| Description | This article describes how to use Link-Local Signaling (LLS), an extension used in OSPF Hello and Database Description (DBD) packets, to exchange additional information between directly connected routers. |
| Scope | FortiGate. |
| Solution |
When the OSPF process is reset, it drops all neighbor adjacencies, requiring other OSPF routers to rerun the SPF algorithm and determine new network paths. With an OSPF graceful restart, the OSPF process can restart without dropping neighbor adjacencies, allowing traffic forwarding to continue uninterrupted. Similarly, LLS improves OSPF stability by reducing disruptions during restarts and aiding in faster synchronization of neighbor states.
It ensures that critical information is retained and exchanged efficiently to maintain network stability.
CLI Syntax:
config router ospf
GUI:
By enabling LLS, OSPF can leverage improved signaling mechanisms to maintain adjacency states and minimize disruptions. This configuration helps reduce OSPF disruptions and improves network convergence by ensuring faster neighbor-state synchronization.
LLS Type Values: LLS type values in the range of 0-32767 are allocated through an IETF Review, while values in the range of 32768-65535 are reserved for private use.
The following LLS TLV types are assigned in OSPFv2/OSPFv3:
Cryptographic Authentication TLV is only defined for OSPFv2. LLS Type 1 Extended Options to LLS Type 1 Extended Options and Flags.
The following bits are assigned in the EOF-TLV:
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