On 8/12/23 12:09 PM, Andrea Mayer wrote:
The NEXT-C-SID mechanism described in [1] offers the possibility of encoding several SRv6 segments within a single 128 bit SID address. Such a SID address is called a Compressed SID (C-SID) container. In this way, the length of the SID List can be drastically reduced.
A SID instantiated with the NEXT-C-SID flavor considers an IPv6 address logically structured in three main blocks: i) Locator-Block; ii) Locator-Node Function; iii) Argument.
C-SID container+------------------------------------------------------------------+ | Locator-Block |Loc-Node| Argument | | |Function| | +------------------------------------------------------------------+ <--------- B -----------> <- NF -> <------------- A --------------->
(i) The Locator-Block can be any IPv6 prefix available to the provider;
(ii) The Locator-Node Function represents the node and the function to be triggered when a packet is received on the node;
(iii) The Argument carries the remaining C-SIDs in the current C-SID container.
This patch leverages the NEXT-C-SID mechanism previously introduced in the Linux SRv6 subsystem [2] to support SID compression capabilities in the SRv6 End.X behavior [3]. An SRv6 End.X behavior with NEXT-C-SID flavor works as an End.X behavior but it is capable of processing the compressed SID List encoded in C-SID containers.
An SRv6 End.X behavior with NEXT-C-SID flavor can be configured to support user-provided Locator-Block and Locator-Node Function lengths. In this implementation, such lengths must be evenly divisible by 8 (i.e. must be byte-aligned), otherwise the kernel informs the user about invalid values with a meaningful error code and message through netlink_ext_ack.
If Locator-Block and/or Locator-Node Function lengths are not provided by the user during configuration of an SRv6 End.X behavior instance with NEXT-C-SID flavor, the kernel will choose their default values i.e., 32-bit Locator-Block and 16-bit Locator-Node Function.
[1] - https://datatracker.ietf.org/doc/html/draft-ietf-spring-srv6-srh-compression [2] - https://lore.kernel.org/all/20220912171619.16943-1-andrea.mayer@uniroma2.it/ [3] - https://datatracker.ietf.org/doc/html/rfc8986#name-endx-l3-cross-connect
Signed-off-by: Andrea Mayer andrea.mayer@uniroma2.it
net/ipv6/seg6_local.c | 108 ++++++++++++++++++++++++++++++++++-------- 1 file changed, 88 insertions(+), 20 deletions(-)
Reviewed-by: David Ahern dsahern@kernel.org