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Day 2: Networking Fundamentals, Spanning Tree Protocol STP - Coggle Diagram
Day 2: Networking Fundamentals
Switching Concepts
Cisco iOS
A router or switch cannot function without an OS
IOS networking operating system
IOS Modes
IOS is a MODAL OS
When you are in different modes, you can do different things
modes
User EXEC mode
use "enable" to get to privilaged mode
Priviliged EXEC mode
Clobal Configuration Mode
Spesific Config Mode
basic command structure
not case sensitive
Following the command ...
PROMPT>COMMAND KEYWORD/ARGUMENT
Router>show ip protocols
help
use the "?" and enter
or you can get help with a spesific command that start with something you can type the characters it starts with then ? like: "sh?"
Need help with a commend "clock ?", or "clock set ?"
you will only get back negitive feedback, if a command is successfull, it won't show anything
Command hot keys
Tab - USE IT
Ctrl-R - Redisplay the line
Ctrl-Z Exit Config mode
Ctrl-Shift-6 - ESCAPE SEQUENCE
Up and Down arrows - previous commands
...
you can also shortan things like: for "Configure terminal" you can us "conf t"
if there's too much info you can hit SPACE to go an entire screen or ENTER to get one more line
the SHOW command
show interfaces
displays stats for al interfaces on the device
to view the stats for a spesific interfacese ...
show arp
show mac-address-table
show startup-config
show running-config
show ip intorfaces
show ip interfaces breif
devices need names
a hostname is used in CLI propts
if it is not set up it will just be a generic "Router" or "Switch"
applying a name
1 type enable
2 then configure terminal
hostname whateverthefuck
boom it's done your prompt will look like whateverthefuck>
Memory inside router or switch
RAM - Volitile
ROM - Non-Volitile - post, bootstrap, basic diagnostic software, Limited IOS
NVRAM - Non volitile - startup config
Flash - Non-volitile - IOS, other system files
Router/switch boot sequence
1 POST
Test hardware
takes stock of all the interfaces
2 BOOTSTRAP
Locates and loads Cisco IOS
3 IOS loads valid startup config file
loads startup-config from NVRAM into RAM
If not found in NVRAM it looks for TFTP
if not found, then it will go into setup mode
Access methods
Console
the CLI can be accessed through a console session by connecting to the console port
console uses a low speed serial connection to connect to the PC to the consol port on the router switch
the console port is accessable even if no networking servises have bin configed on the device
Examples of consoles are
...
Telnet
Can be accesed by the VTY (Virtual TeletYpe) session on the sisco device
For security reasons a password has to be set
AUX
the router's AUX port provides a dialup connectioun using a modem
this method dose not require any networking services to be configured
Aux port is used locally like a console port using a terminal emulation program
not all...
Configuration Files
The running configuration file
used by the device as it is operating
Stored in ram
the startup configuration file
used as a backup config and is used when the devices is started
stored in NVRAM
loaded into RAM each time the rrouter is started or reloaded
IPv4 Supnetting and VLSM
Multicast addresses
224.0.0.0/4
224 - 239
VLSM
Variable lenth subnet mask
Config and messing with router config
Steps to set the hostname of a router
configure terminal
hostname [NAME]
exit
enable
steps to look at interfaces and determine whether cables are attached
show ip interface brief
shows all the interfaces
shows if they are enabled or down
shows what type of interfaces you have
show controllers serial 0/0/0
shows information about an interfaces (spesificly this one is serial 0/0/0)
you can see if there is a cable connected and what type of cable is connected as well
VLANs
Virtual LAN
logical networkthot graups devices into separate brodcast domains
in a LAN all the interfaces on a switch are all on the same brodcast domain
making a VLAN Limits the broadcast or multicast traffict and is only heard by devices inside the same VLAN
We create VLANS to
Create secure network zones for servers, DMZs, guest, and quarantined networks
Segrigate devise based on type
phone
camera
AP
Prioritize traffic based on user or device type
VLAN IDs Range from 1 to 4094
1 is the default VLAN
All ports on a Cisco switch are assigned to VLAN 1 until they are configured to another
cisco switches that are connected will all use the single brotcast domain until you configure other VLANs
ALL the parameters of the default VLAN are set to default values the default VLAN cannot be renamed or removed from the VLAN database
1 to 1005 is the normal range, stored in the VLAN database
1006 - 4094 is the extended range, stored in running config or the VLAN database
ID 0, and 4095 are reserved for system use
VLAN configuration is stored in the VLAN database file,
vlan.dat
Config is also stored in the running-config file
Voice Access Ports
all access ports associated with one VLAN and brodcast domain
there are 2 types
Data access - Trasmit user data
voice access - carry voice traffic
They are assigned 2 ways
statically by the network admin
Dynamically through VMPS using params such as username computer account or MAC address
piggybacking combines phone and access VLAN to one swich port to reduse the number of switchports used
VMPS
VLAN Management Policy Server
A switch that contains a mappning of device informaiton to VLAN
Primary goal is VLAN assignment
Can also be used for providing serurity through segregating clients with an unknown MAC address
Now DEPRECATED by cisco in favour of 802.1X
IEEE 802.1X
PNAC Port-based Network Access Control
Provides an authentication mechanism to devises wishing to attach to a LAN or WLAN
ASK about this
Proprietary to Cisco
VLAN connectivity
VLANs can't communicate with eachother without a router
assign each VLAN a subnet, with all the hosts on the VLAN belonging to the same subnet
Configure a default gateway to sond traffic to other VLANs, remote networks, and the internet
router must provide an interface for each VLAN
Can be configured on Access-Layer switches
VLAN routing happens at the Distrobution Layer - Layer 3
Layer 3 switches can act like routers for VLANS
limitations of VLAN interfaces
only ethernet traffic can be routed, not other layer 2 protorols
rely on at least one physical switchport being up
you must reate a VLAN on the switch before createing a VLAN interface
Identify Physical issues
Make sure it's plugged in
make sure that the speeds match the lowest common speed ie Gb connected to Fast will only go at 100Mbps
show interface command can help identify speed
Make sure the Duplex mode mach
for connection speed, and duplex mode it's better to just leave them in auto so they can negotiate themselfs
IPv6
128 bits
fe80:: addressses are self assigned, local link addresses
FC00::/7
Reserved for UNIQUE local addresses
are private IP addr
LACP (Link Aggregation Control Protocol)
Port priority is used with the port number to form the port ID
Bundles individual links into a single logical unit to aggregate bandwidth to improve performance
Spanning Tree Protocol STP
IEEE 802.1D
Builds a loop-free logical topology for ethernet networks
there can only be one existing active path betweet 2 stations for the proper fuctioning of layer 2 ethernet network
STP operation is trasparent to end stations. they can't tell if they are connected to a switched lan with multiple segments or a single LAN segment
Root Bridges
the central reference pornt in a spanning tree topology
there is one root bridge for each VLAN
You can also designate a secandary root bridge in case the primary fails or becomes unavailable
Port States
each port transitions between these states to make sure that setting a port to forwarding dosn't create a loop
.
Blocking
Ports start in this state when STP is enabled
Recieves BPDUs
Dose not forward frames or learn addresses
Listening
STP sets a port to start for warding frames
recieves BPDUs
Dose not lear addresses
lasts 15 sec
Learning
Discards frames recived on the port
Dose not learn addresses
recieves BPDUs
lasts for 15 sec
forwarding
Receives and forwards frames
learns addresses
recievs BPDUs
Disabled
Non operational
dose not forward frames
dose not participate in spanning tree
Discards frames
Dose not learn addresses
Dose not reciev BPDUs
PVST Per-VLAN spanning tree