Concept Guide

Usage Information You can enable the mechanism to congure the source or the originating interface from which the packet (the
device that generates the ICMP error messages) is received by the switch to send the loopback address instead of
its source IP address to be used in the ICMP unreachable messages and in the traceroute command output.
The loopback address must be unique in a particular domain.
In network environments that contain a large number of devices, ranging up to thousands of systems, and with
each device congured for equal-cost multipath (ECMP) links, you cannot eectively and optimally use the
traceroute and ping applications to examine the network reachability and identify any broken links for diagnostic
purposes. In such cases, if the reply that is obtained from each hop on the network path contains the IP address of
the adjacent, neighboring interface from which the packet is received, it is dicult to employ the ping and
traceroute utilities. You can enable the ICMP unreachable messages to contain the loopback address of the source
device instead of the previous hop's IP address to be able to easily and quickly identify the device and devices
along the path because the DNS server maps the loopback IP address to the hostname and does not translate the
IP address of every interface of the switch to the hostname.
Example
Dell(conf)#ipv6 icmp source-interface tengigabitethernet 0/1
Dell(conf)#
ip max-frag-count
Set the maximum number of fragments allowed in one packet for packet re-assembly.
Syntax
ip max-frag-count count
To place no limit on the number of fragments allowed, use the no ip max-frag-count command.
Parameters
count Enter a number for the number of fragments allowed for re-assembly. The range is from 2
to 256.
Defaults No limit is set on number of fragments allowed.
Command Modes CONFIGURATION
Supported Modes Full–Switch
Command History
Version Description
9.9(0.0) Introduced on the FN IOM.
8.3.16.1 Introduced on the MXL 10/40GbE Switch IO Module.
Usage Information To avoid denial of service (DOS) attacks, keep the number of fragments allowed for re-assembly low.
ip name-server
Enter up to six IPv4 addresses of name servers. The order you enter the addresses determines the order of their use.
Syntax
ip name-server ipv4-address [ipv4-address2...ipv4-address6]
To remove a name server, use the no ip name-server ip-address command.
Parameters
ipv4-address Enter the IPv4 address, in dotted decimal format, of the name server to be used.
IPv4 Routing 621