IS-IS Link Protocol Attribute Tagging for IPv4 IPv6 Routing
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Solution Overview
Problem
In networks that implement both IPv4 and IPv6, existing IS-IS protocols often lead to routing calculation errors due to inconsistent topology identification between IPv4 and IPv6 links, as a link supporting one protocol may be incorrectly identified as supporting the other.
Innovation Solution
A network device adds protocol attributes to LSPs, including information on the supported protocols for its ports and neighboring devices, to accurately record and update network topology information, ensuring correct routing calculations by distinguishing between IPv4 and IPv6 links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the IS-IS protocol is used in mixed IPv4 and IPv6 networks without protocol attribute identification, then routing calculation simplicity is maintained, but routing accuracy deteriorates due to topology inconsistency between IPv4 and IPv6 links
Solution Approach 1:
The patent segments the network topology information by protocol type, maintaining separate topology records for IPv4 and IPv6 links. Each link is tagged with protocol attributes (IPv4, IPv6, or both), allowing the routing calculator to select and process only the relevant topology for each protocol, thereby improving routing accuracy without requiring complete protocol differentiation across all network elements
Solution Approach 2:
The patent applies local quality by adding protocol attributes specifically to link state protocol data units (LSPs) where topology information is exchanged, rather than modifying the entire IS-IS protocol structure. The protocol attribute is embedded in the LSP's TLV (Type-Length-Value) field, enabling precise identification of link protocol support at the local link level while maintaining overall protocol compatibility
2Reliability
If protocol attributes are added to all LSPs to ensure accurate topology identification, then routing calculation accuracy improves, but information processing overhead increases
Solution Approach 1:
The patent implements partial action by adding protocol attributes only to the minimum necessary LSP elements required for routing calculation, rather than embedding protocol information in every possible LSP field. The protocol attribute is added selectively to link state information that directly impacts route selection, reducing unnecessary information processing overhead while maintaining sufficient topology identification reliability
Solution Approach 2:
The protocol attribute field in the LSP serves multiple functions: it identifies link protocol support (IPv4/IPv6), enables topology segmentation, guides routing calculation selection, and maintains backward compatibility with existing IS-IS implementations. This multi-functionality reduces the need for separate information structures for each purpose, thereby minimizing overall information processing overhead
Data Source
AI summary
According to an example, in a method for calculating a route, a first network device may add a protocol attribute supported by a link to a link state protocol data unit (LSP) of the first network device according to a protocol attribute supported by a port of the first network device and a protocol attribute supported by a port of a neighbor network device when establishing an adjacency, and may flood the LSP. The first network device may receive a LSP from a neighbor network device, parse a protocol attribute supported by a link contained in the received LSP, record the protocol attribute supported by the link contained in the received LSP in local network topology information, to obtain updated network topology information. And the first network device may calculate a route according to the updated network topology information. A network device and a computing device may calculate a route.