Cisco Discovery Protocol

What is CDP?

CDP is the Cisco Discovery Protocol. It is a Cisco Proprietary Protocol that discovers and shows information about directly connected Cisco devices. CDP works on layer two (Data Link layer) of the OSI Reference Model.
Cisco Discovery Protocol (CDP) works only with the Cisco manageable devices such as Cisco Catalyst Switches and Cisco Routers and Access Server. It is a useful utility of Cisco IOS that runs on the routers with the Cisco IOS version 10.3 or later and Cisco switches and hubs. CDP is basically network monitor software that is used for managing your network environment. It gives you a summary of some important information about neighbour and remote Cisco devices that are implemented in your network. CDP discovers neighbour devices regardless of which protocol suite they are running. Physical media must support the SNAP (Subnetwork Access Protocol) encapsulation. Cisco also offers the PC generating Cisco Discovery Protocol to provide the summary information about PC that are connected with Cisco devices and the Cisco VoIP Cisco Discovery Protocol for providing the summary information of Cisco Voice integrated routers.

The summary information includes:

• Device Identifiers
• Address List
• Port Identifier
• Capabilities List
• Platform

For better understanding the Cisco Discovery Protocol (CDP), we should have to discuss the protocol in layering element.

The layering elements of CDP are as follows:

• Physical layer: Media supporting SNAP such as LANs, Frame Relay ATM and others

 

• Data Link Layer: Cisco Proprietary Data Link protocol that discovers and shows information about directly and remotely connected devices

• Network Layer: Upper layer entry addresses of any protocol suite such as TCP/IP, Novell IPX/SPX, Apple Talk and others

Configuring CDP on a Cisco Router

CDP Cisco runs on the routers with Cisco IOS 10.3 or later and Cisco Catalyst switches and hubs. Cisco cdp has two versions for sending CDP advertisements on Cisco neighbour devices such as CDP version 1 and CDP version 2.
CDP is by default enabled in Cisco routers and switches with Cisco IOS 10.3 or later. You can verify the status of CDP by following privileged-exec mode command:

• Router # show cdp

The output of the command shows that CDP is running on the router. If you are not interested to run CDP on your router for some reasons then you have to execute this set of command:

• Router # configure terminal

 

• Router (config) # no cdp run

 

• Router # show cdp

Execute the following set of command to run CDP on the router on which CDP is currently not running:

• Router # configure terminal

 

• Router (config) # cdp run

 

• Router # show cdp

By default, the CDP advertisements are sending after every 60 seconds by an update CDP packet with a hold time value of 180 seconds. You can change the default configuration by these set of commands:

• Router # configure terminal

 

• Router (config) # cdp timer 30

 

• Router (config) # cdp hold time 90

 

• Router # show cdp

You can configure the cdp timer value from 5 to 254 seconds and cdp hold time value from 10 to 255 seconds. It is recommended that the hold time value should be three times greater than the value of cdp timer.

To disable the Cisco Discovery Protocol on a specific interface, you have to perform the following interface configuration command:

• Router (config) # interface serial 0

 

• Router (config-if) # no cdp enable

 

• Router # show cdp interface

For enabling the Cisco Discovery Protocol on a specific interface, you have to perform the following interface configuration command:

• Ruter (config) # interface serial 0

 

• Router (config-if) # cdp enable

 

• Router # show cdp interface

There are some other show commands are available in the privileged mode of the Cisco IOS for verifying the CDP configuration.

Followings are the commands and their short description used for verifying the CDP:

• R1 # show cdp entry R2: displays CDP information for specific neighbour entry

 

• R1 # show cdp entry : displays CDP information for all the neighbour entries

 

• R1 # show cdp interface: displays the CDP status and configuration of interfaces

 

• R1 # show cdp traffic: displays CDP traffic statistics

 

• R1 # show cdp neighbours: displays CDP neighbour entries

 

• R1 # show cdp neighbours detail: displays the detailed CDP neighbours entries

CDP is also by default enabled in Cisco Catalyst switches such as Cisco Catalyst 1900 series switch and Cisco Catalyst 2950 series switch. Cisco Catalyst 1900 series switch also provides its MAC address in the summary information through the output of show cdp neighbourscommand.

Cisco VoIP Cisco Discovery Protocol

Voice and data networks have traditionally been two separated networks. Over the few years, many organizations have begun merging the voice and data network. This trend is gradually accelerating and it will continue to accelerate for coming years. This technology is called Voice over IP (VOIP).

Cisco also provides the hardware and software solution of Voice over IP networks. Cisco offers voice modules in different router models such as Cisco 2610 series. If two or more Cisco routers having voice modules are connected via voice port such as FXO port or FXS port, then the Cisco VoIP Cisco Discovery Protocol displays the summary information of neighbour Cisco devices.

The summary information includes:

• Device Identifiers such as the name of the Cisco Voice router

 

• Address List such as the IP address of the Voice interface of the Cisco router

 

• Port Identifier such as the incoming and outgoing Voice interfaces that are using to connect two Cisco routers

• Capabilities List such as the capabilities of the Cisco Voice device.

 

• Platform such as the series and model no of Cisco Voice router.

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Cisco Network Management

Cisco Network Management

Overview of Network Management

Different people may take network management as different meanings. It may be considered as solitary network consultant for monitoring network activity using outdated protocol analyzer. While network management in distributed database environment, managing network nodes for generating real time graphics and auto polling of network devices. There are number of tools and applications which are used for network management to support network administrators to monitor and maintain networks of all types.

In the early 1980s remarkable growth in field of network deployment was noted and companies have found productivity and cost benefits by use of network and they started with networks very fast as new products came into the market. In middle of 1980s specific company’s troubles were increased by the use of different network technologies.
Network expansion troubles influence the networks day by day as networks grow and each new network needs some experts for maintaining and troubleshooting it. At early stages employee requirements for managing network created crisis for some organizations.

Cisco Network Management Architecture

Basic structure is used in Cisco Network Management Architecture and network devices such as computer systems , Cisco routers , Cisco switches run applications which enable them to find out problems in network . Software are installed on network devices which are programmed in such a way that upon receiving alerts these execute number of actions like operator notification, even log, system shutdown and automatic attempts to repair that device.

These Management tools are also used to check or poll end stations and check values for specific variables. Polling could be automatic or user initiated while agents in these managed devices could respond to all polls. Agents are known as applications or software modules which are used to compile information of managed device and store this information in management database and generate it proactive or reactive entities using network management protocol within network management system. Cisco devices make use of SNMP (simple network management protocol) for this and management proxies are know as those entities which provide management information on the basis of other entities.

ISO Network Management Model

ISO has played a big role in standardizing network specifications. ISO model is basically used to understand the main functions of network management systems. This model contains the following concepts.

• Performance Management
• Configuration Management
• Fault Management
• Security Management

Performance Management

The main objective of performance management is to calculate the performance level of network and make it available and this level could be maintained at acceptable level. Some examples of performance variables consist of network throughput and user response time and line utilization.

There are three major steps which involve in performance management. First, data is collected for variables which are according to interest of network administrators. Secondly, data is analyzed to find out normal levels and finally 3rd step is to find out suitable for each important variable because increase in thresholds may cause network problem. Network Management entities are used to monitor network performance variables on regular basis. Whenever performance of specific threshold is increased entity will generate an alert signal to network management system.

Every step mentioned above is part of the procedure to make a reactive system. Performance may be unacceptable due to increase in user defined threshold and system may react by sending messages. Performance management may allow some proactive procedures like network simulation which could be used in projects. These simulations are used to alert administrators to be ready for impending problems and take necessary measures.

Configuration Management

Configuration Management objective to examine Cisco Network and system configurations database so that effects on network operation for different versions of Cisco IOS applications could be managed.

Every Cisco device contains number of versions information which is associated to it like.

• Internetwork Operating System, Version 12.4
• Ethernet Interface, Version 5.3
• TCP/IP software, Version 2.0
• Netware Software, Version 4.2
• NFS software, Version 5.1
• Serial Communications controller, Version 1.1
• X.25 software, Version 1.0
• SNMP software, Version 3.2

This information is stored in database for easy access without any problems and when problem occurs database could be searched to take help about specific problem.

Fault Management

The objective of fault management is to find out, log and notify users on network and automatically fix problems to keep the network in working position. Network faults could cause downtime3e and unacceptable network degradation and implementation of fault management is significant. Fault management may contain formative symptoms and separating problems. Problems are fixed and solution is tested and finally problems are detected.

Security Management

Security Management objective is to manage network resources with respect to local guide and sensitive information could not be accessed without proper authentication. Security management subsystem can however examine users to logon on network resources and refuse access to those enter necessary access codes.
Subsystems of security management are working by partitioning network resources towards authorized and unauthorized areas. Some users have an inappropriate access to network because they are company outsiders. While internal network users access information which is generated from specific department.

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Cisco Router Commands

Cisco Router IOS

Cisco routers are manageable devices, which means that they have the Cisco IOS software for network and internetwork management. The Cisco’s IOS software delivers network services and enabled networked applications. The Cisco IOS is the CLI based software with which Cisco IOS commands can be executed.

Cisco Commands

There are more than 2,000 Cisco router commands in the latest Cisco router IOS software version including the basic router commands along with the advanced level router commands such as Cisco wireless router commands. The Cisco router IOS has different executable modes with different prompts. These modes execute different tasks. Each mode has a set of specific commands.

Cisco IOS User Interface Fundamentals

Bear the following in mind when using a command line interface:

• Operations vary on different internetworking devices
• Type or paste entries into the console command modes
• Enter key instructs device to parse and execute the commands
• Two primary EXEC modes for executing basic Cisco commands are user mode and privileged mode
• Command modes have distinctive prompts

Cisco IOS Software Exec

There are two main EXEC modes for entering commands:

User Mode

• Limited router examination

 

• Command prompt on the router is Router

Privileged (or enabled) Mode

• Detailed router examination

 

• Enables configuration and debugging

 

• Prerequisites for other configuration modes

 

• Command prompt on the router is Router#

Configured versus Unconfigured Router

After completing the booting process, the configured Cisco router prompts in user mode while the Cisco router prompts in setup mode for initial configuration dialogue if there is no configuration in the memory.

Cisco Router Setup Mode

The Cisco router setup mode commands are as follows:

Setup: The Initial Configuration Dialog

Router # setup

System Configuration Dialog

Continue with configuration dialog? [Yes/no]: Y

At any point, enter a question mark “?” for help

Use ctrl-c to abort the configuration dialog at any prompt

Default settings are in square brackets “[ ]”

Basic management setup configures only enough connectivity for system management. Extended setup will ask the user to configure each interface on the system:

Would you like to enter basic management setup? [Yes/no] n

Setup Interface Summary

First, would you like to see the current interface summary? [Yes]

Setup Global Parameters

Configuring global parameters:

Enter host name [router]: R1

The enable secret is the password that protects access to Privileged and configuration modes. This password, after entered, becomes encrypted in the configuration.

Enter enable secret: Cisco

Enable password is used with some older software versions and boot images when an enable secret password is not specified.

Enter enable password: sanfran

The virtual terminal password that protects the access to the router over a network interface.

Enter virtual terminal password: sanjose

Configure SNMP Network Management? [No]:

Configure IP? [Yes]:

Setup Interface Parameters

Configuring interface parameters:

Do you want to configure Ethernet 0 interface? [No]: Y

Configure IP on this interface? [No] Y

IP address for this interface: 10.1.1.33

Subnet mask for this interface [255.0.0.0]: 255.255.255.0

Class A network is 10.0.0.0. 245 subnet bits: mask is /24

Do you want to configure serial 0 interface? [No]:

Setup Script Review and Use

The following command script was created:

[0] go to the IOS command prompt without saving this configuration

[1] Return to the setup without saving this configuration

[2] Save this configuration to NVRAM and exit.

Enter the selection [2]:

What are the Basic Router Commands?

Below are some basic router commands for user and privileged exec modes that verify, copy, and delete the configuration:

• Show version: To view the hardware and software status of the Cisco router

 

• Show flash: To view the files and directories in the Cisco router’s flash

 

• Show running-config: To view the status of RAM, the Cisco router’s current configuration

• Show startup-config: To view the status of NVRAM, the Cisco router’s saved configuration

• Show interfaces: To view the detailed information about all of the Cisco router’s interfaces

• Show ip interfaces: To view the detailed ip configuration on all of the Cisco router’s interfaces

• Show interfaces serial 0: To view the detailed information about the Cisco router’s specific interface

• Show ip interfaces serial 0: To view the detailed IP configuration on the Cisco router’s specific interface

• Show ip interface brief: To view the brief ip configuration on all the Cisco router interfaces

• Show line: To view the brief information about all the Cisco router lines

 

• Show line console 0: To view the detailed information about a specific Cisco router line

• Show user: To view some details about the users that are currently logged onto the Cisco router through any line.

• Show ip route: To view the Cisco router’s IP routing table

 

• Show ip protocols: To view the IP routing protocols that are currently running on the Cisco router

• Show history: To view the last ten IOS commands that were executed on the Cisco router

• Erase startup-config: To erase the Cisco router’s NVRAM contents

 

• Erase Flash: To erase the contents of Flash of the Cisco router

 

• Copy running-config startup-config: To copy the contents of RAM into the Cisco router’s NVRAM

• Copy startup-config tftp: To copy the saved configurations from NVRAM into the TFTP server for backup purposes

• Copy flash tftp: To copy the IOS image file from Flash into the TFTP server for backup purposes

• Copy tftp startup-config: To restore the copy of saved configuration into NVRAM from the TFTP server

• Copy tftp flash: To restore the IOS file image copy into Flash from the TFTP server

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