Re: [PATCH net-next 1/2] seg6: add FIB table attribute for post-encap SID route lookup

On 7/11/26 10:29 AM, Andrea Mayer wrote:

After SRv6 encapsulation the kernel looks up the route for the first SID,
that is the outer IPv6 destination of the encapsulated packet. This
post-encap SID route lookup uses the FIB table of the current routing
context. When the encap route is installed in a VRF, the VRF's table may
not have a route matching the SID. In that case another table should
handle it, e.g. one configured for underlay connectivity.

Add an optional SEG6_IPTUNNEL_TABLE attribute that selects the FIB table
used for this lookup. When set by the user, the attribute is honored on
both the input path (forwarded traffic) and the output path (locally
originated traffic). SRv6 encap routes that do not set the attribute use
the current routing context, as before.

For example:

  # SID route installed in the underlay table 500
  ip -6 route add fc00::100/128 via fd00::1 dev veth0 table 500

  # encap route in vrf-100; the first SID is looked up in table 500
  ip -6 route add cafe::1/128 vrf vrf-100 \
      encap seg6 mode encap segs fc00::100 lookup 500 dev veth0

  # or look up the SID in the main table
  ip -6 route add cafe::1/128 vrf vrf-100 \
      encap seg6 mode encap segs fc00::100 lookup main dev veth0

Suggested-by: Nicolas Dichtel <redacted>
Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Reviewed-by: Nicolas Dichtel <redacted>
---
 include/uapi/linux/seg6_iptunnel.h |   1 +
 net/ipv6/seg6_iptunnel.c           | 132 +++++++++++++++++++++++++----
 2 files changed, 117 insertions(+), 16 deletions(-)

Acked-by: David Ahern <dsahern@kernel.org>