Host Cache Packet Forwarding for Multi-Active Gateway Path Consistency
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Solution Overview
Problem
In multi-active gateway scenarios, the inconsistency between the paths used for incoming and outgoing packets leads to service failures, as the path for packet forwarding does not match the path for response packet forwarding, resulting in inconsistent bidirectional packet paths.
Innovation Solution
A packet forwarding method and system that involves parsing incoming packets to obtain source IP and MAC addresses, querying and saving these mappings in a host cache table, and using the cached MAC address to forward response packets through the same gateway, ensuring bidirectional packets pass through consistent paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If equal-cost multi-path routing (ECMP) is used on the router to enable multiple gateways to simultaneously provide gateway services, then gateway service availability is improved, but path consistency between incoming and outgoing packets deteriorates
Solution Approach 1:
The host performs preliminary actions by caching the mapping relationship between source IP addresses and source MAC addresses from incoming packets before sending response packets. This preliminary caching enables the host to determine the correct gateway MAC address in advance, ensuring that response packets are sent through the same gateway that delivered the original packet, thus maintaining path consistency while using ECMP for load distribution.
2Productivity
If the router sends packets to servers through different gateways based on ECMP, then load balancing is improved, but service reliability deteriorates due to inconsistent bidirectional packet paths
Solution Approach 1:
The host implements a feedback mechanism by examining the source MAC address of incoming packets from external networks and using this information to determine the correct gateway for sending response packets. This feedback loop ensures that the host adapts its routing behavior based on the actual path taken by incoming packets, maintaining bidirectional path consistency while allowing the router to perform load balancing across multiple gateways.
3Adaptability or versatility
If multiple gateways advertise the same network segment routes to the router, then gateway redundancy is improved, but path determination complexity increases
Solution Approach 1:
The host performs self-service by autonomously determining the correct gateway for response packets based on the source MAC address information contained in incoming packets. Instead of relying on complex routing protocols or external path determination mechanisms, the host uses the information already present in the packet headers to make intelligent routing decisions, simplifying the overall system while maintaining gateway redundancy.
Data Source
AI summary
A packet forwarding method, apparatus, and system in which a host receives a first packet sent by a gateway, and parses the first packet to obtain a source IP address and a source MAC address from the first packet; queries a host cache table, when a mapping relationship between the source IP address and the source MAC address does not exist in the host cache table, saves the mapping relationship between the source IP address and the source MAC address in the host cache table; the host generates a response packet according to the first packet, and queries the host cache table to acquire a first destination MAC address corresponding to a first destination IP address that is in the response packet; and forwards, according to the first destination MAC address, the response packet to an external network by using the gateway.