VLAN manipulation action in tc(8) | Linux | VLAN manipulation action in tc(8) |
vlan - vlan manipulation module
tc ... action vlan { pop | pop_eth | PUSH | MODIFY | PUSH_ETH } [ CONTROL ]
PUSH := push [ protocol VLANPROTO ] [ priority VLANPRIO ] id VLANID
MODIFY := modify [ protocol VLANPROTO ] [ priority VLANPRIO ] id VLANID
PUSH_ETH := push_eth dst_mac LLADDR src_mac LLADDR
CONTROL := { reclassify | pipe | drop | continue | pass | goto chain CHAIN_INDEX }
The vlan action allows one to perform 802.1Q en- or decapsulation on a packet, reflected by the operation modes POP, PUSH and MODIFY. The POP mode is simple, as no further information is required to just drop the outer-most VLAN encapsulation. The PUSH and MODIFY modes require at least a VLANID and allow one to optionally choose the VLANPROTO to use.
The vlan action can also be used to add or remove the base Ethernet header. The pop_eth mode, which takes no argument, is used to remove the base Ethernet header. All existing VLANs must have been previously dropped. The opposite operation, adding a base Ethernet header, is done with the push_eth mode. In that case, the packet must have no MAC header (stacking MAC headers is not permitted). This mode is mostly useful when a previous action has encapsulated the whole original frame behind a network header and one needs to prepend an Ethernet header before forwarding the resulting packet.
The following example encapsulates incoming ICMP packets on eth0 from 10.0.0.2 into VLAN ID 123:
#tc qdisc add dev eth0 handle ffff: ingress #tc filter add dev eth0 parent ffff: pref 11 protocol ip \ u32 match ip protocol 1 0xff flowid 1:1 \ match ip src 10.0.0.2 flowid 1:1 \ action vlan push id 123
Here is an example of the pop function: Incoming VLAN packets on eth0 are decapsulated and the classification process then restarted for the plain packet:
#tc qdisc add dev eth0 handle ffff: ingress #tc filter add dev $ETH parent ffff: pref 1 protocol 802.1Q \ u32 match u32 0 0 flowid 1:1 \ action vlan pop reclassify
For an example of the pop_eth and push_eth modes, see tc-mpls(8).
12 Jan 2015 | iproute2 |