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Virtual Router Redundancy Protocol
The Virtual Router Redundancy Protocol (VRRP) is a computer networking protocol that provides for automatic assignment of available Internet Protocol (IP) routers to participating hosts. This increases the availability and reliability of routing paths via automatic default gateway selections on an IP subnetwork. The protocol achieves this by the creation of virtual routers, which are an abstract representation of multiple routers, i.e. primary/active and secondary/Standby routers, acting as a group. The virtual router is assigned to act as a default gateway of participating hosts, instead of a physical router. If the physical router that is routing packets on behalf of the virtual router fails, another physical router is selected to automatically replace it. The physical router that is forwarding packets at any given time is called the primary/active router. VRRP provides information on the state of a router, not the routes processed and exchanged by that router. Each VRRP insta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Networking Protocol
A communication protocol is a system of rules that allows two or more entities of a communications system to transmit information via any kind of variation of a physical quantity. The protocol defines the rules, syntax, semantics and synchronization of communication and possible error recovery methods. Protocols may be implemented by hardware, software, or a combination of both. Communicating systems use well-defined formats for exchanging various messages. Each message has an exact meaning intended to elicit a response from a range of possible responses pre-determined for that particular situation. The specified behavior is typically independent of how it is to be implemented. Communication protocols have to be agreed upon by the parties involved. To reach an agreement, a protocol may be developed into a technical standard. A programming language describes the same for computations, so there is a close analogy between protocols and programming languages: ''protocols are to co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Booting
In computing, booting is the process of starting a computer as initiated via hardware such as a button or by a software command. After it is switched on, a computer's central processing unit (CPU) has no software in its main memory, so some process must load software into memory before it can be executed. This may be done by hardware or firmware in the CPU, or by a separate processor in the computer system. Restarting a computer also is called rebooting, which can be "hard", e.g. after electrical power to the CPU is switched from off to on, or "soft", where the power is not cut. On some systems, a soft boot may optionally clear RAM to zero. Both hard and soft booting can be initiated by hardware such as a button press or by a software command. Booting is complete when the operative runtime system, typically the operating system and some applications,Including daemons. is attained. The process of returning a computer from a state of sleep (suspension) does not involve bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cisco Systems
Cisco Systems, Inc., commonly known as Cisco, is an American-based multinational corporation, multinational digital communications technology conglomerate (company), conglomerate corporation headquartered in San Jose, California. Cisco develops, manufactures, and sells networking hardware, software, telecommunications equipment and other high-technology services and products. Cisco specializes in specific tech markets, such as the Internet of Things (IoT), internet domain, domain security, videoconferencing, and energy management with List of Cisco products, leading products including Webex, OpenDNS, XMPP, Jabber, Duo Security, and Cisco Jasper, Jasper. Cisco is one of the List of largest technology companies by revenue, largest technology companies in the world ranking 74 on the Fortune 100 with over $51 billion in revenue and nearly 80,000 employees. Cisco Systems was founded in December 1984 by Leonard Bosack and Sandy Lerner, two Stanford University computer scientists who ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gateway Load Balancing Protocol
Gateway Load Balancing Protocol (GLBP) is a Cisco proprietary protocol that attempts to overcome the limitations of existing redundant router protocols by adding basic load balancing functionality. In addition to being able to set priorities on different gateway routers, GLBP allows a weighting parameter to be set. Based on this weighting (compared to others in the same virtual router group), ARP requests will be answered with MAC addresses pointing to different routers. Thus, by default, load balancing is not based on traffic load, but rather on the number of hosts that will use each gateway router. By default, GLBP load balances in round-robin fashion. GLBP elects one AVG (Active Virtual Gateway) for each group. Other group members act as backup in case of AVG failure. In case there are more than two members, the second best AVG is placed in the Standby state and all other members are placed in the Listening state. This is monitored using hello and holdtime timers, which are 3 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common Address Redundancy Protocol
The Common Address Redundancy Protocol or CARP is a computer networking protocol which allows multiple hosts on the same local area network to share a set of IP addresses. Its primary purpose is to provide failover redundancy, especially when used with firewalls and routers. In some configurations, CARP can also provide load balancing functionality. CARP provides functionality similar to Virtual Router Redundancy Protocol (VRRP) and to Cisco Systems' Hot Standby Router Protocol (HSRP). It is implemented in several BSD-based operating systems and has been ported to Linux (ucarp). Example If there is a single computer running a packet filter, and it goes down, the networks on either side of the packet filter can no longer communicate with each other, or they communicate without any packet filtering. If, however, there are two computers running a packet filter, running CARP, then if one fails, the other will take over, and computers on either side of the packet filter will not ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foundry Networks
Foundry Networks, Inc. was a networking hardware vendor selling high-end Ethernet switches and routers. The company was acquired by Brocade Communications Systems on December 18, 2008. History The company was founded in 1996 by Bobby R. Johnson, Jr. and was headquartered in Santa Clara, California, United States. In its first year the company operated under the names Perennium Networks and StarRidge Networks, but by January 1997 the name Foundry Networks was adopted. Foundry Networks had their initial public offering in 1999, during the Internet bubble, with the company reaching a valuation of $9 billion on its first day of trading on NASDAQ with the symbol FDRY. Foundry Networks designed, manufactured and sold high-end enterprise and service provider switches and routers, as well as wireless, security, and traffic management solutions. It was best known for its Layer 2 & 3 Ethernet switches. Foundry Networks was the first company to build and ship a gigabit Ethernet switc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mellanox
Mellanox Technologies Ltd. ( he, מלאנוקס טכנולוגיות בע"מ) was an Israeli-American multinational supplier of computer networking products based on InfiniBand and Ethernet technology. Mellanox offered adapters, switches, software, cables and silicon for markets including high-performance computing, data centers, cloud computing, computer data storage and financial services. On March 11, 2019, Nvidia announced its intent to acquire the company for $6.9 billion. Other companies willing to acquire Mellanox were Intel, Xilinx and Microsoft. The deal closed on April 27, 2020, with approval from the EU, U.S. and Chinese antitrust authorities. The company was integrated into Nvidia's networking division in 2020 and Nvidia stopped using the brand name "Mellanox" for its new networking products. History 1999–2009 Mellanox was founded in May 1999 by former Israeli executives of Intel Corporation and Galileo Technology (which was acquired by Marvell Technology Group ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hot Standby Router Protocol
In computer networking, the Hot Standby Router Protocol (HSRP) is a Cisco proprietary redundancy protocol for establishing a fault-tolerant default gateway. Version 1 of the protocol was described in in 1998. Version 2 of the protocol includes improvements and supports IPv6 but there is no corresponding RFC published for this version. The protocol establishes an association between gateways in order to achieve default gateway failover if the primary gateway becomes inaccessible. HSRP gateways send multicast ''hello'' messages to other gateways to notify them of their priorities (which gateway is preferred) and current status (''active'' or ''standby''). Operation The primary router with the highest configured priority will act as a ''virtual'' router with a pre-defined gateway IP address and will respond to the ARP or ND request from machines connected to the LAN with a virtual MAC address. If the primary router should fail, the router with the next-highest priority would tak ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cisco
Cisco Systems, Inc., commonly known as Cisco, is an American-based multinational digital communications technology conglomerate corporation headquartered in San Jose, California. Cisco develops, manufactures, and sells networking hardware, software, telecommunications equipment and other high-technology services and products. Cisco specializes in specific tech markets, such as the Internet of Things (IoT), domain security, videoconferencing, and energy management with leading products including Webex, OpenDNS, Jabber, Duo Security, and Jasper. Cisco is one of the largest technology companies in the world ranking 74 on the Fortune 100 with over $51 billion in revenue and nearly 80,000 employees. Cisco Systems was founded in December 1984 by Leonard Bosack and Sandy Lerner, two Stanford University computer scientists who had been instrumental in connecting computers at Stanford. They pioneered the concept of a local area network (LAN) being used to connect distant compute ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internet Engineering Task Force
The Internet Engineering Task Force (IETF) is a standards organization for the Internet and is responsible for the technical standards that make up the Internet protocol suite (TCP/IP). It has no formal membership roster or requirements and all its participants are volunteers. Their work is usually funded by employers or other sponsors. The IETF was initially supported by the federal government of the United States but since 1993 has operated under the auspices of the Internet Society, an international non-profit organization. Organization The IETF is organized into a large number of working groups and birds of a feather informal discussion groups, each dealing with a specific topic. The IETF operates in a bottom-up task creation mode, largely driven by these working groups. Each working group has an appointed chairperson (or sometimes several co-chairs); a charter that describes its focus; and what it is expected to produce, and when. It is open to all who want to particip ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thundering Herd Problem
In computer science, the thundering herd problem occurs when a large number of processes or threads waiting for an event are awoken when that event occurs, but only one process is able to handle the event. When the processes wake up, they will each try to handle the event, but only one will win. All processes will compete for resources, possibly freezing the computer, until the herd is calmed down again. Mitigation The Linux kernel serializes responses for requests to a single file descriptor, so only one thread or process is woken up. For epoll() in version 4.5 of the Linux kernel, the EPOLLEXCLUSIVE flag was added. Thus several epoll sets (different threads or different processes) may wait on the same resource and only one set will be woken up. For certain workloads this flag can give significant processing time reduction. Similarly in Microsoft Windows, I/O completion ports can mitigate the thundering herd problem, as they can be configured such that only one of the threads ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timing Skew
Clock skew (sometimes called timing skew) is a phenomenon in synchronous digital circuit systems (such as computer systems) in which the same sourced clock signal arrives at different components at different times due to gate or, in more advanced semiconductor technology, wire signal propagation delay. The instantaneous difference between the readings of any two clocks is called their skew. The operation of most digital circuits is synchronized by a periodic signal known as a "clock" that dictates the sequence and pacing of the devices on the circuit. This clock is distributed from a single source to all the memory elements of the circuit, which for example could be registers or flip-flops. In a circuit using edge-triggered registers, when the clock edge or tick arrives at a register, the register transfers the register input to the register output, and these new output values flow through combinational logic to provide the values at register inputs for the next clock tick. Ideal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
