On Wed, Mar 06, 2013 at 02:57:59PM -0800, Ben Pfaff wrote:
> RFC 3443 says that an outgoing MPLS TTL of zero is invalid, so we must send
> packets that have such a TTL post-decrement to the controller rather than
> allowing them to continue through the OpenFlow tables.
>
> Here is the text from RFC 3443 that implies this behavior:
>
> oTTL: This is the TTL value used as the outgoing TTL value (see
> section 3.5 for exception). It is always (iTTL - 1) unless otherwise
> stated.
>
> oTTL Check: Check if oTTL is greater than 0. If the oTTL Check is
> false, then the packet is not forwarded. Note that the oTTL check is
> performed only if any outgoing TTL (either IP or MPLS) is set to oTTL
> (see section 3.5 for exception).
>
> That is, the output TTL is one less than the input TTL, and a packet with
> an output TTL of 0 must not be forwarded.
>
> CC: Bruce Davie <b...@nicira.com>
> Signed-off-by: Ben Pfaff <b...@nicira.com>
No objections here.
Reviewed-by: Simon Horman <ho...@verge.net.au>
> ---
> I swear I sent this out earlier, but I don't see it in the archive
> or in my inbox.
>
> ofproto/ofproto-dpif.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/ofproto/ofproto-dpif.c b/ofproto/ofproto-dpif.c
> index 10e4e23..38b8e55 100644
> --- a/ofproto/ofproto-dpif.c
> +++ b/ofproto/ofproto-dpif.c
> @@ -6062,7 +6062,7 @@ execute_dec_mpls_ttl_action(struct action_xlate_ctx
> *ctx)
> return false;
> }
>
> - if (ttl > 0) {
> + if (ttl > 1) {
> ttl--;
> set_mpls_lse_ttl(&ctx->flow.mpls_lse, ttl);
> return false;
> --
> 1.7.2.5
>
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>
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