Multi-homing Route Suppression via DCAC Attribute
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In multi-homed computer networks, conventional route aggregation is often broken due to longest prefix-matching algorithms, leading to asymmetric traffic patterns and requiring special customer-site configuration, which is impractical for large-scale implementation across the Internet.
Innovation Solution
Implementing a technique where the secondary network suppresses a customer site's route if the primary network has already advertised an aggregated route, using a dynamic conditional advertisement community (DCAC) attribute to prevent unnecessary advertisement and allowing unsuppression only when the primary network loses connectivity, thereby maintaining route aggregation and minimizing asymmetric traffic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the secondary network advertises the customer site's route, then the customer site has backup connectivity, but route aggregation is broken and asymmetric traffic patterns occur
Solution Approach 1:
The patent introduces a DCAC (Dynamic Conditional Advertisement Community) attribute as an intermediary mechanism that carries information about the primary network's aggregated route advertisement. This attribute enables the secondary network to conditionally suppress its own route advertisement based on the presence of the aggregated route in the DCAC attribute, thereby maintaining route aggregation while ensuring backup connectivity is available when needed.
2Reliability
If the secondary network advertises the customer site's route, then backup connectivity is ensured, but asymmetric traffic patterns and special customer-site configuration are required
Solution Approach 1:
The patent implements a self-service mechanism where the secondary network autonomously determines whether to advertise the customer site's route by checking the DCAC attribute. The secondary network's border router automatically suppresses route advertisement when an aggregated route is detected in the DCAC attribute, eliminating the need for special customer-site configuration and manual intervention.
3Device complexity
If the primary network advertises an aggregated route, then route aggregation is maintained, but the secondary network cannot provide backup connectivity
Solution Approach 1:
The patent introduces dynamic conditional advertisement through the DCAC attribute, which enables the secondary network's routing behavior to adapt based on the primary network's state. When the primary network advertises an aggregated route, the secondary network suppresses its advertisement; when the aggregated route is withdrawn, the secondary network automatically begins advertising, providing dynamic backup connectivity without manual intervention.
Data Source
AI summary
A technique for implementing route aggregation in a computer network containing a multi-homed customer site connected to primary and second networks, which in turn are both connected to a common “backbone” network. According to the technique, the primary network allocates a block of network addresses for the customer site, and the customer site notifies the secondary network of its allocated addresses. The secondary network first determines whether the primary network has already advertised an aggregated route which incorporates the customer site's route. If so, the secondary network “suppresses” (i.e., does not advertise) the customer site's route. The secondary network only “unsuppresses” the customer site's route if it detects that the primary network has lost connectivity to the customer site and/or the backbone network.