Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.14.1.0 - Page 636

Fast Convergence (OSPFv2, IPv4 Only) Fast convergence allows you to define the speeds at which LSAs are originated and accepted, and reduce OSPFv2 end-to-end convergence time. Dell EMC Networking OS allows you to accept and originate LSAs as soon as they are available to speed up route information propagation. NOTE: The faster the convergence, the more frequent the route calculations and updates. This impacts CPU utilization and may impact adjacency stability in larger topologies. Multi-Process OSPFv2 with VRF Multi-process OSPF with VRF is supported on the Dell EMC Networking OS. Only one OSPFv2 process per VRF is supported. Multi-process OSPF allows multiple OSPFv2 processes on a single router. Multiple OSPFv2 processes allow for isolating routing domains, supporting multiple route policies and priorities in different domains, and creating smaller domains for easier management. Each OSPFv2 process has a unique process ID and must have an associated router ID. There must be an equal number of interfaces and must be in Layer-3 mode for the number of processes created. For example, if you create five OSPFv2 processes on a system, there must be at least five interfaces assigned in Layer 3 mode. Each OSPFv2 process is independent. If one process loses adjacency, the other processes continue to function. Processing SNMP and Sending SNMP Traps Only the process in default vrf can process the SNMP requests and send SNMP traps. NOTE: SNMP gets request corresponding to the OspfNbrOption field in the OspfNbrTable returns a value of 66. RFC-2328 Compliant OSPF Flooding In OSPF, flooding is the most resource-consuming task. The flooding algorithm described in RFC 2328 requires that OSPF flood LSAs on all interfaces, as governed by LSA's flooding scope (refer to Section 13 of the RFC.) When multiple direct links connect two routers, the RFC 2328 flooding algorithm generates significant redundant information across all links. By default, Dell EMC Networking OS implements an enhanced flooding procedure which dynamically and intelligently detects when to optimize flooding. Wherever possible, the OSPF task attempts to reduce flooding overhead by selectively flooding on a subset of the interfaces between two routers. Enabling RFC-2328 Compliant OSPF Flooding To enable OSPF flooding, use the following command. When you enable this command, it configures Dell EMC Networking OS to flood LSAs on all interfaces. • Enable RFC 2328 flooding. ROUTER OSPF mode flood-2328 Example of Viewing the Debug Log for Flooding Behavior To confirm RFC 2328 flooding behavior, use the debug ip ospf packet command. The following example shows no change in the updated packets (shown in bold). 636 Open Shortest Path First (OSPFv2 and OSPFv3)