IS-OSPF Broadcast Link Extensions for Inter-AS Traffic Engineering
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Solution Overview
Problem
IS-IS and OSPF routing protocols lack methods to efficiently advertise and manage broadcast inter-autonomous system (AS) traffic engineering (TE) links, which hinders efficient path routing across such links.
Innovation Solution
The implementation of extensions to IS-IS and OSPF protocols for advertising, withdrawing, and re-advertising broadcast links, along with the creation of pseudo nodes for efficient path routing, using link state messages with sub-TLVs containing IP addresses, mask lengths, and local AS numbers, enables the efficient management and routing across broadcast inter-AS TE links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If IS-IS and OSPF routing protocols are used without extensions, then basic routing functionality is maintained, but efficient advertisement and management of broadcast inter-AS TE links is not achieved
Solution Approach 1:
The patent segments the broadcast link information into multiple sub-TLVs (Type-Length-Value structures) within link state messages. Each sub-TLV contains specific attributes such as IP addresses, mask lengths, and local AS numbers, allowing granular representation and management of broadcast inter-AS TE link characteristics without requiring protocol-wide changes.
Solution Approach 2:
The patent introduces pseudo nodes as intermediary constructs to represent broadcast links in the routing topology. These pseudo nodes act as mediators that enable efficient path routing calculations across broadcast inter-AS TE links by transforming complex multi-router broadcast connections into simplified routing targets that standard shortest path algorithms can efficiently handle.
2Loss of information
If standard link state messages are used without extensions, then protocol compatibility is maintained, but detailed broadcast link information cannot be advertised
Solution Approach 1:
The patent nests sub-TLV structures within existing link state message formats (IS-IS LSPs or OSPF LSAs). The sub-TLVs are embedded as nested elements containing specific broadcast link attributes, allowing detailed information advertisement while maintaining the hierarchical organization and backward compatibility of the original link state message structure.
Solution Approach 2:
The patent extends link state messages by adding new parameters in the form of sub-TLVs that carry specific broadcast link information such as IP addresses, mask lengths, and local AS numbers. This parameter extension approach allows detailed information advertisement while maintaining compatibility with existing message formats through the use of standardized TLV encoding schemes.
3Productivity
If pseudo nodes are created for broadcast links, then path routing efficiency is improved, but routing protocol complexity increases
Solution Approach 1:
The patent creates pseudo nodes as simplified copies or representations of complex broadcast link topologies. Instead of performing complex shortest path calculations across multiple routers connected to a broadcast medium, the system creates a virtual copy (pseudo node) that represents the broadcast link's routing characteristics, enabling efficient path computation using standard algorithms while abstracting away the underlying complexity.
Data Source
AI summary
A first router in a first AS, the first router comprises: a processor configured to: obtain information about a broadcast link connecting the first router to a second router in a second AS, and generate a link state message comprising the information; and a transmitter coupled to the processor and configured to transmit the link state message to a third router, wherein the third router is in the first AS and is adjacent to the first router. A method comprises: receiving a first link state message from a first router; receiving a second link state message from a second router; receiving a third link state message from a third router; determining which of the first router, the second router, and the third router are ASBRs connected to a broadcast link based on information in the first link state message, the second link state message, and the third link state message.