mpls — mpls manipulation module
Synopsis
tc ... action mpls { POP | PUSH | MODIFY | dec_ttl } [ CONTROL ]
POP := pop protocol MPLS_PROTO
PUSH := push [ protocol MPLS_PROTO ] [ tc MPLS_TC ] [ ttl MPLS_TTL ] [ bos MPLS_BOS ] label MPLS_LABEL
MODIFY := modify [ label MPLS_LABEL ] [ tc MPLS_TC ] [ ttl MPLS_TTL ]
CONTROL := { reclassify | pipe | drop | continue | pass | goto chain CHAIN_INDEX }
Description
The mpls action performs mpls encapsulation or decapsulation on a packet, reflected by the operation modes POP, PUSH, MODIFY and DEC_TTL. The POP mode requires the ethertype of the header that follows the MPLS header (e.g. IPv4 or another MPLS). It will remove the outer MPLS header and replace the ethertype in the MAC header with that passed. The PUSH and MODIFY modes update the current MPLS header information or add a new header. PUSH requires at least an MPLS_LABEL. DEC_TTL requires no arguments and simply subtracts 1 from the MPLS header TTL field.
Options
- pop
Decapsulation mode. Requires the protocol of the next header.
- push
Encapsulation mode. Requires at least the label option.
- modify
Replace mode. Existing MPLS tag is replaced. label, tc, and ttl are all optional.
- dec_ttl
Decrement the TTL field on the outer most MPLS header.
- label MPLS_LABEL
Specify the MPLS LABEL for the outer MPLS header. MPLS_LABEL is an unsigned 20bit integer, the format is detected automatically (e.g. prefix with '0x' for hexadecimal interpretation, etc.).
- protocol MPLS_PROTO
Choose the protocol to use. For push actions this must be mpls_uc or mpls_mc (mpls_uc is the default). For pop actions it should be the protocol of the next header. This option cannot be used with modify.
- tc MPLS_TC
Choose the TC value for the outer MPLS header. Decimal number in range of 0-7. Defaults to 0.
- ttl MPLS_TTL
Choose the TTL value for the outer MPLS header. Number in range of 0-255. A non-zero default value will be selected if this is not explicitly set.
- bos MPLS_BOS
Manually configure the bottom of stack bit for an MPLS header push. The default is for TC to automatically set (or unset) the bit based on the next header of the packet.
- CONTROL
-
How to continue after executing this action.
- reclassify
Restarts classification by jumping back to the first filter attached to this action's parent.
- pipe
Continue with the next action, this is the default.
- drop
Packet will be dropped without running further actions.
- continue
Continue classification with next filter in line.
- pass
Return to calling qdisc for packet processing. This ends the classification process.
Examples
The following example encapsulates incoming IP packets on eth0 into MPLS with a label 123 and sends them out eth1:
#tc qdisc add dev eth0 handle ffff: ingress #tc filter add dev eth0 protocol ip parent ffff: flower \ action mpls push protocol mpls_uc label 123 \ action mirred egress redirect dev eth1
In this example, incoming MPLS unicast packets on eth0 are decapsulated and to ip packets and output to eth1:
#tc qdisc add dev eth0 handle ffff: ingress #tc filter add dev eth0 protocol mpls_uc parent ffff: flower \ action mpls pop protocol ipv4 \ action mirred egress redirect dev eth0