control-word

Usage Guidelines

The no form of the command disables control word for a PW profile.

For a PW that is sensitive to packet misordering to operate correctly, all packets in the PW must follow the same path over a Multi-Protocol Label Switched (MPLS) packet switched network (PSN).

PW control word is a mechanism that prevents packet misordering. Without the control word mechanism, a label switching router (LSR) performing, for example, equal-cost multiple-path load-balancing (ECMP) could mistake a PW payload for an IPv4 or IPv6 packet and route it over a different path, resulting in misordered packet delivery to the egress provider edge (PE) device.

When control word is enabled, LSRs use it to distinguish a specific PW payload from an IP payload and ensure that all packets for the PW follow the same path over the MPLS PSN.

Note

When control word is enabled for a previously configured PW, control word capabilities between PE devices are activated only after LDP neighbors are cleared by using the clear mpls ldp neighbor command. For further information on clearing LDP neighbors, refer to Extreme SLX-OS MPLS Configuration Guide.