bandwidth channel, for transmission.
4. A method as in claim 1 , wherein the high-bandwidth channel and the low-bandwidth channel conform to Ethernet standards.
5. An apparatus for creating a low-bandwidth channel in a high-bandwidth channel, comprising:
a deserializer for converting an input serial datastream, from the high-bandwidth channel, to a high-bandwidth parallel datastream;
a first memory for holding an extra packet, for the low-bandwidth channel;
a second memory for holding the high-bandwidth parallel datastream when the extra packet is routed for transmission;
a serializer for converting the high-bandwidth parallel datastream, forming the high-bandwidth channel, and the extra packet, forming the low-bandwidth channel, to an output serial datastream for transmission; and
control logic for examining the high-bandwidth parallel datastream to sense an appropriate time for transmitting the extra packet, for routing the extra packet to the serializer for transmission at the appropriate time, for routing the high-bandwidth parallel datastream to the serializer for transmission when the extra packet is not routed for transmission, and for routing the high-bandwidth parallel datastream to the second memory when the extra packet is routed for transmission.
6. An apparatus as in claim 5 , wherein the appropriate time is after a minimum inter-packet gap in the high-bandwidth parallel datastream.
7. An apparatus as in claim 6 , wherein the control logic routes the extra packet to the serializer for transmission when the second memory has sufficient free space to hold the high-bandwidth parallel datastream.
8. An apparatus as in claim 7 , wherein the second memory is larger than the size of the extra packet and the minimum inter-packet gap.
9. An apparatus as in claim 8 , wherein the control logic minimizes inter-packet gaps in the high-bandwidth parallel datastream while routing the high-bandwidth parallel datastream to the serializer for transmission.
10. An apparatus as in claim 9 , wherein the control logic includes a hold timer for setting a maximum rate at which extra packets, for the low-bandwidth channel, are routed to the serializer for transmission.
11. An apparatus as in claim 6 , wherein the control logic senses the appropriate time for transmitting the extra packet by counting idle characters in the high-bandwidth parallel datastream to meet the minimum inter-packet gap.
12. A method as in claim 1 , wherein the appropriate time is after a minimum inter-packet gap in the high-bandwidth parallel datastream.
13. A method as in claim 12 , wherein sensing the appropriate time for transmitting the extra packet comprises:
counting idle characters in the high-bandwidth parallel datastream to meet the minimum inter-packet gap.