Filter
Top Products
DES-7200 Configuration Guide Chapter 1 MPLS Configuration
1-14
by MPLS packets with a single layer of labels are forwarded through the global routing table. The
ICMP error messages generated by MPLS packets with multiple layers of labels are forwarded
along the LSP of the original label stack.
Command Function
DES-7200(config)# mpls ip icmp-error
pop labels
Control ICMP error messages generated by
labeled MPLS packets.
DES-7200(config)# no mpls ip
icmp-error pop
Restore the default value.
1.2.1.8 Configuring the MPLS TTL Replication
Function (Optional)
There are two modes for handling the TTL of encapsulated and decapsulated IP (or MPLS)
packets on an MPLS network:
TTL replication mode: This is the default working mode. The procedure is as follows: When a
label is pushed, the label TTL copies the TTL of the existing IP or MPLS header to the
TTL field of the label. When a label is popped out, the TTL is copied back from the
external label to the inner IP packet or MPLS packet.
TTL non-replication mode: In this mode, the TTL is not copied. The procedure is as follows:
When a label is pushed, the TTL value of the label is directly set as 255. When a label
is popped out, the original TTL value of the inner IP packet or MPLS packet is exposed
and retained.
Run the mpls ip ttl propagate { public | VPN } command to configure the TTL replication
function for packets sent and forwarded by a device.
Command Function
DES-7200(config)# [no] mpls ip ttl
propagate public
Enable or disable the TTL replication function
for MPLS packets sent by the device.
DES-7200(config)# [no] mpls ip ttl
propagate VPN
Enable or disable the TTL replication function
for MPLS service packets forwarded by the
device.
After the TTL replication function is enabled on an MPLS network, you can use the Tracert tool
on a CE to track all the LSRs that the packets pass through in the MPLS domain. If the TTL
non-replication mode is configured on PEs, the entire LSP of the packets is considered as only
one hop.