LPC2018 - Leveraging Kernel Tables with XDP

Описание: url: https://linuxplumbersconf.org/event/2...
speaker: David Ahern (Cumulus Networks)


XDP is a framework for running BPF programs in the NIC driver to allow
decisions about the fate of a received packet at the earliest point in
the Linux networking stack. For the most part the BPF programs rely on
maps to drive packet decisions, maps that are managed for example by a
userspace agent. This architecture has implications on how the system is
configured, monitored and debugged.

An alternative approach is to make the kernel networking tables
accessible by BPF programs. This approach allows the use of standard
Linux APIs and tools to manage networking configuration and state while
still achieving the higher performance provided by XDP. An example of
providing access to kernel tables is the recently added helper to allow
IPv4 and IPv6 FIB (and nexthop) lookups in XDP programs. Routing suites
such as FRR manage the FIB tables, and the XDP packet path benefits by
automatically adapting to the FIB updates in real time. While a huge
first step, a FIB lookup alone is not sufficient for general networking
deployments.

This talk discusses the advantages of making kernel tables available to
XDP programs to create a programmable packet pipeline, what features
have been implemented as of October 2018, key missing features, and
current challenges.