Technical data

8 Brocade MLX Series and NetIron Family Documentation Updates

53-1002805-03

IPv6 Traceroute over an MPLS network

Traceroute reports only the IP address of the destination device CE2. No label extension is

added because the received packet is not labeled. The port unreachable message is

label-switched back to the customer source device CE1, as a normal data packet.

5 <1 ms <1 ms <1 ms 2001:DB8:2::2

Configuring IPv6 Traceroute over MPLS

The ipv6 icmp mpls-response command configures the behavior of the traceroute operation by

controlling both the ICMPv6 message format (use ICMPv6 label stack extensions or not) and the

manner in which the ICMPv6 messages are forwarded through an MPLS domain (by way of IP

routing table lookup or through label-switching using LSPs).

MPLS response is enabled by default. To enable the MPLS response after it was disabled, enter the

following command:

Brocade(config)# ipv6 icmp mpls-response

You can use this version of the command if the traceroute is over an IPv6-aware MPLS core. In such

a case, IPv6 traceroute uses the default option of using the routing tables to forward packets. The

IPv6 link local addresses should not be used to send the ICMPv6 packet. At the same time, you can

still use the ipv6 icmp mpls-response use-lsp command to use the configured LSPs.

To specify using LSP to forward the ICMPv6 messages with MPLS label extensions, enter the

following command:

Brocade(config)# ipv6 icmp mpls-response use-lsp

Use this version of the command if the MPLS core is non IPv6-aware, because the IPv6 forwarding

will not work.

To specify generating ICMPv6 messages without MPLS label extensions, enter the following

command:

Brocade(config)# ipv6 icmp mpls-response no-label-extensions

To disable the IPv6 Traceroute over MPLS feature, enter the following command:

Brocade(config)# no ipv6 icmp mpls-response

Syntax: [no] ipv6 icmp mpls-response [use-lsp] [no-label-extension]

The mpls-response parameter enables the ICMPv6 traceroute response in default mode. The

feature is enabled by default and configured to use IP routing to forward ICMP messages.

The use-lsp parameter enables forwarding of ICMPv6 error messages along the LSPs configured for

the MPLS domain. By default, using configured LSPs use is disabled.

The no-label-extension parameter disables the use of label stack information in the ICMPv6 error

messages.

The no option disables the ICMPv6 traceroute response configuration. When the ICMP traceroute

feature is disabled, standard traceroute using IPv6 forwarding is used to trace a traffic path

through an MPLS domain.

NOTE

The ipv6 icmp mpls-response command supports TTL expiry for IPv6 packets only.

The output of the show ipv6 traffic command displays counts for ICMPv6 ttl-exceeded error reply

packets.