2000Trainers.com

Creating an Instant Windows FTP Server

Dan DiNicolo — Mon, 09 Jul 2007 18:42:40 +0000

As part of my consulting work, I regularly find myself in need of a quick and efficient way to transfer files between different operating systems, like Windows and Linux. This is especially the case when I’m trying to deal with a Windows system that won’t boot and I need to recover data. When faced with this situation, I generally boot into Linux, mount the hard drive, and then transfer user data to my Windows desktop. Rather than deal with the hassles associated with SMB/SAMBA connections, I prefer to transfer the files via FTP.

While Windows XP Pro does sport an FTP server in the form of IIS, I find it overkill for my needs. In cases where I want an FTP server up and running instantly, I rely on a basic but effective (and very small) utility called FTPDMIN.

FTPDMIN is described by its author as an “ad-hoc” FTP server and the description fits the bill - it’s best suited to temporary connections only, not meant as a dedicated always-on server. After downloading the file to an appropriate location, you simply double-click to get the server up and running (or run it from a command line). It will then wait for a connection from FTP clients, allowing you to upload and download files as required. Client connections are handled anonymously, so all you need to supply in the username anonymous and an email address as your password to connect.

Available startup options allow you to control whether users can upload files, specify the server’s listening port, and more. As a slender 65K file, FTPDMIN in a tool that every admin should keep in their utility pouch.

Backing Up and Restoring Cisco Switch Settings

Dan DiNicolo — Thu, 05 Jul 2007 13:26:15 +0000

Much like with Cisco routers, it’s generally a good idea to back up the configuration of your switches as well. The syntax to copy the configuration of a Catalyst 1900 series to a TFTP server is different than on a router, although it does following a similar “copy from to” format. The example below shows the configuration of a Catalyst 1912 being backed up to a TFTP server at address 192.168.1.31.

Cisco1912#copy nvram tftp://192.168.1.31/config-1912 Configuration upload is successfully completed

In this example, the contents of NVRAM (the configuration file) are copied to a TFTP server at 192.168.1.31, with a filename of config-1912. The command to copy this same configuration file from the TFTP server back to the switch is shown below.

Cisco1912#copy tftp://192.168.1.31/config-1912 nvram TFTP successfully downloaded configuration file

Unlike with a Cisco router, a Cisco 1900 series switch does not allow you to upload its IOS image to a TFTP server. However, it does allow you to download a new IOS image from a TFTP server. The command to do so is listed below.

Cisco1912#copy tftp://192.168.1.31/cat1900EN_9_00.bin opcode

In this example, the image to be downloaded from the TFTP server is named cat1900EN_9_00.bin. The opcode command is used to instruct the switch to download the file into Flash memory.

Configuring Spanning Tree Protocol Costs on a Cisco Switch

Dan DiNicolo — Thu, 05 Jul 2007 13:24:28 +0000

The purpose of the Spanning Tree Protocol (STP) is to prevent loops on a switched or bridged network. STP is enabled on Catalyst 1900 series switches by default. In fact, one instance of Spanning Tree is enabled for each and every VLAN.

In earlier articles we examined some of the default settings relating to the Spanning Tree Protocol, including bridge priorities, port costs, and port priorities. These settings can all be changed from their default values if required.

The cost or priority of a switch interface is changed using the spantree command from interface configuration mode. Notice that the cost associated with a port can range between 1 and 65536, while the priority of a port can be set to any number between 0 and 255.

Cisco1912#config t Enter configuration commands, one per line. End with CNTL/Z Cisco1912(config)#interface f0/27 Cisco1912(config-if)#spantree ? cost Change an interface's spanning tree path cost priority Change an interface's spanning tree priority start-forwarding Allow a change from blocking to forwarding Cisco1912(config-if)#spantree cost ? <1-65535> Change an interface's spanning tree path cost Cisco1912(config-if)#spantree priority ? <0-255> Change an interface's spanning tree priority

In order to simplify the configuration of Spanning Tree on a switch, global settings are configured using what are known as Spanning Tree templates. These templates include settings such as bridge priority, hello interval, and so forth. On a Cisco 1900 switch, up to four templates can be defined. Ultimately, these templates can be applied to different VLANs, allowing you to configure STP settings once for many different VLANs. By default, all VLANs have the first Spanning Tree template applied, as shown below.

Cisco1912#show span? Spantree spantree-option spantree-template Cisco1912#show spantree-template 1

Bridge Template 1 Bridge Priority : 32768 (8000 hex) Max age when operating as root : 20 second(s) Hello time when operating as root : 2 second(s) Forward delay when operating as root : 15 second(s) VLANs assigned to option : 1-1005

Some of the default values shown above should look familiar. Notice that the default bridge priority is set to 32768, and that the hello interval is set to 2 seconds by default.
If you wanted a particular switch to become the root bridge, it would be a good idea to lower its priority value. This is accomplished using the spantree-template 1 priority command, as shown below. In this case, I have set the priority value to 1000.

Cisco1912#config t Enter configuration commands, one per line. End with CNTL/Z Cisco1912(config)#spantree-template 1 ? forwarding-time Set a Spanning Tree FORWARD Interval hello-time Set a Spanning Tree HELLO Interval max-age Set a Spanning Tree MAX AGE Interval priority Set a Spanning Tree PRIORITY vlan Assign up to ten VLANs to a bridge template Cisco1912(config)#spantree-template 1 priority 1000 Cisco1912(config)#exit Cisco1912#show spantree-template 1

Bridge Template 1 Bridge Priority : 1000 (3E8 hex) Max age when operating as root : 20 second(s) Hello time when operating as root : 2 second(s) Forward delay when operating as root : 15 second(s) VLANs assigned to option : 1-1005

There may of course be times where you want to turn Spanning Tree off, for example if your network topology is loop-free. This is accomplished by issuing the no spantree command from global configuration mode, followed by the VLAN number for which you want Spanning Tree disabled. To re-enable Spanning Tree, simply remove the no option.

Cisco1912(config)#no spantree 100 Cisco1912(config)#spantree 100

Configuring Spanning Tree Protocol Costs on a Cisco Switch

Dan DiNicolo — Thu, 05 Jul 2007 13:24:28 +0000

Cisco1912#show span? Spantree spantree-option spantree-template Cisco1912#show spantree-template 1

Cisco1912(config)#no spantree 100 Cisco1912(config)#spantree 100

Enabling and Configuring VLAN Trunking Protocol (VTP) on Cisco 1900 Switches

Dan DiNicolo — Thu, 05 Jul 2007 13:21:25 +0000

The VLAN Trunking Protocol (VTP) is used to manage the configuration of switches that are part of a VTP management domain, as we learned in Chapter 3. Recall that three VTP modes exist – server, client, and transparent mode. Once a VTP server is configured, any changes made (such as adding or removing VLANs) will be propagated throughout the VTP domain. Remember that all members of the same VTP management domain must be configured with the same VTP password.

Cisco1912#config t Enter configuration commands, one per line. End with CNTL/Z Cisco1912(config)#vtp ? client VTP client domain Set VTP domain name password Set VTP password pruning VTP pruning server VTP server transparent VTP transparent trap VTP trap Cisco1912(config)#vtp server Cisco1912(config)#vtp domain ? WORD Name of the VTP management domain Cisco1912(config)#vtp domain 2000trainers.com Cisco1912(config)#vtp password cisco999 Cisco1912(config)# Cisco1912#show vtp VTP version: 1 Configuration revision: 1 Maximum VLANs supported locally: 1005 Number of existing VLANs: 6 VTP domain name : 2000trainers.com VTP password : cisco999 VTP operating mode : Server VTP pruning mode : Disabled VTP traps generation : Enabled Configuration last modified by: 192.168.1.100 at 00-00-0000 00:00:00

VTP pruning was also discussed in Chapter 3. When VTP pruning is enabled, traffic will not be passed to another switch across a trunk link unless that switch has ports configured for a given VLAN. For example, imagine SwitchA has VLANs 1, 2, and 3 configured, and a trunk link to SwitchB. If VTP pruning is enabled, and SwitchB has no ports on VLAN 2, traffic for VLAN 2 will not passed to it. VLAN pruning is enabled using the command vtp pruning enable.

Cisco1912(config)#vtp pruning ? disable Disable VTP pruning enable Enable VTP pruning Cisco1912(config)#vtp pruning enable

Recall from earlier in this appendix that while the command delete nvram erases the configuration of a switch, it does not delete the VTP database. To delete VTP information from a Cisco 1900 switch, you must issue the delete vtp command, which also requires the switch to reload.

Cisco1912#delete ? nvram NVRAM configuration vtp Reset VTP configuration to defaults Cisco1912#delete vtp

This command resets the switch with VTP parameters set to factory defaults.
All other parameters will be unchanged.

Reset system with VTP parameters set to factory defaults, [Y]es or [N]o? Yes

Enabling and Configuring VLAN Trunking Protocol (VTP) on Cisco 1900 Switches

Dan DiNicolo — Thu, 05 Jul 2007 13:21:25 +0000

Cisco1912(config)#vtp pruning ? disable Disable VTP pruning enable Enable VTP pruning Cisco1912(config)#vtp pruning enable

Cisco1912#delete ? nvram NVRAM configuration vtp Reset VTP configuration to defaults Cisco1912#delete vtp

This command resets the switch with VTP parameters set to factory defaults.
All other parameters will be unchanged.

Reset system with VTP parameters set to factory defaults, [Y]es or [N]o? Yes

Configuring ISL Trunk Links

Dan DiNicolo — Thu, 05 Jul 2007 13:18:11 +0000

Earlier in Chapter 3, we looked at ways to connect switches with trunk links, such that VLANs could span multiple switches. The two main ways to accomplish this are via the Inter-Switch Link (ISL) and 802.1q frame tagging methods. The Cisco 1900 series does not support 802.1q, leaving ISL as the only option for creating trunk connections with other Cisco switches.

Recall that two main types of links exist between switches – access links, which provide a link for only a single VLAN, and trunk links, which are capable of carrying the traffic of many VLANs through the use of a tagging method like ISL. ISL can only be configured on switch ports with speeds of 100 Mbps and above. On a Cisco 1900, this means that only ports 26 and 27 can be used to define ISL trunk links.

The command to configure a trunk port is simply trunk, followed by the state of the port. There are five states into which you can place a trunk port, as shown below.

auto - Will configure the port as a trunk link if the connected system is set to on or auto.
desirable - Port will negotiate to become a trunk link if the other system is set to auto, desirable, or on.
nonegotiate - Port will become a permanent trunk link, will not negotiate the connection.
off - Disables the trunk port and negotiates with the connected system to turn trunking off.
on - Configures the port as a permanent ISL trunk link, and negotiates with the other system to convert their port to trunk mode.

In this example we’ll configure port e0/26 as a trunk port, turning ISL on.

Cisco1912#config t Enter configuration commands, one per line. End with CNTL/Z Cisco1912(config)#int f0/26 Cisco1912(config-if)#trunk ? auto Set DISL state to AUTO desirable Set DISL state to DESIRABLE nonegotiate Set DISL state to NONEGOTIATE off Set DISL state to OFF on Set DISL state to ON Cisco1912(config-if)#trunk on

Once trunking is configured for a given port, that port will trunk traffic for all configured VLANs. However, it is also possible to deny traffic from certain VLANs from being trunked by issuing the no trunk-vlan command. In the example below, traffic from VLAN 50 will not be trunked across the port 26 link.

Cisco1912(config-if)#no trunk-vlan 50

Once trunk links have been configured, their state can be viewed using the show trunk command, followed by a letter associated with that link. Since port 0/26 is the first FastEthernet port, it is known as trunk A, while port 0/27 would be known as trunk B.

Cisco1912#show trunk ? A Trunk A B Trunk B Cisco1912#show trunk A DISL state: On, Trunking: On, Encapsulation type: ISL

Going a step further, you can also view which VLANs are allowed to use the trunk link by appending the command to include allowed-vlans, as shown below.

Cisco1912#show trunk a allowed-vlans 1-49, 51-1005

Configuring ISL Trunk Links

Dan DiNicolo — Thu, 05 Jul 2007 13:18:11 +0000

The command to configure a trunk port is simply trunk, followed by the state of the port. There are five states into which you can place a trunk port, as shown below.

auto - Will configure the port as a trunk link if the connected system is set to on or auto.
desirable - Port will negotiate to become a trunk link if the other system is set to auto, desirable, or on.
nonegotiate - Port will become a permanent trunk link, will not negotiate the connection.
off - Disables the trunk port and negotiates with the connected system to turn trunking off.
on - Configures the port as a permanent ISL trunk link, and negotiates with the other system to convert their port to trunk mode.

In this example we’ll configure port e0/26 as a trunk port, turning ISL on.

Cisco1912(config-if)#no trunk-vlan 50

Cisco1912#show trunk ? A Trunk A B Trunk B Cisco1912#show trunk A DISL state: On, Trunking: On, Encapsulation type: ISL

Going a step further, you can also view which VLANs are allowed to use the trunk link by appending the command to include allowed-vlans, as shown below.

Cisco1912#show trunk a allowed-vlans 1-49, 51-1005

Configuring VLANs on a Cisco Catalyst 1900 Switch

Dan DiNicolo — Thu, 05 Jul 2007 13:13:24 +0000

A VLAN is essentially a broadcast domain, assigned according to switch ports. By default, all ports on a Cisco 1900 are assigned to VLAN 1, sometimes referred to as the management or administrative VLAN. In order to implement additional VLANs, you will first need to define them, and then add ports to that VLAN. New VLANs are created from global configuration mode by using the vlan command and specifying both a VLAN number and name. For example, let’s say that we want to create a new VLAN for our Human Resources department (VLAN 100), and one for executives, VLAN 50.

Cisco1912#config t Enter configuration commands, one per line. End with CNTL/Z Cisco1912(config)#vlan 100 name HR Cisco1912(config)#vlan 50 name Executives

To view all VLANs configured on a switch, use the show vlan command.

Cisco1912#show vlan

VLAN Name Status Ports -------------------------------------- 1 default Enabled 1-12, AUI, A, B 50 Executives Enabled 100 HR Enabled 1002 fddi-default Suspended 1003 token-ring-defau Suspended 1004 fddinet-default Suspended 1005 trnet-default Suspended --------------------------------------

Notice that currently, all ports on our Catalyst 1912 switch are still part of VLAN 1. The next step involves adding ports to the newly configured VLAN. This is done from interface configuration mode, using the vlan-membership static command. In this case, we’ll add Ethernet ports 0/2 and 0/8 to VLAN 100.

Cisco1912#config t Enter configuration commands, one per line. End with CNTL/Z Cisco1912(config)#int e0/2 Cisco1912(config-if)#vlan-membership static 100 Cisco1912(config-if)#int e0/8 Cisco1912(config-if)#vlan-membership static 100

To confirm that the ports are now part of VLAN 100, use the show vlan command. An individual VLAN can be viewed by specifying the VLAN number after this command.

Cisco1912#show vlan

VLAN Name Status Ports -------------------------------------- 1 default Enabled 1, 3-7, 9-12, AUI, A, B 50 Executives Enabled 100 HR Enabled 2, 8 1002 fddi-default Suspended 1003 token-ring-defau Suspended 1004 fddinet-default Suspended 1005 trnet-default Suspended --------------------------------------

Configuring VLANs on a Cisco Catalyst 1900 Switch

Dan DiNicolo — Thu, 05 Jul 2007 13:13:24 +0000

Cisco1912#config t Enter configuration commands, one per line. End with CNTL/Z Cisco1912(config)#vlan 100 name HR Cisco1912(config)#vlan 50 name Executives

To view all VLANs configured on a switch, use the show vlan command.

Cisco1912#show vlan

To confirm that the ports are now part of VLAN 100, use the show vlan command. An individual VLAN can be viewed by specifying the VLAN number after this command.

Cisco1912#show vlan