topic 9 : network implementation essentials Flashcards
what is are small network topologies?
- majority of businesses are small = most business networks are also small
- usually simple
- typically have a single WAN connection provided by DSL, cable, or an Ethernet connection
- managed by a local IT technician or a contracted professional
[large networks require an IT department to maintain, secure and troubleshoot network devices and to protect organizational data]
factors to consider when selecting network devices for a small network
- cost
- speed and types of ports/interfaces
- expandability
- operating system features and services
why do we need to plan before selecting devices in a small network?
- small networks require planning and design to meet user requirements
- ensures that all requirements, cost factors, and deployment options are given due to consideration
devices that will factor into the IP addressing scheme
- end user devices : the number and type of connections (wired, wireless, remote access)
- servers and peripheral devices (printer, security cameras etc)
- intermediary devices including switches and access points
redundancy in a small network
- required in the network design
- helps to eliminate single points of failure
- can be accomplished by installing duplicate network links for critical areas
verify connectivity with ping
- the ping command is the most effective way to quickly test Layer 3 connectivity between a source and destination IP address
- ping command uses the Internet Control Message Protocol (ICMP) echo (ICMP Type 8) and echo reply (ICMP Type 0) messages
ping on a windows 10 host
- the ping command sends 4 consecutive ICMP echo messages and expects 4 consecutive ICMP echo replies from the destination
verify connectivity with traceroute
- helps to locate layer 3 problem areas in a network
- a trace returns a list of hops as a packet is routed through a network
- the syntax of the trace command varies between operating systems
command : tracert (IP address)
network baseline
- for monitoring and troubleshooting network performance is to establish a network baseline
- method for starting a baseline : copy and paste the results from an executed ping, trace or other relevant commands into a text file.
- some items to consider : error messages and response times from host to host
command that verifies the current configuration and settings
show running-config
show ip interface
verifies the layer 3 information of an interface
show arp
verifies the list of known hosts on the local Ethernet LANs
show ip route
verifies the Layer 3 routing information
command that verifies which protocols are operational
show protocols
command that verifies the memory, interfaces and licenses of the device
show version
device identifiers (CDP neighbor device)
the configured hist name of a switch, router or other device
address list (CDP neighbor device)
up to one network layer address for each protocol supported
port identifier (CDP neighbor device)
the name of the local and remote port in the form of an ASCII character string, such as FastEthernet 0/0
capabilities list (CDP neighbor device)
whether a specific device is a layer 2 switch or a layer 3 switch
platform (CDP neighbor device)
the hardware platform of the device
basic troubleshooting approaches (steps)
1) identify the problem
2) establish a theory of probable causes
3) test the theory to determine cause
4) establish a plan of action and implement the solution
5) verify solution and implement preventive measures
6) document findings, actions and outcomes
resolve or escalate the problem?
- sometimes it may not be possible to resolve the problem immediately
- a problem should be escalated when it requires a manager decision, some specific expertise, or network access level unavailable to the troubleshooting technician
(a company should have a policy for this ^^)
IOS debug command
- allows the administrator to display OS process, protocol, mechanism and event messages in real-time for analysis
- allows for narrowing the output of debug to include only the relevant feature or sub-feature
where to use debug commands?
- entered in the privileged EXEC mode
- used only to troubleshoot specific problems
debug commands
- debug ? : lists a brief description of all the debugging command options
- add “no” in front of debug/ undebug : turns off a specific debugging feature
- undebug all : turn off all active debug commands at once
