Setting the Global TTL Value
Context
When devices running different versions interwork with each other, the TTL values and detection modes on both ends of the BFD session are different and BFD packets are discarded. You can set the global TTL value to enable the Huawei device to interwork with each other in different versions, with upgraded devices, and with non-Huawei devices.
Procedure
- Run system-view
The system view is displayed.
- Run bfd
BFD is enabled globally on the local node and the BFD view is displayed.
- Run peer-ip peer-ip mask-length ttl { single-hop | multi-hop } ttl-value
The TTL value of BFD control packets is set.
The TTL value of BFD packets varies with the BFD session type. By default, for a static BFD session, the TTL value of a single-hop BFD packet is 255 and the TTL value of a multi-hop BFD packet is 254. For a dynamic BFD session, the TTL value of a single-hop BFD packet is 255 and the TTL value of a multi-hop BFD packet is 253.
After the TTL value in multi-hop BFD packets is configured, you must configure the same peer IP address, mask length longer than the mask length for the TTL value in multi-hop BFD packets, and TTL value in single-hop BFD packets. This is because the TTL value in multi-hop BFD packets affects dynamic single-hop BFD sessions.
If the MPU has the LE0MFSUA card installed, you must change the global TTL value on both ends of a BFD session in Up state. Otherwise, the BFD session cannot go Up again.
