Ldp Adjacency Capabilities - Alcatel-Lucent 7450 Manual

LDP Adjacency Capabilities

Adjacency-level FEC-type capability advertisement is defined in draft-pdutta-mpls-ldp-adj-
capability. By default, all FEC types supported by the LSR are advertised in the LDP IPv4 or IPv6
session initialization; see
enabled at the session level, it can be disabled over a given LDP interface at the IPv4 or IPv6
adjacency level for all IPv4 or IPv6 peers over that interface. If a given FEC type is disabled at the
session level, then FECs will not be advertised and enabling that FEC type at the adjacency level
will not have any effect. The LDP adjacency capability can be configured on link Hello adjacency
only and does not apply to targeted Hello adjacency.
The LDP adjacency capability TLV is advertised in the Hello message with the D-bit (Disable-bit)
set or reset to disable or enable the resolution of this FEC type over the link of the Hello
adjacency. It is used to restrict which FECs can be resolved over a given interface to a peer. This
provides the ability to dedicate links and data path resources to specific FEC types. For IPv4 and
IPv6 prefix FECs, a subset of ECMP links to a LSR peer may be each be configured to carry one
of the two FEC types. An mLDP P2MP FEC can exclude specific links to a downstream LSR
from being used to resolve this type of FEC.
Like the LDP session-level FEC-type capability, the adjacency FEC-type capability is negotiated
for both directions of the adjacency. If one or both peers advertise the disabling of a capability in
the LDP Hello message, no FECs of the corresponding FEC type will be resolved by either peer
over the link of this adjacency for the lifetime of the LDP Hello adjacency, unless one or both
peers sends the LDP adjacency capability TLV subsequently to explicitly enable it.
The user can enable or disable a specific FEC type for a given LDP interface to a peer by using the
following CLI commands:
•
•
•
•
These commands, when applied for the P2MP FEC, deprecate the existing command
multicast-traffic {enable | disable} under the interface. Unlike the session-level capability, these
commands can disable multicast FEC for IPv4 and IPv6 separately.
The encoding of the adjacency capability TLV uses a PRIVATE Vendor TLV. It is used only in a
hello message to negotiate a set of capabilities for a specific LDP IPv4 or IPv6 hello adjacency.
7450 ESS MPLS Guide
LDP Session Capabilities
configure>router>ldp>interface-parameters>interface>ipv4/ipv6>fec-type-
capability p2mp-ipv4
configure>router>ldp>interface-parameters>interface>ipv4/ipv6>fec-type-
capability p2mp-ipv6
configure>router>ldp>interface-parameters>interface>ipv4/ipv6>fec-type-
capability prefix-ipv4
configure>router>ldp>interface-parameters>interface> ipv4/ipv6>fec-type-
capability prefix-ipv6
Label Distribution Protocol
for more information. If a given FEC type is
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