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Integrate MDB support into the Tx path of the VXLAN driver, allowing it
to selectively forward IP multicast traffic according to the matched MDB
entry.
If MDB entries are configured (i.e., 'VXLAN_F_MDB' is set) and the
packet is an IP multicast packet, perform up to three different lookups
according to the following priority:
1. For an (S, G) entry, using {Source VNI, Source IP, Destination IP}.
2. For a (*, G) entry, using {Source VNI, Destination IP}.
3. For the catchall MDB entry (0.0.0.0 or ::), using the source VNI.
The catchall MDB entry is similar to the catchall FDB entry
(00:00:00:00:00:00) that is currently used to transmit BUM (broadcast,
unknown unicast and multicast) traffic. However, unlike the catchall FDB
entry, this entry is only used to transmit unregistered IP multicast
traffic that is not link-local. Therefore, when configured, the catchall
FDB entry will only transmit BULL (broadcast, unknown unicast,
link-local multicast) traffic.
The catchall MDB entry is useful in deployments where inter-subnet
multicast forwarding is used and not all the VTEPs in a tenant domain
are members in all the broadcast domains. In such deployments it is
advantageous to transmit BULL (broadcast, unknown unicast and link-local
multicast) and unregistered IP multicast traffic on different tunnels.
If the same tunnel was used, a VTEP only interested in IP multicast
traffic would also pull all the BULL traffic and drop it as it is not a
member in the originating broadcast domain [1].
If the packet did not match an MDB entry (or if the packet is not an IP
multicast packet), return it to the Tx path, allowing it to be forwarded
according to the FDB.
If the packet did match an MDB entry, forward it to the associated
remote VTEPs. However, if the entry is a (*, G) entry and the associated
remote is in INCLUDE mode, then skip over it as the source IP is not in
its source list (otherwise the packet would have matched on an (S, G)
entry). Similarly, if the associated remote is marked as BLOCKED (can
only be set on (S, G) entries), then skip over it as well as the remote
is in EXCLUDE mode and the source IP is in its source list.
[1] https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-irb-mcast#section-2.6
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Implement MDB control path support, enabling the creation, deletion,
replacement and dumping of MDB entries in a similar fashion to the
bridge driver. Unlike the bridge driver, each entry stores a list of
remote VTEPs to which matched packets need to be replicated to and not a
list of bridge ports.
The motivating use case is the installation of MDB entries by a user
space control plane in response to received EVPN routes. As such, only
allow permanent MDB entries to be installed and do not implement
snooping functionality, avoiding a lot of unnecessary complexity.
Since entries can only be modified by user space under RTNL, use RTNL as
the write lock. Use RCU to ensure that MDB entries and remotes are not
freed while being accessed from the data path during transmission.
In terms of uAPI, reuse the existing MDB netlink interface, but add a
few new attributes to request and response messages:
* IP address of the destination VXLAN tunnel endpoint where the
multicast receivers reside.
* UDP destination port number to use to connect to the remote VXLAN
tunnel endpoint.
* VXLAN VNI Network Identifier to use to connect to the remote VXLAN
tunnel endpoint. Required when Ingress Replication (IR) is used and
the remote VTEP is not a member of originating broadcast domain
(VLAN/VNI) [1].
* Source VNI Network Identifier the MDB entry belongs to. Used only when
the VXLAN device is in external mode.
* Interface index of the outgoing interface to reach the remote VXLAN
tunnel endpoint. This is required when the underlay destination IP is
multicast (P2MP), as the multicast routing tables are not consulted.
All the new attributes are added under the 'MDBA_SET_ENTRY_ATTRS' nest
which is strictly validated by the bridge driver, thereby automatically
rejecting the new attributes.
[1] https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-irb-mcast#section-3.2.2
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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