Service Manual

NOTE: When you configure the capability to enable
the loopback IP address to be sent for easy
debugging and diagnosis (IP addresses of the
devices for which the ICMP source interface is
configured), the source IP address of the outgoing
ICMP error message is modified, although the
packets are not sent out using the configured
interface. Because the management interface is
configurable only without any parameters such as
the IP address, it is treated to the management
interface of the primary unit or the existing unit.
• For a 10-Gigabit Ethernet interface, enter the keyword
TenGigabitEthernet then the slot/port[/subport]
information.
• For a 40-Gigabit Ethernet interface, enter the keyword
fortyGigE then the slot/port information.
• For a Loopback interface, enter the keyword loopback
then a number from 0 to 16383.
• For a port channel interface, enter the keywords port-
channel
then a number.
• For a VLAN interface, enter the keyword vlan then a
number from 1 to 4094.
Defaults Not configured.
Command Modes CONFIGURATION
Command History
Version Description
9.8(0.0) Introduced on the S3048-ON and S4048-ON.
9.7(0.0) Introduced on the S6000-ON.
9.3(0.0) Introduced on the S4810, S4820T, S6000, and Z9000
platforms.
Usage Information
You can enable the mechanism to configure 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 configured for equal-cost multipath
(ECMP) links, you cannot effectively and optimally use the traceroute and ping
applications to examine the network reachablity 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 difficult to employ the ping and traceroute
utilites. 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
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IPv4 Routing