Command Reference Guide

3Com Router 3000 Ethernet Family
Command Reference Guide Chapter 1 MPLS Basic Configuration Commands
3Com Corporation
1-12
1.1.15 ttl expiration
Syntax
ttl expiration pop
undo ttl expiration pop
View
MPLS view
Parameter
None
Description
Use the ttl expiration command to configure the router to forward ICMP responses by
local IP routing when the MPLS TTL expires.
Use the undo ttl expiration command to disable the function.
For a one-tier MPLS packet with TTL expired, its ICMP response is forwarded by local
IP routing by default.
You are recommended to configure the undo ttl expiration command on the ASBRs or
the SPEs on an HoVPN network. This ensures that you can get the correct forwarding
path of the public-network routers when tracerting to another device on the VPN.
Use the undo mpls command to clear all the configurations related to the ttl
expiration command.
Related command: ttl propagate.
Example
# Send back an ICMP packet along the LSP if the TTL of an MPLS packet expires.
[3Com -mpls] undo ttl expiration pop
1.1.16 ttl propagate
Syntax
ttl propagate { public | vpn }
undo ttl propagate { public | vpn }
View
MPLS view
Parameter
public: Configures to apply TTL duplication to the packets on the public network.