Brocade Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide (Supporting R05.6.00) User Manual
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Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide
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Configuring BGP VPNs on a PE
6
Configuring IP TTL to MPLS TTL propagation in an IPVPN
The vrf-propagate-ttl and label-propagate-ttl commands configure the device to propagate TTL
values in an IPVPN between the IP TTL value and the MPLS TTL value, as described in
and
TABLE 107
MPLS TTL propagation behavior with IPVPNs on Brocade NetIron XMR and Brocade MLX
series.
With vrf-propagate-ttl and label-propagate-ttl configured
Without vrf-propagate-ttl and label-propagate-ttl configured
(default)
•
At the ingress device, the IP TTL value -1 is
copied to both the tunnel label and the VC label.
•
At the transit device, the tunnel label is
decremented by 1.
•
At the PHP device, the tunnel label TTL is set to
the VC label and the tunnel label is popped.
•
At the egress device, the IP TTL value is set to
min (VC label TTL, IP TTL) and the VC label is
popped. The IP TTL value is then decremented
by 1 when it is being forwarded out of the device.
•
At the ingress device, both the tunnel TTL value and
the VC label TTL value are set to 255.
•
At the transit device, the tunnel label is decremented
by 1.
•
At the PHP device, the tunnel label TTL is popped
without changing the VC label’s TTL.
•
At the egress device, the VC label is popped without
copying the TTL value to the IP packet. The IP TTL
value is then decremented by 1 when it is being
forwarded out of the device.
To configure a Brocade MLX Series or NetIron XMR Series device to propagate the IP TTL values to
and from the MPLS TTL values in an IPVPN, enter the vrf-propagate-ttl and label-propagate-ttl
commands, as shown in the following example.
Brocade(config)# router mpls
Brocade(config-mpls)# policy
Brocade(config-mpls-policy)# vrf-propagate-ttl
Brocade(config-mpls-policy)# label-propagate-ttl
Syntax: [no] vrf-propagate-ttl
Using the [no] option returns the condition to the default off state when the vrf-propagate-ttl
command has been previously configured.
Syntax: [no] label-propagate-ttl
Using the [no] option returns the condition to the default off state when the label-propagate-ttl
command has been previously configured.