Chapter 5 - Switch Configuration.pptx

Data and Networking 2 Communication ITP107L Casey Jasper A. Instructor Chavez Switch Configurati on Objectives  5.1 Basic Switch Configuration Configure basic switch settings to meet network requirements. Configure initial settings on a Cisco switch. Configure switch ports to meet net...

Data and Networking 2 Communication ITP107L Casey Jasper A. Instructor Chavez Switch Configurati on Objectives  5.1 Basic Switch Configuration Configure basic switch settings to meet network requirements. Configure initial settings on a Cisco switch. Configure switch ports to meet network requirements.  5.2 Basic Device Configuration Configure a switch using security best practices in a small to medium-sized business network. Configure the management virtual interface on a switch. Configure the port security feature to restrict network access. Configure a Switch Initial Settings Switch Boot Sequence  When a switch is powered on, the boot sequence occurs. Power-on self-test (POST), a program stored in ROM, executes and checks hardware like CPU and RAM. The boot loader, also stored in ROM, runs and initializes parts within the CPU, initializes the flash file system, and then locates and loads an IOS image. The IOS image can be defined within the BOOT environment variable. If the variable is not set, the switch scours through the flash file system searching for an executable image file, loading it into RAM, and launching it if found. If an executable image file is not found, the switch shows the prompt switch: where a few commands are allowed in order to provide access to operating system files found in flash memory and files used to load or reload an operating system. If an IOS operating system loads, the switch interfaces are initialized and any commands stored in the startup-config file load. The startup-config file is stored in NVRAM. Switch Boot Sequence (Cont.)  The boot system command is use to set the BOOT environment variable. Recovering From a System Crash  The boot loader prompt can be accessed through a console connection to the switch: 1.Cable the PC to the switch console port. 2.Configure the terminal emulation software on the PC. 3.Unplug the switch power cord. 4.Reconnect the power cord and at the same time or within 15 seconds, press and hold the Mode button on the front of the switch until the System LED turns an amber color briefly and then turns a solid green.  The boot loader command prompt is switch: (instead of Switch>). The commands available through the boot loader command prompt are limited. Use the help command to display the available commands. Switch LED Indicators  System LED shows if the switch has power applied.  Port LED states: Off – no link or shut down Green – link is present Blinking green – data activity Alternating green and amber – link fault Amber – port is not sending data; common for first 30 seconds of connectivity or activation Blinking amber – port is blocking to prevent a switch loop Preparing for Basic Switch Management  To configure a switch for remote access, the switch must be configured with an IP address, subnet mask, and default gateway.  One particular switch virtual interface (SVI) is used A switch to manage IP address the switch: is assigned to an SVI. By default the management SVI is controlled and configured through VLAN 1. The management SVI is commonly called the management VLAN. Remember that the switch console port is on the back of the switch.  For security reasons, it is best practice to use a VLAN other than VLAN 1 for the management VLAN. Configuring Basic Switch Management Access with IPv4 Important Concept Duplex Communication  Gigabit Ethernet and 10Gb Ethernet NICs require full-duplex connections to operate. Bidirectional communicati on Unidirectional communicatio n Configure Switch Ports at the Physical Layer  Some switches have the default setting of auto for both duplex and speed.  Mismatched duplex and/or speed settings can cause connectivity issues.  Always check duplex and speed settings using the show interface interface_id command.  All fiber ports operate at one speed and are always full-duplex. Auto-MDIX  Some switches have the automatic medium-dependent interface crossover (auto-MDIX) feature that allows an interface to detect the required cable connection type (straight-through or crossover) and configure the connection appropriately. Auto-MDIX (Cont.)  Use the show controllers Ethernet-controller command to verify auto-MDIX settings. Verifying Switch Port Configuration Verifying Switch Port Configuration (Cont.) Verifying Switch Port Configuration (Cont.) Layer 1 Layer 2 OK OK Network Access Layer Issues  Use the show interfaces command to detect common media issues.  The first parameter refers to Layer 1, the physical layer, and indicates if the interface is receiving a carrier detect signal.  The second parameter (protocol status) refers to the data link layer and indicates whether the data link layer protocol has been configured correctly and keepalives are being received. Network Access Layer Issues (Cont.) Troubleshooting Network Access Layer Issues Switch Security SSH Operation  Secure Shell (SSH) An alternative protocol to Telnet. Telnet uses unsecure plaintext of the username and password as well as the data transmitted. SSH is more secure because it provides an encrypted management connection. Wireshark Capture of Telnet Wireshark Capture of SSH SSH Operation (Cont.)  A switch must have an IOS version (k9 at the end of the IOS file name) that includes cryptographic capabilities in order to configure and use SSH. Use the show version command to see the IOS version. Configuring SSH Commonly forgotten command that is used 1. Verify SSH support. in key generation 2. Configure the IP domain name. 3. Generate RSA key pairs. 4. Configure user authentication. 5. Configure the vty lines. 6. Enable SSH version 2. The login local command Default is to accept both Telnet forces the use of the local and SSH (transport input all) database for username/ password. Verifying SSH  On the PC, connect to the switch using SSH. The PC is using SSH to communicate and issue commands on the switch. Secure Unused Ports The interface range command can be used to apply a configuration to several switch ports at one time. Port Security: Operation  Port security limits the number of valid MAC addresses allowed to transmit data through a switch port. If a port has port security enabled and an unknown MAC address sends data, the switch presents a security violation. Default number of secure MAC addresses allowed is 1.  Methods use to configure MAC addresses within port security: Static secure MAC addresses – manually configure switchport port-security mac-address mac-address Dynamic secure MAC addresses – dynamically learned and removed if the switch restarts Sticky secure MAC addresses – dynamically learned and added to the running configuration (which can later be saved to the startup-config to permanently retain the MAC addresses) switchport port-security mac-address sticky mac-address Note: Disabling sticky learning converts sticky MAC addresses to dynamic secure addresses and removes them from the running-config. Port Security: Violation Modes  Protect – data from unknown source MAC addresses are dropped; a security notification IS NOT presented by the switch  Restrict - data from unknown source MAC addresses are dropped; a security notification IS presented by the switch and the violation counter increments.  Shutdown – (default mode) interface becomes error-disabled and port LED turns off. The violation counter increments. Issues the shutdown and then the no shutdown command on the interface to bring it out of the error-disabled state. Port Security: Configuring Port Security: Configuring (Cont.)  Before configuring port-security features, place the port in access mode and use the switchport port-security interface configuration command to enable port security on an interface. Port Security: Configuring (Cont.) Port Security: Verifying  Use the show port-security interface command to verify the maximum number of MAC addresses allowed on a particular port and how many of those addresses were learned dynamically using sticky. Dynamic Sticky Port Security: Verifying (Cont.)  Use the show running-config command to see learned MAC addresses added to the configuration.  The show port-security address command shows how MAC addresses were learned on a particular port. Ports in Error Disabled State  Switch console messages display when a port security violation occurs. Notice the port link status changes to down. Ports in Error Disabled State (Cont.)  Check the port status and the port  Do not re-enable a port until the security security threat is investigated and settings. eliminated.  Notice that you must first shut the port down and then issue the no shutdown command in order to use the particular port again after a security violation has occurred. Chapter Summary Summary Configure basic switch settings to meet network requirements. Configure a switch using security best practices in a small to medium-sized business network. Packet Tracer - Skills Integration Challenge Reference CCNA Routing and Switching: Introduction to Networks v6.0: http://vapenik.s.cnl.sk/pcsiete/CCNA2/05_Switch_C onfiguration.pdf