A Caching SFC Proxy Based on eBPF

Service Functions (SFs) are intermediate processing nodes on the path of IP packets. With SF chaining (SFC), packets can be steered to multiple physical or virtual SFs in a specific order. SFC-unaware SFs can be used flexibly but they do not support SFC-specific encapsulation of packets. Therefore, an SFC proxy needs to remove the encapsulation of a packet before processing by an SFC-unaware SF, and to add it again afterwards. Such an SFC proxy typically runs on a server hosting virtual network functions (VNFs) that serve as SFs. Simple SFC proxies adapt a flow-specific static header stack. That is, each VNF requires an own SFC proxy, and the proxy cannot be extended to support per-packet metadata in the SFC encapsulation. The caching SFC proxy presented in this work caches packet-specific headers while packets are processed by a VNF, i.e., packet-specific header information is preserved. We present concept, use cases, and an eBPF-based implementation of the caching SFC proxy. In addition, we evaluate the performance of a prototype.