I'm not sure you want it to be unconditional. When I wrote the option for netlink and iproute2, it was for some very specialized scenarios.
> On Apr 24, 2023, at 3:14 AM, Stefan Hellermann <ste...@the2masters.de> wrote: > > I have an easier patch in my private repo, maybe it's enough without a new > configuration option? I'm using it in production for a gretap link which is > bridged on both sides to MTU 1500 ethernet links. > > See https://bugzilla.kernel.org/show_bug.cgi?id=14837, which seems to say you > always have to use both options: ignore-df nopmtudisc > > Signed-off-by: Stefan Hellermann <ste...@the2masters.de> > > --- a/system-linux.c > +++ b/system-linux.c > @@ -3496,6 +3496,7 @@ static int system_add_gre_tunnel(const c > ttl = 64; > > nla_put_u8(nlm, IFLA_GRE_PMTUDISC, set_df ? 1 : 0); > + nla_put_u8(nlm, IFLA_GRE_IGNORE_DF, set_df ? 0 : 1); > > nla_put_u8(nlm, IFLA_GRE_TOS, tos); > } > > Am 17.04.23 um 11:29 schrieb Denis Kalashnikov: >> This is useful for GRE TAP tunnel when tunnel is added to a br-lan bridge. >> In this case you need to create it with "nopmtudisc ignore-df". Otherwise >> large IP-packets with DF=1 (TCP-data, large pings) will be silently dropped >> (since DF=1 but stack failed to send ICMP "need fragmentation" back). But >> with >> "ignore-df" packets with DF=1 will be fragmented. >> >> Signed-off-by: Denis Kalashnikov <denis281...@gmail.com> >> --- >> system-linux.c | 5 +++++ >> system.c | 1 + >> system.h | 1 + >> 3 files changed, 7 insertions(+) >> >> diff --git a/system-linux.c b/system-linux.c >> index e4041fb..4397460 100644 >> --- a/system-linux.c >> +++ b/system-linux.c >> @@ -3500,6 +3500,11 @@ static int system_add_gre_tunnel(const char *name, >> const char *kind, >> nla_put_u8(nlm, IFLA_GRE_PMTUDISC, set_df ? 1 : 0); >> + if ((cur = tb[TUNNEL_ATTR_IGNORE_DF])) { >> + nla_put_u8(nlm, IFLA_GRE_IGNORE_DF, >> + blobmsg_get_bool(cur)); >> + } >> + >> nla_put_u8(nlm, IFLA_GRE_TOS, tos); >> } >> diff --git a/system.c b/system.c >> index 32597c1..e773245 100644 >> --- a/system.c >> +++ b/system.c >> @@ -21,6 +21,7 @@ static const struct blobmsg_policy >> tunnel_attrs[__TUNNEL_ATTR_MAX] = { >> [TUNNEL_ATTR_REMOTE] = { .name = "remote", .type = BLOBMSG_TYPE_STRING }, >> [TUNNEL_ATTR_MTU] = { .name = "mtu", .type = BLOBMSG_TYPE_INT32 }, >> [TUNNEL_ATTR_DF] = { .name = "df", .type = BLOBMSG_TYPE_BOOL }, >> + [TUNNEL_ATTR_IGNORE_DF] = { .name = "ignore-df", .type = BLOBMSG_TYPE_BOOL >> }, >> [TUNNEL_ATTR_TTL] = { .name = "ttl", .type = BLOBMSG_TYPE_INT32 }, >> [TUNNEL_ATTR_TOS] = { .name = "tos", .type = BLOBMSG_TYPE_STRING }, >> [TUNNEL_ATTR_LINK] = { .name = "link", .type = BLOBMSG_TYPE_STRING }, >> diff --git a/system.h b/system.h >> index 1f7037d..a7a713d 100644 >> --- a/system.h >> +++ b/system.h >> @@ -29,6 +29,7 @@ enum tunnel_param { >> TUNNEL_ATTR_LOCAL, >> TUNNEL_ATTR_MTU, >> TUNNEL_ATTR_DF, >> + TUNNEL_ATTR_IGNORE_DF, >> TUNNEL_ATTR_TTL, >> TUNNEL_ATTR_TOS, >> TUNNEL_ATTR_LINK, > _______________________________________________ > openwrt-devel mailing list > openwrt-devel@lists.openwrt.org > https://lists.openwrt.org/mailman/listinfo/openwrt-devel _______________________________________________ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/mailman/listinfo/openwrt-devel
