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Cisco & Cisco Network Hardware News and Technology

What is Cisco Chassis, Backplane, and Line Card?

December 30 2011 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco Routers

  Chassis, You Know Here:

A Chassis is a frame/housing for mounting the circuit components for Cisco Switches and Routers or any type of devices that provides power and a high-speed backplane. The frame also protects all of the vital internal equipment from dust, moisture, and tampering.









Making the Chassis to define even easier is;
A chassis is an enclosure; a container that holds things together... i.e. an egg carton holds eggs together inside. A chassis does the same thing; it holds the important things inside like wiring, power supplies etc.








General info of BackplaneCisco-Backplane.jpg

Backplane is a circuit board with sockets that allows Supervisor engines Cards or modules to be inserted into these sockets and connect them to each other. Backplane is mounted on the Chassis.

Modules or line cards provide different types of interfaces, but the processing of packets is usually done in the Supervisor engine. Backplane is the medium for data flow between modules and Supervisor engines.

Additionally, most high-end switches off-load processing away from the supervisors, allowing line cards to switch traffic directly between ports on the same card without using any processing power or even touching the backplane. Naturally, this can't be done for all traffic, but basic layer-2 switching can usually be handled exclusively by the line card, and in many cases also more complex operations can be handled as well.

What is Line Card?
The line cards provide interfaces to the network.

A line card can terminate a line supporting voice POTS service, ISDN service, DSL service, or proprietary ones. Some line cards are capable of terminating more than one type of service.

Since an access network element is usually intended to interface many users (typically a few thousands) some exchanges have multiple line terminations per card. Similarly, it is common to have many line cards in the same network element.


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How to Connect Cisco Console Cable to PC/Laptop Running Linux?

December 29 2011 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco Routers

People who work with Cisco network equipment need to be able to connect to the console port on their devices. In Windows, you can simply fire up HyperTerminal to get basic access to your devices. If you are using Linux, then you need to know how this can be done with an application called Minicom.




First, you are going to need a Cisco console cable, a Cisco device, and a computer. If your computer has a serial port, then you can use the standard console cable that comes with every Cisco device.


If you do not have a serial port (like most new laptops), then you need to purchase a USB to Serial adapter that supports Linux. Many of them do not require a driver in Linux. Make sure the item is plugged in at boot time & the system should find it. This device will allow you to use the standard Cisco cable which has a DB9 serial connector on one end & an RJ45 connector on the other.


Install Minicom

You can easily install Minicom by using "System > Administration > Synaptic Package Manager". Search for "minicom" and choose to install the package. Click "Apply" and Minicom should be installed within a few seconds.


Find the name of your serial port

Next, you need to find out is which device your serial (including the USB adapter) ports are mapped to. The easiest way to do this is to connect the console cable to a running Cisco device. Now open up a Terminal using "Applications > Accessories > Terminal" and type this command:

dmesg | grep tty


The output will look something like one of these:

[    0.788856] serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A

[    0.789144] 00:08: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A

[94023.461242] usb 2-1: pl2303 converter now attached to ttyUSB0

[107561.131086] type=1503 audit(1260922689.994:33): operation="open" pid=27195 parent=27185 profile="/usr/sbin/cupsd" requested_mask="w::" denied_mask="w::" fsuid=0 ouid=0 name="/dev/ttyUSB0


Look in this output for words that contain "tty". In this case, it is "ttyS0". That means the name of the device that corresponds to your serial port is "ttyS0". The name of your device that corresponds to your USB port has a definition of name="/dev/ttyUSB0" (make sure it's plugged in). Now we are ready to configure Minicom to use this information.


Configure Minicom

Open a terminal using "Applications > Accessories > Terminal". Now type this command to enter the configuration menu of Minicom:

sudo minicom -s


Use the keyboard arrow keys to select the menu item labeled "Serial Port Setup" and then hit "Enter". This will open a window that looks similar to the one below:


Change your settings to match the ones in the picture above. Here is what I had to change:

  • Change the line speed (press E) & change to "9600"
  • Change the hardware flow control (press F) & change to "No"
  • Change the serial device (press A) & change to "/dev/ttyS0"
  • Or to use your USB port, change the serial device to "/dev/ttyUSB0"
    • Be sure to use the device name that you learned with the grep output.


Once your screen looks like mine, you can hit "Escape" to go back to the main menu. Next, you need to select "Save setup as dfl" and hit "Enter" to save these settings to the default profile. Then select "Exit Minicom" to exit Minicom... 说明: ;)


To find out if you have configured Minicom correctly, type this command in the terminal:

sudo minicom


After entering your Ubuntu user password, you should be connected to your Cisco device.


Once inside, press Ctrl+A, to access minicom commands. Press 'Ctrl+A', then 'Z' to access help. Ctrl-A, then another letter, like 'X' & you will eXit. Help will show a list of available commands.


Note: You may want to delete the Minicom init string if you see a bunch of gibberish every time you connect to a device. To do this, enter Minicom configuration with:

sudo minicom -s


Then select "Modem and dialing". Press "A" to edit the Init string, and delete all characters so that it becomes empty. Make sure you save this to the default profile with "Save setup as dfl". You should no longer see gibberish when you connect to devices.


Create a desktop launcher

If you want to have quicker access to Minicom, you can create a desktop launcher.

  1. Right-click on the desktop and choose "Create launcher"
  2. Click on "Icon" and choose the picture you want to use
  3. Use the "Type" pull-down menu and select "Application in terminal"
  4. Create a name like "Cisco Console" in the field labeled "Name"
  5. Enter this command into the field labeled "Command"
    • sudo minicom
  6. Hit "OK" and your desktop launcher is ready for you to use.
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Cisco Catalyst 4500 Switches, Key Features and Hot Models

December 28 2011 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco Switches - Cisco Firewall

The Cisco Catalyst 4500 switch is a mid-range modular chassis network switch manufactured by Cisco Systems. A Cisco Catalyst 4500 comprises a chassis, power supplies, one or two supervisors, line cards and service modules.



The Cisco Catalyst 4500 Series includes two series of Catalyst chassis: The Classic and newly launched E-Series chassis. The Classic and E-Series Catalyst 4500 chassis come in four sizes: 3-slot (4503-E), 6-slot (4506-E), 7-slot (4507R+E/4507R-E), and 10-slot (4510R+E/4510R-E).


The Cisco Catalyst 4500 Series Switches enable borderless networks, providing high performance, mobile, and secure user experience through Layer 2-4 switching investments. It enables security, mobility, application performance, video, and energy savings over an infrastructure that supports resiliency, virtualization, and automation.


Cisco 4500 Series Switches provide borderless performance, scalability, and services with reduced total cost of ownership and superior investment protection.


Key features you need to be clear:

Performance and Density:

848 Gbps fabric with 48 Gbps per slot delivers a 2.6x increase in performance over previous generation

Industry’s highest PoEP port density with up to 240 ports of full 30 Watt PoEP


Application Performance:

Unprecedented layer 2 - 4 application visibility and control with Flexible NetFlow

Only modular access platform that can guarantee Service Level Agreements with IP SLA



Cisco TrustSec with 802.1ae (MACSec) hop-by-hop encryption and Security Group Tags (hardware-ready)

Anomaly and malware prevention through predefined, policy-based responses with Flexible NetFlow



End-to-end campus deployment with single software release and common sparing

Complete Life Cycle Management: Design, Install, Operations and Upgrades

Simplified software licensing with a single image for LAN Base, IP base and Enterprise Services software


Operational efficiency:

In Service Software Upgrades for industry leading availability

Zero-touch, intelligent provisioning through Auto SmartPorts, AutoInstall and AutoQoS

Comprehensive automation with Cisco IOS Embedded Event Manager

Proactive diagnostics and remediation with Cisco Smart Call Home

Industry-leading power management with Cisco EnergyWise


Investment protection:

Backward and forward compatibility

Industry-leading investment protection with more than 10 years of backward compatibility

The benefits of Supervisor 7-E without line card upgrades


More details related to Cisco 4500 switches

Catalyst 4500 Line Cards

The Cisco Catalyst 4500 Series offers two classes of line cards: classic and E-Series. Classic line cards provide 6 gigabits of switching capacity per slot. E-Series line cards increase the per slot switching capacity to 24 gigabits.


Cisco 4500 switch power supplies

The Cisco 4500 is able to deliver high densities of Power over Ethernet across the chassis. Due to this, power supplies are a key element of configuration. The Cisco Catalyst 4500 E-Series offers AC power with several internal supplies: 1000W (data only), 1400W (data only), 1300W (data and PoE), 2800W (data and PoE), 4200W (data and PoE), and 6000W (data and PoE).


The Cisco Catalyst 4500 E-Series has two DC power options—one is optimized for data-only deployments in service provider central offices (part number PWR-C45-1400DC), and the other is used for high-power PoE deployments (PWR-C45-1400DC-P).


Operating systems

The Catalyst 4500 currently supports Cisco IOS Operating System.


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Cisco 6500 Series: Retired Veteran or Re-discovered Super Soldier?

December 27 2011 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco Switches - Cisco Firewall


Why Cisco 6500 Series is here to stay?


Tried and true isn't a descriptor awarded lightly. It's earned only after emerging battle-hardened from the front lines. It doesn't matter if you're the only survivor of the super-soldier program, or the flagship switch in the armada that is Cisco - history speaks for itself. For just a moment let's take a quick look at that history.



The Cisco 6500 was debuted in 1999 at the end of a decade that brought us legends such as Pogs, Street Fighter 2, and the Macarena. Even the popularity of the internet was only beginning to catch on.






We began with the Supervisor 1 and its 32gb switch fabric. Next, we graduated to the Supervisor 2 still at 32gb but with the ability to go to 256gb with the switch fabric module. Then we got the Supervisor 720. The 720 introduced 720gb switch fabrics, and then eventually the VSS (virtual switching system) which expanded even further to an upwards of 1.4Tbps!

Now, Cisco has debuted the Supervisor 2T which grows the upwards limits to 2Tbps, and doubles the per slot bandwidth from 40gb to 80gb! 

In addition to the newer supervisor engines, the chassis has also evolved. Now with the E series chassis, the Cisco Catalyst 6500 is capable of supporting the larger wattage power supplies and the newer supervisors and line cards. While it looks the same, these subtle differences help push the platform into the next generation.



What does that mean for the future of the Cisco 6500 platform?

Well with the announcement of new non-blocking 10gb cards and mention of 40gb support coming, it means that the Cisco 6500 series is here to stay. Some are saying it's here to stay for another 10 years. Bold words from an already aging platform. However, I'm reminded of the old adage "if it ain't broke, don't fix it." The Cisco 6500 switch was built around the idea of expandability, and dependability. It has proven itself time and again in both arenas.


So what does this mean for people who purchase pre-owned network hardware or are interested in the Catalyst 6500 switches? It means that purchasing a Cisco 6500 is an investment, and a wise one at that.


For people that already have the platform? They can continue to grow as needed, and as their companies and organizations grow. A recent Network World article mentioned that Cisco says it has 25,000 customers for the Catalyst 6500 and 700,000 chassis installed worldwide. That same article quoted John McCool, senior vice president and general management of Cisco's core technology group, saying: "We'd be silly to walk away from that installed base and loyal set of customers."


Knowing that Cisco is only continuing to develop for the 6500 platform is peace of mind that your budget dollars were spent well. In addition, new cards and expansions mean price drops and pre-owned market availability on current cards like the Supervisor 720s and 6700 series line cards in the not too distant future.


Cisco engineers like me are ready and willing to help you talk through your 6500 growth, and the needs and requirements that come along with it. We can help you navigate the sometimes slippery slope of your network hardware upgrades and save you time and money along the way.  We'd be happy to chat more in depth on the topic!


All things considered, the best just keeps getting better. The Cisco 6500 is here to stay and no one should feel bad about having this shield-slinging super-hero anywhere in their network. After all, it takes a veteran to show the new guys the ropes.



Comments from some Cisco fans:

 It still has its uses, but IMHO the highly oversubscribed, high latency networking architectures of the past won't make sense in the modern Data Center even at the access layer. Even looking at newer Cisco products like the 5548, let alone even higher density products from companies like Force10, Juniper, Brocade and Arista, which have substantially higher densities, substantially lower cost per port, substantially better performance across the board. Not to mention they all use a tiny fraction of the power and space and emit a tiny fraction of the heat. 


  Art Fewell: Cisco 6500 iEven re-purposing this box in the campus has limited utility because of the power, space and heating requirements. Given that the price of 10gig is coming down drastically (on other platforms) and most campus access switches come with 10gig uplinks, so many enterprises are upgrading their campus cores to support higher densities of 10gig. Other platforms can support 64 10gig ports in 1 rack unit with again a small fraction of the overhead costs. These newer platforms have such a lower cost basis that even used 6500's are substantially more expensive. Even keeping an existing 6500 is often much more in overhead costs than purchasing newer higher density equipment.       


Jason: Cisco 6500 is like the C-130 of the network devices. It does the heavy lifting of being the core router or switch of any enterprise or simply aggregating multiple devices on the edge of network. I think the reason it will go on for another decade, are the service modules, like ACE, NAM, VPN, FWSM, AIP etc... I think without these modules, having a 6500 in a SMB, would have been over kill.... The idea of integrating modules in 6500 is the main life saver of this legendary network ANVIL.                        

 Ali_A: I have been working with C6500 since 2000 .great product with great features. You can do whatever you want with the switch .it can be your Service Chassis switch, Campus, Core , … . I always love them and happy to hear that Cisco have plan to support them (maybe) for another decade. The C6500 show its stability and versatility it the battlefield.i still have C6500+SUP-2 with FWSM installed as datacenter service chassis with no problem and constant software update (SUP-2 lasted software update was 2010 even the device is EOS) take the product survived longer. Also the great blue-print, Deign guide , Cisco-SAFE for C6500 make everything straight when you want to deployment the switch in a scenario , more easier without the risk of wrong deployment or down-time.                    

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Cisco OnPlus: Managed Network Services Through SMB VARs

December 26 2011 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco Technology - IT News

Cisco OnPlus Service is offered at a list price of $250, which includes an OnPlus Network Agent appliance.



Expanding on its offerings to small business partners, networking specialist Cisco announced a cloud-based service called OnPlus that offers channel partners a way to provide network assessment, management and advisory services to their small business customers. By enabling value-added resellers (VARs) to create or expand their managed services practice, OnPlus aims to help to evolve the customer relationship from reactive and tactical to more proactive and strategic.


OnPlus Service is offered at a list price of $250, which includes a three-year subscription to the OnPlus service and an OnPlus Network Agent appliance. A separate appliance and subscription service is required for each network being managed. Native applications for Apple and Android mobile devices are available free of charge in the Apple App Store and the Android Market.


The announcement builds on Cisco's Partner Led sales model designed to elevate channel partners' ability to drive sales in the small business and midmarket segments. Earlier this year, Cisco announced it would invest $75 million in its Partner Led initiative throughout 2012, for enablement, systems and support capabilities to help channel partners profitably grow their business.


OnPlus is designed for VARs that are looking to create or expand their managed service offerings, providing remote visibility of the network and the devices attached to the network, through a scalable cloud-based service, OnPlus helps VARs deploy advanced network services for their small business customers from anywhere at any time. To monitor a customer network, VARs plug the OnPlus Network Agent appliance into a switch or router on their customer's network. The OnPlus Agent then transmits information about the customer's network to a secure data center for access by the VAR.


In addition to discovery and monitoring of anything with an IP address from any supplier, OnPlus enables remote connectivity to manageable network devices to facilitate troubleshooting and configuration. For select Cisco devices, OnPlus provides enhanced capabilities that automate typical administrative tasks. In addition, the network-centric capability of OnPlus complements existing classes of managed services tools such as remote monitoring and management and professional services automation.


"Liberty Technology focuses on making technology easy for both consumers and businesses. With Cisco OnPlus, you're able to get a more complete, 360-degree picture of your customer's network," said Ben Johnson, president of Liberty Technology, a Cisco certified partner. “We've used OnPlus in a number of scenarios from doing network surveys to quickly troubleshooting and identifying problems with customer's networks, which has greatly saved us time and of course money."


More Related: If you need to know more details of Cisco OnPlus, you can visit: http://blog.router-switch.com/2011/12/cisco-onplus-cloud-based-managed-services-launched-aimed-at-smbs/


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Cisco Static Routes FAQ: How to Use It?

December 23 2011 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco Switches - Cisco Firewall

Static routes while manually intensive to keep up, are a very quick and effective way to route data from one subnet to different subnet. Let’s start with the basics.

What is a static route?Holiday-Tree-of-Knowledge.jpg
- a static route is a hard coded path in the router that specifies how the router will get to a certain subnet by using a certain path.

What do you mean by "hard coded"?
- you or someone has typed in the network ID and the next hop to get to the network specified

How do I add a static route into my Cisco router?
- Pretty simple
router# config t ; get into the configuration mode
router(config)# ip route A.B.C.D (destination network/host) A.B.C.D (mask) A.B.C.D (next hop); this is a simple static route

Are there any other ways to name the next hop except by using an IP address?
- Yes, you can use the port name i.e. ethernet0, E0, S0 and so on

What is "distance metric" that I can add at the end of the command?
- All routes have a value that allows the router to give a priority to which type of routing is used first. In static routes, the value is 1 which means no matter what other protocol you may have running like OSPF or RIP, the static route will always be used first. This can be changed to special needs. for example, if you have a frame link with ISDN back up, you can static routes for the frame and a second set of the same static routes but with a distance matric of 255. This means while the frame is up, it goes first but when the frame goes down, the router will try to use the 2nd static which is normally ignored due to the 255 value.

Why do I want to use static routes when there are neat routing protocols like OSPF?
- static routes are easy, no overhead either on the link or the the CPU of the router. They also offer good security when coupled with a tight IP mask like 252 which gives only 2 hosts on a given link

If static routes are so easy, why not use them all the time?
- Static routes while easy can be overwhelming in a large or complicated network. Each time there is a change, someone must manually make changes to reflect the change. If a link goes down, even if there is a second path, the router would ignore it and consider the link down.

One of the most common uses of a static map is the default classless route
- ip classless
- ip route [next hop]

This static map says that everything is remote and should be forwarded to the next hop( or supernet) which will take care fo the routing.

Dial on demand is also a big user of static routes. Many times with dial up or ISDN, you do not have the bandwidth or you do not want to pay the connection fees for routing updates so you use static routes.

Static routes allow you to set up load balancing after a fashion. Keep in mind that the IOS load balances across routes first and not interfaces. The easiest way to configure multiple routes on the same interface is to use the secondary IP command

Router 1
interface serial 0
 ip address
 ip address secondary ! second route on same interface
interface serial 1
 ip address
 ip address secondary
ip route; goes to serial 0
ip route; goes to serial 0
ip route; goes to serial 1

Router 2
interface ethernet 0
 ip address
interface serial 0
 ip address
 ip address secondary
interface serial 1
 ip address
 ip address secondary
The traffic would go out router 1 across the two IPs on serial 0 first then across 1 IP on serial 1
This gives you unequal load balancing.
Notes: This is just the basics of static routing. You can get very creative if you want and take things further then described here. I would suggest "Routing TCP/IP Vol 1" from Cisco Press for more information.

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Network Switches: Functions & Types of Switches

December 22 2011 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco Switches - Cisco Firewall

Functions of a Network Switch

A switch is a device that is used at the Access or OSI Layer 2; a switch can be used to connect multiple hosts (PCs) to the network.


Unlike a hub, a switch forwards a message to a specific host. When any host on the network or a switch sends a message to another host on the same network or same switch, the switch receives and decodes the frames to read the physical (MAC) address portion of the message.


Forwards Frames with MAC address

When a message is sent between hosts on a network or the same switch, the switch checks its MAC address table for the destination address. A switch MAC address table contains a list of all active ports, host or PCs MAC addresses that are attached to it. If the destination MAC address is not found in the table, the switch will not have the necessary information to forward the message. When the switch cannot determine where the destination host is located, it will flood or forward the message out to all attached hosts. Each host compares the destination MAC address in the message to its own MAC address, but only the host with the correct destination address processes the message and responds to the it.


How Switches Learn MAC addresses

A switch builds its MAC address table by examining the source MAC address of each frame that is sent between hosts. When a new host sends a message or responds to a flooded message, the switch immediately learns its MAC address and the port to which it is connected. The table is dynamically updated each time a new source MAC address is read by the switch. In this way, a switch quickly learns the MAC addresses of all attached hosts.


Collision Prevention

A switch prevents collisions by providing a circuit between the source and destination ports. This circuit provides a dedicated channel over which the hosts connected to the various ports on the switch can communicate. Each port is allocated with a separate bandwidth; these separate circuits allow many conversations to take place at the same time, without collisions occurring.

Switch to PC connection



Main Types of Switches

Fixed configuration switches:- 

These types of switches are fixed in their configuration. What that means is that you cannot add features or options to the switch beyond those that originally came with the switch. The particular model you purchase determines the features and options available. For example, if you purchase a 24-port gigabit fixed switch, you cannot add additional ports when you need them. There are typically different configuration choices that vary in how many and what types of ports are included.


Modular switches: -

These types of switches offer more flexibility in their configuration. Modular switches typically come with different sized chassis that allow for the installation of different numbers of modular line cards the line cards actually contain the ports. The line card fits into the switch chassis like expansion cards fit into a PC. The larger the chassis, the more modules it can support.


Stackable Switches/

Stackable switches can be interconnected using a special back cable that provides high-bandwidth between the switches. Cisco introduced StackWise technology in one of its switch product lines. Stack Wise allows you to interconnect up to nine switches using fully redundant back plane connections. As you can see in the figure, switches are stacked one atop of the other, and cables connect the switches in daisy chain fashion. The stacked switches effectively operate as a single larger switch. Stackable switches are desirable where fault tolerance and bandwidth availability are critical and a modular switch is too costly to implement. Using cross-connected connections, the network can recover quickly if a single switch fails. Stackable switches use a special port for interconnections and do not use line ports for inter-switch connections. The speeds are also typically faster than using line ports for connection switches.


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How a Network Switch Forward Frames in Ethernet Network

December 19 2011 , Written by Cisco & Cisco Router, Network Switch

A switch uses different method of forwarding frames in Ethernet network. These methods are: Store-and-Forward or Cut-through Switching.


Store-and-Forward Switching

In store-and-forward switching, when the switch receives the frame, it stores the received data in buffers until the complete frame has been received. While in the storage process, the switch checks and analyses the frame for information about its intended destination. During this process, the switch checks the frame for errors using the Cyclic Redundancy Check (CRC) trailer portion of the Ethernet frame - a mathematical formula, based on the number of bits (1s) in the frame.

If the frame contains no error, the frame will be forwarded to the appropriate port towards its destination but when an error is detected the frame is dropped or discarded.


Cut-through Switching

In cut-through switching, the switch works on the frame soon as it is received, even if the transmission is not complete. The switch records destination MAC address so as to determine to which port to forward the data. The destination MAC address is located in the first 6 bytes of the frame following the foreword. The switch in this case does not perform any error checking on the frame.


Cut-through switching is faster than store-and-forward switching. However, because the switch does not check the frame for errors, it forwards corrupt frames throughout the network. The corrupt frames consume bandwidth while they are being forwarded. The destination NIC- Network Interface Card- will eventually drops or discards the corrupt frames.


Cisco Catalyst switches uses solely the store-and-forward method of forwarding frames


Most switches are configured to perform cut-through switching on a per-port basis until a user-defined error mark is reached and then they automatically change to store-and-forward. When the error rate falls below the threshold, the port automatically changes back to cut-through switching.


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Secure Networking

December 14 2011 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco Routers

Secure NetworkingSecure-Networking.jpg 

Our Self-Defending Network is an architectural solution designed for the evolving security landscape. Security is integrated everywhere and with the help of a lifecycle services approach, enterprises can design, implement, operate and optimize network platforms that defend critical business processes against attack and disruption, protect privacy, and support policy and regulatory compliance controls.

Using a Lifecycle approach to Services, Cisco and its partners provide a broad portfolio of Security Services that address all aspects of deploying, operating, and optimizing your network to help increase business value and return on investment






Unified Threat Management (UTM) is a comprehensive solution that has recently emerged in the Network security industry and since 2004, has gained widespread currency as a primary network gateway defense solution for organizations. In theory, it is the evolution of the traditional Firewall into an all-inclusive security product that has the ability to perform multiple security functions in one single appliance: network firewalling network intrusion prevention and anti-virus (AV), Gateway anti-spam VPN, content filtering, load balancing and on-appliance reporting.








Firewall Firewall.png / Cisco Firewall


A firewall is a part of a computer system or network that is designed to block unauthorized access while permitting authorized communications. It is a device or set of devices configured to permit, deny, encrypt, decrypt or proxy all (in and out) computer traffic between different Security gateway based upon a set of rules and other criteria.


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What Is a Layer 3 Switch? Router vs. Layer 3 Switches

December 12 2011 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco Switches - Cisco Firewall

Layer 3 switches were conceived as a technology to improve on the performance of routers used in large local area networks (LANs) like corporate intranets. The key difference between Layer 3 switches and routers lies in the hardware technology used to build the unit. The hardware inside a Layer 3 switch merges that of traditional switches and routers, replacing some of a router's software logic with hardware to offer better performance in some situations.

Layer 3 switches often cost less than traditional routers. Designed for use within local networks, a Layer 3 switch will typically not possess the WAN ports and wide area network features a traditional router will always have.


Discussion: Router vs. Layer 3 Switches   ---from Cisco learning home

Q: As we all know that Layer 3 switch can perform the routing tasks if routing is enabled. But I`ve some questions regarding this:

 1. What is the main difference between this two?

 2. What is the choosing criteria between this two i.e. when should I use which one? What’s about the cost effects?

 3. Why router is needed if there is existence of Layer 3 Switch?


Re1: L3 switches do not have WAN interfaces.

You can connect Ethernet circuits to a switch so you only need a router if you want to connect traditional circuits such as E1 E1 SDH or old technology such as X21 V35 or async circuits. As far as I know Call Manager Express does not run on a switch but does on a router. Switches support Wi-Fi controller, Firewall so are quite powerful. So you need to understand the business requirement before deciding router or switch. Also routers can include switch modules.


Re2: If it routes, it's a router.  说明: https://learningnetwork.cisco.com/4.5.3/images/emoticons/happy.gif

L3-switch is a marketing term.  It's a router with only Ethernet interfaces and lots of them.  It also has a switching function to it. Which makes it both a router and a switch? The differences will vary based on model.  It depends...  Cost varies as well, everywhere from inexpensive to very expensive! And truly there isn't a "need". You need an L3 device of some sort to exit your subnet. How you design that, or what specific piece you use is entirely up to you.


Re3: Traditionally, Routers were devices that connected the LAN to the WAN and switches were just LAN devices and you may add a layer 3 switch to the lan if you had some vlans and didn't want to use a router.


However, as technology changes, the tradition of the WAN and LAN are fading.  My "WAN" links are actually 1 gig single mode fiber circuits that terminate to an ethernet fiber interface on a Layer 3 switch, a 6500, 4500, 3750 or even a 3560.  Now some will say that I have a MAN with those kinds of links.  It seems that as Scott said, Cisco Marketing is still stuck on calling a router a device that terminates a traditional WAN link,  I do agree that if the device routes, it is a router.... to some degree.


One thing I did notice regarding routers and layer 3 switches, and I will admit that router model and IOS version may play very heavily into this, and that is Routers seem to support more traffic monitoring features, such as netflow and nbar where as Layer 3 switches don't seem to have that kind of support.... until you get to the 6500.


Re4: Technically, the differences are:

1- L3 Switch do switching at layer 3 by preserving the source and destination mac and preserving the TTL value of the IP header of the 1st routed packet, so the first packet is routed using normal routing lookup, but after that all packet are switched.

2- router do normal routing lookup, but by introducing fast switching and CEF, packets are also now switched on a router.

3- Switches doesnt support some QoS features.

4- Switches doesnt support NAT.

5- The forwarding on switches is done on ASIC (Application Specific Integrated Circuits) which is done in hardware rather than a software.

6- Forwarding on routers are done in a software.

7- router supports different WAN technologies (modules) unlike switches.


Re5: I was just thinking about this.  I didn't learn about Layer 3 switches until the bcmsn.  I know in CCNA they were still really pushing the router vs switch concept.  Talk about throwing a monkey wrench into things when you throw in the concept of Layer 3 switch.


So to review:

1. A pure router will do just that, typically no switch ports, in today’s cisco world I don't even know if they make one of these, wouldn't that be something like an ASA with 1 or (2) 100 mb or gig ports with a serial port or similiar?

2.  A switch will just allow connections to edge devices, a true layer 2 switch like a 2960, Int vlan's is what allows management of the switch at layer 3.  No routing between vlans, this is where router on a stick comes into play.

3.  A layer 3 switch integrates both abilities, but it depends on the model on how integrated and featurific it is.  Will it support netflow?  Will it route between vlans?  If you do a show ip route what will be displayed?  How does it implement vlans, is it traditional vlan.dat file or will it do the switching way with show vlan? -- The simplest true layer 3 switch will support all switching features, but have the ability to do routed ports and route between the vlans.  I have had a Integrated services router like a 1760 or 3725 or similiar where they had a small switch module, say 4-24 (100).


The definition of a layer 3 switch also may include the ability for a port to be either a routed port or a switched port, the commands switch port vs no switch port followed by having to assign it an ip address.


This is another point that also took some getting used to.  In a port that can be either layer 2 or layer 3, or strictly layer 3 or layer 2.    Example, a router can only do layer 3, so to do inter vlan routing  while connecting to another switch via  trunk port you have to give it sub interfaces to a physical switch port, give each one its own ip address and tag it with the encapsulation dot1q #.  Router on a stick, vs. switchport mode trunk command with layer 3 interfaces via the "int vlan 1" with an ip address assignment.


While I understand the ccna approach to teaching fundamentals and where thing started, it no doubts confuses someone especially when a question asks about the differences between a hub/switch/router.  In today’s world, hubs don't really exist, and in a large company odds are you’re going to be using a layer 3 switch.


Re6: Not sure that is accurate. I think most layer 3 switches can handle BGP, but to what extent? Full tables? Probably not. Dishing out money for 2 Cisco 2821's or Cisco 2921's is going to be way cheaper than purchasing another Cisco 6500 for our network....not to mention our Catalyst 6500 already does a lot of work...and now I am going to throw BGP at it....AH it would just shut off and give me the middle line card!

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