SUMMARIZATION AND LONGEST-PREFIX MATCH WITHIN MPLS NETWORKS

• US 20110194561A1
• Filed: 04/18/2011
• Published: 08/11/2011
• Est. Priority Date: 11/14/2008
• Status: Active Grant

• Current Assignee: Juniper Networks Incorporated
• Original Assignee: Juniper Networks Incorporated
• Inventors: Kompella, Kireeti
• Granted Patent: US 8,363,667 B2
• Time in Patent Office: Days
• US Class Current: 370/392
• CPC Class Codes: H04L 45/04 Interdomain routing, e.g. hierarchical routing
• CPC Class Codes: H04L 45/50 using label swapping, e.g. multi-protocol label switch [MPLS]
• CPC Class Codes: H04L 45/507 Label distribution
• CPC Class Codes: H04L 61/10 of different types
• CPC Class Codes: H04L 61/5061 Pools of addresses
• CPC Class Codes: H04L 69/22 Parsing or analysis of headers

Abstract

In general, techniques are described for summarizing label mappings and thereby enabling longest-prefix match within Multi-Protocol Label Switching (MPLS) networks. More specifically, a first router included within a first area of a network comprises a control unit that maintains a label space defining labels available for mapping to a plurality of addresses assigned to network devices within the network. The control unit reserves a contiguous set of the labels of the label space and maps the contiguous set of labels to first area addresses. The first area addresses include those addresses of the plurality of addresses available for assignment to network devices within the first area. The first router also includes an interface card that transmits, to a second router of a second area of the network, an advertisement that advertises a summarized version of the mapping between the contiguous set of labels and the first area addresses.

Claims

1. A method comprising:

maintaining, with a first router of a first area of a network, a label space defining a plurality of labels available for mapping to a plurality of addresses assigned to network devices within the network;

reserving, with the first router, a contiguous set of the plurality of labels defined by the label space;

mapping, with the first router, the contiguous set of labels to a plurality of first area addresses, wherein the first area addresses include those addresses of the plurality of addresses available for assignment to network devices within the first area of the network; and

transmitting, with the first router to a second router different than the first router of a second area of the network different from the first area, an advertisement that advertises a summarized version of the mapping between the contiguous set of labels and the first area addresses as a prefix mapping between a label prefix that summarizes the contiguous set of labels and a network address prefix that summarizes the first area addresses.

2. The method of claim 1, wherein the network address prefix comprises an Internet Protocol (IP) prefix that summarizes the first area addresses.

3. The method of claim 1, wherein reserving the contiguous set of the plurality of labels comprises:

receiving configuration data that defines the first area addresses;

determining, based on the configuration data, a number of the plurality of labels to reserve; and

reserving the determined number of the plurality of labels as the contiguous set of the plurality of labels.

4. The method of claim 3,

wherein receiving the configuration data comprises receiving an Internet Protocol (IP) address prefix that defines a contiguous set of IP addresses assigned to devices included within the first area,

wherein determining the number of the plurality of labels to reserve comprises determining the number of the plurality of labels based on a number of IP addresses included within the contiguous set of IP addresses, and

wherein reserving the determined number of the plurality of labels comprises reserving the determined number of labels such that the number of reserved labels equals the number of IP addresses included within the contiguous set of IP addresses.

5. The method of claim 1, wherein mapping the contiguous set of labels to a plurality of first area addresses comprises mapping one or more of the contiguous set of labels to Internet Protocol (IP) addresses assigned to devices within the first area, wherein the first area is defined by an IP address prefix.

6. The method of claim 1, further comprising:

receiving, from the second router included within the second area, an MPLS packet that includes one of the contiguous set of reserved labels, wherein each of the contiguous set of reserved labels comprise an inter-area label;

swapping, with the first router, the inter-area label with an intra-area label; and

forwarding, within the first area, the MPLS packet with the intra-area label.

7. The method of claim 1,

wherein the label space comprises a first label space,

wherein the contiguous set of labels comprises a first contiguous set of labels, and

wherein transmitting the advertisement comprises transmitting the advertisement such that the second router coordinates a second label space maintained by the second router with the first label space maintained by the first router in order to reserve a second contiguous set of labels different from the first set of contiguous labels within the second label space.

8. The method of claim 1,

wherein the network comprises an MPLS network,

wherein the first area of the network comprises a first Internet Protocol (IP) sub-network (subnet) identified by a first IP prefix,

wherein the second area of the network comprises a second IP subnet identified by a second IP prefix,

wherein the first router comprises a first Label Switching Router (LSR), and

wherein the second router comprises a second LSR.

9. A first router included within a first area of a network, the first router comprising:

a control unit that maintains a label space defining a plurality of labels available for mapping to a plurality of addresses assigned to network devices within the network, reserves a contiguous set of the plurality of labels defined by the label space and maps the contiguous set of labels to a plurality of first area addresses, wherein the first area addresses include those addresses of the plurality of addresses available for assignment to network devices within the first area of the network; and

at least one interface card that transmits, to a second router different than the first router of a second area of the network different from the first area, an advertisement that advertises a summarized version of the mapping between the contiguous set of labels and the first area addresses as a prefix mapping between a label prefix that summarizes the contiguous set of labels and a network address prefix that summarizes the first area addresses.

10. The first router of claim 9, wherein the network address prefix comprises an Internet Protocol (IP) prefix that summarizes the first area addresses.

11. The first router of claim 9, wherein the control unit includes:

a user interface module that receives configuration data that defines the first area addresses; and

a Multi-Protocol Label Switching (MPLS) protocol module that determines, based on the configuration data, a number of the plurality of labels to reserve, and reserves the determined number of the plurality of labels as the contiguous set of the plurality of labels.

12. The first router of claim 11,

wherein the user interface module receives an Internet Protocol (IP) address prefix that defines a contiguous set of IP addresses assigned to devices included within the first area, and

wherein the MPLS protocol module determines the number of the plurality of labels based on a number of IP addresses included within the contiguous set of IP addresses, and reserves the determined number of labels such that the number of reserved labels equals the number of IP addresses included within the contiguous set of IP addresses.

13. The first router of claim 9, wherein the control unit comprises an Multi-Protocol Label Switching (MPLS) protocol module that maps one or more of the contiguous set of labels to Internet Protocol (IP) addresses assigned to devices within the first area, wherein the first area is defined by an IP address prefix.

14. The first router of claim 9, wherein the at least one interface card receives, from the second router included within the second area, an MPLS packet that includes one of the contiguous set of reserved labels, wherein each of the contiguous set of reserved labels comprise an inter-area label, swaps the inter-area label with an intra-area label, and forwards, within the first area, the MPLS packet with the intra-area label.

15. The first router of claim 9,

wherein the label space comprises a first label space,

wherein the contiguous set of labels comprises a first contiguous set of labels, and

wherein the interface card transmits the advertisement such that the second router coordinates a second label space maintained by the second router with the first label space maintained by the first router in order to reserve a second contiguous set of labels different from the first set of contiguous labels within the second label space.

16. The first router of claim 9,

wherein the network comprises an MPLS network,

wherein the first area of the network comprises a first Internet Protocol (IP) sub-network (subnet) identified by a first IP prefix,

wherein the second area of the network comprises a second IP subnet identified by a second IP prefix,

wherein the first router comprises a first Label Switching Router (LSR), and wherein the second router comprises a second LSR.

17. A network system comprising:

a network that includes a first area and a second area, wherein the first and second areas are different from each other;

a first router included within the first area; and

a second router included within the second area, wherein the second router is different from the first router, and

wherein the first router includes;

a control unit that maintains a label space defining a plurality of labels available for mapping to a plurality of addresses assigned to network devices within the network, reserves a contiguous set of the plurality of labels defined by the label space and maps the contiguous set of labels to a plurality of first area addresses, wherein the first area addresses include those addresses of the plurality of addresses available for assignment to network devices within the first area of the network; and

at least one interface card that transmits, to a second router different than the first router of a second area of the network different from the first area, an advertisement that advertises a summarized version of the mapping between the contiguous set of labels and the first area addresses as a prefix mapping between a label prefix that summarizes the contiguous set of labels and a network address prefix that summarizes the first area addresses.

18. The network system of claim 17, wherein the network address prefix comprises an Internet Protocol (IP) prefix that summarizes the first area addresses.

19. A non-transitory computer-readable medium comprising instructions for causing a programmable processor to:

maintain, with a first router of a first area of a network, a label space defining a plurality of labels available for mapping to a plurality of addresses assigned to network devices within the network;

reserve, with the first router, a contiguous set of the plurality of labels defined by the label space;

map, with the first router, the contiguous set of labels to a plurality of first area addresses, wherein the first area addresses include those addresses of the plurality of addresses available for assignment to network devices within the first area of the network; and

transmit, with the first router to a second router different than the first router of a second area of the network different from the first area, an advertisement that advertises a summarized version of the mapping between the contiguous set of labels and the first area addresses as a prefix mapping between a label prefix that summarizes the contiguous set of labels and a network address prefix that summarizes the first area addresses.

20. The non-transitory computer-readable medium of claim 26, wherein the network address prefix comprises an Internet Protocol (IP) prefix that summarizes the first area addresses.