Leaf-Switch Packet Routing via System Ports for Unresolved MACs
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Solution Overview
Problem
Conventional networks experience packet forwarding failures and unknown unicast flooding when the Media Access Control (MAC) address of a remote host device is not resolved, leading to data loss and reduced network performance.
Innovation Solution
Implementing a packet routing logic that determines a host Internet Protocol (IP) address, establishes a communication session, and generates update messages using Ethernet Virtual Private Network (EVPN) Route Types to resolve the MAC address and assign a system port as a next hop interface, facilitating efficient packet forwarding through a Disaggregated Scheduled Fabric (DSF).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MAC address-based packet forwarding is used, then packet forwarding works when MAC address is known, but packet forwarding fails when MAC address is not resolved
Solution Approach 1:
The patent introduces a next-hop interface as an intermediary mechanism between the leaf switch and the destination host. When MAC address resolution fails, the system uses a predefined next-hop interface (such as a gateway or router interface) to forward packets, allowing traffic to continue flowing through the network even without direct MAC address knowledge.
Solution Approach 2:
The system performs preliminary configuration of next-hop interfaces and routing information before packet forwarding is needed. By pre-establishing forwarding paths and next-hop relationships, the network can immediately route packets with unresolved MAC addresses without waiting for ARP or other resolution mechanisms to succeed.
2Reliability
If unknown unicast flooding is used for unresolved MAC addresses, then packets can reach destination, but network performance deteriorates and connectivity may be lost
Solution Approach 1:
The patent applies different forwarding behaviors based on the specific condition of the packet and the state of MAC address resolution. Instead of universally flooding all unknown unicast traffic, the system selectively applies next-hop interface forwarding only to packets with unresolved MAC addresses, while maintaining normal efficient forwarding for resolved addresses. This localized differentiation preserves network performance while ensuring delivery reliability.
3Measurement precision
If MAC address resolution is required before forwarding, then forwarding accuracy is improved, but data loss occurs when resolution fails
Solution Approach 1:
The system pre-configures next-hop interfaces and routing information in advance, so that when MAC address resolution fails, packets can immediately be forwarded through the pre-established path without being dropped. This eliminates the all-or-nothor approach where packets are either forwarded with high accuracy (when MAC is known) or dropped (when MAC is unknown).
Solution Approach 2:
The next-hop interface acts as a mediator that bridges the gap between unknown MAC addresses and the destination. By introducing this intermediate forwarding target, the system maintains forwarding accuracy (packets go to the correct next hop) while ensuring delivery reliability (packets are not dropped due to unresolved MAC addresses).
Data Source
AI summary
Devices, networks, systems, methods, and processes for packet forwarding and routing are described herein. A leaf switch can be in communication with a host device. The leaf switch may configure a subnet comprising the host device. The leaf switch can assign a next hop interface as a system port of the leaf switch and generate subnet information indicative of the assignment. The leaf switch may distribute the subnet information to one or more network devices through one or more internal Border Gateway Protocol sessions. A data packet destined to the host device can be transmitted to the system port of the leaf switch when a host Media Access Control (MAC) address of the host device is not resolved. The leaf switch can resolve the host MAC address and transmit the data packet to the host device based on the host MAC address.