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seg6: add support for SRv6 End.DT46 Behavior 

We introduce the new "End.DT46" action for supporting the SRv6 End.DT46
Behavior in iproute2.
The SRv6 End.DT46 Behavior, defined in RFC 8986 [1] section 4.8, can be
used to implement L3 VPNs based on Segment Routing over IPv6 networks in
multi-tenants environments and it is capable of handling both IPv4 and
IPv6 tenant traffic at the same time.
The SRv6 End.DT46 Behavior decapsulates the received packets and it
performs the IPv4 or IPv6 routing lookup in the routing table of the
tenant.

As for the End.DT4 and for the End.DT6 in VRF mode, the SRv6 End.DT46
Behavior leverages a VRF device in order to force the routing lookup into
the associated routing table using the "vrftable" attribute.

To make the End.DT46 work properly, it must be guaranteed that the
routing table used for routing lookup operations is bound to one and
only one VRF during the tunnel creation. Such constraint has to be
enforced by enabling the VRF strict_mode sysctl parameter, i.e.:

 $ sysctl -wq net.vrf.strict_mode=1

Note that the same approach is used for the End.DT4 Behavior and for the
End.DT6 Behavior in VRF mode.

An SRv6 End.DT46 Behavior instance can be created as follows:

 $ ip -6 route add 2001:db8::1 encap seg6local action End.DT46 vrftable 100 dev vrf100

Standard Output:
 $ ip -6 route show 2001:db8::1
 2001:db8::1  encap seg6local action End.DT46 vrftable 100 dev vrf100 metric 1024 pref medium

JSON Output:
$ ip -6 -j -p route show 2001:db8::1
[ {
        "dst": "2001:db8::1",
        "encap": "seg6local",
        "action": "End.DT46",
        "vrftable": 100,
        "dev": "vrf100",
        "metric": 1024,
        "flags": [ ],
        "pref": "medium"
} ]

This patch updates the route.8 man page and the ip route help with the
information related to End.DT46.
Considering that the same information was missing for the SRv6 End.DT4 and
the End.DT6 Behaviors, we have also added it.

[1] https://www.rfc-editor.org/rfc/rfc8986.html#name-enddt46-decapsulation-and-s

Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Signed-off-by: Paolo Lungaroni <paolo.lungaroni@uniroma2.it>
Signed-off-by: David Ahern <dsahern@kernel.org>
This commit is contained in:
Paolo Lungaroni 2021-06-17 19:23:54 +02:00 committed by David Ahern
parent 1d11326a57
commit 3e26254f31
3 changed files with 51 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
ip/iproute.c
View File

@ -107,8 +107,8 @@ static void usage(void)
"SEGMODE := [ encap | inline ]\n"
"SEG6LOCAL := action ACTION [ OPTIONS ] [ count ]\n"
"ACTION := { End | End.X | End.T | End.DX2 | End.DX6 | End.DX4 |\n"
" End.DT6 | End.DT4 | End.B6 | End.B6.Encaps | End.BM |\n"
" End.S | End.AS | End.AM | End.BPF }\n"
" End.DT6 | End.DT4 | End.DT46 | End.B6 | End.B6.Encaps |\n"
" End.BM | End.S | End.AS | End.AM | End.BPF }\n"
"OPTIONS := OPTION [ OPTIONS ]\n"
"OPTION := { srh SEG6HDR | nh4 ADDR | nh6 ADDR | iif DEV | oif DEV |\n"
" table TABLEID | vrftable TABLEID | endpoint PROGNAME }\n"

1
ip/iproute_lwtunnel.c
View File

@ -220,6 +220,7 @@ static const char *seg6_action_names[SEG6_LOCAL_ACTION_MAX + 1] = {
[SEG6_LOCAL_ACTION_END_AS] = "End.AS",
[SEG6_LOCAL_ACTION_END_AM] = "End.AM",
[SEG6_LOCAL_ACTION_END_BPF] = "End.BPF",
[SEG6_LOCAL_ACTION_END_DT46] = "End.DT46",
};
static const char *format_action_type(int action)

48
man/man8/ip-route.8.in
View File

@ -834,6 +834,49 @@ rules. This action only accepts packets with either a zero Segments
Left value or no SRH at all, and an inner IPv6 packet. Other
matching packets are dropped.
.BR End.DT6 " { " table " | " vrftable " } "
.I TABLEID
- Decapsulate the inner IPv6 packet and forward it according to the
specified lookup table.
.I TABLEID
is either a number or a string from the file
.BR "@SYSCONFDIR@/rt_tables" .
If
.B vrftable
is used, the argument must be a VRF device associated with
the table id. Moreover, the VRF table associated with the
table id must be configured with the VRF strict mode turned
on (net.vrf.strict_mode=1). This action only accepts packets
with either a zero Segments Left value or no SRH at all,
and an inner IPv6 packet. Other matching packets are dropped.
.B End.DT4 vrftable
.I TABLEID
- Decapsulate the inner IPv4 packet and forward it according to the
specified lookup table.
.I TABLEID
is either a number or a string from the file
.BR "@SYSCONFDIR@/rt_tables" .
The argument must be a VRF device associated with the table id.
Moreover, the VRF table associated with the table id must be configured
with the VRF strict mode turned on (net.vrf.strict_mode=1). This action
only accepts packets with either a zero Segments Left value or no SRH
at all, and an inner IPv4 packet. Other matching packets are dropped.
.B End.DT46 vrftable
.I TABLEID
- Decapsulate the inner IPv4 or IPv6 packet and forward it according
to the specified lookup table.
.I TABLEID
is either a number or a string from the file
.BR "@SYSCONFDIR@/rt_tables" .
The argument must be a VRF device associated with the table id.
Moreover, the VRF table associated with the table id must be configured
with the VRF strict mode turned on (net.vrf.strict_mode=1). This action
only accepts packets with either a zero Segments Left value or no SRH
at all, and an inner IPv4 or IPv6 packet. Other matching packets are
dropped.
.B End.B6 srh segs
.IR SEGMENTS " [ "
.B hmac
@ -1172,6 +1215,11 @@ ip -6 route add 2001:db8:1::/64 encap seg6 mode encap segs 2001:db8:42::1,2001:d
Adds an IPv6 route with SRv6 encapsulation and two segments attached.
.RE
.PP
ip -6 route add 2001:db8:1::/64 encap seg6local action End.DT46 vrftable 100 dev vrf100
.RS 4
Adds an IPv6 route with SRv6 decapsulation and forward with lookup in VRF table.
.RE
.PP
ip route add 10.1.1.0/30 nhid 10
.RS 4
Adds an ipv4 route using nexthop object with id 10.