Overlay Route Programming for Forwarding Hardware Resource Limits
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Solution Overview
Problem
In multi-fabric overlay networks, existing technologies inefficiently utilize forwarding hardware resources by programming large numbers of host routes that are rarely used, leading to resource wastage due to infrequent and short-lived traffic flows among hosts.
Innovation Solution
Incorporating an indicator in overlay-route packets to determine selective programming of host routes in forwarding hardware, allowing only necessary routes to be programmed based on actual traffic needs, using an extended community in EVPN route updates to differentiate between host and prefix routes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If host routes are programmed in forwarding hardware for all hosts in multi-fabric overlay networks, then routing completeness is improved, but forwarding hardware resource utilization deteriorates due to large numbers of rarely used routes
Solution Approach 1:
The patent applies preliminary action by programming host routes in forwarding hardware before actual traffic flows are established. The system proactively installs host routes based on route advertisements received from border devices, so that when traffic needs to be forwarded to a host, the route is already in place and ready for immediate use, eliminating the need for route installation delays
Solution Approach 2:
The patent applies local quality by selectively programming host routes in forwarding hardware only for specific hosts that are likely to generate or receive traffic, rather than uniformly programming all host routes. The system uses indicators in route advertisements to identify which hosts require forwarding hardware programming, applying different treatment (programming vs. not programming) to different hosts based on their actual traffic needs
2Speed
If host routes are programmed in forwarding hardware, then data forwarding speed is improved, but device complexity increases due to managing large numbers of routes
Solution Approach 1:
The patent reduces device complexity by applying local quality - it selectively programs only certain host routes in the forwarding hardware based on indicators received in route advertisements, rather than uniformly programming all host routes. This differentiated approach reduces the number of routes that need to be managed in the forwarding hardware while still maintaining fast forwarding performance for the most important hosts
3Loss of energy
If selective programming based on indicators is implemented, then forwarding hardware resource efficiency is improved, but route advertisement complexity increases
Solution Approach 1:
The patent uses an indicator as an intermediary element embedded in route advertisements. This indicator acts as a signal that tells the receiving device whether to program the associated host route in forwarding hardware or not. The indicator simplifies the communication protocol by providing a clear yes/no instruction, avoiding the need for complex negotiations or multiple message exchanges between devices
Data Source
AI summary
A network device in a first fabric of an overlay network is provided. During operation, the network device can receive a route advertisement from a border device via which the network device communicates outside of the first fabric. The network device can determine, based on an indicator in the route advertisement, whether a host route associated with a host coupled to a second fabric of the overlay network is included in the route advertisement. If the indicator indicates that the host route is included in the route advertisement, the network device can store the host route in a data structure on the network device. The network device can also program, in the local forwarding hardware, a prefix route associated with the host route. If the network device detects a packet destined to the host device, the network device can program the host route in the forwarding hardware.