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RHEL/CentOS 7: Revert To Old Network Interface Naming Convention

RHEL/CentOS 7 uses SystemD predictable network interface names. This post shows you how to rename a network interfcae to eth0,/em>without modifying the kernel commnad line or any udev rules, and without requiring a sytem reboot.

IPv4 Link Local Addresses in Fedora

A network link-local address is an address that is valid only for use within the network segment or the broadcast domain that a host is connected to. Link local addresses can be layer 2 or layer 3. For example, a 48-bit Ethernet MAC address is one form of a layer 2 link-local address. Link-local addresses are generally not guaranteed to be unique beyond a network segment. Because of this, layer 3 switches (routers) do not forward packets with layer 3 link-local addresses. For Layer 3 IPv4 link-local (IPv4LL) addresses, RFC3927 specifies the address block 169.254.0.0/16. Zero-configuration Networking (zeroconf) is a

Precision Time Protocol

Most Linux users are familiar with the Network Time Protocol (NTP) but few are aware of Precision Time Protocol (PTP) which is another protocol that can be used to synchronize clocks throughout a computer network. PTP is defined in IEEE 1588-2008 (Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems). PTP is designed for computing systems requiring time accuracies beyond those attainable using NTP, i.e. high time precision systems. By the way, NTP is documented in RFC 5905. PTP is an on-the-wire protocol and typically includes hardware support in the servers, clients and switches to capture

Software Defined Networking

We are being to enter the era of software defined networking (SDN), an emerging paradigm where network control logic (learning and forwarding decisions) is decoupled from the underlying physical network topology (routers, switches). To quote from Nick Feamster who is the Darnell-Kanal Associate Professor of Computer Science at University of Maryland: Separating a network’s control logic from the underlying physical routers and switches that forward traffic allows operators to write high-level control programs that specify the behavior of an entire network, in contrast to conventional networks, whereby network operators must codify functionality in terms of low-level device configuration. Logically centralized