Missing (Top 10 Useful Teams Missing CCNA)
The CCNA course contains a great many commands for setting up and debugging a wide variety of network protocols and technologies. All the necessary tools are in our hands, but these are far from all the tools with which we can work with network equipment. We have compiled a list of the 10 most useful teams that should have been up to date with CCNA , but for some mysterious reason they disappeared somewhere.
The default console port speed is 9600 bps, and you can change it with the speed command . What for? In case of catastrophes. Firstly, some routers and switches have a non-recoverable flash, and IOS recovery is only possible from monitor mode using the console. Secondly, some useful debugging commands (debug or show tech-support) generate such a volume of output that the standard speed is not enough. And the more information you collect, the easier and faster you identify and fix the problem, and the less complaints about lack of communication you will receive from management and users.
By the way, there is another reason to change the speed of the console port - this is protection from the fool. You won’t stop a serious hacker, but an intern who suddenly decided to try changing something is fine.
Suppose you connect another device to the interface, and you need to significantly change the configuration. You can execute all existing commands with the no prefix. And it is possible to execute the default interface command type number from the configuration mode , which will reset the interface settings to default values, i.e. to an empty configuration. Saving time is obvious, plus you will definitely not forget anything.
Surely you had to look at the long output of show something in search of a specific entry. Well, if you know where to look. Even better if this entry is there. But what if you need to make sure that there is no specific command in the configuration? Here, output modifiers will come to our aid. So, we enter the command I include a substring and we get only those lines from the output of the command that contain the specified substring (case sensitive). Say by typing show run | include dhcp, we get all the settings related to DHCP. Simple and convenient. The following modifier is equally useful: the I section command substring. In this case, not separate dates will be displayed, but entire sections corresponding to a given substring. For example, by typing show run | section router rip, we will see all the current routing settings using RIP.
Have you heard about the password recovery procedure? The problem is that not only you, but also the attackers heard about it. And if they suddenly get to the equipment, they can thus learn the unencrypted passwords stored in your configuration (service password-encryption in this case does not help, since this encryption has already been cracked). In this case, the no service password-recovery configuration mode command is useful , which prohibits password recovery while saving the configuration (i.e., the configuration will be deleted when the password is restored). It is worth considering one point: the configuration backup now has to be stored somewhere else, from where it can also be safely stolen. So it’s better to hang a large barn lock on the server room.
The show interfaces command provides extensive statistics on a wide variety of package types. What if you are not interested in general but instant statistics? In this case, it is worth executing the clear counters privileged mode command , which will reset all packet counters to zero. Now you will immediately see which packets pass through the interface at present and which are safely missing. Interestingly, this command is present in the output of the show interfaces command, but despite this, it is never mentioned in the course text.
Does your router suffer from high processor load? Most likely, he has to pass a significant proportion of packets through the CPU. To check if this is the case, use the show interfaces stats command , which will show the number of packets that have used each of the available switching methods for each interface in each direction. At the same time and localize the problem.
The copy startup-config running-config command is pretty crafty. The fact is that it does not replace the current configuration, but only executes all the commands written in startup-config. And this is not the same! For example, the shutdown command was executed on the interface, and the interface was turned on in the start configuration - copying the configuration in this case would cause the interface to remain in the administratively down state, because no shutdown command was not issued (because it not saved in the configuration). In order not to waste time rebooting and not catching fleas manually, it is worthwhile to configure configure replace nvram: startup-config in privileged mode , which will lead to honest copying with full replacement of the current settings.
Have you had to painfully look for the port into which a specific node is stuck in a large switched network, sorting through all the MAC tables? If so, then greet the ovation with the traceroute mac command MAC_source_address MAC_recipient_address , which performs tracing at the second level of the OSI model. The only “but” is that the CDP must be enabled for this service to work.
The main commandment when setting up the equipment remotely is to not disconnect yourself. Otherwise, you have to grab a laptop and rush off somewhere. Well, if the server room is around the corner, and if it was a branch in another city, where there are no own administrators? After all, you will have to talk for a long time on the phone with the cleaning lady, explain to her what to insert where and with what end, painfully ask what she sees, dictate what to type in letters ... And then anyway arrange a business trip to correct, including the consequences of such a repair.
Rejoice, for there is a privileged mode command reload in time, which will restart the device after a specified period of time. If you disconnect yourself, then after the timer expires, a reboot will occur with the restoration of the original configuration. And you can try again. And if everything went well, then using the reload cancel command , you will cancel the upcoming reboot.
We give an unconditional victory to the auto configure team , after the introduction of which absolutely all the settings necessary for your particular situation are automatically performed. Moreover, if the company's policy changes, the settings will also be changed, and without the need for any action on your part. One trouble - they forgot to include this team not only in the CCNA course , but also in IOS itself.
Number 10
The default console port speed is 9600 bps, and you can change it with the speed command . What for? In case of catastrophes. Firstly, some routers and switches have a non-recoverable flash, and IOS recovery is only possible from monitor mode using the console. Secondly, some useful debugging commands (debug or show tech-support) generate such a volume of output that the standard speed is not enough. And the more information you collect, the easier and faster you identify and fix the problem, and the less complaints about lack of communication you will receive from management and users.
By the way, there is another reason to change the speed of the console port - this is protection from the fool. You won’t stop a serious hacker, but an intern who suddenly decided to try changing something is fine.
Number 9
Suppose you connect another device to the interface, and you need to significantly change the configuration. You can execute all existing commands with the no prefix. And it is possible to execute the default interface command type number from the configuration mode , which will reset the interface settings to default values, i.e. to an empty configuration. Saving time is obvious, plus you will definitely not forget anything.
Number 8
Surely you had to look at the long output of show something in search of a specific entry. Well, if you know where to look. Even better if this entry is there. But what if you need to make sure that there is no specific command in the configuration? Here, output modifiers will come to our aid. So, we enter the command I include a substring and we get only those lines from the output of the command that contain the specified substring (case sensitive). Say by typing show run | include dhcp, we get all the settings related to DHCP. Simple and convenient. The following modifier is equally useful: the I section command substring. In this case, not separate dates will be displayed, but entire sections corresponding to a given substring. For example, by typing show run | section router rip, we will see all the current routing settings using RIP.
Number 7
Have you heard about the password recovery procedure? The problem is that not only you, but also the attackers heard about it. And if they suddenly get to the equipment, they can thus learn the unencrypted passwords stored in your configuration (service password-encryption in this case does not help, since this encryption has already been cracked). In this case, the no service password-recovery configuration mode command is useful , which prohibits password recovery while saving the configuration (i.e., the configuration will be deleted when the password is restored). It is worth considering one point: the configuration backup now has to be stored somewhere else, from where it can also be safely stolen. So it’s better to hang a large barn lock on the server room.
Number 6
The show interfaces command provides extensive statistics on a wide variety of package types. What if you are not interested in general but instant statistics? In this case, it is worth executing the clear counters privileged mode command , which will reset all packet counters to zero. Now you will immediately see which packets pass through the interface at present and which are safely missing. Interestingly, this command is present in the output of the show interfaces command, but despite this, it is never mentioned in the course text.
Number 5
Does your router suffer from high processor load? Most likely, he has to pass a significant proportion of packets through the CPU. To check if this is the case, use the show interfaces stats command , which will show the number of packets that have used each of the available switching methods for each interface in each direction. At the same time and localize the problem.
Number 4
The copy startup-config running-config command is pretty crafty. The fact is that it does not replace the current configuration, but only executes all the commands written in startup-config. And this is not the same! For example, the shutdown command was executed on the interface, and the interface was turned on in the start configuration - copying the configuration in this case would cause the interface to remain in the administratively down state, because no shutdown command was not issued (because it not saved in the configuration). In order not to waste time rebooting and not catching fleas manually, it is worthwhile to configure configure replace nvram: startup-config in privileged mode , which will lead to honest copying with full replacement of the current settings.
No. 3
Have you had to painfully look for the port into which a specific node is stuck in a large switched network, sorting through all the MAC tables? If so, then greet the ovation with the traceroute mac command MAC_source_address MAC_recipient_address , which performs tracing at the second level of the OSI model. The only “but” is that the CDP must be enabled for this service to work.
Number 2
The main commandment when setting up the equipment remotely is to not disconnect yourself. Otherwise, you have to grab a laptop and rush off somewhere. Well, if the server room is around the corner, and if it was a branch in another city, where there are no own administrators? After all, you will have to talk for a long time on the phone with the cleaning lady, explain to her what to insert where and with what end, painfully ask what she sees, dictate what to type in letters ... And then anyway arrange a business trip to correct, including the consequences of such a repair.
Rejoice, for there is a privileged mode command reload in time, which will restart the device after a specified period of time. If you disconnect yourself, then after the timer expires, a reboot will occur with the restoration of the original configuration. And you can try again. And if everything went well, then using the reload cancel command , you will cancel the upcoming reboot.
Number 1
We give an unconditional victory to the auto configure team , after the introduction of which absolutely all the settings necessary for your particular situation are automatically performed. Moreover, if the company's policy changes, the settings will also be changed, and without the need for any action on your part. One trouble - they forgot to include this team not only in the CCNA course , but also in IOS itself.