Loopback (Ping) Message - Cisco Nexus 9000 Series Configuration Manual

Loopback (Ping) Message

Table 5: VXLAN OAM Tools
Category
Fault Verification
Fault Isolation
Performance
Auxiliary

Loopback (Ping) Message

The loopback message (The ping and the loopback messages are the same and they are used interchangeably
in this guide) is used for the fault verification. The loopback message utility is used to detect various errors
and the path failures. Consider the topology in the following example where there are three core (spine)
switches labeled Spine 1, Spine 2, and Spine 3 and five leaf switches connected in a Clos topology. The path
of an example loopback message initiated from Leaf 1 for Leaf 5 is displayed when it traverses via Spine 3.
When the loopback message initiated by Leaf 1 reaches Spine 3, it forwards it as VXLAN encapsulated data
packet based on the outer header. The packet is not sent to the software on Spine 3. On Leaf 3, based on the
appropriate loopback message signature, the packet is sent to the software VXLAN OAM module, that in
turn, generates a loopback response that is sent back to the originator Leaf 1.
The loopback (ping) message can be destined to VM or to the (VTEP on) leaf switch. This ping message can
use different OAM channels. If the ICMP channel is used, the loopback message can reach all the way to the
VM if the VM's IP address is specified. If NVO3 draft Tissa channel is used, this loopback message is
terminated on the leaf switch that is attached to the VM, as the VMs do not support the NVO3 draft Tissa
headers in general. In that case, the leaf switch replies back to this message indicating the reachability of the
VM. The ping message supports the following reachability options:
Ping
Check the network reachability (Ping command):
• From Leaf 1 (VTEP 1) to Leaf 2 (VTEP 2) (ICMP or NVO3 draft Tissa channel)
Cisco Nexus 9000 Series NX-OS VXLAN Configuration Guide, Release 7.x
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Tools
Loopback Message
Path Trace Message
Delay Measurement, Loss Measurement
Address Binding Verification, IP End Station Locator,
Error Notification, OAM Command Messages, and
Diagnostic Payload Discovery for ECMP Coverage
Configuring VXLAN OAM