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Layer 2 Tunneling of Dynamic Host Configuration Protocol Messages to Improve Efficiency and Security

IP.com Disclosure Number: IPCOM000131777D
Original Publication Date: 2005-Nov-18
Included in the Prior Art Database: 2005-Nov-18
Document File: 5 page(s) / 59K

Publishing Venue

Motorola

Related People

Charles R. Barker, Jr: AUTHOR

Abstract

In typical packet-oriented wireless networks, groupcast packets are often more costly to distribute than unicast packets. This is particularly true for mesh networks, where distribution of groupcast packets may depend on multiple retransmissions of the same data by different nodes in the mesh. In some cases, it is possible to reduce groupcast transmissions by relying on higher-layer protocol information in the packets to intelligently tunnel or filter the packets. If certain concessions are made, packets containing Dynamic Host Configuration Protocol (DHCP) data provide enough information that intelligent filters can reduce all stages of the protocol to unicast packets in the wireless domain, thus saving resources in the wireless network.

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Layer 2 Tunneling of Dynamic Host Configuration Protocol Messages to Improve Efficiency and Security

Author:  Charles R. Barker, Jr.

Abstract

In typical packet-oriented wireless networks, groupcast packets are often more costly to distribute than unicast packets.  This is particularly true for mesh networks, where distribution of groupcast packets may depend on multiple retransmissions of the same data by different nodes in the mesh.  In some cases, it is possible to reduce groupcast transmissions by relying on higher-layer protocol information in the packets to intelligently tunnel or filter the packets.  If certain concessions are made, packets containing Dynamic Host Configuration Protocol (DHCP) data provide enough information that intelligent filters can reduce all stages of the protocol to unicast packets in the wireless domain, thus saving resources in the wireless network.

Problem

Packet-oriented wireless networks generally suffer tighter resource constraints than similar wired networks.  First, they tend to offer lower payload bandwidth, as transmitters are typically bounded in terms of output power and spectrum and receivers suffer from environmental interference.  Second, they are often targeted at battery-powered devices for which power is a limited resource.  In wireless networks, broadcast or multicast (hereafter collectively called “groupcast”) packets generally put higher demands on these limited resources than unicast packets.  Transmitters of groupcast packets might be required to adjust their modulation and output power in order to reach all the nodes dependent on them for the data.  This may mean increasing output power or decreasing the effective bit rate in order to meet the lowest common denominator of all their dependents, consuming more bandwidth than for a unicast transmission.  All receivers must then wake and decode the packets regardless of whether the data was ultimately of interest to them, consuming power from each.

Wireless mesh networks, in which wireless nodes relay data on behalf of other wireless nodes to expand the range of the network, suffer these groupcast distribution problems in greater proportions.  This owes to the “repeating” nature of broadcast distribution in that receivers typically retransmit groupcast data as the packet “floods” the network, thus consuming more bandwidth and power.

In practice, groupcast packets are often not useful to all of the nodes that receive them.  For example, groupcast packets may be used when the sender needs to locate a network service without prior knowledge of the service provider’s unicast address.  In this instance, it is only important that the service provider receive the packet; other nodes will likely ignore the packet entirely.  If some application-level knowledge is available to the transmitters, it is possible to apply filtering techniques to limit excess resource consumption by limiting distribution to only the nodes that may...