IP Router Configuration
Router Configuration Guide 139
The none value reverts to the default mode which disables TTL propagation. This changes the existing
default behavior which propagates the TTL to the transport label stack. When a customer upgrades, the
new default becomes in effect. This command does not have a no version.
This feature also controls the TTL propagation at an LDP-BGP stitching LSR in the LDP to BGP
stitching direction. It also controls the TTL propagation in Carrier Supporting Carrier (CsC) VPRN at
both the CsC CE and CsC PE.
SR OS does not support ASBR or data path RR functionality for labeled IPv6 routes in the global
routing instance (6PE). As such the CLI command of this feature has no impact on prefix packets
forwarded in this context.
Default none
Parameters none — The TTL of the swapped label is not propagated into the transport label stack.
all — The TTL of the swapped label is propagated into all labels of the transport label stack.
vprn-local
Syntax vprn-local [all | vc-only | none]
Context config>router>ttl-propagate
Description This command configures the TTL propagation for locally generated packets which are forwarded
over a MPLS LSPs in all VPRN service contexts.
For vpn-ipv4 and vpn-ipv6 packets forwarded in the context of all VPRN services in the system,
including 6VPE packets, the all value of the command enables TTL propagation from the IP header
into all labels in the stack:
The user can enable the TTL propagation behavior separately for locally generated packets by CPM
(vprn-local) and for user and control packets in transit at the node (vprn-transit).
The vc-only value reverts to the default behavior by which the IP TTL is propagated into the VC label
but not to the transport labels in the stack. The user can explicitly set the default behavior by
configuring the vc-only value. This command does not have a no version.
The value none allows the user to disable the propagation of the IP TTL to all labels in the stack,
including the VC label. This is needed for a transparent operation of UDP traceroute in VPRN inter-
AS option B such that the ingress and egress ASBR nodes are not traced.
The user can override the global configuration within each VPRN instance using the following
commands:
• config service vprn ttl-propagate local [inherit | none | vc-only | all]
• config service vprn ttl-propagate transit [inherit | none | vc-only | all]
The default behavior for a given VPRN instance is to inherit the global configuration for the same
command. The user can explicitly set the default behavior by configuring the inherit value.
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