BGP Opaque Attribute Handling for VPN Routing Consistency

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Solution Overview

Problem

In Virtual Private Networks (VPNs), the modification of routing attributes as routing information is advertised across public networks can lead to incorrect operations and inconsistencies, as if customer networks were directly connected rather than virtually coupled.

Innovation Solution

Extending the Border Gateway Protocol (BGP) to include an attribute set data type that encodes original routing attributes, allowing them to be carried opaquely through the network, thereby maintaining their integrity and consistency across customer networks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If routing attributes are modified as routing information is advertised across the public network, then routing information can be propagated through intermediate networks, but the customer networks cannot operate as if directly connected and routing consistency is compromised

Engineering Contradiction:

Improverouting information propagationVSAvoidrouting attribute consistency

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The routing attribute set is segmented into two distinct parts: a first attribute set for internal network use and a second attribute set for customer network use. This segmentation allows the public network to modify internal attributes while preserving customer-specific attributes, thereby maintaining routing consistency for VPN customers while enabling propagation through intermediate networks.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The customer-specific routing attributes are extracted from the overall attribute set and placed in a separate second attribute set. This extraction ensures that these critical attributes are not modified by intermediate public network routers, allowing customer networks to operate as if directly connected while still enabling routing information propagation through the public network.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If routing protocols are extended to carry opaque attribute sets, then customer networks can exchange routing information as if directly connected, but the protocol complexity increases

Engineering Contradiction:

Improverouting attribute integrityVSAvoidrouting protocol structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The second attribute set containing customer-specific attributes is nested within the overall BGP routing information structure. This nesting allows the extended attribute sets to be carried within existing BGP UPDATE messages without requiring fundamental protocol changes, thereby maintaining attribute integrity while limiting the increase in protocol complexity.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The extended attribute set mechanism is designed to be universal and can carry any BGP path attribute except MP_REACH and MP_UNREACH attributes. This multi-functionality allows a single extended protocol structure to handle diverse customer requirements without requiring separate protocol extensions for each attribute type, thus managing complexity while ensuring attribute integrity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS7420958B1Providing transparent virtual private network connectivity across intermediate networks

Publication Date: 2008.09.02 JUNIPER NETWORKS INC

AI summary

A routing protocol, such as the Border Gateway Protocol (BGP), is extended in a manner that allows the protocol to opaquely carry routing attributes associated with an origin of a routing advertisement, e.g., a customer network of associated with a virtual private network (VPN). These attributes are carried within routing communications using a separate attribute set, and are automatically utilized when delivering the routing advertisement to other customer networks associated with the VPN. As a result, the customer networks are isolated from the routing attributes used within an intermediate network coupling the customer networks.