Encoding Control Plane Info in UDP Source Port for Overlay Networks
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Solution Overview
Problem
Existing network systems face challenges in maintaining layer 2 connectivity and accurately forwarding broadcast/unknown-unicast/multicast traffic across overlay logical and physical networks, as Reverse Path Filtering policies often drop packets with mismatched source IP addresses, leading to loss of original sender context.
Innovation Solution
Encoding control plane information in the source port field of packet headers, using a mapping table to infer semantically richer information, and employing replication offload engines to preserve the original sender's IP address, enabling ECMP routing and multicast proxying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the replication node modifies the source IP address to pass RPF checks, then packet forwarding reliability is improved, but the original sender context is lost
Solution Approach 1:
The patent embeds the original sender IP address information within the VXLAN header's source port field, creating a nested structure where the encapsulation header carries metadata about the original packet. This allows the replication node to modify the outer IP header for RPF compliance while preserving the inner original sender information through the encoded source port
Solution Approach 2:
The source port field acts as an intermediary carrier that transfers the original sender IP address information through the replication node. The replication node can modify other parts of the packet while the encoded source port maintains the original sender context, enabling both RPF compliance and information preservation
2Reliability
If BUM traffic is replicated to all endpoints, then layer 2 connectivity is maintained, but network bandwidth is consumed
Solution Approach 1:
The patent performs preliminary encoding of control plane information in the source port field before replication. This allows receiving endpoints to pre-process and filter packets based on the encoded information, enabling selective forwarding that maintains L2 connectivity while reducing unnecessary bandwidth consumption by avoiding replication to endpoints that don't need the traffic
3Productivity
If the source port field is used to encode control plane information, then routing efficiency is improved, but the port field capacity is reduced
Solution Approach 1:
The patent changes the interpretation of the source port field from a standard transport parameter to an encoded control plane information carrier. By treating the source port as an encoded field that can represent IP addresses or other identifiers through mapping tables, the system gains routing efficiency without requiring additional packet header space, as the encoding leverages existing field capacity
Data Source
AI summary
A novel method that uses the source port field in the transport or connection layer (L4) header to encode control plane information is provided. Specifically, the method encodes control plane information in UDP or TCP source port field of data plane tunnels in an overlay network such as VXLAN. Network virtualization is implemented by a network controller over an overlay network on the physical fabric. The network controller provides a mapping table to the data plane hosts for mapping the encoded bits in the source port field to semantically richer information. The data plane hosts in turn uses the encoded source bits and the mapping table to infer this semantically richer information. This semantically richer information is used to allow receivers of proxied traffic to learn the address of the original sender. The semantically richer information can also be used to enable ECMP for the transmitted packets.