Debugging IPv6 on IS-ISng
The debug command is very useful to see what is happening on the network at the packet level. The following CLI commands specify both IPv6 and IS-IS, so only IS-ISng packets will be reported. The output from these commands will show you the IS-ISng traffic on your FortiGate unit including RECV, SEND, and UPDATE actions.
FGT # diagnose ipv6 router isis level info
FGT # diagnose ipv6 router isis all enable
FGT # diagnose debug enable
These three commands will:
• turn on debugging in general
• set the debug level to information, a verbose reporting level
• turn on all IS-IS router settings
Part of the information displayed from the debugging is the metric (hop count). If the metric is 16, then that destination is unreachable since the maximum hop count is 15.
In general, you should see an update announcement, followed by the routing table being sent out, and a received reply in response.