Designated router assginment per multicast group address/range

• US 20060268869A1
• Filed: 05/31/2005
• Published: 11/30/2006
• Est. Priority Date: 05/31/2005
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Boers, Arjen, Wijnands, Ijsbrand
• Granted Patent: US 7,911,977 B2
• Time in Patent Office: Days
• US Class Current: 370/390
• CPC Class Codes: H04L 45/00 Routing or path finding of packets in data switching networks routing or path finding in wireless networks H04W40/00

Abstract

Each of several routers connected to a LAN elects the same router as the designated router for a multicast group identified by a multicast address. Each of the several routers implements a method for electing the designated router. The method includes in one embodiment, generating several values corresponding to the several routers, respectively. The several values are generated as a function of the several routers'"'"' IP addresses, respectively, and an IP address of a first multicast group. The values, in one embodiment, are then compared to determine which is the largest. Thereafter each router elects as the designated router for the multicast group, the router corresponding to the largest value.

Claims

1. A method comprising:

a first router receiving first and second IGMP membership reports via a LAN, wherein the first IGMP membership report comprises an IP address for a first multicast group, and wherein the second IGMP membership report comprises an IP address for a second multicast group;

the first router generating and transmitting a first Join message in response to receiving the first IGMP membership report;

the first router dropping the second IGMP membership report.

2. The method of claim 1 further comprising:

a second router receiving the first and second IGMP membership reports via the LAN;

the second router generating and transmitting a second Join message in response to receiving the second IGMP membership report;

the second router dropping the first IGMP membership report.

3. The method of claim 2 further comprising:

the first router receiving a first multicast data packet after the first router transmits the first Join message, wherein the first multicast data packet comprises first multicast data and the IP address of the first multicast group;

the second router receiving a second multicast data packet after the second router transmits the second Join message, wherein the second multicast data packet comprises second multicast data and the IP address of the second multicast group.

4. The method of claim 3 further comprising:

the first router transmitting the first multicast data to the LAN;

the second router transmitting the second multicast data to the LAN.

5. A method comprising:

a first router selecting itself as a designated router for a first multicast group;

the first router selecting a second router as a designated router for a second multicast group, wherein the first router is distinct from the second router, and wherein the first multicast group is distinct from the second multicast group.

6. The method of claim 5 wherein the first router is one of a plurality of routers directly coupled to a LAN, and wherein the second router is one of the plurality of routers directly coupled to the LAN.

7. The method of claim 5 further comprising:

the second router selecting itself as the designated router for the second multicast group, and;

the second router selecting the first router as the designated router for the first multicast group.

8. The method of claim 5 further comprising:

the first router receiving a first multicast data packet after the first router selects itself as the designated router for the first multicast group, wherein the first multicast data packet comprises first multicast data and an IP address of the first multicast group;

the second router receiving a second multicast data packet after the first router selects the second router as the designated router for the second multicast group, wherein the second multicast data packet comprises second multicast data and an IP address of the second multicast group.

9. The method of claim 8 further comprising:

the first router transmitting the first multicast data to a LAN;

the second router transmitting the second multicast data to the LAN.

10. The method of claim 5 further comprising:

the first router generating a first value as a function of an IP address of the first router and an IP address of the first multicast group;

the first router generating a second value as a function of an IP address of the second router and the IP address of the first multicast group;

the first router comparing the first value to the second value;

the first router selecting itself as the designated router for the first multicast group in response to comparing the first and second values.

11. The method of claim 10 further comprising;

the first router generating a third value as a function of the IP address of the first router and an IP address of the second multicast group;

the first router generating a forth value as a function of the IP address of the second router and the IP address of the second multicast group;

the first router comparing the third value to the forth value;

the first router selecting the second router as the designated router for the second multicast group in response to comparing the third and fourth values.

14. The apparatus of claim 11 wherein the first router is configured to select itself or the second router as a designated router for the first multicast group, wherein the first router selects itself as the designated router if the first value is numerically greater than the second value, and wherein the first router selects the second router as the designated router if the second value is numerically greater than the first value.

16. The apparatus of claim 11 wherein the first circuit is configured to generate third and fourth values, wherein the third value is generated as a function of the first router'"'"'s IP addresses and an IP address of a second multicast group, and wherein the fourth value is generated as a function of the second router'"'"'s IP addresses and the IP address of the second multicast group.

17. The apparatus of claim 16 wherein the first router is configured to select itself or the second router as a designated router for the second multicast group, wherein the first router selects itself as the designated router for the second multicast group if the third value is numerically greater than the fourth value, and wherein the first router selects the second router as the designated router for the second multicast group if the fourth value is numerically greater than the third value.

12. An apparatus comprising:

a first router, the first router comprising;

a first circuit for generating first and second values, wherein the first value is generated as a function of the first router'"'"'s IP addresses and an IP address of a first multicast group, and wherein the second value is generated as a function of a second router'"'"'s IP addresses and the IP address of the first multicast group;

a second circuit for comparing the first and second values with each other.

13. The apparatus of claim 12 further comprising:

the second router, the second router comprising;

a third circuit for generating third and fourth values, wherein the third value is generated as a function of the first router'"'"'s IP addresses and the IP address of the first multicast group, and wherein the fourth value is generated as a function of the second router'"'"'s IP addresses and the IP address of the first multicast group;

a forth circuit for comparing the third and fourth values with each other;

wherein the first and third values are identical to each other, and;

wherein the second and fourth values are identical to each other.

15. The apparatus of claim 13 wherein the second router is configured to select itself or the first router as a designated router for the first multicast group, wherein the second router selects itself as the designated router if the fourth value is numerically greater than the third value, and wherein the second router selects the first router as the designated router if the third value is numerically greater than the fourth value.

18. The apparatus of claim 12 wherein the second circuit is configured to generate fifth and sixth values, wherein the fifth value is generated as a function of the first router'"'"'s IP addresses and the IP address of a second multicast group, and wherein the sixth value is generated as a function of the second router'"'"'s IP addresses and the IP address of the second multicast group.

20. The apparatus of claim 18 further comprising a means for selecting a first router or a second router as a designated router of the first multicast group, wherein the means for selecting selects the first router as the designated router if the first value is numerically greater than the second value, and wherein the means for selecting selects the second router as the designated router if the first value is numerically less than the second value.

19. An apparatus comprising:

means for generating first and second values, wherein the first value is generated as a function of a first router'"'"'s IP addresses and an IP address of a first multicast group, and wherein the second value is generated as a function of a second router'"'"'s IP addresses and the IP address of the first multicast group;

means for comparing the first and second values.