linux/net/bridge
Nikolay Aleksandrov 2756f68c31 net: bridge: add support for backup port
This patch adds a new port attribute - IFLA_BRPORT_BACKUP_PORT, which
allows to set a backup port to be used for known unicast traffic if the
port has gone carrier down. The backup pointer is rcu protected and set
only under RTNL, a counter is maintained so when deleting a port we know
how many other ports reference it as a backup and we remove it from all.
Also the pointer is in the first cache line which is hot at the time of
the check and thus in the common case we only add one more test.
The backup port will be used only for the non-flooding case since
it's a part of the bridge and the flooded packets will be forwarded to it
anyway. To remove the forwarding just send a 0/non-existing backup port.
This is used to avoid numerous scalability problems when using MLAG most
notably if we have thousands of fdbs one would need to change all of them
on port carrier going down which takes too long and causes a storm of fdb
notifications (and again when the port comes back up). In a Multi-chassis
Link Aggregation setup usually hosts are connected to two different
switches which act as a single logical switch. Those switches usually have
a control and backup link between them called peerlink which might be used
for communication in case a host loses connectivity to one of them.
We need a fast way to failover in case a host port goes down and currently
none of the solutions (like bond) cannot fulfill the requirements because
the participating ports are actually the "master" devices and must have the
same peerlink as their backup interface and at the same time all of them
must participate in the bridge device. As Roopa noted it's normal practice
in routing called fast re-route where a precalculated backup path is used
when the main one is down.
Another use case of this is with EVPN, having a single vxlan device which
is backup of every port. Due to the nature of master devices it's not
currently possible to use one device as a backup for many and still have
all of them participate in the bridge (which is master itself).
More detailed information about MLAG is available at the link below.
https://docs.cumulusnetworks.com/display/DOCS/Multi-Chassis+Link+Aggregation+-+MLAG

Further explanation and a diagram by Roopa:
Two switches acting in a MLAG pair are connected by the peerlink
interface which is a bridge port.

the config on one of the switches looks like the below. The other
switch also has a similar config.
eth0 is connected to one port on the server. And the server is
connected to both switches.

br0 -- team0---eth0
      |
      -- switch-peerlink

Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-23 09:32:15 -07:00
..
netfilter netfilter: nft_reject_bridge: remove unnecessary ttl set 2018-07-16 17:51:48 +02:00
br_arp_nd_proxy.c bridge: suppress nd pkts on BR_NEIGH_SUPPRESS ports 2017-10-08 21:12:04 -07:00
br_device.c net: bridge: disable bridge MTU auto tuning if it was set manually 2018-03-31 22:19:00 -04:00
br_fdb.c net: bridge: Fix locking in br_fdb_find_port() 2018-06-08 19:58:31 -04:00
br_forward.c net: bridge: add support for backup port 2018-07-23 09:32:15 -07:00
br_if.c net: bridge: add support for backup port 2018-07-23 09:32:15 -07:00
br_input.c net: bridge: add support for port isolation 2018-05-25 14:37:20 -04:00
br_ioctl.c net: bridge: add notifications for the bridge dev on vlan change 2017-11-02 15:53:40 +09:00
br_mdb.c net: use rtnl_register_module where needed 2017-12-04 11:32:39 -05:00
br_multicast.c treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
br_netfilter_hooks.c net: Drop pernet_operations::async 2018-03-27 13:18:09 -04:00
br_netfilter_ipv6.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
br_netlink_tunnel.c bridge: netlink: make setlink/dellink notifications more accurate 2017-10-29 11:03:43 +09:00
br_netlink.c net: bridge: add support for backup port 2018-07-23 09:32:15 -07:00
br_nf_core.c xfrm: Move dst->path into struct xfrm_dst 2017-11-30 09:54:26 -05:00
br_private_stp.h net: bridge: add helper to set topology change 2016-12-10 21:27:23 -05:00
br_private_tunnel.h bridge: netlink: make setlink/dellink notifications more accurate 2017-10-29 11:03:43 +09:00
br_private.h net: bridge: add support for backup port 2018-07-23 09:32:15 -07:00
br_stp_bpdu.c net: introduce __skb_put_[zero, data, u8] 2017-06-20 13:30:14 -04:00
br_stp_if.c net: bridge: add notifications for the bridge dev on vlan change 2017-11-02 15:53:40 +09:00
br_stp_timer.c net: bridge: Convert timers to use timer_setup() 2017-11-03 15:42:49 +09:00
br_stp.c net: bridge: add notifications for the bridge dev on vlan change 2017-11-02 15:53:40 +09:00
br_switchdev.c net: bridge: Extract boilerplate around switchdev_port_obj_*() 2018-05-31 14:13:42 -04:00
br_sysfs_br.c net: Use octal not symbolic permissions 2018-03-26 12:07:48 -04:00
br_sysfs_if.c net: bridge: add support for backup port 2018-07-23 09:32:15 -07:00
br_vlan_tunnel.c bridge: vlan_tunnel: explicitly reset metadata attrs to NULL on failure 2017-02-17 13:33:41 -05:00
br_vlan.c net: bridge: Notify about bridge VLANs 2018-05-31 14:13:44 -04:00
br.c net: bridge: Notify about !added_by_user FDB entries 2018-05-03 13:46:47 -04:00
Kconfig bridge: Add vlan filtering infrastructure 2013-02-13 19:41:46 -05:00
Makefile Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00