linux/Documentation/networking/mpls-sysctl.txt
Robert Shearman a59166e470 mpls: allow TTL propagation from IP packets to be configured
Allow TTL propagation from IP packets to MPLS packets to be
configured. Add a new optional LWT attribute, MPLS_IPTUNNEL_TTL, which
allows the TTL to be set in the resulting MPLS packet, with the value
of 0 having the semantics of enabling propagation of the TTL from the
IP header (i.e. non-zero values disable propagation).

Also allow the configuration to be overridden globally by reusing the
same sysctl to control whether the TTL is propagated from IP packets
into the MPLS header. If the per-LWT attribute is set then it
overrides the global configuration. If the TTL isn't propagated then a
default TTL value is used which can be configured via a new sysctl,
"net.mpls.default_ttl". This is kept separate from the configuration
of whether IP TTL propagation is enabled as it can be used in the
future when non-IP payloads are supported (i.e. where there is no
payload TTL that can be propagated).

Signed-off-by: Robert Shearman <rshearma@brocade.com>
Acked-by: David Ahern <dsa@cumulusnetworks.com>
Tested-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-03-13 15:29:22 -07:00

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/proc/sys/net/mpls/* Variables:
platform_labels - INTEGER
Number of entries in the platform label table. It is not
possible to configure forwarding for label values equal to or
greater than the number of platform labels.
A dense utilization of the entries in the platform label table
is possible and expected as the platform labels are locally
allocated.
If the number of platform label table entries is set to 0 no
label will be recognized by the kernel and mpls forwarding
will be disabled.
Reducing this value will remove all label routing entries that
no longer fit in the table.
Possible values: 0 - 1048575
Default: 0
ip_ttl_propagate - BOOL
Control whether TTL is propagated from the IPv4/IPv6 header to
the MPLS header on imposing labels and propagated from the
MPLS header to the IPv4/IPv6 header on popping the last label.
If disabled, the MPLS transport network will appear as a
single hop to transit traffic.
0 - disabled / RFC 3443 [Short] Pipe Model
1 - enabled / RFC 3443 Uniform Model (default)
default_ttl - BOOL
Default TTL value to use for MPLS packets where it cannot be
propagated from an IP header, either because one isn't present
or ip_ttl_propagate has been disabled.
Possible values: 1 - 255
Default: 255
conf/<interface>/input - BOOL
Control whether packets can be input on this interface.
If disabled, packets will be discarded without further
processing.
0 - disabled (default)
not 0 - enabled