| Message ID | 20170823075541.26764-1-jkbs@redhat.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Jakub Sitnicki <jkbs@redhat.com> Date: Wed, 23 Aug 2017 09:55:41 +0200 > Reflecting IPv6 Flow Label at server nodes is useful in environments > that employ multipath routing to load balance the requests. As "IPv6 > Flow Label Reflection" standard draft [1] points out - ICMPv6 PTB error > messages generated in response to a downstream packets from the server > can be routed by a load balancer back to the original server without > looking at transport headers, if the server applies the flow label > reflection. This enables the Path MTU Discovery past the ECMP router in > load-balance or anycast environments where each server node is reachable > by only one path. > > Introduce a sysctl to enable flow label reflection per net namespace for > all newly created sockets. Same could be earlier achieved only per > socket by setting the IPV6_FL_F_REFLECT flag for the IPV6_FLOWLABEL_MGR > socket option. > > [1] https://tools.ietf.org/html/draft-wang-6man-flow-label-reflection-01 > > Signed-off-by: Jakub Sitnicki <jkbs@redhat.com> Ok, applied.
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index 84c9b8c..6b0bc0f 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -1350,6 +1350,15 @@ flowlabel_state_ranges - BOOLEAN FALSE: disabled Default: true +flowlabel_reflect - BOOLEAN + Automatically reflect the flow label. Needed for Path MTU + Discovery to work with Equal Cost Multipath Routing in anycast + environments. See RFC 7690 and: + https://tools.ietf.org/html/draft-wang-6man-flow-label-reflection-01 + TRUE: enabled + FALSE: disabled + Default: FALSE + anycast_src_echo_reply - BOOLEAN Controls the use of anycast addresses as source addresses for ICMPv6 echo reply diff --git a/include/net/netns/ipv6.h b/include/net/netns/ipv6.h index 0e50bf3..2544f97 100644 --- a/include/net/netns/ipv6.h +++ b/include/net/netns/ipv6.h @@ -36,6 +36,7 @@ struct netns_sysctl_ipv6 { int idgen_retries; int idgen_delay; int flowlabel_state_ranges; + int flowlabel_reflect; }; struct netns_ipv6 { diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c index 3b58ee7..fe5262f 100644 --- a/net/ipv6/af_inet6.c +++ b/net/ipv6/af_inet6.c @@ -211,6 +211,7 @@ static int inet6_create(struct net *net, struct socket *sock, int protocol, np->mc_loop = 1; np->pmtudisc = IPV6_PMTUDISC_WANT; np->autoflowlabel = ip6_default_np_autolabel(net); + np->repflow = net->ipv6.sysctl.flowlabel_reflect; sk->sk_ipv6only = net->ipv6.sysctl.bindv6only; /* Init the ipv4 part of the socket since we can have sockets diff --git a/net/ipv6/sysctl_net_ipv6.c b/net/ipv6/sysctl_net_ipv6.c index 69c50e7..6fbf8ae 100644 --- a/net/ipv6/sysctl_net_ipv6.c +++ b/net/ipv6/sysctl_net_ipv6.c @@ -90,6 +90,13 @@ static struct ctl_table ipv6_table_template[] = { .mode = 0644, .proc_handler = proc_dointvec }, + { + .procname = "flowlabel_reflect", + .data = &init_net.ipv6.sysctl.flowlabel_reflect, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec, + }, { } }; @@ -149,6 +156,7 @@ static int __net_init ipv6_sysctl_net_init(struct net *net) ipv6_table[6].data = &net->ipv6.sysctl.idgen_delay; ipv6_table[7].data = &net->ipv6.sysctl.flowlabel_state_ranges; ipv6_table[8].data = &net->ipv6.sysctl.ip_nonlocal_bind; + ipv6_table[9].data = &net->ipv6.sysctl.flowlabel_reflect; ipv6_route_table = ipv6_route_sysctl_init(net); if (!ipv6_route_table)
Reflecting IPv6 Flow Label at server nodes is useful in environments that employ multipath routing to load balance the requests. As "IPv6 Flow Label Reflection" standard draft [1] points out - ICMPv6 PTB error messages generated in response to a downstream packets from the server can be routed by a load balancer back to the original server without looking at transport headers, if the server applies the flow label reflection. This enables the Path MTU Discovery past the ECMP router in load-balance or anycast environments where each server node is reachable by only one path. Introduce a sysctl to enable flow label reflection per net namespace for all newly created sockets. Same could be earlier achieved only per socket by setting the IPV6_FL_F_REFLECT flag for the IPV6_FLOWLABEL_MGR socket option. [1] https://tools.ietf.org/html/draft-wang-6man-flow-label-reflection-01 Signed-off-by: Jakub Sitnicki <jkbs@redhat.com> --- Documentation/networking/ip-sysctl.txt | 9 +++++++++ include/net/netns/ipv6.h | 1 + net/ipv6/af_inet6.c | 1 + net/ipv6/sysctl_net_ipv6.c | 8 ++++++++ 4 files changed, 19 insertions(+)