On 10/30/16 at 06:28pm, Tom Herbert wrote: > On Sun, Oct 30, 2016 at 2:47 PM, Thomas Graf <tg...@suug.ch> wrote: > > Instead of building complex logic, we can allow the program to return > > a code to indicate when to perform another route lookup just as we do > > for the redirect case. Just because the destination address has > > changed may not require another lookup in all cases. A typical example > > would be a program rewriting addresses for the default route to other > > address which are always handled by the default route as well. An > > unconditional lookup would hurt performance in many cases. > > Right, that's why we rely on a dst cache. Any use of LWT that > encapsulates or tunnels to a fixed destination (ILA, VXLAN, IPIP, > etc.) would want to use the dst cache optimization to avoid the second > lookup. The ILA LWT code used to call orig output and that worked as > long as we could set the default router as the gateway "via". It was > something we were able to deploy, but not a general solution. > Integrating properly with routing gives a much better solution IMO. > Note that David Lebrun's latest LWT Segment Routing patch does the > second lookup with the dst cache to try to avoid it.
Yes, I saw both ILA and SR dst_cache. I was planning on addressing the conditional reroute in a second step but it looks fairly simple actually so I'm fine adding this in a v2 based on a return code. I will limit lwt-bpf to AF_INET && AF_INET6 though.
