US6115385A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and system for subnetting in a switched IP network
Assignee: Cisco Technology Inc
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Filing: 1998-03-11
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Granted: 2000-09-05
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Expires: 2018-03-11
Abstract
Abstract A large flat IP network is created in a switched layer-2 network by adjusting the subnet masks of hosts such that these hosts can communicate directly with other hosts without the use of an intermediate router. The layer-2 switches are configured with user-selected IP subnets and monitor and analyze multicast packets to learn the mapping between IP subnets and switch ports. The layer-2 switches selectively forward the mulitcast packets based on the learned mappings between IP subnets and ports. After the destination host responds to the forwarded multicast, a direct connection is established between the source and destination hosts using the media access control addresses of both hosts.
Inventors
- 👤 Deepak Vig
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 02:18
CPC Classifications
H; H04; H04L; H04L49/00; H04L49/60; H04L49/602; H04L61/00; H04L2101/00; H04L2101/60; H04L2101/604; H04L49/20; H04L49/201; H04L49/35; H04L49/351
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
315 words
A data communication system having a plurality of interconnected subnetworks for enabling end stations on distinct subnetworks to communicate directly without the use of router devices, comprising: at least one switch for providing a data link layer switching function between said distinct subnetworks, said switch having a subnet mask and a plurality of subnets specified by a user via a user interface; a source end station on a first distinct subnetwork, said source end station having a network layer address, a subnet mask that is smaller in value than said switch subnet mask, and a data link layer address; a destination end station on a second distinct subnetwork, said destination end station having a network layer address, a subnet mask that is smaller in value than said switch subnet mask, and a data link address; packet analysis and forwarding programming code, operating on a processing unit in said switch, for analyzing a multicast packet, having both network layer information and a medium access control (MAC) address, received from said source end station, and selectively forwarding said multicast packet to all ports associated with a destination subnet; and a subnet to port mapping table in said switch for storing a mapping of said plurality of subnets to a plurality of ports associated with each said subnet; the packet analysis and programming code also analyzing the MAC address of the multicast packet to make a determination of whether the packet is an all stations multicast message, and if the code determines that the multicast packet is an all stations multicast message, the code then analyzes the network layer information to determine whether the multicast packet is an address resolution protocol packet, and if the code determines that the multicast packet is an address resolution protocol packet, the code then makes a forwarding decision for the multicast packet based upon subnet information derived from the network layer information.
Claim 2
Dependent Claim
315 words
A data communication system having a plurality of interconnected subnetworks for enabling end stations on distinct subnetworks to communicate directly without the use of router devices, comprising: at least one switch for providing a data link layer switching function between said distinct subnetworks, said switch having a subnet mask and a plurality of subnets specified by a user via a user interface; a source end station on a first distinct subnetwork, said source end station having a network layer address, a subnet mask that is smaller in value than said switch subnet mask, and a data link layer address; a destination end station on a second distinct subnetwork, said destination end station having a network layer address, a subnet mask that is smaller in value than said switch subnet mask, and a data link address; packet analysis and forwarding programming code, operating on a processing unit in said switch, for analyzing a multicast packet, having both network layer information and a medium access control (MAC) address, received from said source end station, and selectively forwarding said multicast packet to all ports associated with a destination subnet; and a subnet to port mapping table in said switch for storing a mapping of said plurality of subnets to a plurality of ports associated with each said subnet; the packet analysis and programming code also analyzing the MAC address of the multicast packet to make a determination of whether the packet is an all stations multicast message, and if the code determines that the multicast packet is an all stations multicast message, the code then analyzes the network layer information to determine whether the multicast packet is an address resolution protocol packet, and if the code determines that the multicast packet is an address resolution protocol packet, the code then makes a forwarding decision for the multicast packet based upon subnet information derived from the network layer information.
Claim 3
Dependent Claim
53 words
The data communication system of claim 1 further comprising a data link layer address to port mapping table in said switch for storing a mapping of data link layer addresses to ports based on address information in a reply packet received from said destination end station in response to said forwarded multicast packet.
Claim 4
Dependent Claim
35 words
The data communication system of claim 2 wherein said at least one switch conveys packets from said source end station to said destination end station using said data link layer address to port mapping table.
Claim 5
Dependent Claim
64 words
The data communication system of claim 1 wherein said subnet to port mapping table is built by said packet analysis and forwarding programming code by logically combining said switch subnet mask with the source network layer address in each multicast packet received from a source end station attached to one of said switch ports to determine the subnet corresponding to said source end station.
Claim 6
Dependent Claim
18 words
The data communication system of claim 1 wherein said plurality of subnetworks communicate using the Internet Protocol (IP).
Claim 7
Dependent Claim
29 words
The data communication system of claim 1 wherein said data link layer addresses of said source end station and said destination end sation are media access control (MAC) addresses.
Claim 8
Dependent Claim
18 words
The data communication of system of claim 1 wherein said distinct subnetworks are each Ethernet local area networks.
Claim 9
Dependent Claim
17 words
The data communication of system of claim 1 wherein said distinct subnetworks are each token ring networks.
Claim 10
Dependent Claim
25 words
The data communication system of claim 1 wherein each multicast packet received is automatically forwarded to said switch processing unit for packet analysis and forwarding.
Claim 11
Dependent Claim
266 words
In a data communication system having a plurality of interconnected subnetworks and having at least one switch providing a data link layer switching function for transmitting data frames between a source end station on a first subnetwork and a destination end station on a second subnetwork, a method for enabling source and destination end stations to communicate directly without the use of router devices, comprising: specifying a plurality of subnets for said data communication system and a subnet mask in said switch; at said source end station, specifying a subnet mask that is smaller in value than in said switch subnet mask; at said destination end station, specifying a subnet mask that is smaller in value than said switch subnet mask; determining each port associated with each of said plurality of subnets in said data communication system; analyzing a multicast packet, having both network layer information and a Medium Access Control (MAC) address, received from said source end station to determine the ports associated with a destination subnet; and selectively forwarding said multicast packet to said ports associated with said destination subnet; analysis of the multicast packet including determining whether the MAC address indicates that the multicast packet is an all stations multicast message, and if the multicast packet is an all stations multicast message, the method also includes analyzing the network layer information to determine whether the multicast packet is an address resolution protocol packet, and if the multicast packet is an address resolution protocol packet, a forwarding decision is made for the multicast packet based upon subnet information derived from the network layer information.
Claim 12
Dependent Claim
266 words
In a data communication system having a plurality of interconnected subnetworks and having at least one switch providing a data link layer switching function for transmitting data frames between a source end station on a first subnetwork and a destination end station on a second subnetwork, a method for enabling source and destination end stations to communicate directly without the use of router devices, comprising: specifying a plurality of subnets for said data communication system and a subnet mask in said switch; at said source end station, specifying a subnet mask that is smaller in value than in said switch subnet mask; at said destination end station, specifying a subnet mask that is smaller in value than said switch subnet mask; determining each port associated with each of said plurality of subnets in said data communication system; analyzing a multicast packet, having both network layer information and a Medium Access Control (MAC) address, received from said source end station to determine the ports associated with a destination subnet; and selectively forwarding said multicast packet to said ports associated with said destination subnet; analysis of the multicast packet including determining whether the MAC address indicates that the multicast packet is an all stations multicast message, and if the multicast packet is an all stations multicast message, the method also includes analyzing the network layer information to determine whether the multicast packet is an address resolution protocol packet, and if the multicast packet is an address resolution protocol packet, a forwarding decision is made for the multicast packet based upon subnet information derived from the network layer information.
Claim 13
Dependent Claim
33 words
The method of claim 10 further comprising building a subnet to port mapping table in said switch which maps said plurality of subnets to a plurality of ports associated with each said subnet.
Claim 14
Dependent Claim
51 words
The method of claim 10 wherein said determining each port step includes logically combining said switch subnet mask with a source network layer address in each multicast packet received from said source end station attached to one of said switch ports to determine the subnet corresponding to said source end station.
Claim 15
Dependent Claim
49 words
The method of claim 10 further comprising building a data link layer address to port mapping table in said switch which maps data link layer addresses to ports based on address information in a reply packet received from said destination end station in response to said forwarded multicast packet.
Claim 16
Dependent Claim
29 words
The method of claim 10 further comprising automatically forwarding each multicast packet from said source end station to a processing unit in said switch for packet analysis and forwarding.
Claim 17
Dependent Claim
25 words
The method of claim 10 wherein said multicast packet is sent to all switch ports if said multicast packet is not an IP ARP packet.
Claim 18
Dependent Claim
30 words
The method of claim 10 wherein said plurality of subnetworks are local area networks with said source end station communicating with said destination end station using the Internet Protocol (IP).
Claim 19
Dependent Claim
28 words
The method of claim 10 wherein said analyzing and selectively forwarding steps are performed by packet analysis and forwarding code operating on a processing unit in said switch.
Claim 20
Dependent Claim
29 words
The method of claim 13 further comprising conveying packets from said source end station to said destination end station using said data link layer address to port mapping table.
Claim 21
Dependent Claim
285 words
A data communication system having a plurality of interconnected subnetworks for enabling communication between end stations on distinct subnetworks, comprising: at least one switch for providing a data link layer switching function between said distinct subnetworks, said switch having a subnet mask and a plurality of subnets specified through a user interface; a source end station on a first distinct subnetwork, said source end station having a network layer address, a subnet mask that is smaller in value than said switch subnet mask, and a data link layer address; a destination end station on a second distinct subnetwork, said destination end station having a network layer address, and a data link layer address; packet analysis and forwarding programming code, operating on a processing unit in said switch, for analyzing a multicast packet, having both network layer information and a medium access control (MAC) address, received from said source end station, and selectively forwarding said multicast packet to all ports associated with a destination subnet; and a subnet to port mapping table in said switch for storing a mapping of said plurality of subnets to a plurality of ports associated with each said subnet; the code also analyzing the MAC address of the multicast packet to determine whether the multicast packet is an all stations multicast message, and if the code determines that the multicast packet is an all stations multicast message, the code analyzes the network layer information to determine whether the multicast packet is an address resolution protocol packet, and if the code determines that the multicast packet is an address resolution protocol packet, the code makes a forwarding decision for the multicast packet based upon subnet information derived from the network layer information.
Claim 22
Dependent Claim
285 words
A data communication system having a plurality of interconnected subnetworks for enabling communication between end stations on distinct subnetworks, comprising: at least one switch for providing a data link layer switching function between said distinct subnetworks, said switch having a subnet mask and a plurality of subnets specified through a user interface; a source end station on a first distinct subnetwork, said source end station having a network layer address, a subnet mask that is smaller in value than said switch subnet mask, and a data link layer address; a destination end station on a second distinct subnetwork, said destination end station having a network layer address, and a data link layer address; packet analysis and forwarding programming code, operating on a processing unit in said switch, for analyzing a multicast packet, having both network layer information and a medium access control (MAC) address, received from said source end station, and selectively forwarding said multicast packet to all ports associated with a destination subnet; and a subnet to port mapping table in said switch for storing a mapping of said plurality of subnets to a plurality of ports associated with each said subnet; the code also analyzing the MAC address of the multicast packet to determine whether the multicast packet is an all stations multicast message, and if the code determines that the multicast packet is an all stations multicast message, the code analyzes the network layer information to determine whether the multicast packet is an address resolution protocol packet, and if the code determines that the multicast packet is an address resolution protocol packet, the code makes a forwarding decision for the multicast packet based upon subnet information derived from the network layer information.
Claim 23
Dependent Claim
53 words
The data communication system of claim 19 further comprising a data link layer address to port mapping table in said switch for storing a mapping of data link layer addresses to ports based on address information in a reply packet received from said destination end station in response to said forwarded multicast packet.
Claim 24
Dependent Claim
35 words
The data communication system of claim 19 wherein said at least one switch conveys packets from said source end station to said destination end station using said data link layer address to port mapping table.
Claim 25
Dependent Claim
64 words
The data communication system of claim 19 wherein said subnet to port mapping table is built by said packet analysis and forwarding programming code by logically combining said switch subnet mask with the source network layer address in each multicast packet received from a source end station attached to one of said switch ports to determine the subnet corresponding to said source end station.
Claim 26
Dependent Claim
25 words
The data communication system of claim 19 wherein each multicast packet received is automatically forwarded to said switch processing unit for packet analysis and forwarding.
Claim 27
Dependent Claim
223 words
In a data communication system having a plurality of interconnected subnetworks and having at least one switch providing a data link layer switching function for transmitting data frames between a source end station on a first subnetwork and a destination end station on a second subnetwork, a method for enabling communication between source and destination end stations, comprising: specifying a plurality of subnets for said data communication system and a subnet mask in said switch; at said source end station, specifying a subnet mask that is smaller in value than said switch subnet mask; determining each port associated with each of said plurality of subnets in said data communication system; analyzing a multicast packet, having both network layer information and a medium access control (MAC) address, received from said source end station to determine the ports associated with a destination subnet; and selectively forwarding said multicast packet to said ports associated with said destination subnet; analysis of the multicast packet including determining if the multicast packet is an all stations multicast message, the method also includes analyzing the network layer information to determine whether the multicast packet is an address resolution protocol packet, and if the multicast packet is an address resolution protocol packet, a forwarding decision is made for the multicast packet based upon subnet information derived from the network layer information.
Claim 28
Dependent Claim
223 words
In a data communication system having a plurality of interconnected subnetworks and having at least one switch providing a data link layer switching function for transmitting data frames between a source end station on a first subnetwork and a destination end station on a second subnetwork, a method for enabling communication between source and destination end stations, comprising: specifying a plurality of subnets for said data communication system and a subnet mask in said switch; at said source end station, specifying a subnet mask that is smaller in value than said switch subnet mask; determining each port associated with each of said plurality of subnets in said data communication system; analyzing a multicast packet, having both network layer information and a medium access control (MAC) address, received from said source end station to determine the ports associated with a destination subnet; and selectively forwarding said multicast packet to said ports associated with said destination subnet; analysis of the multicast packet including determining if the multicast packet is an all stations multicast message, the method also includes analyzing the network layer information to determine whether the multicast packet is an address resolution protocol packet, and if the multicast packet is an address resolution protocol packet, a forwarding decision is made for the multicast packet based upon subnet information derived from the network layer information.
Claim 29
Dependent Claim
33 words
The method of claim 24 further comprising building a subnet to port mapping table in said switch which maps said plurality of subnets to a plurality of ports associated with each said subnet.
Claim 30
Dependent Claim
51 words
The method of claim 24 wherein said determining each port step includes logically combining said switch subnet mask with a source network layer address in each multicast packet received from said source end station attached to one of said switch ports to determine the subnet corresponding to said source end station.
Claim 31
Dependent Claim
49 words
The method of claim 24 further comprising building a data link layer address to port mapping table in said switch which maps data link layer addresses to ports based on address information in a reply packet received from said destination end station in response to said forwarded multicast packet.
Claim 32
Dependent Claim
29 words
The method of claim 24 further comprising automatically forwarding each multicast packet from said source end station to a processing unit in said switch for packet analysis and forwarding.
Claim 33
Dependent Claim
29 words
The method of claim 27 further comprising conveying packets from said source end station to said destination end station using said data link layer address to port mapping table.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2003-09-05 | 2004-03-06 | 2004-09-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-09-05 | 2008-03-06 | 2008-09-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-09-05 | 2012-03-06 | 2012-09-05 | $7700.00 | Window Closed / Lapsed |