How to handle switch and router failures

first, Switch, Bridge, Hub

Broadcast domain: controlled by router

Conflict domain: Controlled by switch or bridge

Switch and Hub comparisons:

Type Switch Hub

Unicasts Send to target only to all ports

Broadcasts sends all ports in the same VLAN to all ports

Aggregate bandwidth equals bandwidth per port x port equals media rate

Full/half-duplex Full duplex connection only half duplex

Support for mixed Media:token ring,ethernet,fddi ... Depending on the switch, you can transfer between different frame types and physical media to support only the same media

Support for mixed media depends on bridge configuration

Process frame hardware (ASIC) software or

The number of ports from 4 to more than 100 is usually 16 below

Frame type conversions depend on bridge configuration

　　Second, Catalyst Fault handling tools

1, Catalyst command line interface:

command-line interfaces have native and hybrid modes. The native mode is configured with layers 3rd and 2nd, and the blending mode is configured with the 3rd and 2nd layers under different CLI, often the set based CLI.

2. CLI in mixed mode:

1 Show System: Advanced summary information on switch, including power supply status, uptime, and management settings

2 Show Port: Displays information for all ports on a specified port or on a module (VLAN, rate, duplex, status, type 、...)

3 Show log: Reports important events, including reboot, trap, power failure of all modules 、...。

4 show Logging buffer: equivalent to the router's show log command, according to the logging level, report port up or down, STP 、...

5 Show Interface: VLAN information on the IP configuration and SC0 interface on the report management module. (Sl0, SC0)

6 Show CDP: displaying neighboring Cisco device information

7 show config: equivalent to shows running-config command, display switch except MSFC all the settings on all modules, show only non-default settings. Show config all displays all settings.

8 Show test: Only display switch management module status, including interface card, power supply, memory, etc.

9 Show Mac: Displays a large number of counts, including the per-port frame flow, the total number of frames emitted and entered, discarded 、...

Show VTP domain:

One) show Cam: Displays the MAC address associated with the port

12 Duplicate MAC Address

Show Spantree: SPT process status for each VLAN

Show version: Displays hardware and software version numbers, including memory, system up time statistics, etc.

3, RMON (Remote monitoring)

RMON is based on Rmonprobe and collects data from the circuit (physical media). Router and switches do not support all levels of rmon information, and more monitoring can be achieved with SPAN (Switched Port Analyzer switching ports analysis, also known as Port mirroring ports monitoring).

4, LED:

The management engine contains a load led that prompts for the current load on the switch. During the boot process, the LED will blink, under normal circumstances, led Evergreen, Orange led prompts a problem, red LED hint of failure.

　　Third, using STP control loop

The STP algorithm is defined in 802.1D to control repetitive paths in multiple switches to avoid network loops.

When Cisco uses port fast and uplink fast, you should prevent network loops from being generated.

　　Four, VLAN

VLAN has a port based static VLAN and a Mac based dynamic VLAN

1, Isl:cisco Special protocol, used to connect two devices to support multiple VLANs.

ISL can only be used on products that support ISL

ISL must be point to point

ISL is only available for 100Mb Full-duplex