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a6db4494d2
Multipath route lookups should consider knowledge about next hops and not
select a hop that is known to be failed.
Example:
[h2] [h3] 15.0.0.5
| |
3| 3|
[SP1] [SP2]--+
1 2 1 2
| | /-------------+ |
| \ / |
| X |
| / \ |
| / \---------------\ |
1 2 1 2
12.0.0.2 [TOR1] 3-----------------3 [TOR2] 12.0.0.3
4 4
\ /
\ /
\ /
-------| |-----/
1 2
[TOR3]
3|
|
[h1] 12.0.0.1
host h1 with IP 12.0.0.1 has 2 paths to host h3 at 15.0.0.5:
root@h1:~# ip ro ls
...
12.0.0.0/24 dev swp1 proto kernel scope link src 12.0.0.1
15.0.0.0/16
nexthop via 12.0.0.2 dev swp1 weight 1
nexthop via 12.0.0.3 dev swp1 weight 1
...
If the link between tor3 and tor1 is down and the link between tor1
and tor2 then tor1 is effectively cut-off from h1. Yet the route lookups
in h1 are alternating between the 2 routes: ping 15.0.0.5 gets one and
ssh 15.0.0.5 gets the other. Connections that attempt to use the
12.0.0.2 nexthop fail since that neighbor is not reachable:
root@h1:~# ip neigh show
...
12.0.0.3 dev swp1 lladdr 00:02:00:00:00:1b REACHABLE
12.0.0.2 dev swp1 FAILED
...
The failed path can be avoided by considering known neighbor information
when selecting next hops. If the neighbor lookup fails we have no
knowledge about the nexthop, so give it a shot. If there is an entry
then only select the nexthop if the state is sane. This is similar to
what fib_detect_death does.
To maintain backward compatibility use of the neighbor information is
based on a new sysctl, fib_multipath_use_neigh.
Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Reviewed-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>
142 lines
3.2 KiB
C
142 lines
3.2 KiB
C
/*
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* ipv4 in net namespaces
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*/
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#ifndef __NETNS_IPV4_H__
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#define __NETNS_IPV4_H__
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#include <linux/uidgid.h>
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#include <net/inet_frag.h>
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#include <linux/rcupdate.h>
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struct tcpm_hash_bucket;
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struct ctl_table_header;
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struct ipv4_devconf;
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struct fib_rules_ops;
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struct hlist_head;
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struct fib_table;
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struct sock;
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struct local_ports {
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seqlock_t lock;
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int range[2];
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bool warned;
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};
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struct ping_group_range {
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seqlock_t lock;
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kgid_t range[2];
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};
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struct netns_ipv4 {
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#ifdef CONFIG_SYSCTL
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struct ctl_table_header *forw_hdr;
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struct ctl_table_header *frags_hdr;
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struct ctl_table_header *ipv4_hdr;
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struct ctl_table_header *route_hdr;
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struct ctl_table_header *xfrm4_hdr;
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#endif
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struct ipv4_devconf *devconf_all;
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struct ipv4_devconf *devconf_dflt;
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#ifdef CONFIG_IP_MULTIPLE_TABLES
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struct fib_rules_ops *rules_ops;
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bool fib_has_custom_rules;
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struct fib_table __rcu *fib_local;
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struct fib_table __rcu *fib_main;
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struct fib_table __rcu *fib_default;
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#endif
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#ifdef CONFIG_IP_ROUTE_CLASSID
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int fib_num_tclassid_users;
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#endif
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struct hlist_head *fib_table_hash;
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bool fib_offload_disabled;
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struct sock *fibnl;
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struct sock * __percpu *icmp_sk;
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struct sock *mc_autojoin_sk;
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struct inet_peer_base *peers;
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struct sock * __percpu *tcp_sk;
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struct netns_frags frags;
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#ifdef CONFIG_NETFILTER
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struct xt_table *iptable_filter;
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struct xt_table *iptable_mangle;
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struct xt_table *iptable_raw;
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struct xt_table *arptable_filter;
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#ifdef CONFIG_SECURITY
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struct xt_table *iptable_security;
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#endif
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struct xt_table *nat_table;
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#endif
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int sysctl_icmp_echo_ignore_all;
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int sysctl_icmp_echo_ignore_broadcasts;
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int sysctl_icmp_ignore_bogus_error_responses;
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int sysctl_icmp_ratelimit;
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int sysctl_icmp_ratemask;
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int sysctl_icmp_errors_use_inbound_ifaddr;
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struct local_ports ip_local_ports;
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int sysctl_tcp_ecn;
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int sysctl_tcp_ecn_fallback;
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int sysctl_ip_default_ttl;
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int sysctl_ip_no_pmtu_disc;
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int sysctl_ip_fwd_use_pmtu;
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int sysctl_ip_nonlocal_bind;
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/* Shall we try to damage output packets if routing dev changes? */
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int sysctl_ip_dynaddr;
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int sysctl_ip_early_demux;
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int sysctl_fwmark_reflect;
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int sysctl_tcp_fwmark_accept;
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#ifdef CONFIG_NET_L3_MASTER_DEV
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int sysctl_tcp_l3mdev_accept;
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#endif
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int sysctl_tcp_mtu_probing;
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int sysctl_tcp_base_mss;
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int sysctl_tcp_probe_threshold;
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u32 sysctl_tcp_probe_interval;
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int sysctl_tcp_keepalive_time;
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int sysctl_tcp_keepalive_probes;
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int sysctl_tcp_keepalive_intvl;
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int sysctl_tcp_syn_retries;
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int sysctl_tcp_synack_retries;
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int sysctl_tcp_syncookies;
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int sysctl_tcp_reordering;
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int sysctl_tcp_retries1;
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int sysctl_tcp_retries2;
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int sysctl_tcp_orphan_retries;
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int sysctl_tcp_fin_timeout;
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unsigned int sysctl_tcp_notsent_lowat;
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int sysctl_igmp_max_memberships;
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int sysctl_igmp_max_msf;
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int sysctl_igmp_llm_reports;
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int sysctl_igmp_qrv;
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struct ping_group_range ping_group_range;
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atomic_t dev_addr_genid;
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#ifdef CONFIG_SYSCTL
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unsigned long *sysctl_local_reserved_ports;
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#endif
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#ifdef CONFIG_IP_MROUTE
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#ifndef CONFIG_IP_MROUTE_MULTIPLE_TABLES
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struct mr_table *mrt;
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#else
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struct list_head mr_tables;
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struct fib_rules_ops *mr_rules_ops;
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#endif
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#endif
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#ifdef CONFIG_IP_ROUTE_MULTIPATH
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int sysctl_fib_multipath_use_neigh;
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#endif
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atomic_t rt_genid;
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};
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#endif
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