CA2365395A1 - Default route coding - Google Patents

Default route coding Download PDF

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Publication number
CA2365395A1
CA2365395A1 CA002365395A CA2365395A CA2365395A1 CA 2365395 A1 CA2365395 A1 CA 2365395A1 CA 002365395 A CA002365395 A CA 002365395A CA 2365395 A CA2365395 A CA 2365395A CA 2365395 A1 CA2365395 A1 CA 2365395A1
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Prior art keywords
subtree
default route
default
lookup table
sparse
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Granted
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CA002365395A
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French (fr)
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CA2365395C (en
Inventor
David A. Brown
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Chartoleaux KG LLC
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Mosaid Technologies Inc
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Publication date
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Publication of CA2365395A1 publication Critical patent/CA2365395A1/en
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Publication of CA2365395C publication Critical patent/CA2365395C/en
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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/74—Address processing for routing
    • H04L45/745—Address table lookup; Address filtering

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Data Exchanges In Wide-Area Networks (AREA)
  • Complex Calculations (AREA)

Abstract

A multi-level lookup table includes a plurality of search levels with each search level including a plurality of subtrees, each subtree representing a plurality of nodes. A search of the multi-level lookup table for an entry corresponding to a search key results in a value stored in an entry associated with the node in a subtree. A default value is associated with the root of the subtree. Multiple entries for the subtree can store the default value. To minimize route update time, the default value associated with the subtree is stored in a single location. Instead of storing the default value in multiple entries, each entry stores a use default indicator to indicate that the default value stored in the single location is to be used. To further reduce the number of locations to modify to update the default route, the single location can store an inherit indicator to indicate that the default value for the subtree is inherited from another subtree.

Claims (26)

1. A method for updating a multi-level lookup table comprising the steps of:
providing a default route memory for storing a default route for a subtree;
sharing the default route by nodes in the subtree; and modifying the default route by performing a single write to the default route memory.
2. The method as claimed in Claim 1 wherein the default route memory stores a route corresponding to the route associated with the root of the subtree.
3. The method as claimed in Claim 1 wherein the default route memory stores an inherit indicator to indicate that the default route corresponding to the route associated with the root of the subtree is inherited from another subtree.
4. The method as claimed in Claim 3 wherein the inherited default route is forwarded by a default index pipeline.
5. The method as claimed in Claim 1 wherein the subtree is a dense subtree and a dense subtree descriptor associated with the subtree includes the default route memory.
6. The method as claimed in Claim 5 wherein the default route is shared by storing a use default indicator in a mapper entry associated with at least one node in the subtree.
7. The method as claimed in Claim 6 further comprising the step of:
returning the default route as a result of a search of the lookup table upon detecting the use default indicator stored in the mapper entry.
8. The method as claimed in Claim 1 wherein the subtree is a sparse subtree, the number of routes in the sparse subtree is greater than one and a sparse subtree entry associated with the subtree includes the default route memory.
9. The method as claimed in Claim 1 wherein the subtree is a sparse subtree, the number of routes in the sparse subtree is one, and a default route memory associated with the sparse subtree stores the default route.
10. A multi-level lookup table comprising:
a default route memory which stores a default route shared by nodes in a subtree; and default logic which returns the default route as a result of a search of the lookup table.
11. The multi-level lookup table as claimed in Claim 10 wherein the default route memory stores a default route for the route corresponding to the root of the subtree.
12. The multi-level lookup table as claimed in Claim 10 wherein the default route memory stores an inherit indicator to indicate that the route corresponding to the root of the subtree is inherited from another subtree.
13. The multi-level lookup table as claimed in Claim 12 further comprising:
a default index pipeline which forwards the inherited default route.
14. The multi-level lookup table as claimed in Claim 10 wherein the subtree is a dense subtree and a dense subtree entry associated with the subtree includes the default route memory.
15. The multi-level lookup table as claimed in Claim 14 further comprising:
a mapper entry associated with at least one node in the subtree, the mapper entry stores a use default indicator which indicates that the default route stored in the default route memory is the default route for the at least one node, the default route is modified by performing a single write to the default route memory.
16. The multi-level lookup table as claimed in Claim 15 wherein the default logic returns the default route upon detecting the use default indicator stored in the mapper entry.
17. The multi-level lookup table as claimed in Claim 10 wherein the subtree is a sparse subtree number of routes in the sparse subtree is greater than one and a sparse subtree entry associated with the subtree includes the default route memory.
18. The multi-level lookup table as claimed in Claim 10 wherein the subtree is a sparse subtree, the number of routes in the sparse subtree is one, and the default route memory is stored in a default mapper entry associated with the sparse subtree descriptor.
19. A multi-level lookup table comprising:
a default route memory which stores a default route for nodes in a subtree; and means for returning the default route as a result of a search of the lookup table upon detecting the use default indicator stored in the mapper entry.
20. The lookup table as claimed in Claim 19 wherein the default route memory stores a default route associated with the root of the subtree.
21. The lookup table as claimed in Claim 19 wherein the default route memory stores an inherit indicator to indicate that the default route associated with the root of the subtree is inherited from another subtree.
22. The lookup table as claimed in Claim 21 further comprising:
means for forwarding the inherited default index.
23. The lookup table as claimed in Claim 19 wherein the subtree is a dense subtree and a dense subtree descriptor associated with the subtree includes the default route memory.
24. The lookup table as Claimed in Claim 19 further comprising:
means for sharing the default route amongst nodes in the subtree by storing a use default indicator in a mapper entry associated with at least one node in the subtree and modifying the default route by performing a single write to the default route memory.
25. The lookup table as claimed in Claim 19 wherein the subtree is a sparse subtree the number of routes in the sparse subtree is greater than one and a sparse subtree descriptor associated with the sparse subtree includes the default route memory.
26. The lookup table as claimed in Claim 19 wherein the subtree is a sparse subtree, the number of routes in the sparse subtree is one, and the default route memory is stored in a default mapper entry associated with the sparse subtree descriptor.
CA2365395A 2000-12-27 2001-12-17 Default route coding Expired - Lifetime CA2365395C (en)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
US25843600P 2000-12-27 2000-12-27
US60/258,436 2000-12-27
US29438701P 2001-05-30 2001-05-30
US60/294,387 2001-05-30
US10/004,280 2001-10-31
US10/004,280 US7106732B2 (en) 2000-12-27 2001-10-31 Default route coding

Publications (2)

Publication Number Publication Date
CA2365395A1 true CA2365395A1 (en) 2002-06-27
CA2365395C CA2365395C (en) 2011-04-12

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Family Applications (1)

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CA2365395A Expired - Lifetime CA2365395C (en) 2000-12-27 2001-12-17 Default route coding

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US (2) US7106732B2 (en)
CA (1) CA2365395C (en)

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Also Published As

Publication number Publication date
US20070115968A1 (en) 2007-05-24
US7715385B2 (en) 2010-05-11
US20020091856A1 (en) 2002-07-11
US7106732B2 (en) 2006-09-12
CA2365395C (en) 2011-04-12

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