Anycast MAC Address for Distributed Logical Router Connectivity
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Solution Overview
Problem
Current network services face issues when using IP addresses outside of a subnet, leading to message drops and service malfunctions due to lack of direct connectivity between routers and switches, particularly in load balancing and SNAT operations.
Innovation Solution
Implementing a method with distributed and centralized logical routers using anycast IP and MAC addresses for message forwarding within a managed network, ensuring direct connectivity and proper service delivery across logical switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a router uses an IP address not in the same subnet as the DCN, then the router can provide services to multiple subnets, but data messages may be dropped as irrelevant by switches or DCNs expecting messages from the same subnet
Solution Approach 1:
The patent introduces an anycast MAC address as an intermediary between the router and DCNs. The router uses this anycast MAC address when communicating with DCNs on the same logical switch, even though the router's IP address is in a different subnet. This intermediary address allows switches and DCNs to correctly identify and deliver messages to the router as if it were a local device, preventing message drops while maintaining the router's ability to serve multiple subnets.
2Ease of operation
If a router provides services using an IP address in the subnet of a switch, then the service can be accessed by DCNs on that switch, but the router must directly connect to the switch to receive ARP requests
Solution Approach 1:
The anycast MAC address serves as a mediator that allows the router to be logically present on the switch without requiring a physical direct connection. When DCNs on the switch need to access the router's service, they send ARP requests that are delivered to the router via the anycast MAC address, eliminating the need for direct physical connectivity while maintaining service accessibility.
Solution Approach 2:
The anycast MAC address provides universal functionality by enabling the router to participate in multiple subnets and logical switches simultaneously. A single router instance can use the same anycast MAC address to provide services across different network segments without requiring separate physical connections or additional router instances, simplifying the overall network topology.
3Ease of operation
If a load balancing service uses a VIP address on the same logical switch as client DCNs, then clients can resolve the VIP address, but the router responsible for the VIP cannot receive ARP requests if not directly connected to the switch
Solution Approach 1:
The load balancing router uses an anycast MAC address as an intermediary to receive ARP requests for the VIP address. Even though the router is not directly connected to the logical switch where client DCNs reside, the anycast MAC address enables the router to be the designated recipient of ARP requests for the VIP, ensuring reliable address resolution while maintaining logical separation.
Data Source
AI summary
For a managed network implementing at least one logical router having centralized and distributed components, some embodiments provide a method that better supports the provision of certain network applications and/or services. The method receives at a host implementing (1) a distributed logical router and (2) a plurality of logical switches of a logical network along with other hosts, a message from a first data compute node (DCN) executing on the host. The host logically forwards the message to the distributed logical router that uses a particular anycast internet protocol (IP) address using a first media access control (MAC) address. The distributed router determines that the message requires processing by a centralized logical router (e.g., a service router, edge node, etc.) executing on an edge node host and forwards the message to the centralized logical router using the same anycast IP address and a second, unique MAC address.