[ovs-dev] [patch v2] ovn: Fix gateway load balancing.

Mark Michelson mmichels at redhat.com
Thu Jun 28 16:41:20 UTC 2018


Hi Darrell,

I'm not 100% sure this is correct. I think this change would only be 
correct if the router's IP addresses are also load balancer VIPs. In the 
case where the VIPs do not overlap with the router IP addresses, I think 
we'd want to have the ICMP responses still in place.

On 06/28/2018 01:15 AM, Darrell Ball wrote:
> Non-distributed and distributed gateway load balancing is broken.
> Recent changes for port unreachable handling broke the associated
> unsnat functionality.  The fix approach is check for gateway
> contexts and accept packets directed to gateway router IPs.
> 
> Fixes:  86558ac2e476 ("OVN: add UDP port unreachable support to OVN logical router.")
> Fixes:  159932c9e4ea ("OVN: add TCP port unreachable support to OVN logical router.")
> Fixes:  0e858e05f76b ("OVN: add protocol unreachable support to OVN router ports.")
> CC: Lorenzo Bianconi <lorenzo.bianconi at redhat.com>
> Signed-off-by: Darrell Ball <dlu998 at gmail.com>
> ---
>   ovn/northd/ovn-northd.8.xml |  17 ++++---
>   ovn/northd/ovn-northd.c     | 106 ++++++++++++++++++++++----------------------
>   2 files changed, 64 insertions(+), 59 deletions(-)
> 
> diff --git a/ovn/northd/ovn-northd.8.xml b/ovn/northd/ovn-northd.8.xml
> index cfd3511..280efd0 100644
> --- a/ovn/northd/ovn-northd.8.xml
> +++ b/ovn/northd/ovn-northd.8.xml
> @@ -1310,8 +1310,9 @@ nd_na {
>           <p>
>             UDP port unreachable.  Priority-80 flows generate ICMP port
>             unreachable messages in reply to UDP datagrams directed to the
> -          router's IP address.  The logical router doesn't accept any UDP
> -          traffic so it always generates such a reply.
> +          router's IP address, except in the special case of gateways,
> +          which accept traffic directed to a router IP for load balancing
> +          purposes.
>           </p>
>   
>           <p>
> @@ -1321,10 +1322,10 @@ nd_na {
>   
>         <li>
>           <p>
> -          TCP reset.  Priority-80 flows generate TCP reset messages in reply to
> -          TCP datagrams directed to the router's IP address.  The logical
> -          router doesn't accept any TCP traffic so it always generates such a
> -          reply.
> +          TCP reset.  Priority-80 flows generate TCP reset messages in reply
> +          to TCP datagrams directed to the router's IP address, except in
> +          the special case of gateways, which accept traffic directed to a
> +          router IP for load balancing purposes.
>           </p>
>   
>           <p>
> @@ -1336,7 +1337,9 @@ nd_na {
>           <p>
>             Protocol unreachable.  Priority-70 flows generate ICMP protocol
>             unreachable messages in reply to packets directed to the router's IP
> -          address on IP protocols other than UDP, TCP, and ICMP.
> +          address on IP protocols other than UDP, TCP, and ICMP, except in the
> +          special case of gateways, which accept traffic directed to a router
> +          IP for load balancing purposes.
>           </p>
>   
>           <p>
> diff --git a/ovn/northd/ovn-northd.c b/ovn/northd/ovn-northd.c
> index 72fe4e7..7648bce 100644
> --- a/ovn/northd/ovn-northd.c
> +++ b/ovn/northd/ovn-northd.c
> @@ -5141,48 +5141,49 @@ build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,
>                             ds_cstr(&match), ds_cstr(&actions));
>           }
>   
> -        /* UDP/TCP port unreachable */
> -        for (int i = 0; i < op->lrp_networks.n_ipv4_addrs; i++) {
> -            const char *action;
> -
> -            ds_clear(&match);
> -            ds_put_format(&match,
> -                          "ip4 && ip4.dst == %s && !ip.later_frag && udp",
> -                          op->lrp_networks.ipv4_addrs[i].addr_s);
> -            action = "icmp4 {"
> -                        "eth.dst <-> eth.src; "
> -                        "ip4.dst <-> ip4.src; "
> -                        "ip.ttl = 255; "
> -                        "icmp4.type = 3; "
> -                        "icmp4.code = 3; "
> -                        "next; };";
> -            ovn_lflow_add(lflows, op->od, S_ROUTER_IN_IP_INPUT, 80,
> -                          ds_cstr(&match), action);
> +        if (!smap_get(&op->od->nbr->options, "chassis")
> +            && !op->od->l3dgw_port) {
> +            /* UDP/TCP port unreachable. */
> +            for (int i = 0; i < op->lrp_networks.n_ipv4_addrs; i++) {
> +                ds_clear(&match);
> +                ds_put_format(&match,
> +                              "ip4 && ip4.dst == %s && !ip.later_frag && udp",
> +                              op->lrp_networks.ipv4_addrs[i].addr_s);
> +                const char *action = "icmp4 {"
> +                                     "eth.dst <-> eth.src; "
> +                                     "ip4.dst <-> ip4.src; "
> +                                     "ip.ttl = 255; "
> +                                     "icmp4.type = 3; "
> +                                     "icmp4.code = 3; "
> +                                     "next; };";
> +                ovn_lflow_add(lflows, op->od, S_ROUTER_IN_IP_INPUT, 80,
> +                              ds_cstr(&match), action);
>   
> -            ds_clear(&match);
> -            ds_put_format(&match,
> -                          "ip4 && ip4.dst == %s && !ip.later_frag && tcp",
> -                          op->lrp_networks.ipv4_addrs[i].addr_s);
> -            action = "tcp_reset {"
> -                        "eth.dst <-> eth.src; "
> -                        "ip4.dst <-> ip4.src; "
> -                        "next; };";
> -            ovn_lflow_add(lflows, op->od, S_ROUTER_IN_IP_INPUT, 80,
> -                          ds_cstr(&match), action);
> +                ds_clear(&match);
> +                ds_put_format(&match,
> +                              "ip4 && ip4.dst == %s && !ip.later_frag && tcp",
> +                              op->lrp_networks.ipv4_addrs[i].addr_s);
> +                action = "tcp_reset {"
> +                         "eth.dst <-> eth.src; "
> +                         "ip4.dst <-> ip4.src; "
> +                         "next; };";
> +                ovn_lflow_add(lflows, op->od, S_ROUTER_IN_IP_INPUT, 80,
> +                              ds_cstr(&match), action);
>   
> -            ds_clear(&match);
> -            ds_put_format(&match,
> -                          "ip4 && ip4.dst == %s && !ip.later_frag",
> -                          op->lrp_networks.ipv4_addrs[i].addr_s);
> -            action = "icmp4 {"
> -                        "eth.dst <-> eth.src; "
> -                        "ip4.dst <-> ip4.src; "
> -                        "ip.ttl = 255; "
> -                        "icmp4.type = 3; "
> -                        "icmp4.code = 2; "
> -                        "next; };";
> -            ovn_lflow_add(lflows, op->od, S_ROUTER_IN_IP_INPUT, 70,
> -                          ds_cstr(&match), action);
> +                ds_clear(&match);
> +                ds_put_format(&match,
> +                              "ip4 && ip4.dst == %s && !ip.later_frag",
> +                              op->lrp_networks.ipv4_addrs[i].addr_s);
> +                action = "icmp4 {"
> +                         "eth.dst <-> eth.src; "
> +                         "ip4.dst <-> ip4.src; "
> +                         "ip.ttl = 255; "
> +                         "icmp4.type = 3; "
> +                         "icmp4.code = 2; "
> +                         "next; };";
> +                ovn_lflow_add(lflows, op->od, S_ROUTER_IN_IP_INPUT, 70,
> +                              ds_cstr(&match), action);
> +            }
>           }
>   
>           ds_clear(&match);
> @@ -5306,19 +5307,20 @@ build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,
>           }
>   
>           /* TCP port unreachable */
> -        for (int i = 0; i < op->lrp_networks.n_ipv6_addrs; i++) {
> -            const char *action;
> -
> -            ds_clear(&match);
> -            ds_put_format(&match,
> -                          "ip6 && ip6.dst == %s && !ip.later_frag && tcp",
> -                          op->lrp_networks.ipv6_addrs[i].addr_s);
> -            action = "tcp_reset {"
> -                        "eth.dst <-> eth.src; "
> -                        "ip6.dst <-> ip6.src; "
> -                        "next; };";
> -            ovn_lflow_add(lflows, op->od, S_ROUTER_IN_IP_INPUT, 80,
> +        if (!smap_get(&op->od->nbr->options, "chassis")
> +            && !op->od->l3dgw_port) {
> +            for (int i = 0; i < op->lrp_networks.n_ipv6_addrs; i++) {
> +                ds_clear(&match);
> +                ds_put_format(&match,
> +                              "ip6 && ip6.dst == %s && !ip.later_frag && tcp",
> +                              op->lrp_networks.ipv6_addrs[i].addr_s);
> +                const char *action = "tcp_reset {"
> +                                     "eth.dst <-> eth.src; "
> +                                     "ip6.dst <-> ip6.src; "
> +                                     "next; };";
> +                ovn_lflow_add(lflows, op->od, S_ROUTER_IN_IP_INPUT, 80,
>                             ds_cstr(&match), action);
> +            }
>           }
>       }
>   
> 



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