Users Guide

• Link aggregation control protocol (refer to Link Aggregation Control Protocol (LACP)).
• Spanning tree protocol. (Refer to Configuring Spanning Trees as Hitless).
• Bi-directional Forwarding Detection (refer to Bidirectional Forwarding Detection (BFD))
Graceful Restart
Graceful restart (also known as non-stop forwarding) is a protocol-based mechanism that preserves the
forwarding table of the restarting router and its neighbors for a specified period to minimize the loss of
packets.
A graceful-restart router does not immediately assume that a neighbor is permanently down and so does not
trigger a topology change.
Dell Networking OS supports graceful restart for the following protocols:
• Border gateway protocol
• Open shortest path first
• Protocol independent multicast — sparse mode
• Intermediate system to intermediate system
Software Resiliency
During normal operations, Dell Networking OS monitors the health of both hardware and software
components in the background to identify potential failures, even before these failures manifest.
System Health Monitoring
Dell Networking OS also monitors the overall health of the system.
Key parameters such as CPU utilization, free memory, and error counters (for example, CRC failures and
packet loss) are measured, and after exceeding a threshold can be used to initiate recovery mechanism.
Failure and Event Logging
Dell Networking systems provide multiple options for logging failures and events.
Trace Log
Developers interlace messages with software code to track the execution of a program.
These messages are called trace messages and are primarily used for debugging and to provide lower-level
information then event messages, which system administrators primarily use. Dell Networking OS retains
executed trace messages for hardware and software and stores them in files (logs) on the internal flash.
High Availability (HA) 442