Network Device Load Balancing via Ingress Identifier Tagging
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Solution Overview
Problem
Existing load balancing techniques in computer networks, such as WECMP, are disrupted by the application of services like NAT and firewall services, which cause routers to lose proper load balancing across multiple paths due to the lack of service card functionality in path selection and forwarding decisions.
Innovation Solution
The implementation of a method where routers mark or tag packets with an ingress identifier to specify the ingress forwarding component, allowing service cards to maintain load balancing after service application without upgrading to perform path selection, thereby ensuring consistent load distribution across forwarding components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If service cards are used to apply services like NAT and firewall, then service functionality is improved, but load balancing across multiple paths is disrupted
Solution Approach 1:
The patent introduces service cookies as an intermediary mechanism that carries path identification information through the service application process. These cookies enable the service cards to forward packets to the correct egress forwarding component without performing path selection themselves, thus maintaining load balancing while providing service functionality.
2Measurement precision
If service cards perform path selection, then load balancing accuracy is improved, but device complexity increases
Solution Approach 1:
The patent segments the path selection function from the service application function. Egress forwarding components perform path selection and assign path identifiers, while service cards only forward packets based on these identifiers carried in service cookies. This segmentation allows load balancing accuracy to be maintained by the forwarding components without adding complex path selection capabilities to service cards.
3Adaptability or versatility
If service cards apply services to packets, then service application capability is improved, but packet forwarding disruption occurs
Solution Approach 1:
The patent implements preliminary action by having egress forwarding components insert service cookies with path identification information into packets before they are forwarded to service cards. This preliminary tagging enables service cards to efficiently forward serviced packets to the correct egress component without needing to perform path selection or causing forwarding disruptions.
Data Source
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AI summary
In general, techniques are described for maintaining load balancing after service application. A network device comprising ingress and egress forwarding components and a service card may implement the techniques. An ingress forwarding component receives a packet and, in response to a determination that the service is to be applied to the packet, updates the packet to include an ingress identifier that identifies the ingress forwarding component, thereafter transmitting the updated packet to the service card. The service card applies the service to the updated packet to generate a serviced packet and transmits the serviced packet to the ingress forwarding component identified by the ingress identifier so as to maintain load balancing of packet flows across the plurality of forwarding components. The ingress forwarding component determines a next hop to which to forward the serviced packet and the egress forwarding component forwards the serviced packet to the determined next hop.