Switch MAC Learning for Network Control Notification
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Solution Overview
Problem
Existing network control software faces inefficiencies in receiving notifications about new and moved virtual machines, leading to potential bandwidth waste and delayed validation due to the lack of control over notification rates and contents.
Innovation Solution
A method is introduced where a switch determines if a packet is from a new or moved virtual machine, inserts or updates a forwarding database entry with the source MAC address, and sends a notification to the network control software, using flags to manage retry attempts and prevent overwhelming the software with redundant notifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a packet rate limiter is used to control notification rate, then the network control software is not overwhelmed, but some notifications are delayed or discarded causing increased validation time
Solution Approach 1:
The switch performs advance MAC address learning by inserting forwarding database entries for new VMs before network control software validation is complete. This preliminary action allows the VM to be recognized and forwarded immediately upon arrival, eliminating validation delays while maintaining software stability through controlled notification mechanisms.
Solution Approach 2:
The notification process is segmented into two independent parts: (1) immediate forwarding database entry creation for rapid VM recognition, and (2) controlled notification sending to network control software. This segmentation allows the forwarding function to operate without delay while the notification rate is independently controlled to prevent software overload.
2Speed
If notifications are sent for every new VM packet, then the network control software receives timely information, but bandwidth is wasted and software is overwhelmed
Solution Approach 1:
The switch creates forwarding database entries in advance for new VMs before sending notifications to network control software. This preliminary forwarding setup enables immediate VM recognition and traffic forwarding, allowing notifications to be sent at a controlled, optimized rate without impacting network performance or overwhelming the software.
Solution Approach 2:
The switch maintains a local copy of VM MAC address information in its forwarding database, eliminating the need to continuously query or send redundant notifications to network control software. This local caching reduces notification frequency and bandwidth consumption while maintaining fast forwarding decisions.
3Reliability
If the switch waits for validation before forwarding, then network security is improved, but VM communication is delayed
Solution Approach 1:
The switch performs preliminary MAC address learning and creates forwarding database entries for new VMs immediately upon packet receipt, before network control software validation is complete. This allows VM traffic to be forwarded immediately upon arrival, achieving fast communication while security is maintained through subsequent validation and ACL rule installation.
Solution Approach 2:
The forwarding database entry state transitions dynamically: initially created for immediate forwarding, then updated upon validation completion with ACL rules. This dynamic state change allows the system to provide fast forwarding initially and then enforce security restrictions, balancing speed and security based on validation status.
Data Source
AI summary
Techniques are disclosed for notifying network control software of new and moved source MAC addresses. In one embodiment, a switch detects packets sent by a new or migrated virtual machine, and sends a copy of a detected packet to the network control software as a notification. The switch further learns the source MAC address, thereby permitting the entry to be used for normal forwarding prior to validation of the entry and the VM associated therewith by the network control software. Until the network control software has validated the VM, the switch may periodically retry the notification to the network control software. “No_Redirect” and “Not_Validated” flags may be used to indicate whether a notification has already been attempted and thus no retry is necessary, and that the VM associated with the VM has not yet been validated, respectively.