Dell Configuration Guide for the S4048–ON System 9.14.2.5

ICMP error or unreachable messages are now sent with the configured IP address of the source interface instead of the front-end port IP address as the source IP address. Enable the generation of ICMP unreachable messages through the ip unreachable command in Interface mode. When a ping or traceroute packet from an endpoint or a device arrives at the null 0 interface configured with a static route, it is discarded. In such cases, you can configure Internet Control Message Protocol (ICMP) unreachable messages to be sent to the transmitting device.

Configuring the ICMP Source Interface

You can enable the ICMP error and unreachable messages to contain the configured IP address of the source device instead of the previous hop's IP address. This configuration helps identify the devices along the path because the DNS server maps the loopback IP address to the host name, and does not translate the IP address of every interface of the switch to the host name.

Configure the source to send the configured source interface IP address instead of using its front-end IP address in the ICMP unreachable messages and in the traceroute command output. Use the ip icmp source-interface interface or the ipv6 icmp source-interface interface commands in Configuration mode to enable the ICMP error messages to be sent with the source interface IP address. This functionality is supported on loopback, VLAN, port channel, and physical interfaces for IPv4 and IPv6 messages. feature is not supported on tunnel interfaces. ICMP error relay, PATH MTU transmission, and fragmented packets are not supported for tunnel interfaces. The traceroute utilities for IPv4 and IPv6 list the IP addresses of the devices in the hops of the path for which ICMP source interface is configured.