Configuring OSPFv3 GTSM
Context
GTSM only checks the TTL values of packets that match a GTSM policy. You can configure a switch to allow mismatched packets to pass through the filter or be discarded. If you configure the switch to discard mismatched packets, enable GTSM on the switches with which the switch may communicate. Otherwise, connections cannot be established, because the switch discards all packets from non-GTSM switches.
In addition, you can configure the switch to log discarded packets. This facilitates future fault locating.
Procedure
- Run system-view
The system view is displayed.
- Run ospfv3 valid-ttl-hops valid-ttl-hops-value [ vpn-instance vpn-instance-name ]
OSPFv3 GTSM is configured.
GTSM must be enabled at both ends of an OSPFv3 connection.
The ospfv3 valid-ttl-hops command both enables OSPFv3 GTSM and sets a TTL value. If you specify the vpn-instance parameter, the switch sets only the TTL values of packets in this VPN but does not enable OSPFv3. Therefore, if you want to apply the configured TTL value only to packets in a VPN instance or a public network instance, set the default action to pass for packets that does not match the GTSM policy. This prevents OSPFv3 packets in other instances from being discarded.
The range of valid TTL value is from (255 – valid-ttl-hops-value + 1) to 255. - (Optional) Run gtsm default-action { drop | pass }
An action is configured for the switch to perform on the packets that do not match the GTSM policy.
By default, pass is executed on these packets.
If an action is configured but a GTSM policy is not, GTSM does not take effect.
- (Optional) Run gtsm log drop-packet all
The switch is configured to log the packets discarded on the switch.