Multi-channel support for virtual private networks in a packet to ATM cell cable system
View Patent ↗A two-way cable network offering high-speed broadband communications delivered via virtual private networks over a multi-channel shared media system. Bi-directional transmission of packet to ATM cell based communications is established between a head end communication controller and a number of subscriber terminal units, whereby individual cells are prioritized and routed according to a virtual connection. Virtual connections are organized to support multiple virtual private networks in a shared media CATV system. The virtual private network to which a particular STU belongs is user selectable and has the flexibility of handling multi up/downstream channels with different MAC domains. The present invention can also handle non-ATM MAC domains via the same common ATM switch. To overcome the limited number of addresses inherent to common ATM switches, a mapping/remapping function is implemented in the port cards. Furthermore, downstream as well as upstream traffic are filtered at each STU. In one embodiment, information pertaining to downstream traffic is used to implement predictive scheduling in order to improve the timing associated with the request/grant cycle. In another embodiment, a user has the ability to select a quality of service that best suits the needs of the current application. In a further embodiment, the scheduling function is associated with each of the receivers in order to provide improved scalability.
1. In a communication system, a method for controlling receipt of upstream data and transmission of downstream data, comprising the steps of:
storing a plurality of valid IP addresses in a memory;
receiving packets transmitted by a subscriber terminals on one or more upstream channels, wherein the packets are received by a packet interface on a first upstream path;
examining the packets to determine destination addresses;
comparing IP addresses corresponding to an address resolution protocol packet with the valid IP addresses stored in memory to determine whether packets are valid or invalid;
processing valid packets;
discarding invalid packets
selectively forwarding the packets from the packet interface on a first downstream path for transmission over one or more downstream channels to designated subscriber terminal units according to the destination addresses.
2. The method of claim 1 , further comprising the steps of:
storing information pertaining to which packets are intended to be received by a particular subscriber terminal unit in a memory;
examining each packet received by the particular subscriber terminal unit to determine whether the packet was intended to be received by that particular subscriber terminal unit;
processing only downstream multicast packets that were intended to be received by that particular subscriber terminal unit;
discarding downstream multicast packets that were not intended to be received by that particular subscriber terminal unit.
3. A communication system comprising:
a cable network having one or more downstream channels and one or more upstream channels;
a plurality of subscriber terminal units coupled to the cable network;
a head end controller coupled to the cable network for controlling upstream and downstream communications, wherein the head end controller includes:
a packet interface for receiving packets from subscriber terminal units on a first upstream path;
a packet forwarder coupled to the packet interface for selectively forwarding packets from the packet interface on a first downstream path for transmission over one or more downstream channels to designated subscriber terminal units:
a memory for storing a plurality of valid IP addresses;
a filter coupled to the memory for comparing IP addresses corresponding to an address resolution protocol packet with the valid IP addresses stored in memory,
wherein only valid packets are processed and invalid packets are discarded.
4. The communication system of claim 3 , wherein one of the subscriber terminal units comprises:
a memory for storing a plurality of valid IP addresses;
a filter coupled memory for comparing IP addresses corresponding to an address resolution protocol packet with the valid IP addresses stored in memory,
wherein only valid packets are allowed to proceed upstream and invalid packets are discarded.
5. The communication system of claim 3 , wherein one of the subscriber terminal units is comprised of:
a memory for storing information pertaining to which packets are to be received by the subscriber terminal unit;
a filter coupled to memory for selectively processing only downstream multicast packets according to the information stored in the memory.