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mvrpd

This daemon implements MVRP (supersedes GRVP) for linux bridges. It aims at automatically configuring vlans on links, especially inter-bridge/inter-switch.

overview

naive approach:

• Given a tree of network devices like an ethernet spanning tree.
• The information of any device that is interested in a VLAN is then propagated along all edges.
• Any switch that has two or more ports that are interested in the same VLAN adds the VLAN to these ports.

mvrp approach:

• The switch records which ports are interested in a VLAN, either because they declared interest for a VLAN using MVRP or because it is configured manually.
• The switch declares interest in a VLAN on each dynamic (MVRP-enabled) port, that indicates whether there are other ports on itself that also want this VLAN by registering for that VLAN.
• If the bridge has two or more ports that are interested in a VLAN, it will activate (aka configure or register) the VLAN on all interested ports.

mvrpd

This daemon scans a set of bridge ports (defaults to all non-dynamic and the bridge itself) for VLANs it is statically configured to be interested it. Additionally, it listens on all dynamic (MVRP-enabled) ports for other devices or bridges interested in a VLAN.

If a bridge is interested in a VLAN, it registers for that VLAN on all dynamic ports. If a port is the only one interested in a VLAN, it is not registering for that VLAN (no loopback).

If a bridge has two or more ports that are interested in a VLAN, it will configure that VLAN on all interested ports.

Optionally, some VLANs may be skipped.

This daemon operates on vlan_filtering enabled linux bridges.

cmdline

• --bridge (exactly once)
• --uplinkif : matches interfaces that are configured using MVRP (maybe repeated, takes precedence over --epif)
• --epif : matches interfaces that are statically configured (maybe repeated, ususally includes the bridge itself)
• --ptpif : matches interfaces. If those are configured by MVRP, it is assumed that at most one MVRP-enabled applicant (peer) is connected to this bridge port (e.g. another MVRP enabled bridge)
• --ignore-vlan : ignore this vlan id
• --restrict-to-ep: only declare (announce) and thus register (configure) VLANs that are already added to the (statically configured) ports

Where pattern is matched using fnmatch, e.g. eth* would match eth0, eth1, etc.

extra cmdline

• --bridge-dump-netlink: dump netlink messages send/received in bridge module
• --debug
• --debug-all
• --debug-bridge
• --debug-ether
• --debug-mvrp
• --debug-nflog
• --debug-port
• --nflog-group: nflog group for MVRP snooping
• --verbose

test-setup

ip link add dev mvrp-bridge type bridge
ip link set dev mvrp-bridge type bridge vlan_filtering 1
ip link set dev mvrp-bridge type bridge vlan_default_pvid 0
ip link set dev mvrp-bridge up
bridge vlan add vid 300 dev mvrp-bridge self

for i in $(seq 0 10); do
  ip link add dev mvrp-p$i type veth peer name mvrp-c$i
  ip link set dev mvrp-p$i up
  ip link set dev mvrp-c$i up
  ip link add link mvrp-c$i name mvrp-c$i.100 type vlan id 100
  ip link set dev mvrp-c$i.100 type vlan mvrp on
  ip link set dev mvrp-c$i.100 up
  ip link set dev mvrp-p$i master mvrp-bridge
done

nft add table bridge nat
nft add chain bridge nat PREROUTING { type filter hook prerouting priority dstnat\; policy accept\; }
nft add rule bridge nat PREROUTING meta ibrname "mvrp-bridge" ether daddr 01:80:c2:00:00:21 log group 3 drop

for i in $(seq 0 10); do
 ip link set dev mvrp-p$i down
 ip link del dev mvrp-p$i
done
ip link set dev mvrp-bridge down
ip link del dev mvrp-bridge