Loopback interface
A loopback interface is a virtual network interface that routes traffic back through the same host or network stack without using an external network.
Acing the CCNA Exam: Volume 1 Fundamentals and Protocols
A loopback interface is a virtual software-based router interface that remains operational while the device is operational unless administratively disabled.
- How it is used
- Uses a stable virtual interface to support OSPF router identification and reachability independent of one physical port.
- How deep it goes
- Defines behavior, explains OSPF RID selection, and demonstrates Cisco IOS configuration, but does not detail broader loopback applications.
- Examples
- Demonstrates Loopback0 configuration, OSPF RID selection, process resetting, and SSH access during physical-interface failure.
- What you can do after
- Configure Cisco IOS Loopback0, assign an address, verify its OSPF RID, and understand when resetting OSPF is necessary.
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Kubernetes in Action, Second Edition
A loopback device is a network interface that routes traffic within the same host or network namespace without sending it through an external network.
- How it is used
- Uses the loopback interface to connect port-forwarded local requests to an application inside a pod.
- How deep it goes
- Explains the communication path and binding requirement, but stops short of implementing loopback networking internally.
- Examples
- Demonstrates kubectl port-forward kiada 8080 followed by curl localhost:8080.
- What you can do after
- Operate kubectl port-forward and diagnose failures caused by applications listening only on eth0.
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Related concepts
- loopback addresscontrasts with · A loopback address is an IP address that routes network traffic back to the same host; localhost is the hostname that resolves to a loopback address.
- network interfacecontrasts with · A network interface is a physical or logical connection point through which a system sends and receives network traffic.
- Envoyused by · Envoy is an open-source, high-performance proxy for service-to-service communication, edge traffic management, and distributed application networking.
- NTP serverused by · An NTP server is a device or service that provides clock information for synchronizing NTP clients.
- virtual interfacekind of · A virtual interface is a logical network interface implemented in software rather than as a dedicated physical device.
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