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جدول مقایسه مدل های سوئیچ سیسکو Nexus 9500 در لینک زیر :
http://faradsys.com/nexus-9500/
در این جدول توانایی سخت افزاری سوئیچ های سیسکو سری Nexus 9000 را مبنای مقایسه قرار گرفته است . جهت کسب جزئیات بیشتر در مورد این سوئیچ ها می توانید به صفحه سوئیچ سیسکو Nexus 9000 مراجعه کنید . همچنین پیشنهاد می شود از دانش متخصصان نیز بهره مند شوید.
سوئیچ سیسکو Nexus 9000 یکی از محصولاتی است که کمپانی سیسکو به بازار عرضه کرده است . این مدل از سوئیچ ها نیز از قابلیت های ویژه ای برخوردارند ، یکی از این توانمندی ها بهره وری کاراتر و بهینه تر از توان مصرفی می باشد و این امر موجب صرفه جویی چشم گیری در مصرف انرژی برق می شود . دیگر قابلیت این سوئیچ ، تعدد در پورت است که منجر می شود این محصول را بتوان در محیط های بسیار بزرگ بکار برد. سوئیچ Nexus 9000 نیز مانند سایر محصولات هم رده خود زمان تاخیری کمی را ارائه می دهد . این ویژگی افزایش سرعت عملیات I/O را به ارمغان می آورد . همچنین بستر مناسب برای این محصولات نرم افزار NX-OS کمپانی سیسکو و یا زیرساخت مرکزی اپلیکیشن (ACI) با تکنولوژی Cloud Scale ASIC می باشد. این دسته از محصولات کمپانی سیسکو برای استقرار و بکارگیری در دیتاستر های سنتی و تمام اتوماتیک ایده آل می باشند.
Cloud Scale : این تکنولوژی یک مـــــــــزیت خلاقانه دو ساله را به همراه دارد . درواقع فناوری 16 نانومتری که در مقیاس بزرگتر ارائه می دهد هفت برابر سریع تر از Endpoint Density
می باشد . می توان گفت که با این تکنــــــولوژی کاربران می توانند برنامه های خود را با افزایش سرعت 50 درصدی، داشته باشند.همچنین از قابلیت مانیتورینگ نیز بهره مند شوند. قابلیت
مانیتورینگ از طریق سنسورهای Tetration سیسکو و بافر های هوشمند ارائه می شود.به کمک تکنولوژی Cloud Scale می توان عملکرد بهتر و لذت پیشرو بودن در صنعت، را تجربه کرد.
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به همراه داشتن تکنولوژی Cloud Scale ASIC
امکان برنامه پذیر بودن DevOps
کاملا اتوماتیک
داشتن معماری انعطاف پذیر
مقیاس پذیر بودن
دارا بودن قابلیت مانیتورینگ بلادرنگ و مانیتورینگ از راه دور
منبع : فاراد سیستم
سوئیچ سیسکو Nexus 9000 یکی از محصولاتی است که کمپانی سیسکو به بازار عرضه کرده است . این مدل از سوئیچ ها نیز از قابلیت های ویژه ای برخوردارند ، یکی از این توانمندی ها بهره وری کاراتر و بهینه تر از توان مصرفی می باشد و این امر موجب صرفه جویی چشم گیری در مصرف انرژی برق می شود . دیگر قابلیت این سوئیچ ، تعدد در پورت است که منجر می شود این محصول را بتوان در محیط های بسیار بزرگ بکار برد. سوئیچ Nexus 9000 نیز مانند سایر محصولات هم رده خود زمان تاخیری کمی را ارائه می دهد . این ویژگی افزایش سرعت عملیات I/O را به ارمغان می آورد . همچنین بستر مناسب برای این محصولات نرم افزار NX-OS کمپانی سیسکو و یا زیرساخت مرکزی اپلیکیشن (ACI) با تکنولوژی Cloud Scale ASIC می باشد. این دسته از محصولات کمپانی سیسکو برای استقرار و بکارگیری در دیتاستر های سنتی و تمام اتوماتیک ایده آل می باشند.
Cloud Scale : این تکنولوژی یک مـــــــــزیت خلاقانه دو ساله را به همراه دارد . درواقع فناوری 16 نانومتری که در مقیاس بزرگتر ارائه می دهد هفت برابر سریع تر از Endpoint Density
می باشد . می توان گفت که با این تکنــــــولوژی کاربران می توانند برنامه های خود را با افزایش سرعت 50 درصدی، داشته باشند.همچنین از قابلیت مانیتورینگ نیز بهره مند شوند. قابلیت
مانیتورینگ از طریق سنسورهای Tetration سیسکو و بافر های هوشمند ارائه می شود.به کمک تکنولوژی Cloud Scale می توان عملکرد بهتر و لذت پیشرو بودن در صنعت، را تجربه کرد.
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به همراه داشتن تکنولوژی Cloud Scale ASIC
امکان برنامه پذیر بودن DevOps
کاملا اتوماتیک
داشتن معماری انعطاف پذیر
مقیاس پذیر بودن
دارا بودن قابلیت مانیتورینگ بلادرنگ و مانیتورینگ از راه دور
منبع : فاراد سیستم
switch
A network switch (also called switching hub, bridging hub, officially MAC bridge[1]) is a computer networking device that connects devices together on a computer network by using packet switching to receive, process, and forward data to the destination device.
A network switch is a multiport network bridge that uses hardware addresses to process and forward data at the data link layer (layer 2) of the OSI model. Some switches can also process data at the network layer (layer 3) by additionally incorporating routing functionality that most commonly uses IP addresses to perform packet forwarding; such switches are commonly known as layer-3 switches or multilayer switches.[2]
Switches for Ethernet are the most common form, and 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]
Cisco small business SG300-28 28-port Gigabit Ethernet rackmount switch and its internals
A switch is a device in a computer network that electrically and logically connects together other devices. 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 regulate the flow of traffic. This maximizes the security and efficiency of the network.
When a repeater hub is replaced with an Ethernet switch, the single large collision domain used by the hub is split up into smaller ones, reducing or eliminating the possibility and scope of collisions and, as a result, increasing the potential throughput. Because broadcasts are still being forwarded to all connected devices, the newly formed network segment continues to be a broadcast domain.
A switch is more intelligent than a repeater 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.
Network design[edit]
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 ones at a time, and the transmissions will not interfere – with the limitation that, 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]
In the case of using a repeater hub, only a single transmission could take place at a time for all ports combined, so they would all share the bandwidth and run in half duplex. Necessary arbitration would also result in collisions, requiring retransmissions.
Applications[edit]
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 converged 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) protocol.
Micro-segmentation[edit]
Segmentation involves the use of a bridge or a switch (or a router) 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 without collisions. Full-duplex mode has only one transmitter and one receiver per "collision domain", making collisions impossible.
Role of switches in a network[edit]
Switches may operate at one or more layers of the OSI model, including the data link and network layers. A device that operates simultaneously at more than one of these layers is known as a multilayer switch.
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-T G.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 easier at layer 3 or via routing.[6] Devices that interconnect at the layer 3 are traditionally called routers, so layer 3 switches can also be regarded as relatively primitive and specialized 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]
In other cases, the switch is used to create a mirror image of data that can go to an external device. Since most switch port mirroring provides only one mirrored stream, network hubs can be useful for fanning out data to several read-only analyzers, such as intrusion detection systems and packet sniffers.
Layer-specific functionality[edit]
Main article: Multilayer switch
A modular network switch with three network modules (a total of 24 Ethernet and 14 Fast Ethernet ports) and one power supply.
While switches may learn about topologies at many layers, and forward at one or more layers, they do tend to have common features. Other than for high-performance applications, modern commercial switches use primarily Ethernet interfaces.
At any layer, 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.
Layer 1 (hubs vs. higher-layer switches)[edit]
A network hub, or a repeater, is a simple network device that does not manage any of the traffic coming through it. Any packet entering a port is flooded out or "repeated" on every other port, except for the port of entry. Specifically, each bit or symbol is repeated as it flows in (with a minimum delay for the line interface). Due to this, a repeater hub can only receive and forward at a single speed.[12] Since every packet is repeated on every other port, packet collisions affect the entire network, limiting its overall capacity.
There are specialized applications in which a network hub can be useful, such as copying traffic to multiple network sensors. High-end network switches usually have a feature called port mirroring that provides the same functionality.
A network switch creates the layer 1 end-to-end connection only virtually, while originally it was mandatory. The bridging function of a switch uses information taken from layer 2 to select for each packet the particular port(s) it has to be forwarded to, removing the requirement that every node is presented with all traffic. As a result, the connection lines are not "switched" literally, instead they only appear that way on the packet level.
By the early 2000s, there was little price difference between a hub and a low-end switch.[13]
Layer 2[edit]
A network bridge, operating at the data link layer, may interconnect a small number of devices in a home or the office. This is a trivial case of bridging, in which 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.
Classic bridges may also interconnect using a spanning tree protocol 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. The older IEEE 802.1D spanning tree protocol could be quite slow, with forwarding stopping for 30 seconds while the spanning tree reconverged. A Rapid Spanning Tree Protocol was introduced as IEEE 802.1w. The newest standard Shortest path bridging (IEEE 802.1aq) is the next logical progression and incorporates all the older Spanning Tree Protocols (IEEE 802.1D STP, IEEE 802.1w RSTP, IEEE 802.1s MSTP) that blocked traffic on all but one alternative path. IEEE 802.1aq (Shortest Path Bridging SPB) allows all paths to be active with multiple equal cost paths, provides much larger layer 2 topologies (up to 16 million compared to the 4096 VLANs limit),[14] faster convergence, and improves the use of the mesh topologies through increased bandwidth and redundancy between all devices by allowing traffic to load share across all paths of a mesh network.[15][16][17][18]
While layer 2 switch remains more of a marketing term than a technical term,[citation needed] the products that were introduced as "switches" tended to use microsegmentation and full duplex to prevent collisions among devices connected to Ethernet. By using an internal forwarding plane much faster than any interface, they give the impression of simultaneous paths among multiple devices. 'Non-blocking' devices use a forwarding plane or equivalent method fast enough to allow full duplex traffic for each port simultaneously.
Once a bridge learns the addresses of its connected nodes, it forwards data link layer frames using a layer 2 forwarding method. There are four forwarding methods a bridge can use, of which the second through fourth methods were performance-increasing methods when used on "switch" products with the same input and output port bandwidths:
Store and forward: the switch buffers and verifies each frame before forwarding it; a frame is received in its entirety before it is forwarded.
Cut through: the switch starts forwarding after the frame's destination address is received. There is no error checking with this method. When the outgoing port is busy at the time, the switch falls back to store-and-forward operation. Also, when the egress port is running at a faster data rate than the ingress port, store-and-forward is usually used.
Fragment free: a method that attempts to retain the benefits of both store and forward and cut through. Fragment free checks the first 64 bytes of the frame, where addressing information is stored. According to Ethernet specifications, collisions should be detected during the first 64 bytes of the frame, so frames that are in error because of a collision will not be forwarded. This way the frame will always reach its intended destination. Error checking of the actual data in the packet is left for the end device.
Adaptive switching: a method of automatically selecting between the other three modes.[19][20]
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.
Layer 3[edit]
Within the confines of the Ethernet physical layer, a layer-3 switch can perform some or all of the functions normally performed by a router. The most common layer-3 capability is awareness of IP multicast through IGMP snooping. With this awareness, a layer-3 switch can increase efficiency by delivering the traffic of a multicast group only to ports where the attached device has signalled that it wants to listen to that group.
Layer 4[edit]
While the exact meaning of the term layer-4 switch is vendor-dependent, it almost always starts with a capability for network address translation, but then adds some type of load distribution based on TCP sessions.[21]
The device may include a stateful firewall, a VPN concentrator, or be an IPSec security gateway.
Layer 7[edit]
Layer-7 switches may distribute the load based on uniform resource locators (URLs), or by using some installation-specific technique to recognize application-level transactions. A layer-7 switch may include a web cache and participate in a content delivery network (CDN).[22]
Types of switches[edit]
A rack-mounted 24-port 3Com switch
Form factors[edit]
Switches are available in many form factors, including: desktop units not mounted in an [[enclosure (engineering)|enclosure] 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; large chassis units with swappable module cards; 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 FTTO Infrastructures.
This section is in a list format that may be better presented using prose. You can help by converting this section to prose, if appropriate. Editing help is available. (November 2014)
Configuration options[edit]
Unmanaged switches – these 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 – these 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 marketed today:
Smart (or intelligent) switches – these are managed switches with a limited set of management features. Likewise "web-managed" switches are switches which 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.[23]
Enterprise managed (or fully managed) switches – these 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 larger number of switches and connections, where centralized management is a significant savings in administrative time and effort. A stackable switch is a version of enterprise-managed switch.
Typical switch management features[edit]
A couple of managed D-Link Gigabit Ethernet rackmount switches, connected to the Ethernet ports on a few patch panels using Category 6 patch cables (all equipment is installed in a standard 19-inch rack)
Turn particular port range on or off
Link bandwidth and duplex settings
Priority settings for ports
IP management by IP clustering
MAC filtering and other types of "port security" features which prevent MAC flooding
Use of Spanning Tree Protocol (STP) and Shortest Path Bridging (SPB) technologies
Simple Network Management Protocol (SNMP) monitoring of device and link health
Port mirroring (also known as: port monitoring, spanning port, SPAN port, roving analysis port or link mode port)
Link aggregation (also known as bonding, trunking or teaming) allows the use of multiple ports for the same connection achieving higher data transfer rates
VLAN settings. Creating VLANs can serve security and performance goals by reducing the size of the broadcast domain
802.1X network access control
IGMP snooping
Traffic monitoring on a switched network[edit]
Unless port mirroring or other methods such as RMON, SMON or sFlow are implemented in a switch,[24] it is difficult to monitor traffic that is bridged using a switch because only the sending and receiving ports can see the traffic. These monitoring features are rarely present on consumer-grade switches.
Two popular methods that are specifically designed to allow a network analyst to monitor traffic are:
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.
Another method to monitor may be to connect a layer-1 hub between the monitored device and its switch port. This will induce minor delay, but will provide multiple interfaces that can be used to monitor the individual switch port.
منبع : ویکی پدیا
Cisco Nexus solutions simplify the data center network by converging LANs and SANs, using Data Center Bridging (DCB), Fibre Channel over Ethernet (FCoE)protocols, and Unified Ports.
Cisco Nexus solutions help enterprises scale for the more-complex workloads of virtualization, the proliferation of virtual machines, and the challenges of cloud computing.
Cisco Nexus delivers intelligent services directly into the network fabric. It transparently extends the network to encompass all network locations into a single, extended environment with consistent services and policy.
منبع : cisco.com
پلت فرم سیسکو Nexus 5600 از اتصالات گسترده ای پشتیبانی می کند . قابلیت هایی که این محصول دارد زمان تاخیر کم و پشتیبانی از تکنولوژی (Virtual Extensible LAN (VXLAN می باشد . این قابلیت ها سوئیچ فوق را به یک سوئیچ ایده آل جهت دسترسی به Access Point و (End-of-Rack (EoR تبدیل کرده است. از دیگر توانمندی های این پلت فرم می توان به سریع تر شدن دسترسی به (Fabric Extender (FEX ، همگراشدن ، مجازی سازی و توسعه ابری (Cloud) اشاره کرد .
ویژگی ها :
امکان ارائه مقیاس پذیری در ابعاد بزرگتر
ایجاد سهولت بیشتر در عملیات
پشتیبانی از معماری انعطاف پذیر
سوئیچ سیسکو Nexus 5500 یکی از انواع سوئیچ های " سیسکو nexus 5000 " است که از قابلیت همگرایی پشتیبانی می کند . این قابلیت از طریق اتصالات گسترده ای که سرعت بالایی دارند ، ارائه می شود . قابلیت بیان شده منجر شده است که سوئیچ Nexus 5500 جهت دسترسی به top-of-rack در محیط های سنتی بسیار ایده آل و مناسب باشد .
ویژگی ها :
امکان ارائه مقیاس پذیری در ابعاد بزرگتر
ایجاد سهولت بیشتر در عملیات
پشتیبانی از معماری انعطاف پذیر
سوئیچ سیسکو X انواع سوئیچ سیسکو X قیمت سوئیچ سیسکو X نصب سوئیچ سیسکوX پیکربندی سوئیچ سیسکو X ارائه راه کار های سوئیچینگ X سوئیچ سیسکو Nexus 5000 X سوئیچ سیسکو Nexus X سوئیچ سیسکو Catalyst
یکی دیگر از محصولات میان رده کمپانی سیسکو ، سوئیچ های سری Nexus 5000 می باشد . این سوئیچ ها نیز جهت ارائه (ToR)وtop-of-rack با گنجایش و ظرفیت بالا در لایه های 2 و 3 بهینه شده اند. یکی از قابلیت های چشم گیر این رده از محصولات ، پشتیبانی از 10/40 گیگابیت اترنت می باشد . کمپانی سیسکو این محصولات را در فرم فاکتورهای 2 و 4 یونیت با پورت های متعدد طراحی کرده است . سوئیچ های سری Nexus 5000 مانند بخشی از Cisco Unified Fabric portfolio ، در دو پلت فرم Nexus 5500 و Nexus 5600 به بازار عرضه شده اند .
این محصولات از مجموعه کامل ویژگی های جامع NX-OS پشتبانی می کنند و علاوه بر این قابلیت مقیاس پذیری را تا 10/40 گیگابیت اترنت ارائه می دهند . ویژگی های بیان شده از سوئیچ سیسکو Nexus 5000 توانمند کردن این محصولات شده است . از جمله قابلیت های دیگری که می توان به آنها اشاره کرد کارایی بالا و بهره وری عملیاتی است . لازم به ذکر است که طراحی بکار رفته در این محصولات بسیار انعطاف پذیر است .
منبع : فاراد سیستم
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سوئیچ های لایه 2 : در مدل ارتباطات OSI یک سوئیچ در Layer 2 یا لایه Data-link عمل کرده و توابع سوئیچینگ را اجرا می کند . این نوع ، ساده ترین مدل سوئیچ ها می باشند . به عبارت دیگر، این مدل از سوئیچ ها “مک آدرس ” را با توجه به packet or data unit تعیین می کند. . سوئیچ های لایه 2 ساده ترین نوع از سوئیچ ها می باشند .مانند سوئیچ 2960
سوئیچ های لایه 3 : در شبکه های گسترده ای مانند اینترنت، تعیین آدرس مقصد نیازمند جستجو در جدول مسیریابی می باشد . با وجود اینکه این عمل توسط روتر انجام می شود اما برخی از سوئیچ های امروزه قابلیت انجام عمل routing را نیز دارند . این مدل از سوئیچ ها که قادر به انجام توابع مسیریابی هستند در لایه 3 یا لایه شبکه مدل OSI قرار می گیرند . سوئیچ های لایه 3 را می توان ، سوئیچ های IP نامید. به عنوان مثال می توان به انواع سوئیچ سیسکو اشاره کرد از جمله سوئیچ سیسکو 6500 Catalyst ، سوئیچ سیسکو Catalyst 6800 و سوئیچ سیسکو Nexus از این مدل سویئچ ها می باشند .
منبع : فاراد سیستم
سوئیچ دستگاهی است که در شبکه های مخابراتی مورد استفاده قرار می گیرد. کاری که سوئیچ به انجام می رساند این است که داده های ورودی را از هر یک از پورت های ورودی چندگانه ، به پورت خروجی خاص هدایت می کند ، به این ترتیب اطلاعات در مقصد مورد نظر دریافت می شوند . در شبکه تلفن سنتی (circuit-switched) ، یک یا چند سوئیچ به کار گرفته می شوند . این سوئیچ ها یک مدار اختصاصی را جهت برقراری اتصال موقت ، بوجود می آورند ، به این ترتیب ارتباط بین دو یا چند نفر برقرار می شود. در شبکه محلی اترنت (LAN) ، یک سوئیچ با توجه به فریم ورودی آدرس فیزیکی ( MAC آدرس ) مقصد را تعیین می کند و فریم حاوی دیتا را به طور مستقیم به سمت مقصد هدایت می کند . در شبکه گسترده مانند اینترنت، سوئیچ آدرس مقصد را با توجه به آدرس IP که در هر بسته دیتا به طور اختصاصی تعریف شده است؛ مشخص می کند. از جمله مهمترین کمپانی های تولید کننده سوئیچ ، کمپانی سیسکو است که سوئیچ های سیسکو را در مدل های مختلف تولید می کند .