Hierarchically interconnected routers for exclusively polling low activity network nodes to reduce polling traffic

• US 6,396,845 B1
• Filed: 04/27/1998
• Issued: 05/28/2002
• Est. Priority Date: 04/25/1997
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Sugita, Masahiro
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): Duong, Frank
• Application Number:
  US09/067,145
• Time in Patent Office: 1,492 Days
• Field of Search: 370/400,401,408,449,389,396,398,422 709/201,223,224 340/825.02,825.08
• US Class Current: 370/449
• CPC Class Codes: H04L 43/00 Arrangements for monitoring or testing data switching networks

Abstract

In a communication network, routers are interconnected in a hierarchical tree structure and local network nodes are connected to each of the routers located at the lowest level of the tree structure. A network monitor is connected to one of the routers which is located at the top of the tree structure. Each router comprises a first memory having a plurality of entries and a second memory. In response to a packet from the network, a physical address and a corresponding logical address are mapped in one of the entries and a predetermined timer value is set. The timer value is decremented at regular intervals. At regular intervals, the first memory is searched for an entry whose timer value is decremented to a predefined threshold and one of the local network nodes corresponding to this entry is polled to receive a response therefrom indicating an operating state of the polled node. The response is stored in the second memory. The network monitor transmits a polling signal to each router at the lowest level and receives the contents of the second memory.

Claims

1. A communication network comprising:

a plurality of routers interconnected in a hierarchical tree structure;

a plurality of local network nodes connected to said routers located at a lowest level of the tree structure; and

a network monitor connected to one of said routers which is located at a top of said tree structure,

each of said routers comprising;

polling means for detecting a local network node having no access from the network for a period longer than a predetermined length and polling the local network node to receive a response therefrom indicating an operating state of the polled node; and

a memory for storing said response,

said network monitor transmitting a polling signal to each router at the lowest level and receiving the contents of said memory.

2. A communication network comprising:

a plurality of routers interconnected in a hierarchical tree structure;

a plurality of local network nodes connected to said routers located at a lowest level of the tree structure; and

a network monitor connected to one of said routers which is located at a top of said tree structure,

each of said routers comprising;

a first memory having a plurality of entries;

address resolution means for mapping a physical address to a corresponding logical address in one of said entries, setting a predetermined timer value in said one entry in response to a packet from the network, and varying the timer value by a predetermined amount at regular intervals;

polling means for making a search through said first memory at regular intervals to detect an entry whose timer value has crossed a threshold and polling one of said local network nodes corresponding to the entry to receive a response therefrom indicating an operating state of the polled node; and

a second memory for storing said response;

said network monitor transmitting a polling signal to each router at the lowest level and receiving the contents of said second memory.

3. A method for polling a communication network, wherein the network comprises a plurality of routers interconnected in a hierarchical tree structure, a plurality of local network nodes connected to said routers located at lowest level of the tree structure, and a network monitor connected to one of said routers which is located at a top of said tree structure, wherein each of said routers comprises a memory, said method comprising:

detecting a local network node having no access from the network for a period longer than a predetermined length;

detecting a local network node to receive a response therefrom indicating an operating state of the polled node;

storing said response in said memory; and

transmitting a polling signal from the network monitor to each router at the lowest level and receiving the contents of said memory.

4. A polling method for a communication network, wherein the network comprises a plurality of routers interconnected in a hierarchical tree structure, a plurality of local network nodes connected to the routers located at lowest level of the tree structure, and a network monitor connected to one of said routers which is located at a top of said tree structure, wherein each of said routers includes a first memory having a plurality of entries and a second memory, the method comprising:

mapping a physical address to a corresponding logical address in one of said entries;

setting a predetermined timer value in said one entry in response to a packet from the network;

varying, at regular intervals, the timer value of each entry of said first memory by a predetermined amount;

making a search through said first memory at regular intervals to detect any entry whose timer value has crossed a threshold;

polling one of said local network nodes which corresponds to the entry to receive a response therefrom indicating an operating state of the polled network node;

storing said response in said second memory; and

transmitting a polling signal from the network monitor at periodic intervals to each router at the lowest level and receiving the contents of said second memory.

5. A communication network comprising:

a plurality of interconnected routers;

at least one local network node connected to said routers;

a network monitor connected to at least one of said routers;

each of said routers comprising;

a polling control circuit which detects a particular network node, said particular network node having no access from said network for a period longer than a threshold, said polling control circuit further polls said particular network node to receive a response therefrom indicating an operating state of said particular network node; and

a memory which stores said response;

wherein

said network monitor transmits a polling signal to each router and receives the contents of said memory.

6. The communication network as recited in claim 5, wherein:

said routers are connected in a hierarchical tree structure having a top and a bottom;

said network monitor is connected to a router at said top of said tree structure; and

said network nodes are connected to said bottom of said hierarchical tree structure.

7. A communication network comprising:

a plurality of interconnected routers;

at least one local network node connected to said routers;

a network monitor connected to at least one of said routers;

each of said routers comprising;

a first memory;

an address resolution processor, wherein said address resolution processor receives a packet including a logical address, said address resolution process maps a physical address to said logical address and sets a timer value in response thereto, said address resolution processor stores said timer value in said first memory and varies all said timer values at regular intervals;

a polling control circuit which performs a search through said first memory at regular intervals and detects a particular entry whose timer value has crossed a threshold, said polling control circuit polls a particular node of said local network nodes corresponding to said particular entry and receives a response therefrom indicating an operating state of said particular node; and

a second memory which stores said response;

wherein

said network monitor transmits a polling signal to each router and receives the contents of said second memory.

8. The communication network as recited in claim 7, wherein:

said routers are connected in a hierarchical tree structure having a top and a bottom;

said network monitor is connected to a router at said top of said tree structure; and

said network nodes are connected at said bottom of said hierarchical tree structure.

9. A method for polling a communication network, wherein the network comprises a plurality of interconnected routers, at least one local network node connected to said routers, a network monitor connected to at least one of said routers, and wherein each of said routers includes a memory, said method comprising:

detecting a particular local network node having no access from said network for a period longer than a threshold;

polling said particular local network node and receiving a response therefrom indicating an operating state of said particular local network node;

storing said response in said memory;

transmitting a polling signal from said network monitor to each router; and

receiving the contents of said memory by said network monitor.

10. The method as recited in claim 9, wherein:

said routers are connected in a hierarchical tree structure having a top and a bottom;

said network monitor is connected to a router at said top of said tree structure; and

said network nodes are connected at said bottom of said hierarchical tree structure.

11. A method for polling a communication network, wherein the network comprises a plurality of interconnected routers, at least one local network node connected to said routers, a network monitor connected to at least one of said routers, and wherein each of said routers includes a first and a second memory, the method comprising:

receiving a packet including a logical address;

mapping a physical address to said logical address and setting a timer value in response thereto;

storing said timer value in said first memory;

varying, at regular intervals, all timer values in said first memory;

searching said first memory for a particular entry whose timer value has crossed a threshold;

polling a particular node of said local network nodes which corresponds to said particular entry and receiving a response therefrom indicating an operating state of said particular node;

storing said response in said second memory; and

transmitting a polling signal from said network monitor to each router and receiving the contents of said second memory.

12. The method as recited in claim 11, wherein:

said routers are connected in a hierarchical tree structure having a top and a bottom;

said network monitor is connected to a router at said top of said tree structure; and

said network nodes are connected at said bottom of said hierarchical tree structure.