Related Documentation
- M, PTX, T Series
- Configuring Miscellaneous LDP Properties
- M, MX, PTX, T Series
- Configuring RSVP to Pop the Label on the Ultimate-Hop Router
Advertising Explicit Null Labels to BGP Peers
For the IPv4 (inet) family only, BGP peers in a routing group can send an explicit NULL label for a set of connected routes (direct and loopback routes) for the inet labeled-unicast and inet6 labeled-unicast NLRI. By default, peers advertise label 3 (implicit NULL). If the explicit-null statement is enabled, peers advertise label 0 (explicit NULL). The explicit NULL labels ensures that labels are always present on packets traversing an MPLS network. If the implicit NULL label is used. the penultimate hop router removes the label and sends the packet as a plain IP packet to the egress router. This might cause issues in queuing the packet properly on the penultimate hop router if the penultimate hop is another vendor’s router. Some other vendors queue packets based on the CoS bits in the outgoing label rather than the incoming label.
To advertise an explicit null label, include the following statements in the configuration:
For a list of hierarchy levels at which you can include this statement, see the statement summary section for this statement.
The connected-only statement is required to advertise explicit null labels.
To verify that the explicit NULL label is being advertised for connected routes, use the show route advertising-protocol bgp neighbor-address command.
Related Documentation
- M, PTX, T Series
- Configuring Miscellaneous LDP Properties
- M, MX, PTX, T Series
- Configuring RSVP to Pop the Label on the Ultimate-Hop Router
Published: 2012-11-29
Related Documentation
- M, PTX, T Series
- Configuring Miscellaneous LDP Properties
- M, MX, PTX, T Series
- Configuring RSVP to Pop the Label on the Ultimate-Hop Router
