Router Commands

In this section you will learn about the router commands, configurations, privileged mode commands, routing protocols, cisco labs and network configurations.

There are hundreds of basic and advance level commands of a router. It is not easy to remember all the commands. But some commands are frequently used and can be remembered with some practice. I have provided a list of the most commonly used commands based on their features and usage. You will find here some basic terminology of a router.

Routing: Routing is a process of moving the data (packets) through an inter network. Routing performs the two basic tasks. Define the paths for a packet and then forward the packets on the basis of defined paths. Routing can also be defined as the communication between two or more logically and physical networks and this communication (packet transfer) is brought by a router.

First of all you should remember the keyboard shortcuts of a router.

Keyboard Shortcuts
CTRL-N - show next command
CTRL-P - show previous command
SHIFT-CTRL-6 – Break

Configuring the Router

You will be able to learn the basic commands for configuring a router.
sh running-config - details the running configuration file (RAM)
sh startup-config - displays the configuration stored in NVRAM
setup - Will start the the automatic setup; the same as when you first boot the router
config t - use to execute configuration commands from the terminal
config mem - executes configuration commands stored in NVRAM; copies startup-config to running-config

config net - used to retrieve configuration info from a TFTP server
copy running-config startup-config - copies saved config in running config (RAM) to NVRAM or "write memory" for IOS under ver.11
copy startup-config running-config - copies from non-volatile (NVRAM) to current running config (RAM)
boot system flash - tells router which IOS file in flash to boot from
boot system tftp - tells router which IOS file on the tftp server to boot from
boot system rom - tell router to boot from ROM at next boot
copy flash tftp - Copies flash to tftp server
copy tftp flash - Restores flash from tftp server
copy run tftp - Copies the current running-config to tftp server
copy tftp run - Restores the running-config from tftp server

General Commands

Here is a list of the general commands. These are the basic level commands and most commonly used
no shutdown - (enables the interface)
reload - restarts the router
sh ver - Cisco IOS version, uptime of router, how the router started, where system was loaded from, the interfaces the POST found, and the configuration register
sh clock - shows date and time on router
sh history - shows the history of your commands
sh debug - shows all debugging that is currently enabled
no debug all - turns off all debugging
sh users - shows users connected to router
sh protocols - shows which protocols are configured
banner motd # Your customized message here # - Set/change banner
hostname - use to configure the hostname of the router
clear counters - clear interface counters

Privileged Mode commands of a router

Learn how to work in the privileged mode of a router.
enable - get to privileged mode
disable - get to user mode
enable password - sets privileged mode password
enable secret - sets encrypted privileged mode password
Setting Passwords on router
Here you will be able to learn how to set the password on a router.
enable secret - set encrypted password for privileged access
enable password - set password for privileged access (used when there is no enable secret and when using older software)
Setting the password for console access:
(config)#line console 0
(config-line)#login
(config-line)#password
Set password for virtual terminal (telnet) access (password must be set to access router through telnet):
(config)#line vty 0 4
(config-line)#login
(config-line)#password
Set password for auxiliary (modem) access:
(config)#line aux 0
(config-line)#login
(config-line)#password

Router Processes & Statistics

By these command you can see the statistics and different processes of the router.
sh processes - shows active processes running on router
sh process cpu - shows cpu statistics
sh mem - shows memory statistics
sh flash - describes the flash memory and displays the size of files and the amount of free flash memory
sh buffers - displays statistics for router buffer pools; shows the size of the Small, Middle, Big, Very Big, Large and Huge Buffers
sh stacks - shows reason for last reboot, monitors the stack use of processes and interrupts routines

IP Commands

Here is a list of the IP Commands
Configure IP on an interface:
int serial 0
ip address 157.89.1.3 255.255.0.0
int eth 0
ip address 2008.1.1.4 255.255.255.0

Other IP Commands:

sh ip route - view ip routing table
ip route [administrative_distance] - configure a static IP route
ip route 0.0.0.0 0.0.0.0 - sets default gateway
ip classless - use with static routing to allow packets destined for unrecognized subnets to use the best possible route
sh arp - view arp cache; shows MAC address of connected routers
ip address 2.2.2.2 255.255.255.0 secondary - configure a 2nd ip address on an interface
sh ip protocol

CDP Commands (Cisco Discovery Protocol uses layer 2 multicast over a SNAP-capable link to send data):

sh cdp neighbor - shows directly connected neighbors
sh cdp int - shows which interfaces are running CDP
sh cdp int eth 0/0 - show CDP info for specific interface
sh cdp entry - shows CDP neighbor detail
cdp timer 120 - change how often CDP info is sent (default cdp timer is 60)
cp holdtime 240 - how long to wait before removing a CDP neighbor (default CDP holdtime is 180)
sh cdp run - shows if CDP turned on
no cdp run - turns off CDP for entire router (global config)
no cdp enable - turns off CDP on specific interface

IPX Commands

Enable IPX on router:
ipx routing
Configure IPX + IPX-RIP on an int:
int ser 0
ipx network 4A

Other Commands:

sh ipx route - shows IPX routing table
sh ipx int e0 - shows ipx address on int
sh ipx servers - shows SAP table
sh ipx traffic - view traffic statistics
debug ipx routing activity - debugs IPS RIP packets
debug ipx sap - debugs SAP packets

Routing Protocols

RIP, IGPR and OSPF are the routing protocols and here is a list of the commands for the working on the routing protocols.
Configure RIP:
router rip
network 157.89.0.0
network 208.1.1.0
Other RIP Commands:
debug ip rip - view RIP debugging info
Configure IGRP:
router IGRP 200
network 157.89.0.0
network 208.1.1.0
Other IGRP Commands:
debug ip igrp events - view IGRP debugging info
debug ip igrp transactions - view IGRP debugging info
Access Lists
Here is a list of the Access list command of a router.
sh ip int ser 0 - use to view which IP access lists are applies to which int
sh ipx int ser 0 - use to view which IPX access lists are applies to which int
sh appletalk int ser 0 - use to view which AppleTalk access lists are applies to which int
View access lists:
sh access-lists
sh ip access-lists
sh ipx access-lists
sh appletalk access-lists
Apply standard IP access list to int eth 0:
access-list 1 deny 200.1.1.0 0.0.0.255
access-list 1 permit any
int eth 0
ip access-group 1 in
Apply Extended IP access list to int eth 0:
access-list 100 deny tcp host 1.1.1.1 host 2.2.2.2 eq 23
access-list 100 deny tcp 3.3.3.0 0.0.0.255 any eq 80
int eth 0
ip access-group 100 out
Apply Standard IPX access list to int eth 0:
access-list 800 deny 7a 8000
access-list 800 permit -1
int eth 0
ipx access-group 800 out
Apply Standard IPX access list to int eth 0:
access-list 900 deny sap any 3378 -1
access-list 900 permit sap any all -1
int eth 0
ipx access-group 900 out

WAN Configurations Commands

Networking over WAN is the main functionality of a router. The most common use of a router is for the WAN connectivity. Here is a list of the commands for the different methods of the WAN connectivity.

PPP Configuration

Point to point protocol is a method for the WAN connectivity and you will find here some commands of PPP.
encapsulation pppppp authentication
ppp chap hostname
ppp pap sent-username
sh int ser 0 - use to view encapsulation on the interface

Frame-Relay Configuration

One of the methods for the WAN connectivity is the Frame Relay. Find here some basic commands for the WAN connectivity through Frame Relay.
encapsulation frame-relay ietf - use IETF when setting up a frame-relay network between a Ciscorouter and a non-Cisco router
frame-relay lmi-type ansi - LMI types are Cisco, ANSI, Q933A; Cisco is the default; LMI type is auto-sensed in IOS v11.2 and up
frame-relay map ip 3.3.3.3 100 broadcast - if inverse ARP won't work, map Other IP to Your DLCI # (local)
keep alive 10 - use to set keep alive
sh int ser 0 - use to show DLCI, LMI, and encapsulation info
sh frame-relay pvc - shows the configured DLCI's; shows PVC traffic stats
sh frame-relay map - shows route mapssh frame-relay lmi - shows LMI info

Miscellaneous Commands

In the last but not least here is a list of the some miscellaneous and useful commands
sh controller t1 - shows status of T1 lines
sh controller serial 1 - use to determine if DCE or DTE device
(config-if)#clock rate 6400 - set clock on DCE (bits per second)
(config-if)#bandwidth 64 - set bandwidth (kilobits)

source : www.networktutorials.info

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How to chose the best Access Point (AP)

Today the market is flooded with a range of wireless access points. There are dozens of important features to consider, so much variation in cost and several different performance parameters, that it can become quite confusing to decide which one is right for you. To address most of these concerns, we ripped apart 13 wireless access points with a barrage of tests, and analyzed them for over a dozen features. You'll find their individual reviews in the subsequent pages, followed by a table comparing the important features as well as the performance results. These include eight access points of 802.11b and five of 802.11g standards. But, before that, we'll look at the important features that should be considered when buying an access point, followed by the performance parameters. All performance and features parameters discussed here, along with the price and warranty of each access point, have been included in our analysis for the shootout. As usual, we used the Brown-Gibson model to arrive at the weightages for these parameters.

Which standard?
Speaking of standards, it's still not legal to use 802.11g-based products without a license. Only 802.11b based ones can be used indoors freely. While it's not very expensive to obtain a license, it's a long drawn process. Alternatively, you could go for an 802.11b access point that's upgradable to the g standard, apply for a license and then upgrade once you get the license. It's, therefore, an important feature to consider when going for an 802.11b access point. If you have a license or don't mind putting in the effort to get one, then you could also go for 802.11g based access points as they have a maximum throughput capability of 54 Mbps, unlike 802.11b that can deliver only 11 Mbps. Plus, the g standard is backward compatible with b, so even if you have b based wireless clients, they would still work, albeit at 11 Mbps.

How much security?
Security has always been a concern in wireless networks, so it's important to check out the security features of an access point before you buy it. First, define the level of security you need in your setup. For instance, if your office is in a crowded area and the chances of your WiFi signal going out of your premise is high, then it's better to go for tighter security because it would be easy for someone from outside to misuse your WiFi network. What level of accessibility are you planning to provide through your WiFi network to your mobile users? Is it just to surf the Net or will they also be able to access your servers? There are various security modes providing different levels of protection. The most basic is WEP (Wireless Equivalent Privacy) encryption, which is present by default in all access points. But, Wireless Equivalent Privacy has been found to be weak and, therefore, not always suitable for security a WiFi network. Look for other security modes, such as MAC-address based filtering, Radius-based authentication and WPA before you go out on your hunt for the right access point.

Modes of operation
Most access points can be used in more ways than one, but this functionality varies across vendors. Besides working as a standard access point, it can also work as an access point-to-access point bridge, repeater, gateway and more . Having more modes of operation gives an organization the flexibility to use the access point in any way they need. So, support for more modes is always better.

Management features
How easy is it for you to manage your access point? Most of them provide a Web-based interface for management, but that's not enough. Look for more management features available in this interface. Does it support SNMP, so that if you have your network management software running in your organization, it can easily be added in? Is it simple support for SNMP or can you also set traps for certain conditions so it sends out information to the administrator every time there's a problem? What other information can the access point provide? Does it maintain log files of all system activity? What level of activity can it put in the log file? What kind of statistics can it display about itself? The more management features it has, the easier it will be on the network administrator.

Load balancing and fault tolerance
If the number of users connecting to a particular access point with load-balancing support increases beyond a predefined limit, it will shift some users to a nearby access point. This feature can be useful if you have high user density per access point. So, look for one that supports load balancing. Fault tolerance, of course, means that if one access point goes down due to some reason, then the clients connecting to it should be diverted to another access point.

Other features
There are several other features that need to be considered. One is automatic channel selection, which becomes important if you're deploying lots of access points. This way the administrator doesn't have to manually define each channel, thereby reducing chances of human error. Can the antenna of the access point be upgraded to a different type or of higher power? What kind of software ships with the access point? How useful is it when deploying WiFi? Does the access point support power over Ethernet? This can be useful if you're placing an access point where you don't have a power connection nearby.

What about the quality of the power adapter itself? We noticed that several access points still shipped with the bulky transformer-based adapters. Today, most devices come with the lightweight, SMPS-based adapters, which have a longer life because they consume lesser power and generate lesser heat. So, an SMPS-based adapter is always preferable over transformer based one.

Performance parameters
There are a number of parameters that we considered for performance. For measuring all data transfers, we used NetIQ's Qcheck benchmark. The tests are as follows:

Max range: What's the maximum distance that a client can go from an access point without loosing connectivity and also be able to transfer data? While doing this test, we ensured there were no obstructions between the access point and the client. We stopped measuring beyond 200 mtrs as only a few Access Points showed connectivity beyond that distance.

Max range with max signal strength: While the signal strength of an access point reduces with distance, up till what distance can an access point keep it in excellent condition? The higher this is, the better.Here again we stopped measuring beyond 150 mtrs for same reasons as above.

Max throughput: For clients connected in close vicinity to the access point, what's the maximum throughput that it can offer? Surely, it's impossible to obtain 11 and 54 Mbps, the maximum theoretical limits of 802.11b and g standards, respectively. So, we measured the maximum that each access point could provide with a client when:

*It used a WiFi card from the same vendor.
*It used a third-party WiFi card. Most laptops shipping today are Centrino based, which means that they use an Intel WiFi card. For this test, we used a Centrino-based laptop.

Latency: We measured the average latency between the client and the access point while transferring some data. Here, lower latency is better.

Throughput with streaming data: This becomes important when you're using WiFi for applications that require a constant stream of data without any break., like voice and video apps. For this, we configured the test to maintain 1000 Kbps for 15 seconds.

Resistance to interference: The 2.4 GHz frequency band that's used by all these access points is susceptible to interference from other devices like cordless phones and Bluetooth. We checked how susceptible was an Access Point to such interference by measuring the throughput with a Bluetooth device in between.

A few tips Finally, here are a few tips to keep in mind.

*Please check that the features mentioned on the packaging of your access point are actually there. In one access point we found the packaging said 256 bit WEP encryption, while it actually only supported 128.
*Before setting up an access point, read the instructions carefully. Some access points provide a MAC address that has to be entered during the installation.
*Place the access point where there's minimum interference from other devices. Usually, it's advisable to place it near the ceiling.
*Many access points specify how to position their antennas, so please check the manuals for that. Don't tamper with the antenna when it's working.
*Coexistence of 802.11g and 802.11b wireless clients on the same wireless network could slow down your network performance. So, when upgrading to 802.11g, also try to shift your clients to the same.

Lastly, there's a wide price variation that we found in all the access points, ranging from Rs 8,000 to Rs 52,000. So, choose carefully, depending upon the features you want.

resource : pcquest.ciol.com

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