Alcatel-Lucent 7450 Configuration Manual page 117

If the egress LER does not have a route to the destination of the ICMP packet, it drops the packets.
The rate of the tunneled ICMP replies at the LSR can be directly or indirectly controlled by the
existing IOM level and CPM levels mechanisms. Specifically, the rate of the incoming UDP
traceroute packets received with a label stack can be controlled at ingress IOM using the distributed
CPU protection feature. The rate of the ICMP replies by CPM can also be directly controlled by
configuring a system wide rate limit for packets ICMP replies to MPLS expired packets which are
successfully forwarded to CPM using the command 'configure system security vprn-network-
exceptions'. Note that while this command's name refers to VPRN service, this feature rate limits
ICMP replies for packets received with any label stack, including VPRN and shortcuts.
The 7x50 implementation supports appending to the ICMP reply of type Time Exceeded the MPLS
label stack object defined in RFC 4950. It does not include it in the ICMP reply type of Destination
unreachable.
The new MPLS Label Stack object permits an LSR to include label stack information including label
value, EXP, and TTL field values, from the encapsulation header of the packet that expired at the LSR
node. The ICMP message continues to include the IP header and leading payload octets of the
original datagram.
In order to include the MPLS Label Stack object, the SROS implementation adds support of RFC
4884 which defines extensions for a multi-part ICMPv4/v6 message of type Time Exceeded.
The no form of command disables the tunneling of ICMP reply packets over MPLS LSP at a LSR
node.
Default no icmp-tunneling
ignore-icmp-redirect
Syntax [no] ignore-icmp-redirect
Context config>router
Description
This command drops ICMP redirects received on the management interface.
The no form of the command accepts ICMP redirects received on the management interface.
ip-fast-reroute
Syntax [no] ip-fast-reroute
Context config>router
Description This command enables IP Fast-Reroute (FRR) feature on the system.
This feature provides for the use of a Loop-Free Alternate (LFA) backup next-hop for forwarding in-
transit and CPM generated IP packets when the primary next-hop is not available. IP FRR is
supported on IPv4 and IPv6 OSPF/IS-IS prefixes forwarded in the base router instance to a network
IP interface or to an IES SAP interface or spoke interface. It is also supported for VPRN VPN-IPv4
OSPF prefixes and VPN-IPv6 OSPF prefixes forwarded to a VPRN SAP interface or spoke interface.
IP FRR also provides a LFA backup next-hop for the destination prefix of a GRE tunnel used in an
SDP or in VPRN auto-bind.
7450 ESS Router Configuration Guide
IP Router Configuration
Page 117