From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Graf <tgraf@suug.ch>
Subject: Re: [PATCH net-next 3/4] bpf: BPF for lightweight tunnel
 encapsulation
Date: Mon, 31 Oct 2016 13:59:07 +0100
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Cc: "David S. Miller" <davem@davemloft.net>,
        Alexei Starovoitov <alexei.starovoitov@gmail.com>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Linux Kernel Network Developers <netdev@vger.kernel.org>,
        roopa <roopa@cumulusnetworks.com>
To: Tom Herbert <tom@herbertland.com>
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On 10/30/16 at 06:28pm, Tom Herbert wrote:
> 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.

Noticed while implementing this: How does ILA ensure that dst_output()
is not invoked in a circular manner?

dstA->output() -> dstB->otuput() -> dstA->output() -> ...