QoS queuing and configuration file transfers

Interface congestion and packet queuing

Quality of service (QoS) changes how traffic is handled, particularly when a link is busy. Classification identifies traffic. Marking writes a value, such as a DSCP marking, that other devices may use. Queuing decides how packets wait for transmission. A label alone does not create a policy or extra bandwidth.

Shaping usually buffers traffic to smooth its rate. Policing commonly drops or remarks traffic that exceeds a policy. Congestion occurs when offered traffic exceeds available forwarding capacity for a period. Voice can be sensitive to delay and variation in delay, so queue choices matter; unlimited priority can harm other traffic.

Configuration backup and file transfer

TFTP is a simple UDP-based file transfer protocol without built-in login or encryption. FTP has separate control and data connections and does not provide encryption in its basic form. SFTP transfers files using SSH and is a different protocol. Use a supported secure transfer method for real credentials and sensitive configurations.

For a lab backup, first check the server address, route, access rules, filename and available storage. Record whether you backed up the running configuration or saved startup configuration. They can differ. A downloaded file should be inspected before being applied to a device.