Ingress PE BUM Packet Forwarding Optimization
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Solution Overview
Problem
In Ethernet Virtual Private Networks (EVPN), the multi-homing phenomenon leads to bandwidth waste in the bearer network during the forwarding of Broadcast, Unknown Unicast, and Multicast (BUM) packets, as not all Egress PEs finally send the packets to remote sites, resulting in inefficient use of network resources.
Innovation Solution
An Ingress PE determines the state of EVIs on multiple Egress PEs using BGP UPDATE messages, skipping the forwarding of BUM packets to Egress PEs with inactive states and directing them only to those with active states, thereby reducing redundant traffic and conserving bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an Ingress PE forwards BUM packets to all Egress PEs in the same EVI, then complete packet delivery coverage is achieved, but bandwidth waste increases due to redundant traffic to inactive PEs
Solution Approach 1:
The Ingress PE performs preliminary actions by determining the state (active or inactive) of each Egress PE's EVI before forwarding BUM packets. This advance checking allows the system to prepare forwarding decisions in advance, avoiding redundant transmissions to inactive PEs while ensuring complete delivery to active ones, thus resolving the contradiction between delivery coverage and bandwidth efficiency
Solution Approach 2:
The system implements feedback mechanisms where Egress PEs send BGP UPDATE messages to the Ingress PE indicating their active or inactive state. This feedback loop enables the Ingress PE to dynamically adjust forwarding decisions based on real-time PE states, ensuring packets are delivered to all active PEs while avoiding inactive ones, thereby balancing reliability and energy efficiency
2Reliability
If BUM packets are forwarded to all Egress PEs regardless of state, then no packet delivery is lost, but network resource utilization deteriorates due to redundant traffic
Solution Approach 1:
The Ingress PE performs preliminary determination of Egress PE states before forwarding BUM packets. By checking the active/inactive status in advance through BGP UPDATE messages, the system can make informed forwarding decisions that ensure complete packet delivery to active PEs while avoiding redundant transmissions to inactive ones, thus improving network resource utilization without compromising delivery completeness
Solution Approach 2:
The feedback mechanism through BGP UPDATE messages provides real-time information about Egress PE states to the Ingress PE. This enables dynamic adjustment of forwarding behavior, ensuring that packets are delivered to all active PEs while being withheld from inactive ones, thereby optimizing network resource utilization while maintaining complete packet delivery to where it is needed
Data Source
AI summary
A packet forwarding method, a packet forwarding system, and a provider edge (PE) device. The method applied to an Ingress PE includes: determining, in an Ethernet virtual private network instance (EVI), that a state of the EVI on a first Egress PE is Active, where an Ethernet virtual private network (EVPN) corresponding to the EVI includes a first customer edge (CE); determining that a state of the EVI on a second Egress PE is Inactive; skipping, forwarding a broadcast, unknown unicast, and multicast (BUM) packet to the second Egress PE, where the BUM packet is from the first CE; and forwarding, the BUM packet to the first Egress PE. According to the application, repeated BUM traffic that is transmitted in a bearer network and is not finally sent to a remote site is reduced; therefore, a waste of bandwidth in the bearer network is reduced.