Contexts 3 4 2 – Fast Window Switcher Kit

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Consider switchers built by trusted manufacturers and those with high-quality components. If you're using your switcher in the field, you'll require one with heavy-duty construction and a durable frame. With technology changing so fast, future-proof elements such as. The machine is Windows 7 Pro, Core 2 Duo P9700 with 8gb of memory. An interesting fact is that sandbox solution uses 42% of CPU vs 55% of in-process solution. Another noteworthy fact is that sandbox solution contains 350k context switches, which is much more than the 200k context switches that we can infer from source code. WI NDOWS 4 - Double-Hung (DH) Transom Windows (1994 to 2006) Unit Sizes Unit viewed from exterior. Unit Size Chart Note: Unit Dimension refers to overall outside-to-outside frame. Unobstructed Glass refers to visible glass dimensions.

A network switch (also called switching hub, bridging hub, and by the IEEEMAC bridge^[1]) is networking hardware that connects devices on a computer network by using packet switching to receive and forward data to the destination device.

A network switch is a multiport network bridge that uses MAC addresses to forward data at the data link layer (layer 2) of the OSI model. Some switches can also forward data at the network layer (layer 3) by additionally incorporating routing functionality. Such switches are commonly known as layer-3 switches or multilayer switches.^[2]

Switches for Ethernet are the most common form of network switch. The first Ethernet switch was introduced by Kalpana in 1990.^[3] Switches also exist for other types of networks including Fibre Channel, Asynchronous Transfer Mode, and InfiniBand.

Unlike less advanced repeater hubs, which broadcast the same data out of each of its ports and let the devices decide what data they need, a network switch forwards data only to the devices that need to receive it.^[4]

Overview[edit]

A switch is a device in a computer network that connects other devices together. Multiple data cables are plugged into a switch to enable communication between different networked devices. Switches manage the flow of data across a network by transmitting a received network packet only to the one or more devices for which the packet is intended. Each networked device connected to a switch can be identified by its network address, allowing the switch to direct the flow of traffic maximizing the security and efficiency of the network.

A switch is more intelligent than an Ethernet hub, which simply retransmits packets out of every port of the hub except the port on which the packet was received, unable to distinguish different recipients, and achieving an overall lower network efficiency.

An Ethernet switch operates at the data link layer (layer 2) of the OSI model to create a separate collision domain for each switch port. Each device connected to a switch port can transfer data to any of the other ports at any time and the transmissions will not interfere.^[a] Because broadcasts are still being forwarded to all connected devices by the switch, the newly formed network segment continues to be a broadcast domain. Switches may also operate at higher layers of the OSI model, including the network layer and above. A device that also operates at these higher layers is known as a multilayer switch.

Segmentation involves the use of a switch to split a larger collision domain into smaller ones in order to reduce collision probability and to improve overall network throughput. In the extreme case (i.e. micro-segmentation), each device is located on a dedicated switch port. In contrast to an Ethernet hub, there is a separate collision domain on each of the switch ports. This allows computers to have dedicated bandwidth on point-to-point connections to the network and also to run in full-duplex mode. Full-duplex mode has only one transmitter and one receiver per collision domain, making collisions impossible.

The network switch plays an integral role in most modern Ethernet local area networks (LANs). Mid-to-large sized LANs contain a number of linked managed switches. Small office/home office (SOHO) applications typically use a single switch, or an all-purpose device such as a residential gateway to access small office/home broadband services such as DSL or cable Internet. In most of these cases, the end-user device contains a router and components that interface to the particular physical broadband technology. User devices may also include a telephone interface for Voice over IP (VoIP).

Role in a network[edit]

Switches are most commonly used as the network connection point for hosts at the edge of a network. In the hierarchical internetworking model and similar network architectures, switches are also used deeper in the network to provide connections between the switches at the edge.

Ia writer mac. In switches intended for commercial use, built-in or modular interfaces make it possible to connect different types of networks, including Ethernet, Fibre Channel, RapidIO, ATM, ITU-TG.hn and 802.11. This connectivity can be at any of the layers mentioned. While the layer-2 functionality is adequate for bandwidth-shifting within one technology, interconnecting technologies such as Ethernet and token ring is performed more easily at layer 3 or via routing.^[6] Devices that interconnect at the layer 3 are traditionally called routers.^[7]

Where there is a need for a great deal of analysis of network performance and security, switches may be connected between WAN routers as places for analytic modules. Some vendors provide firewall,^[8][9] network intrusion detection,^[10] and performance analysis modules that can plug into switch ports. Some of these functions may be on combined modules.^[11]

Through port mirroring, a switch can create a mirror image of data that can go to an external device such as intrusion detection systems and packet sniffers.

A modern switch may implement power over Ethernet (PoE), which avoids the need for attached devices, such as a VoIP phone or wireless access point, to have a separate power supply. Since switches can have redundant power circuits connected to uninterruptible power supplies, the connected device can continue operating even when regular office power fails.

Contexts 3 4 2 – Fast Window Switcher Kit Kat

Bridging[edit]

Modern commercial switches use primarily Ethernet interfaces. The core function of an Ethernet switch is to provide multiport layer-2 bridging. Layer-1 functionality is required in all switches in support of the higher layers. Many switches also perform operations at other layers. A device capable of more than bridging is known as a multilayer switch.

A layer 2 network device is a multiport device that uses hardware addresses, MAC address, to process and forward data at the data link layer (layer 2).

A switch operating as a network bridge may interconnect devices in a home or office. The bridge learns the MAC address of each connected device. Bridges also buffer an incoming packet and adapt the transmission speed to that of the outgoing port. While there are specialized applications, such as storage area networks, where the input and output interfaces are the same bandwidth, this is not always the case in general LAN applications. In LANs, a switch used for end-user access typically concentrates lower bandwidth and uplinks into a higher bandwidth.

Interconnect between switches may be regulated using spanning tree protocol (STP) that disables links so that the resulting local area network is a tree without loops. In contrast to routers, spanning tree bridges must have topologies with only one active path between two points. Shortest path bridging is a layer 2 alternative to STP that allows all paths to be active with multiple equal cost paths.^[12][13]

Types[edit]

Form factors[edit]

Switches are available in many form factors, including stand-alone, desktop units which are typically intended to be used in a home or office environment outside a wiring closet; rack-mounted switches for use in an equipment rack or an enclosure; DIN rail mounted for use in industrial environments; and small installation switches, mounted into a cable duct, floor box or communications tower, as found, for example, in fiber to the office infrastructures.

Rack-mounted switches may be standalone units, stackable switches or large chassis units with swappable line cards.

Configuration options[edit]

• Unmanaged switches have no configuration interface or options. They are plug and play. They are typically the least expensive switches, and therefore often used in a small office/home office environment. Unmanaged switches can be desktop or rack mounted.
• Managed switches have one or more methods to modify the operation of the switch. Common management methods include: a command-line interface (CLI) accessed via serial console, telnet or Secure Shell, an embedded Simple Network Management Protocol (SNMP) agent allowing management from a remote console or management station, or a web interface for management from a web browser. Examples of configuration changes that one can do from a managed switch include: enabling features such as Spanning Tree Protocol or port mirroring, setting port bandwidth, creating or modifying virtual LANs (VLANs), etc. Two sub-classes of managed switches are smart and enterprise managed switches.
• Smart switches (aka intelligent switches) are managed switches with a limited set of management features. Likewise, 'web-managed' switches are switches that fall into a market niche between unmanaged and managed. For a price much lower than a fully managed switch they provide a web interface (and usually no CLI access) and allow configuration of basic settings, such as VLANs, port-bandwidth and duplex.^[14]
• Enterprise managed switches (aka managed switches) have a full set of management features, including CLI, SNMP agent, and web interface. They may have additional features to manipulate configurations, such as the ability to display, modify, backup and restore configurations. Compared with smart switches, enterprise switches have more features that can be customized or optimized and are generally more expensive than smart switches. Enterprise switches are typically found in networks with a larger number of switches and connections, where centralized management is a significant savings in administrative time and effort. A stackable switch is a type of an enterprise-managed switch.

Typical management features[edit]

• Enable and disable ports
• Link bandwidth and duplex settings
• Quality of service configuration and monitoring
• MAC filtering and other access control list features
• Configuration of Spanning Tree Protocol (STP) and Shortest Path Bridging (SPB) features
• Simple Network Management Protocol (SNMP) monitoring of device and link health
• Port mirroring for monitoring traffic and troubleshooting
• Link aggregation configuration to set up multiple ports for the same connection to achieve higher data transfer rates and reliability
• VLAN configuration and port assignments including IEEE 802.1Q tagging
• Network Access Control features such as IEEE 802.1X
• IGMP snooping for control of multicast traffic

Traffic monitoring[edit]

It is difficult to monitor traffic that is bridged using a switch because only the sending and receiving ports can see the traffic.

Methods that are specifically designed to allow a network analyst to monitor traffic include:

• Port mirroring – the switch sends a copy of network packets to a monitoring network connection.
• SMON – 'Switch Monitoring' is described by RFC 2613 and is a protocol for controlling facilities such as port mirroring.
• RMON^[15]

These monitoring features are rarely present on consumer-grade switches. Other monitoring methods include connecting a layer-1 hub or network tap between the monitored device and its switch port.^[16]

See also[edit]

Contexts 3 4 2 – Fast Window Switcher Kit Download

Notes[edit]

1. ^In half duplex mode, each switch port can only either receive from or transmit to its connected device at a certain time. In full duplex mode, each switch port can simultaneously transmit and receive, assuming the connected device also supports full-duplex mode.^[5]

References[edit]

1. ^IEEE 802.1D
2. ^Thayumanavan Sridhar (September 1998). 'Layer 2 and Layer 3 Switch Evolution'. cisco.com. The Internet Protocol Journal. Cisco Systems. Retrieved 2014-08-05.
3. ^Robert J. Kohlhepp (2000-10-02). 'The 10 Most Important Products of the Decade'. Network Computing. Archived from the original on 2010-01-05. Retrieved 2008-02-25.
4. ^'Hubs Versus Switches – Understand the Tradeoffs'(PDF). ccontrols.com. 2002. Retrieved 2013-12-10.
5. ^'Cisco Networking Academy's Introduction to Basic Switching Concepts and Configuration'. Cisco Systems. 2014-03-31. Retrieved 2015-08-17.
6. ^Joe Efferson; Ted Gary; Bob Nevins (February 2002). 'Token-Ring to Ethernet Migration'(PDF). IBM. p. 13. Archived from the original(PDF) on 2015-09-24. Retrieved 2015-08-11.
7. ^Thayumanavan Sridhar (September 1998). 'The Internet Protocol Journal - Volume 1, No. 2: Layer 2 and Layer 3 Switch Evolution'. Cisco Systems. Retrieved 2015-08-11.
8. ^Cisco Catalyst 6500 Series Firewall Services Module, Cisco Systems,2007
9. ^Switch 8800 Firewall Module, 3Com Corporation, 2006
10. ^Cisco Catalyst 6500 Series Intrusion Detection System (IDSM-2) Module, Cisco Systems,2007
11. ^Getting Started with Check Point Fire Wall-1, Checkpoint Software Technologies Ltd., n.d.
12. ^Peter Ashwood-Smith (24 February 2011). 'Shortest Path Bridging IEEE 802.1aq Overview'(PDF). Huawei. Archived from the original(PDF) on 15 May 2013. Retrieved 11 May 2012.
13. ^'IEEE Approves New IEEE 802.1aq Shortest Path Bridging Standard'. Tech Power Up. 7 May 2012. Retrieved 11 May 2012.
14. ^'Tech specs for a sample HP 'web-managed' switch'. Archived from the original on December 13, 2007. Retrieved 2007-05-25.CS1 maint: BOT: original-url status unknown (link)
15. ^Remote Network Monitoring Management Information Base, RFC 2819, S. Waldbusser,May 2000
16. ^'How to Build a Miniature Network Monitor Device'. Retrieved 2019-01-08.

External links[edit]

Latest versions

Quick News

As most already expected it, the HAProxyConf 2020 which was initially planned around November will be postponed to a yet unknown date in 2021 depending on how the situation evolves regarding the pandemic. At this point it's useless to forecast anything, so we'll start to announce it upfront once we have a better visibility of what is possible.

In the mean time, if you're impatient, please be aware that all the 2019 talks are available on https://www.haproxyconf.com/2019/presentations/.

July 7th, 2020 : HAProxy 2.2.0 is ready!

HAProxy 2.2 is tha latest LTS release, delivered few weeks late, but for good given that many early bugs were addressed during this time! New features include runtime certificate addition and crtlist management, dynamic error pages and return statements, logging over TCP, refined idle connection pools saving server resources, extensible health checks, improved I/O processing and scheduling for even lower latency processing, even more debugging information. Please check the announce here for more details.

Doctor 1 1 0 – convert your documents pdf. November 25th, 2019 : HAProxy 2.1.0 is out!

Delivered on time, for once, proving that our new development process works better. In short this provides hot-update of certificates, FastCGI to backends, better performance, more debugging capabilities and some extra goodies. Please check the announce here for more details.

Description

HAProxy is a free, very fast and reliable solution offering high availability, load balancing, and proxying for TCP and HTTP-based applications. It is particularly suited for very high traffic web sites and powers quite a number of the world's most visited ones. Over the years it has become the de-facto standard opensource load balancer, is now shipped with most mainstream Linux distributions, and is often deployed by default in cloud platforms. Since it does not advertise itself, we only know it's used when the admins report it :-)

Its mode of operation makes its integration into existing architectures very easy and riskless, while still offering the possibility not to expose fragile web servers to the net, such as below :

We always support at least two active versions in parallel and an extra old one in critical fixes mode only. The currently supported versions are :

• version 2.2 : runtime certificate additions, improved idle connection management, logging over TCP, HTTP 'return' directive, errorfile templates, TLSv1.2 by default, extensible health-checks
• version 2.1 : improved I/Os and multi-threading, FastCGI, runtime certificate updates, HTX-only, improved debugging, removal of obsolete keywords
• version 2.0 : gRPC, layer 7 retries, process manager, SSL peers, log load balancing/sampling, end-to-end TCP fast-open, automatic settings (maxconn, threads, HTTP reuse, pools), ..
• version 1.9 : improved multi-threading, end-to-end HTTP/2, connection pools, queue priority control, stdout logging, ..
• version 1.8 : multi-threading, HTTP/2, cache, on-the fly server addition/removal, seamless reloads, DNS SRV, hardware SSL engines, ..
• version 1.7 : added server hot reconfiguration, content processing agents, multi-type certs, ..
• version 1.6 : added DNS resolution support, HTTP connection multiplexing, full stick-table replication, stateless compression, ..
• version 1.5 : added SSL, IPv6, keep-alive, DDoS protection, ..

Main features

Supported platforms

• Linux 2.4 on x86, x86_64, Alpha, Sparc, MIPS, PARISC
• Linux 2.6-5.x on x86, x86_64, ARM, AARCH64, MIPS, Sparc, PPC64
• Solaris 8/9 on UltraSPARC 2 and 3
• Solaris 10 on Opteron and UltraSPARC
• FreeBSD 4.10 - current on x86
• OpenBSD 3.1 to -current on i386, amd64, macppc, alpha, sparc64 and VAX (check the ports)
• AIX 5.1 - 5.3 on Power™ architecture

Highest performance is achieved with modern operating systems supporting scalable polling mechanisms such as epoll on Linux 2.6/3.x or kqueue on FreeBSD and OpenBSD. This requires haproxy version newer than 1.2.5. Fast data transfers are made possible on Linux 3.x using TCP splicing and haproxy 1.4 or 1.5. Forwarding rates of up to 40 Gbps have already been achieved on such platforms after a very careful tuning. While Solaris and AIX are supported, they should not be used if extreme performance is required.

Wirecast 6 0 3 – stream live from the desktop. Current typical 1U servers equipped with a dual-core Opteron or Xeon generally achieve between 15000 and 40000 hits/s and have no trouble saturating 2 Gbps under Linux.

Performance

[ warning: information in this section dates 2007, things have improved by an order of magnitude since then ]
Well, since a user's testimony is better than a long demonstration, please take a look at Chris Knight's experience with haproxy saturating a gigabit fiber in 2007 on a video download site. Since then, the performance has significantly increased and the hardware has become much more capable, as my experiments with Myricom's 10-Gig NICs have shown two years later. Now as of 2014, 10-Gig NICs are too limited and are hardly suited for 1U servers since they do rarely provide enough port density to reach speeds above 40-60 Gbps in a 1U server. 100-Gig NICs are coming and I expect to run new series of tests when they are available.

HAProxy involves several techniques commonly found in Operating Systems architectures to achieve the absolute maximal performance :

Contexts 3 4 2 – Fast Window Switcher Kit Free

• a single-process, event-driven model considerably reduces the cost of context switch and the memory usage. Processing several hundreds of tasks in a millisecond is possible, and the memory usage is in the order of a few kilobytes per session while memory consumed in preforked or threaded servers is more in the order of megabytes per process.
• O(1) event checker on systems that allow it (Linux and FreeBSD) allowing instantaneous detection of any event on any connection among tens of thousands.
• Delayed updates to the event checker using a lazy event cache ensures that we never update an event unless absolutely required. This saves a lot of system calls.
• Single-buffering without any data copy between reads and writes whenever possible. This saves a lot of CPU cycles and useful memory bandwidth. Often, the bottleneck will be the I/O busses between the CPU and the network interfaces. At 10-100 Gbps, the memory bandwidth can become a bottleneck too.
• Zero-copy forwarding is possible using the splice() system call under Linux, and results in real zero-copy starting with Linux 3.5. This allows a small sub-3 Watt device such as a Seagate Dockstar to forward HTTP traffic at one gigabit/s.
• MRU memory allocator using fixed size memory pools for immediate memory allocation favoring hot cache regions over cold cache ones. This dramatically reduces the time needed to create a new session.
• Work factoring, such as multiple accept() at once, and the ability to limit the number of accept() per iteration when running in multi-process mode, so that the load is evenly distributed among processes.
• CPU-affinity is supported when running in multi-process mode, or simply to adapt to the hardware and be the closest possible to the CPU core managing the NICs while not conflicting with it.
• Tree-based storage, making heavy use of the Elastic Binary tree I have been developping for several years. This is used to keep timers ordered, to keep the runqueue ordered, to manage round-robin and least-conn queues, to look up ACLs or keys in tables, with only an O(log(N)) cost.
• Optimized timer queue : timers are not moved in the tree if they are postponed, because the likeliness that they are met is close to zero since they're mostly used for timeout handling. This further optimizes the ebtree usage.
• optimized HTTP header analysis : headers are parsed an interpreted on the fly, and the parsing is optimized to avoid an re-reading of any previously read memory area. Checkpointing is used when an end of buffer is reached with an incomplete header, so that the parsing does not start again from the beginning when more data is read. Parsing an average HTTP request typically takes half a microsecond on a fast Xeon E5.
• careful reduction of the number of expensive system calls. Most of the work is done in user-space by default, such as time reading, buffer aggregation, file-descriptor enabling/disabling.
• Content analysis is optimized to carry only pointers to original data and never copy unless the data needs to be transformed. This ensures that very small structures are carried over and that contents are never replicated when not absolutely necessary.

All these micro-optimizations result in very low CPU usage even on moderate loads. And even at very high loads, when the CPU is saturated, it is quite common to note figures like 5% user and 95% system, which means that the HAProxy process consumes about 20 times less than its system counterpart. This explains why the tuning of the Operating System is very important. This is the reason why we ended up building our own appliances, in order to save that complex and critical task from the end-user.

In production, HAProxy has been installed several times as an emergency solution when very expensive, high-end hardware load balancers suddenly failed on Layer 7 processing. Some hardware load balancers still do not use proxies and process requests at the packet level and have a great difficulty at supporting requests across multiple packets and high response times because they do no buffering at all. On the other side, software load balancers use TCP buffering and are insensible to long requests and high response times. A nice side effect of HTTP buffering is that it increases the server's connection acceptance by reducing the session duration, which leaves room for new requests.

There are 3 important factors used to measure a load balancer's performance :

• The session rate
  This factor is very important, because it directly determines when the load balancer will not be able to distribute all the requests it receives. It is mostly dependant on the CPU. Sometimes, you will hear about requests/s or hits/s, and they are the same as sessions/s in HTTP/1.0 or HTTP/1.1 with keep-alive disabled. Requests/s with keep-alive enabled is generally much higher (since it significantly reduces system-side work) but is often meaningless for internet-facing deployments since clients often open a large amount of connections and do not send many requests per connection on avertage. This factor is measured with varying object sizes, the fastest results generally coming from empty objects (eg: HTTP 302, 304 or 404 response codes). Session rates around 100,000 sessions/s can be achieved on Xeon E5 systems in 2014.
• The session concurrency
  This factor is tied to the previous one. Generally, the session rate will drop when the number of concurrent sessions increases (except with the epoll or kqueue polling mechanisms). The slower the servers, the higher the number of concurrent sessions for a same session rate. If a load balancer receives 10000 sessions per second and the servers respond in 100 ms, then the load balancer will have 1000 concurrent sessions. This number is limited by the amount of memory and the amount of file-descriptors the system can handle. With 16 kB buffers, HAProxy will need about 34 kB per session, which results in around 30000 sessions per GB of RAM. In practise, socket buffers in the system also need some memory and 20000 sessions per GB of RAM is more reasonable. Layer 4 load balancers generally announce millions of simultaneous sessions because they need to deal with the TIME_WAIT sockets that the system handles for free in a proxy. Also they don't process any data so they don't need any buffer. Moreover, they are sometimes designed to be used in Direct Server Return mode, in which the load balancer only sees forward traffic, and which forces it to keep the sessions for a long time after their end to avoid cutting sessions before they are closed.
• The data forwarding rate
  This factor generally is at the opposite of the session rate. It is measured in Megabytes/s (MB/s), or sometimes in Gigabits/s (Gbps). Highest data rates are achieved with large objects to minimise the overhead caused by session setup and teardown. Large objects generally increase session concurrency, and high session concurrency with high data rate requires large amounts of memory to support large windows. High data rates burn a lot of CPU and bus cycles on software load balancers because the data has to be copied from the input interface to memory and then back to the output device. Hardware load balancers tend to directly switch packets from input port to output port for higher data rate, but cannot process them and sometimes fail to touch a header or a cookie. Haproxy on a typical Xeon E5 of 2014 can forward data up to about 40 Gbps. A fanless 1.6 GHz Atom CPU is slightly above 1 Gbps.

A load balancer's performance related to these factors is generally announced for the best case (eg: empty objects for session rate, large objects for data rate). This is not because of lack of honnesty from the vendors, but because it is not possible to tell exactly how it will behave in every combination. So when those 3 limits are known, the customer should be aware that it will generally perform below all of them. A good rule of thumb on software load balancers is to consider an average practical performance of half of maximal session and data rates for average sized objects.

You might be interested in checking the 10-Gigabit/s page.

Reliability - keeping high-traffic sites online since 2002

Security - Not even one intrusion in 13 years

HAProxy also provides regex-based header control. Parts of the request, as well as request and response headers can be denied, allowed, removed, rewritten, or added. This is commonly used to block dangerous requests or encodings (eg: the Apache Chunk exploit), and to prevent accidental information leak from the server to the client. Other features such as Cache-control checking ensure that no sensible information gets accidentely cached by an upstream proxy consecutively to a bug in the application server for example.

Download

• Development version (2.2) :
  • Browse directory for docs, sources and binaries
  • Daily snapshots are built once a day when the GIT repository changes
• Latest LTS version (2.2) :
  • Release Notes for version 2.2.4
  • haproxy-2.2.4.tar.gz (MD5) : Source code under GPL
  • Browse directory for other files or versions
• Previous version (2.1) :
  • Release Notes for version 2.1.9
  • haproxy-2.1.9.tar.gz (MD5) : Source code under GPL
  • Browse directory for other files or versions
• Previous LTS version (2.0) :
  • Release Notes for version 2.0.18
  • haproxy-2.0.18.tar.gz (MD5) : Source code under GPL
  • Browse directory for other files or versions
• Previous version (1.9) :
  • Release Notes for version 1.9.16
  • haproxy-1.9.16.tar.gz (MD5) : Source code under GPL
  • Browse directory for other files or versions
• Previous version (1.8) :
  • Release Notes for version 1.8.26
  • haproxy-1.8.26.tar.gz (MD5) : Source code under GPL
  • Browse directory for other files or versions
• Older version (1.7) :
  • Release Notes for version 1.7.12
  • haproxy-1.7.12.tar.gz (MD5) : Source code under GPL
  • Browse directory for other files or versions
• Older version (1.6) :
  • Release Notes for version 1.6.15
  • haproxy-1.6.15.tar.gz (MD5) : Source code under GPL
  • Browse directory for other files or versions
• Oldest version (1.5) :
  • Release Notes for version 1.5.19
  • haproxy-1.5.19.tar.gz (MD5) : Source code under GPL
  • Browse directory for other files or versions
• Unmaintained version (1.4) :
  • Release Notes for version 1.4.27
  • haproxy-1.4.27.tar.gz (MD5) : Source code under GPL
  • haproxy-1.4.26-linux-i586.gz : (MD5) Linux/i586 executable linked with Glibc 2.2
  • haproxy-1.4.26-pcre-solaris-sparc.notstripped.gz : (MD5) Solaris8/Sparc executable
  • Browse directory for other files or versions
• Unmaintained version (1.3) :
  • Release Notes for version 1.3.28
  • haproxy-1.3.28.tar.gz (MD5) : Source code under GPL
  • haproxy-1.3.27-linux-i586.gz : (MD5) Linux/i586 executable linked with Glibc 2.2
  • haproxy-1.3.27-pcre-solaris-sparc.notstripped.gz : (MD5) Solaris8/Sparc executable
  • Browse directory for other files or versions
• Unmaintained branch (1.2) :
  • Release Notes for version 1.2.18
  • haproxy-1.2.18.tar.gz (MD5) : Source code under GPL
  • haproxy-1.2.18-linux-i586.gz : (MD5) Linux/i586 executable linked with Glibc 2.2
  • haproxy-1.2.18-sol8-ultrasparc-static-pcre.gz : (MD5) Solaris8/Sparc executable
  • Browse directory for other files or versions
• Various Patches :
  • Some patches for Stunnel by HAProxy Technologies (formerly Exceliance), such X-Forwarded-For, send-proxy, unix-sockets, multi-process SSL session synchronization, transparent binding and performance improvements.
  • http://www.haproxy.com/download/free/patches/linux/epoll-2.4/ : kernel patches to enable epoll on standard Linux 2.4 kernels and on Red Hat Enterprise Linux 3.
  • HAProxy Technologies' public patch repository for other patches (stud, stunnel, linux, keepalived, ..)
  • Browse directory for other (outdated) patches.
• Browsable directory for other files (not only patches)

Documentation

• Reference Manual for version 2.3 (development) :
  • Starter guide in HTML (up to date, maintained by Cyril Bonté)
  • Configuration Manual in HTML (up to date, maintained by Cyril Bonté)
  • Management Guide in HTML (up to date, maintained by Cyril Bonté)
  • Lua reference manual in HTML (up to date, maintained by Thierry Fournier)
  • Lua Architecture in HTML (up to date, maintained by Thierry Fournier)
  • intro.txt : Starter guide in text format
  • management.txt : Management guide in text format
  • configuration.txt : Configuration Manual in text format
  • Browsable directory : Various other docs and diagrams
• Reference Manual for version 2.2 (Stable) :
  • Starter guide in HTML (up to date, maintained by Cyril Bonté)
  • Configuration Manual in HTML (up to date, maintained by Cyril Bonté)
  • Management Guide in HTML (up to date, maintained by Cyril Bonté)
  • Lua reference manual in HTML (up to date, maintained by Thierry Fournier)
  • Lua Architecture in HTML (up to date, maintained by Thierry Fournier)
  • intro.txt : Starter guide in text format
  • management.txt : Management guide in text format
  • configuration.txt : Configuration Manual in text format
  • Browsable directory : Various other docs and diagrams
• Reference Manual for version 2.1 (Stable) :
  • Starter guide in HTML (up to date, maintained by Cyril Bonté)
  • Configuration Manual in HTML (up to date, maintained by Cyril Bonté)
  • Management Guide in HTML (up to date, maintained by Cyril Bonté)
  • Lua reference manual in HTML (up to date, maintained by Thierry Fournier)
  • Lua Architecture in HTML (up to date, maintained by Thierry Fournier)
  • intro.txt : Starter guide in text format
  • management.txt : Management guide in text format
  • configuration.txt : Configuration Manual in text format
  • Browsable directory : Various other docs and diagrams
• Reference Manual for version 2.0 (Stable (LTS)) :
  • Starter guide in HTML (up to date, maintained by Cyril Bonté)
  • Configuration Manual in HTML (up to date, maintained by Cyril Bonté)
  • Management Guide in HTML (up to date, maintained by Cyril Bonté)
  • Lua reference manual in HTML (up to date, maintained by Thierry Fournier)
  • Lua Architecture in HTML (up to date, maintained by Thierry Fournier)
  • intro.txt : Starter guide in text format
  • management.txt : Management guide in text format
  • configuration.txt : Configuration Manual in text format
  • Browsable directory : Various other docs and diagrams
• Reference Manual for version 1.9 (unmaintained) :
  • Starter guide in HTML (up to date, maintained by Cyril Bonté)
  • Configuration Manual in HTML (up to date, maintained by Cyril Bonté)
  • Management Guide in HTML (up to date, maintained by Cyril Bonté)
  • Lua reference manual in HTML (up to date, maintained by Thierry Fournier)
  • Lua Architecture in HTML (up to date, maintained by Thierry Fournier)
  • intro.txt : Starter guide in text format
  • management.txt : Management guide in text format
  • configuration.txt : Configuration Manual in text format
  • Browsable directory : Various other docs and diagrams
• Reference Manual for version 1.8 (Stable (LTS)) :
  • Starter guide in HTML (up to date, maintained by Cyril Bonté)
  • Configuration Manual in HTML (up to date, maintained by Cyril Bonté)
  • Management Guide in HTML (up to date, maintained by Cyril Bonté)
  • Lua reference manual in HTML (up to date, maintained by Thierry Fournier)
  • Lua Architecture in HTML (up to date, maintained by Thierry Fournier)
  • intro.txt : Starter guide in text format
  • management.txt : Management guide in text format
  • configuration.txt : Configuration Manual in text format
  • Browsable directory : Various other docs and diagrams
• Reference Manual for version 1.7 (Critical fixes only) :
  • Starter guide in HTML (up to date, maintained by Cyril Bonté)
  • Configuration Manual in HTML (up to date, maintained by Cyril Bonté)
  • Management Guide in HTML (up to date, maintained by Cyril Bonté)
  • Lua reference manual in HTML (up to date, maintained by Thierry Fournier)
  • Lua Architecture in HTML (up to date, maintained by Thierry Fournier)
  • intro.txt : Starter guide in text format
  • management.txt : Management guide in text format
  • configuration.txt : Configuration Manual in text format
  • Browsable directory : Various other docs and diagrams
• Reference Manual for version 1.6 (Critical fixes only) :
  • Starter guide in HTML (up to date, maintained by Cyril Bonté)
  • Configuration Manual in HTML (up to date, maintained by Cyril Bonté)
  • Management Guide in HTML (up to date, maintained by Cyril Bonté)
  • Lua reference manual in HTML (up to date, maintained by Thierry Fournier)
  • Lua Architecture in HTML (up to date, maintained by Thierry Fournier)
  • intro.txt : Starter guide in text format
  • configuration.txt : Configuration Manual in text format
  • management.txt : Management guide in text format
  • Browsable directory : Various other docs and diagrams
• Reference Manual for version 1.5 (unmaintained) :
  • Configuration Manual in HTML (up to date, maintained by Cyril Bonté)
  • configuration.txt : Configuration Manual in text format
  • Browsable directory : Various other docs and diagrams
• Reference Manual for version 1.4 (unmaintained) :
  • Configuration Manual in HTML (up to date, maintained by Cyril Bonté)
  • configuration.txt : Configuration Manual in text format
  • Browsable directory : Various other docs and diagrams
• Reference Manual for version 1.3 (unmaintained) :
  • configuration.txt : Configuration Manual
  • architecture.txt : Architecture Guide
  • haproxy-en.txt : old English version, outdated
  • haproxy-fr.txt : old French version, outdated
  • Browsable directory : Various other docs and diagrams
• Reference Manual for version 1.2 (unmaintained) :
  • haproxy-en.txt : English version
  • haproxy-fr.txt : French version
• Reference Manual for version 1.1 (unmaintained) :
  • haproxy-en.txt : English version
  • haproxy-fr.txt : French version
• architecture.txt : Architecture Guide
• Article on Load Balancing (HTML version) : worth reading for people who don't know what type of load balancer they need

In addition to Cyril's HTML converter above, an automated format converter is being developed by Pavel Lang. At the time of writing these lines, it is able to produce a PDF from the documentation, and some heavy work is ongoing to support other output formats. Please consult the project's page for more information. Here's an example of what it is able to do on version 1.5 configuration manual.

Commercial Support and availability

1. contact HAProxy Technologies to hire some professional services or subscribe a support contract ;
2. install HAProxy Enterprise Edition (HAPEE), which is a long-term maintained HAProxy package accompanied by a well-polished collection of software, scripts, configuration files and documentation which significantly simplifies the setup and maintenance of a completely operational solution ; it is particularly suited to Cloud environments where deployments must be fast.
3. try an ALOHA appliance (hardware or virtual), which will even save you from having to worry about the system, hardware and from managing a Unix-like system.

Contexts 3 4 2 – Fast Window Switcher Kits

Add-on features and contributions

• sFlow support

Neil Mckee posted a patch to the list in early 2013, and unfortunately this patch did not receive any sign of interest nor feedback, which is sad considering the amount of work that was done. I personally am clueless about sFlow and expressed my skepticism to Neil about the benefits of sampling some HTTP traffic when you can get much more detailed informations for free with existing logs.

Neil kindly responded with the following elements :

I agree that the logging you already have in haproxy is more flexible and detailed, and I acknowledge that the benefit of exporting sFlow-HTTP records is not immediately obvious.

The value that sFlow brings is that the measurements are standard, and are designed to integrate seamlessly with sFlow feeds from switches, routers, servers and applications to provide a comprehensive end to end picture of the performance of large scale multi-tier systems. So the purpose is not so much to troubleshoot haproxy in isolation, but to analyze the performance of the whole system that haproxy is part of.

Perhaps the best illustration of this is the 1-in-N sampling feature. If you configure sampling.http to be, say, 1-in-400 then you might only see a handful of sFlow records per second from an haproxy instance, but that is enough to tell you a great deal about what is going on -- in real time. And the data will not bury you even if you have a bank of load-balancers, hundreds of web-servers, a huge memcache-cluster and a fast network interconnect all contributing their own sFlow feeds to the same analyzer.

Even after that explanation, no discussion emerged on the subject on the list, so I guess there is little interest among users for now. I suspect that sFlow is probably more deployed among network equipments than application layer equipments, which could explain this situation. The code is large (not huge though) and I am not convinced about the benefits of merging it and maintaining it if nobody shows even a little bit of interest. Thus for now I prefer to leave it out of tree. Neil has posted it on GitHub here : https://github.com/sflow/haproxy.

Please, if you do use this patch, report your feedback to the mailing list, and invest some time helping with the code review and testing.

This table enumerates all known significant contributions that led to version 1.4, as well as proposed fundings and features yet to be developped but waiting for spare time. It is not more up to date though.

Some older code contributions which possibly do not appear in the table above are still listed here.

• Application Cookies

  Aleksandar Lazic and Klaus Wagner implemented this feature which was merged in 1.2. It allows the proxy to learn cookies sent by the server to the client, and to find it back in the URL to direct the client to the right server. The learned cookies are automatically purged after some inactive time.

• Least Connections load balancing algorithm

  This patch for haproxy-1.2.14 was submitted by Oleksandr Krailo. It implements a basic least connection algorithm. I've not merged this version into 1.3 because of scalability concerns, but I'm leaving it here for people who are tempted to include it into version 1.2, and the patch is really clean.

  haproxy-1.2.14-leastconn.diff
• Soft Server-Stop

  Aleksandar Lazic sent me this patch against 1.1.28 which in fact does two things. The first interesting part allows one to write a file enumerating servers which will have to be stopped, and then sending a signal to the running proxy to tell it to re-read the file and stop using these servers. This will not be merged into mainline because it has indirect implications on security since the running process will have to access a file on the file-system, while current version can run in a chrooted, empty, read-only directory. What is really needed is a way to send commands to the running process. However, I understand that some people might need this feature, so it is provided here. The second part of the patch has been merged. It allowed both an active and a backup server to share a same cookie. This may sound obvious but it was not possible earlier.

  haproxy_comafile+multi-cookie.diff

  Usage: Aleks says that you just have to write the server names that you want to stop in the file, then kill -USR2 the running process. I have not tested it though.

• Server Weight

  Sébastien Brize sent me this patch against 1.1.27 which adds the 'weight' option to a server to provide smoother balancing between fast and slow servers. It is available here because there may be other people looking for this feature in version 1.1.
  I did not include this change because it has a side effect that with high or unequal weights, some servers might receive lots of consecutive requests. A different concept to provide a smooth and fair balancing has been implemented in 1.2.12, which also supports weighted hash load balancing.

  patch-haproxy-1.1.27-weight

  Usage: specify 'weight X' on a server line.
  Note: configurations written with this patch applied will normally still work with future 1.2 versions.

• IPv6 support for 1.1.27

  I implemented IPv6 support on client side for 1.1.27, and merged it into haproxy-1.2. Anyway, the patch is still provided here for people who want to experiment with IPv6 on HAProxy-1.1.

  haproxy-1.1.27-ipv6.diff
• Other patches

  Please browse the directory for other useful contributions.

Other Solutions

• Linux Virtual Servers (LVS)
  Very fast layer 3/4 load balancing merged in Linux 2.4 and 2.6 kernels. Should be coupled with Keepalived to monitor servers. This generally is the solution embedded by default in most IP-based load balancers.
• Nginx ('engine X')
  Nginx is an excellent piece of software. Initially it's a very fast and reliable web server, but it has grown into a full-featured proxy which can also offer load-balancing capabilities. Nginx's load balancing features are less advanced than haproxy's but it can do extra things (eg: caching, running FCGI apps), which explains why they are very commonly found together. I strongly recommend it to whoever needs a fast, reliable and flexible web server !
• Pound
  Pound is very small and reasonably good. It aims at remaining small and auditable prior to being fast. It used to support SSL and keep-alive before HAProxy. Its configuration file is small and simple. It's thread-based, but can be a simpler alternative to HAProxy for a small site when the flexibility and performance of HAProxy are not required.
• Pen
  Pen is a very simple load balancer for TCP protocols. It supports source IP-based persistence for up to 2048 clients. Supports IP-based ACLs. Uses select() and supports higher loads than Pound but will not scale very well to thousands of simultaneous connections. It's more versatile however, and could be considered as the missing link between HAProxy and socat.

Contacts

• mailing-list :
  Read the list archives on mail-archive
  Read the list archives on Marc.info(temporarily broken)
  Read the list archives on gmane.org(temporarily broken)
  Subscribe to the list :
  Unsubscribe from the list :
• Willy' main site : http://1wt.eu/
• This site in IPv6 only : http://ipv6.haproxy.org/ (should be OK if you see a green square here ⇒ )
• e-mail :

Some people regularly ask if it is possible to send donations, so I have set up a Paypal account for this. Click here if you want to donate.

An IRC channel for haproxy has been opened on FreeNode (but don't seek me there, I'm not) :

irc://irc.gnu.org/%23haproxy

https://slack.haproxy.org/

External links

• Linux networking stack from the ground up (parts 1-5) (useful to whoever wants to know what happens below haproxy)