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Configuring VTP on a Cisco Switch

January 30 2012 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco Switches - Cisco Firewall

During the early days of networking, it was difficult to implement VLANs across networks. Each VLAN was manually configured on each network switch. Managing a large switched network used to be a complicated tasks, VLAN trunking methods has helped to ease this problem.

 

 VLAN Trunking Protocol (VTP) is a Cisco Proprietary which basic aim is to manage all configured VLANs across a switched network.  VTP helps to propagate and maintain VLAN configurations consistency to other switches on the network.

 

VTP is a messaging protocol that uses layer 2 trunk frames to add, delete and rename VLANs on a single domain. It helps to centralize changes which are sent to other switches on the network.

 

A switch had to be configured in the role of a VTP server to manage your VLAN configuration on your network. The sever(s) will share VLAN information with other switches on the network which must use the same domain name.

 

VTP learns only normal-range VLANs (VLAN IDs 1 to 1005).

The primary role of VTP is to maintain VLAN configuration consistency across a network administration domain.

 

VTP stores VLAN configurations in the VLAN database called vlan.dat.

After a trunk is established between switches, VTP advertisement is exchanged between the switches. Both the server switch and client exchange and monitor advertisement from one another to ensure each has an accurate record of VLAN information. VTP advertisement will not be exchanged if the trunk between the switches is inactive.

 

 

In the diagram above, a trunk link is configured between switch S1, - VTP Server, S2 and S3 - VTP client. After a trunk is established between the switches, VTP summary advertisement is exchanged among the switches.

 

More Notes:

VTP Configuration Guidelines 

Follow these steps to configure a Cisco Catalyst switch to use VTP successfully:

 

VTP Server Switches 

i. Before you begin configuration, ensure that all of the switches are set to their default settings.

 

ii. Always reset the configuration revision number before installing a previously configured switch into a VTP domain. Not resetting the configuration revision number allows for potential disruption in the VLAN configuration across the rest of the switches in the VTP domain.

iii. Configure at least two VTP server switches in your network. Because only server switches can create, delete, and modify VLANs, you should make sure that you have one backup VTP server in case the primary VTP server becomes disabled. If all the switches in the network are configured in VTP client mode, you cannot create new VLANs on the network.

 

iv. Configure a VTP domain on the VTP server. Configuring the VTP domain on the first switch enables VTP to start advertising VLAN information. Other switches connected through trunk links receive the VTP domain information automatically through VTP advertisements.

 

v. If there is an existing VTP domain, make sure that you match the name exactly. VTP domain names are case-sensitive.

 

vi. If you are configuring a VTP password, ensure that the same password is set on all switches in the domain that need to be able to exchange VTP information. Switches without a password or with the wrong password reject VTP advertisements.

 

vii. Ensure that all switches are configured to use the same VTP protocol version. VTP version 1 is not compatible with VTP version 2. By default, Cisco Catalyst 2960 switches run version 1 but are capable of running version 2. When the VTP version is set to version 2, all version 2 capable switches in the domain auto configure to use version 2 through the VTP announcement process. Any version 1-only switches cannot participate in the VTP domain after that point.

 

viii. Create the VLAN after you have enabled VTP on the VTP server. VLANs created before you enable VTP are removed. Always ensure that trunk ports are configured to interconnect switches in a VTP domain. VTP information is only exchanged on trunk ports.

 

VTP Client Switches 

i. As on the VTP server switch, confirm that the default settings are present.

ii. Configure VTP client mode. Recall that the switch is not in VTP client mode by default. You have to configure this mode.

iii. Configure trunks. VTP works over trunk links.

iv. Connect to a VTP server. When you connect to a VTP server or another VTP-enabled switch, it takes a few moments for the various advertisements to make their way back and forth to the VTP server.

v. Verify VTP status. Before you begin configuring the access ports, confirm that the revision mode and number of VLANs have been updated.

vi. Configure access ports. When a switch is in VTP client mode, you cannot add new VLANs. You can only assign access ports to existing VLANs.

 

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Cisco 7600 Series Router, Ideal for Enterprise WAN Aggregation

January 19 2012 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco Routers

Ideal for Enterprise WAN aggregation or service provider environments, Cisco 7600 series is the industry's first carrier-class edge router to offer integrated, high-density Ethernet switching, carrier-class IP/MPLS routing, and 10-Gbps interfaces, benefiting enterprises and helping enable service providers to deliver both consumer and business services over a single converged Carrier Ethernet network.

Cisco-7600.jpg

 

The Cisco 7600 Internet Router delivers optical wide- and metropolitan-area network (WAN and MAN) services with high-touch IP services at the network edge. Now, service providers (SPs) and enterprises can "service enable" their networks at optical speeds, providing competitive advantage and service differentiation to the SP and high-speed connectivity and link usage efficiency to the enterprise.

 

 

Cisco 7600 Router’s Key Features

High performance, with up to 720 Gbps in a single chassis, or 40 Gbps capacity per slot

A choice of form factors purpose-built for high availability

Cisco I-Flex design: A portfolio of shared port adapters (SPAs) and SPA interface processors (SIPs) that controls voice, video, and data experiences

Scalable and extensible suite of hardware and software capabilities to enable intelligent Carrier Ethernet services

Integrated Video Call Admission Control with innovative visual quality of experience for both broadcast and video on demand (VoD)

Intelligent Services Gateway, providing scalable subscriber and application awareness with multidimensional identity capabilities and policy controls

Integrated Session Border Control with quality of experience in both Session Initiated Protocol (SIP) and non-SIP applications

 

What Cisco 7600 series Supports

Supports Services modules such as IPsec, firewall, SSL VPN

Intrusion Prevention System (IPS) Modularity

Chassis supports up to 4-, 6-, 9-, and 13-slot chassis for redundant supervisors and line cards

Supervisor engines supporting up to 15 Mpps with broad range of edge services

Support for Shared Port Adapter (SPA) and SPA Interface Processors (SIP), which offers intelligent services.

Supports up to 12 SPA bays

Support for the Enhanced FlexWAN module, which offers Port Adapter investment protection

 

Cisco 7600 Router’s Price & Availability

Cisco 7600 series ranges from US$5000 to US$20000, not all the types are required by enterprise head offices. There are some 7600 series items such as Cisco 7606, Cisco 7609, Cisco 7609-S, Cisco 7606-S; these are popular among large enterprises. Prices of Cisco 7606 and Cisco 7609 are available here:

CISCO7606: List price: US$6,000.00 / Wholesale Price: US$2,940.00

CISCO7609: List price: US$10,500.00 / Wholesale Price: US$5,145.00

CISCO7606-S: List price: US$6,000.00 / Wholesale Price: US$2,940.00

CISCO7609-S: List price:  US$10,500.00 / Wholesale Price: US$5,145.00

 

If you want to know more pricing and purchasing information of Cisco router and other Cisco IT equipments, you can visit Cisco router at Router-switch.com…

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How to Use the Cisco Aironet 1242?

January 18 2012 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco Routers

The Cisco Aironet 1242 is a wireless access point created by Cisco. The main difference between this device and most other Cisco products is that the Aironet1242 provides support for mesh wireless networks. Mesh networks extend wireless network range by relaying information from an access point to other access points, instead of requiring that each access point have its own wired backbone connection.

Cisco Aironet 1240 Series

 

Ethernet cable you first need

 

Instructions to Use the Cisco Aironet 1242

1. Power on the 1242.

 

2. Connect your network switch to the "Ethernet" port on the back of the 1242, using the Ethernet cable.

 

3. Log in to any computer connected to the same network switch. Click "Start," then "Programs." Select "Accessories" and "Telnet." A new Telnet window will come up.

 

4. Click "Connect," then "Remote system" on the Telnet window. Type the Internet Protocol (IP) of the 1242; the default is 192.168.1.1. Click "Connect."

 

5. Type the following commands into the Telnet session to configure an IP address for the 1242:

configure terminal

interface bvi1

IP address 192.168.40.9 255.255.0.0

Replace "192.168.40.9" and "255.255.0.0" with the IP address and network mask, respectively, assigned to the 1242 by your network's administrator. Press "Enter" after each command.

 

6. Launch a Web browser on the computer and navigate to the Web address "http://192.168.40.9" (replace the IP address with the one assigned in Step 5). Type "Cisco" as the user name and "Cisco" as the password, then press "Enter." The 1242's configuration utility will come up on the browser.

 

7. Click "Express Set-up." Type a host name of your choice if the default value is already being used by another 1242 on the same network. Select "Enable" for the "Aironet Extensions" for both the 802.11a and the 802.11g radios. Click "Apply." At that point, the 1242 will provide a wireless network ready for client computers to join.



More Related: Password Recovery on Cisco 1242 Access Point

 



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CCNA Certification: IPv6 Features

January 16 2012 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco Routers

Main Feature of IPv6 

IPv6 address a lot concerns and issues that are faced today in using IPv4. Cisco CCNA Certification requires that a candidate must have a general overview of IPv6 and what new features it brings into the world of networking. Here we will go through some of the features of Internet Protocol Version 6 (IPv6).

 

The main feature of IPv6 are described in the sections below

Larger Address Space 

IPv6 addresses are 128-bits long which gives us a theoretical address space of 3.4 x 1038 addresses, like IPv4 some address space is reserved for special purpose but still there is a huge number of public routable addresses.

 

Aggregation 

A larger address space allows for large address allocations to ISPs and Organization. This allows them to use a single prefix for the entire network making summarization easy and flexible which turn promotes efficient and scalable routing.

 

New Improved Header Format

Optional and non-essential fields are removed from the IPv6 Header and are moved the Extension Header that is placed after the IPv6 Header. Fewer fields of fixed lengths mean Header overhead is minimized and processing performance is improved.  Another significant enhancement is that all routers in a path do need to do checksum recalculation for an IPv6 Packet instead error detection is handled by data-link layer technologies checksums of the end-to-end connection at transport layer. 

Allocation

IPv6 addresses are composed of two parts, 64-bit Network Prefix and 64-bit host part. The IPv6 address allocation follows a generally acceptable assignment policy as shown in figure 1. This allows for an efficient, hierarchical, and summarizable routing infrastructure.

 

Easy Address Assignment Methods

IPv6 has three assignment methods

  • Static
  • DHCPv6 (Stateful)
  • Autoconfiguration (Stateless)

An IPv6 host can configure a link-local address for each interface automatically. By using ICMPv6 router discovery messages, a host can also determine the addresses of routers, additional addresses, and other configuration parameters.

 

Built-in Security

IPSec is built into IPv6 unlike IPv4 in which it is optional. IPSec requirement is mandatory in IPv6 Protocol Suite Implementation. IPv6 networks have potentially more end-to-end security because of IPSec availability on all nodes.

 

Extensibility

New futures for IPv6 can be added through the use of Extension Headers. At present there are various Extension Headers specified for QoS, Security, Mobility and Routing purposes.

 

Mobility

Mobility is built in to IPv6 which allows any node to use Mobile IP. Mobility is achieved using Mobility Extension Headers.

 

Better Quality of Service Support

IPv6 Header includes a new field called Flow Label that allows routers to identify and provide special handling for packets that belong to a particular flow. This field allows for easier identification of traffic without doing any tricks even when the packet payload is encrypted with IPSec.

 

Neighbor Discovery Protocol

Neighbor Discovery Protocol uses ICMPv6 messages to perform various functions such as

  • Stateless Auto-configuration
  • Router Discovery
  • Prefix Discovery
  • Address Resolution
  • Neighbor Unreachability Detection
  • Link MTU Discovery
  • Duplicate Address Detection
  • Next Hop Determination

 

Transition

The transition options supported by IPv6 to transition from IPv4 are another key feature of the protocol. Many Transitions mechanism are available for different scenarios. They are mentioned below

  • Dual-Stack
  • Tunneling IPv6 over IPv4 networks
  • Protocol Translation

 

Within each option are various different techniques to support transition. A few tunneling mechanism are mentioned below

  • Static GRE Tunnels
  • 6to4 Tunnels
  • ISATAP
  • Automatic IPv4-Compatible IPv6 Tunnels

 

These rich features of IPv6 enable easy deployment, migration and operation of IPv6 networks.

 

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How to Make Your Web Site Popular?

January 13 2012 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco Routers

Anyone can put up a web site. The hard part is helping people discover it, and then stay with it. Your first priority: Make your site people friendly. Your second: Make it search-engine friendly.

Make-Your-Web-Site-Popular.jpg

Here are a few more specific suggestions:

Design it well. Make it pleasing to the eye, and easy to navigate. If the site has a lot of pages, develop a structure that people can easily navigate, rather than throwing too many links up at once.

 

Write well. Re-read your text before posting it. Correct spelling and grammar errors. Use clear and concise language.

 

Stick to your subject(s). Don't be all over the map with content. Keep the site focused, at most, on a handful of topics that you're passionate about.

 

Link with words, not pictures. For web navigation, a word is worth a million pictures. A link that reads "The eternal allure of the Three Stooges" says more about the page it leads to than a photo of Larry, Moe, and Curly. That holds true for search engines as well as for people.

 

Use title and description tags. Search engines give priority to the text in these tags, and usually display their contents in result pages. So think carefully about what you want to put here.

 

Try to read your title through the eyes of a stranger. It should clearly describe the page. See the comments on this post to see how I messed up in this area.

 

And where do you put this text? In your page's HTML code, the title text goes between the <title>and </title> tags. The description goes inside a meta tag that looks something like this:

·         <meta name="description" content="This is where you put the content of your description. It can be longer and thus more descriptive than a title." />.

 

Describe your images. When you do use pictures, give them descriptive file names. Also, describe the picture in the image tag's alt attribute. The Alt text is there for people who can't see the images, but it also helps search engines. In the HTML code, that tag looks something like this:

 

·         <img src="http://urltopicture/filename.jpg" alt="Put your alt text here" />.

 

Finally, links can be extremely helpful in drawing people to your site. That's one of several reasons why I always suggest that people read the original forum discussion. And then I include additional links in the italicized "bio" paragraph below.

 

More news and info about  networking you can visit: http://blog.router-switch.com/

 

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Overview on CISCO 7200VXR Series Routers

January 12 2012 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco Routers

With processing speeds up to 2 million packets per second, port- and service adapters ranging from NxDS0 to Gigabit Ethernet, and OC-3 as well as an unparalleled number of high-touch IP services, the Cisco 7200 VXR series is the ideal Services Aggregation WAN/MAN edge device for enterprises and service providers deploying any of the following solutions:

WAN edge-Award-winning quality-of-service (QoS) feature performance

Broadband aggregation-Up to 16,000 Point-to-Point Protocol (PPP) sessions per chassis

Multiprotocol Label Switching provider edge (MPLS PE)-Number one choice for provider edge deployment today

Voice/video/data integration-Time-division multiplexer (TDM)-enabled VXR chassis and voice port adapters

IP-to-IP Gateway Support-Direct IP-interconnections

IP Security virtual private networking (IPSec VPN)-Scalable to 5,000 tunnels per chassis

High-End Customer Premises Equipment (CPE)-For managed WAN services saving equipment, transport and administrative cost

 

The Cisco 7200 VXR addresses these solution requirements by integrating functions previously performed by separate devices into a single platform. Through this integration, the Cisco 7200 VXR provides a single, cost-effective platform that supports:

• High-density LAN and WAN interfaces

• Broadband subscriber services aggregation, including PPP, RFC 1483 termination, and Layer 2 Tunneling Protocol (L2TP) tunneling

• Digital T1/E1 TDM trunk termination for voice, video, and data

• High-density multichannel T3/E3 and T1/E1 with integrated channel service unit/data service unit (CSU/DSU)

• ATM and Packet over SONET (POS) connectivity

• ATM IMA (Inverse Multiplexing over ATM) for voice, video, and data

• Light-density Layer 2 Ethernet switching

 

 The Cisco 7200 VXR Router Series with Network Processing En

The Cisco 7200 VXR Router Series with Network Processing Engine NPE-G2

 

The Cisco 7200 VXR Series offers a rich set of capabilities that address requirements for performance, density, high reliability, availability, serviceability, and manageability.

 

Cisco 7200 VXR Features and Benefit

Features

Benefits

Up to 2 Mpps Processing Capability

Provides high-performance routing and processing performance

Maximum Connectivity Options

Meets a variety of topology requirements with the widest range of port densities and interface options

Breadth of Services

Supports QoS, security, MPLS, broadband, multiservice, voice, IP-to-IP Gateway and management features for next-generation networks

Investment Protection

Low initial investment with upgrade and redeployment capability

 

Hardware for Cisco 7200 VXR Series Router includes:

7204 VXR or Cisco 7206 VXR chassis

• Network Processing Engine

• Input/Output controller

• Processor memory

• Input/Output controller memory

• Power supply

• Console and auxiliary cables

• Second power supply, accessories

• Port adapters

• Service adapters

 

More Notes: If you need to know more about Cisco 7200VXR series (for enterprise head offices and service provider edge), such as its applications, Specifications--- Cards, Ports, Slots; Components--- Chassis, Environmental Conditions; Processors, Input/Output Controllers, Port Adapter Jacket Card, Interfaces, Performance---Memory; Network Management, Power; Protocols; Product Regulatory Approvals and Compliance; Software Requirements, you can visit Cisco's official website...

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Cisco: Huge Challenges Lie Ahead In 2012

January 11 2012 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco Routers

Over the last several years, the technology industry has been facing a number of different challenges. This is because the sector has experienced tremendous amounts of growth that were related to the evolution of the Internet. At the same time many different consumer devices (i.e. smartphones, tablets and readers) have given everyone the power to access the latest information on the go. This has caused a number of firms to experience rapid increases in their growth rates and earnings per share.

Cisco--Challenge--2012.jpg

 

In the case of Cisco Systems (CSCO), it has been realizing similar trends. As it has been supporting the expansion of the internet through the various routers/switches it is selling and the IT security solutions it offers. This has helped the firm to experience above average rates of growth of 10.9% in revenues and 26.6% in growth from 2009 to 2010, and remains a proverbial cash cow.

 

The problem is that the company has lost its focus by going into ventures that are not considered to be profitable and it has seen declining demand from its core customers. This is a common trend that occurs in some of the strongest industries (at some point in time). As this is measured through the S Curve, which states that customer needs will start to slow after periods of rapid growth. The reason why is due to the fact that the industry was able to effectively address them over the course of many years. Under this approach is when a firm will enter a period of flat to negative declines in their earnings. The reason why is because management will believe that these kinds of increases will continue on a regular basis. This is when the company will refocus its efforts in order to improve its overall bottom line numbers. As a result, Cisco has been going through a similar situation by trying to redefine itself in areas that are seeing declining customer demand.

 

A Tale of Two Viewpoints on Cisco

If investors are listening to Wall Street analysts, it appears as if the company has been able to make the adjustments to the changes that have taken place. Evidence of this can be seen by looking at the total number of analysts that are optimistic on the stock, with 36 rating the company as a strong buy or buy. While the total number of analysts that are bearish or neutral on the company is 20. This is important, because it shows how the majority of analysts are overly optimistic on the stock. As a result this could be an indication that the majority of successful investors have already purchased the company and may be in the process of taking their profits.

 

Moreover, the mainstream press is continuing to claim that Cisco is on the verge of taking advantage of new changes that are occurring in the way everyone is storing and retrieving information through cloud computing. This is when large amounts of data are stored on mainframe computers at remote locations versus having everyone place them in their devices. A good example of this can be seen in an article in Forbes:

 

Cisco Systems recently released a new cloud-based service, OnPlus, that helps its small-business partners provide network assessment, management and advisory services to their customers more easily. One of the major features of the new offering is that it allows value-added resellers (VARs) the ability to provide remote visibility of a customer’s network and attached devices. Cisco primarily competes with other network equipment and service providers like Juniper Network and Lucent Alcatel. We currently have a $21.21 price estimate for Cisco about 15% above the market price.

 

This is significant because it is showing how the mainstream press is taking the same kind of views as different analysts. Once this occurs, the odds increase that the company could be facing a number of different challenges when it comes to its earnings and future growth expectations.

This is the point that there could be some kind of negative surprise (which may cause the analysts to downgrade the stock) leading to a major reversal in prices. From a contrarian point of view, this is troubling as the current price is a reflection of these positive expectations. This increases the chances that the company could miss future earnings and revenue estimates.

 

Chambers Speaks Out

Despite the positive sentiment that is associated with the company, CEO John Chambers has said the firm is facing challenges associated with the culture inside the organization and the negative backlash from unsuccessful business ventures. Chambers commented that the firm is facing a number of issues going forward:

 

It is aspects of our operational execution that are not very strong . We have been slow to make decisions, we have had surprises where we should not, and we have lost the accountability that has been a hallmark of our ability to execute consistently for our customers and our shareholders. That is unacceptable. Today we face a simple truth: we have disappointed our investors and we have confused our employees. Bottom line, we have lost some of the credibility that is foundational to Cisco’s success – and we must earn it back. Our market is in transition, and our company is in transition. And the time is right to define this transition for ourselves and our industry. I understand this. It’s time for focus.

 

These comments are important, because they show Cisco is facing challenges from within. This means that the positive sentiments from analysts and the news media are nothing more than hype. Until the company is able to effectively focus on these issues. There will be continuing pressure on the stock. Over the course of time this means that earnings and revenues could come in below what many analyst are expecting. This raises the possibility for some kind of sell-off to occur.

 

Clearly Cisco Systems is facing a number of challenges when it comes to its operating environment and maintaining continuing growth. To be successful, the company will need to change from within, which will be time consuming and difficult. This means that the analysts’ estimates and positive news articles promoting the stock are ignoring these key factors. Once this occurs, the odds increase that Cisco could have some kind of negative earnings surprise.

 

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IPv6 vs IPv4 – What Are They, Exactly?

January 9 2012 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco Technology - IT News

No doubt while browsing the web, dealing with home networking solutions or even participating in some form of network development you’ve come across the terms IPv4 and IPv6. Terms like “IPv4 vs IPv6″, or “IPv6 tutorial”, or even the much broader “Internet Protocol”.

 

Unfortunately, most people have no idea what these terms mean, or what they are in fact referring to. As a general problem the terms are rarely explained well, and when they are, the explanations are not usually in simple form.IPv4 vs IPv6

 

IPv4 vs IPv6

To put it quite bluntly, we’re here to answer one question; what do these terms: “IPv4 vs IPv6″, “IPv6 tutorial” and so on mean exactly?

 

The “I” and “P” in “IPv” stands for “Internet Protocol” which directly refers to the communication protocol, or packet transfer procedure of the internet.

 

Every device that connects to the internet uses a unique address called an IP address, which works very similar to a home/location address. Pieces of data, called “packets”, are transferred via the internet between machines, which in turn gives us the fully functioning interior workings of the online community. In order for two machines, or devices to communicate via the internet, they must transfer these “packets” of data back and forth. Unfortunately the data “packets” can not be transferred if the devices do not each have their own unique address.

 

Think of it basically as a home address. You can’t send a mail correctly if you don’t list a proper return address, because basically if the mail doesn’t reach its destination it must have a way of returning back to you. Also, the mail receiver would have no possible way of responding considering they have no idea what address the should reply to.

 

While the internet does not necessarily return data “packets” that don’t reach their destination, like undelivered mail, proper use or protocol requires two devices to have unique addresses to even begin communications.

 

IPv4 vs IPv6

The “v” and number (“4″ or “6″) in “IPv4 vs IPv6″ refers to the related protocol version number. “IPv4″ is of course “Internet Protocol version 4″, and “IPv6″ is subsequently “Internet Protocol version 6″.

 

IPv4 is of course the older, more supported version of the internet address procedure. But ultimately, there are no longer any free IPv4 addresses, meaning all of them have been occupied or taken up. What does this mean exactly?

 

In a general sense, there will no longer be any alternative IPv4 addresses, directly meaning they will all be occupied and new users will not be able to venture into cyberspace. Although the realistic situation is not quite as dire.

 

Source from: http://www.thetechlabs.com/tech-news/ipv4-vs-ipv6/

 


 

Queue in IPv6, the latest Internet Protocol or address procedure. The older IPv4 only supports a maximum 32 bit internet address, which translates to 2^32 IP addresses available for assignment (about 4.29 billion total). IPv6 utilizes 128 bit web addresses, allowing a maximum 2^128 available addresses: 340,282,366,920,938,000,000,000,000,000,000,000,000; which if you couldn’t already tell is a very big number.

 

So basically the IPv4 protocol has run out of available addresses which is why most websites or internet servers are adopting the newer IPv6 protocol. In most cases, the two versions are compatible. This contrast between the two protocol versions is exactly what’s being referred to when “IPv4 vs IPv6″ is mentioned.

 

Worldwide IPv6 Transfer 

The Internet society has worked together with several huge ISP companies and online organizations to successfully switch the world over from use of the older IPv4 protocol to the newer IPv6. “World IPv6 Day” is scheduled to occur on June 8, 2011 and will involve several major online organizations switching services to IPv6 to test out its overall functionality and reliability.

 

This has no direct consequences or relations to home consumers and average internet users (meaning you), the IPv6 protocol switch only seriously pertains to large online organizations with an extensive listing of online hosted content.

 

 

More Related: http://blog.router-switch.com/

 

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DHCP Protocol & What It Offers?

January 5 2012 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco Technology - IT News

DHCP, Dynamic Host Control Protocol, is a Protocol that operates at Application layer and automatically assigns IP Addresses to requesting Hosts. DHCP eliminates the manual task by a network Administrator. It also provides a central database of devices that are connected to the network and eliminate duplicate resource assignments. DHCP uses UDP (User Datagram Protocol) to send its request messages to the DHCP Server on Port number 67.

networking1.jpg


 

A DHCP Server can provide to a host alot of information when the host is requesting an IP address from a DHCP Server. Here's a list of the information a DHCP Server can provide:

  • IP Address
  • Subnet Mask
  • Domain Name
  • Default Gateway (routers)
  • DNS
  • WINS information

 

How DHCP Server is Discovered by Client to get IP address? 

The client broadcasts messages on the physical subnet to discover available DHCP servers. Network administrators can configure a local router to forward DHCP packets to a DHCP server from a different subnet. This client-implementation creates a User Datagram Protocol (UDP) packet with the broadcast destination of 255.255.255.255 or the specific subnet broadcast address. Addresses in the Packet for DHCP Server Discovery can be as follows;

Source IP = 0.0.0.0
Source Port = 0
Destination IP = 255.255.255.255
Destination Pot = 67

A DHCP client can also request its last-known IP address. If the client remains connected to a network for which the IP is valid, the server may grant the request.

DHCP Offer
When a DHCP server receives an IP lease request from a client, it reserves an IP address for the client and extends an IP lease offer by sending a DHCPOFFER message to the client. This message contains the client's MAC address, the IP address that the server is offering, the subnet mask, the lease duration, and the IP address of the DHCP server making the offer. Source and Destination addresses in the server’s DHCP Offer message are as follows;

Source IP = 192.168.1.1
Source Port = 67
Destination IP = 255.255.255.255
Destination Pot = 68

DHCP Request
A client can receive DHCP offers from multiple servers, but it will accept only one DHCP offer and broadcast a DHCP request message. Based on the Transaction ID field in the request, servers are informed whose offer the client has accepted. When other DHCP servers receive this message, they withdraw any offers that they might have made to the client and return the offered address to the pool of available addresses. The DHCP request message is broadcast, instead of being unicast to a particular DHCP server, because the DHCP client has still not received an IP address. Also, this way one message can let all other DHCP servers know that another server will be supplying the IP address without missing any of the servers with a series of unicast messages.

DHCP Acknowledgement
Upon Receiving DHCP acknowledgment message on server, server sends IP Address, lease duration and other info to the client that requrested, and IP address Assignment process to the client by DHCP Server is completed.

 

More related: How to Configure DHCP on a Cisco ASA 5505?

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How to Configure DHCP on a Cisco ASA 5505?

January 4 2012 , Written by Cisco & Cisco Router, Network Switch Published on #Cisco Switches - Cisco Firewall

Dynamic Host Configuration Protocol (DHCP) is a network application protocol used by devices (DHCP clients) to obtain configuration information for operation in an Internet Protocol network. This protocol reduces system administration workload, allowing devices to be added to the network with little or no manual intervention.

Configure-DHCP-on-a-Cisco-ASA-5505-copy-1.jpg

 

The diagram has the network topology. In this network the firewall is the gateway of the 10.16.74.0/24 network. Firewall and Servers will be excluded from the DHCP pool.

First step is to configure the inside (LAN) interface on the 10.16.74.0/24 network

FIREWALL(config)#interface Vlan1
FIREWALL(config-if)#nameif inside
FIREWALL(config-if)#security-level 100
FIREWALL(config-if)#ip address 10.16.74.1 255.255.255.0

Next assign the LAN ports for the correct VLAN in this case port 1 of firewall will be on VLAN 1

FIREWALL(config)#interface Ethernet0/1
FIREWALL(config-if)#switchport access vlan 1
FIREWALL(config-if)#no shut

Lastly, configure the dhcp range and assign it to an interface. Configure DNS servers, one internal and one external in case the internal fails. Enable DHCP on the inside interface

FIREWALL(config)#dhcpd address 10.16.74.15-10.16.74.35 inside
FIREWALL(config)#dhcpd dns 10.16.74.10 4.2.2.2
FIREWALL(config)#dhcpd enable inside

In order to see which devices are receiving DHCP from the firewall run the following command

FIREWALL(config)#sh dhcpd binding

IP address Hardware address Lease expiration Type

 

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