Chapter 6

Universal Plug and Play(UPnP)

A protocol enabling devices to dynamically add themselves to a network without the need for user intervention/configuration. Although convenient, it isn't secure. The protocol has no method for authentication, therefore it considers every device trustworthy. It also has numerous other security vulnerabilities. EX: Malware can use it to redirect traffic to a different IP outside your network. Search for "vulnerability profiling tools" to determine if your router is exposed to UPnP vulnerabilities.

The ipconfig /release command or ipconfig /renew cmd results in the following message: "The operation failed as no adapter is in the state permissible for this operation."

Possible causes: -The comp has been configed with a static IP addr. Possible Solutions: -Reconfig the NIC to auto-obtain IP addr.

Devices cannot detect the wireless router.

Probable Causes: -Router/AP is configured with a different 802.11 protocol. -The SSID isn't being broadcast. -The WNIC in the laptop is disabled. Probable solutions: -Configure the router with a compatible -protocol for the laptop. -Configure the router to broadcast the SSID. -Enable the WNIC in the laptop.

The nslookup command reports "Can't find server name for address [IP-address] timed out". where IP address can be any IP address.

Probable Causes: -The DNS server isn't responding -The DNS records are incorrect. Possible solutions: -Resolve connectivity to the DNS server and/or restart the DNS server. -Config the DNS server with the correct records.

The FTP client software can't find the FTP server.

Probable Causes: -The FTP client has an incorrect server/domain name or port setting. -The FTP server isn't op, or is offline. -The DNS server isn't op and not resolving names. Possible Solutions: -Enter the correct server/domain name and port settings in the FTP client. -Restart the FTP client. -Restart the DNS server.

A user can access the LAN but can't access the net.

Probable Causes: -The gateway addr is incorrect/not configured. -The ISP is down. Possible Solutions: -Ensure the correct gateway addr is assigned to the NIC. -Call ISP to report outage.

Remote device doesn't respond to a ping request.

Probable Causes: -Windows firewall disables ping by default. -The remote device is configured to not respond to ping requests. Possible Solutions: -Set the firewall to enable the ping protocol. -Configure the remote device to respond to the ping request.

Local resources like fileshares or printers are unavailable.

Probable causes: -Could be a number of issues: bad cabling, switch or router not func, firewall blocking traffic, DNS name res not working, service failure. Possible solutions: -Establish the scope of th eproblem.

Troubleshooting process

Scientific Method really... ID problem Establish causation theory Test Theory Establish plan Verify full system functionality Document findings/actions/outcomes.

Internet of Things(IoT)

The net of today is vastly different than the internet of past decades. The net of today is more than email, webpages, and file transfers. The evolving net is becoming an IoT. Devices addressing the net will no longer only be computers, tablets, and smartphones. Sensor-equipped net-ready devices of 'morrow will include anything from cars and biomedical devices, to household appliances and natural ecosystems.

NAT and IP searching

To see the IP addresses for your device, search the internet for "what is my IP address". Do this for other devices on the same network, and you will see they all share the same public v4 address. NAT makes this possible by tracking the source port numbers for every session established by a device. If your ISP ahs v6 enabled, you will see a unique v6 address for each device.

Configuring NICs

After installing the NIC driver, the IP address settings must be configured. For Windows computers, IP addressing is dynamic by default. After physically connecting one to the network, it will auto-send a req for v4 addressing to the DHCP server. If a DHCP server is available, the comp will receive a message with all its v4 addressing info. This dynamic, default behavior is also typical for smartphones, tablets, gaming consoles, and other end-user devices. Static configs are normally the job of network admins, however one should be familiar with how to access to the IP addressing configs for any device they are asked to manage.

Selecting NIC

An NIC is required to connect to the network. There are different types of NICs, Ethernet, and Wireless Most NICs in desktops are integrated into the motherboard, or connected to an expansion slot. NICs are also available in a USB form factor. Many comps purchased today come with a wired and wireless NIC integrated on the motherboard.

Server Set Identified(SSID)

Another way to say network name.

OOB

Out of Box

Finding the IP Addressing Configuration Information

To find it, search the internet for "IP Address Configuration for Device", where "device is replaced with your device", such as "IPhone".

Internet Control Message Protocol(ICMP)

Used by devices on a network to send control and error msgs. There're several different uses for it, such as announcing network errors, announcing network congestion, and troubleshooting.

WPA2 Personal

Wifi Protected Access v2 Personal

Verify Full Functionality, and If Applicable, Implement Preventive Measures

After correcting the prolbme, verify full func, and, if applicable, implement preventive measures.

Establish Plan of Action to Resolve the Problem and Implement Solutions

After determining causation, establish a plan of action to resolve the problem and implement the solution.

Test the Theory to determine the Cause

After you've developed some theories about what's wrong, test your theories to determine the causation. Once the theory is confirmed, determine the next steps for resolution. If a quick procedure does correct the issue, you can then verify full system func. If a quick procedure doesn't correct it, you might need to research further.

IoT Devices in Packet Tracer

At this point in its infancy, the IoT market has not yet agreed upon a set of standards for IoT device installation and configs. IoT device configs is very much device specific. Consult manufac docs or websites for config guides. Packet Tracer also includes a number of sensors and actuators, along with basic IoT device configs.

NIC LED lights are not lit

Probably Cause: -Network cable is unplugged/damaged. -The NIC is destroyed. Possible Solutions: -Reconnect/replace network connection -Replace NIC

Network Address Translation(NAT)

Process to convert private v4 addresses to internet-routable v4 addresses. This process is reversed(internet-routable to private) for incoming packets.

Ping

Commonly used to test connections between comps. TO see a list of options you can use with the ping command, type "ping /?" in the cmd window. Works by sending an ICMP echo req to the IP address entered. If the address is accessible, the receiving device then sends back an ICMP echo reply msg to confirm connectivity. You can also use the ping command to test connectivity to a website by entering the site's domain name. EX: after entering ping Cisco.com, your comp will first use DNS to find the IP address, then send the ICMP echo request to that IP address.

Link-local IPv4 and v6 Addresses

Link-local addresses for v4 and v6 are used by a device to communicate with other comps connected to the same network within the same address range. The major difference between v4 and v6 is the following: - v4 devices uses the link-local address if the device cannot obtain a v4 address. -v6 devices must always be dynamically or manually configured with a link-local v6 address.

Installing an NIC

Follow the steps to install adapter cards if you're installing an NIC inside the computer. A Wireless NIC for a desktop has an external antenna connected to the back of the card, or attached with a cable so that it can be positioned for the best signal reception. You must connect and position the antenna.

SOHO

Small Office/Home Office

Port Triggering

Allows the router to temporarily forward data through inbound port to a specific device. You can use port triggering to forward data to a computer only when a designated port range is used to make an outbound request. EX: a game might use ports 27k - 27.1k for connecting with other players. These are the trigger ports. A chat client might use port 56 for connecting the same players so that they can interact with each other. In this case, there's gaming graffic on an outbound port with the triggered port range, inbound chat traffic on port 56 is forwarded to the comp that's being used to play the game/chat. When the game is over, and the triggered ports are no longer in use, port 56 is no longer allowed to send traffic of any type.

Subnet Mask

Are a continulous string of ones, with the rest of the mask being all zero bits. This means there are specific values taht a subnet mask would have, such as 225.255.255.0. They can also be represented in slash notation, using a slash followed by the number of one bits in the subnet mask, AKA the prefix length. The dotted decimal subnet mask of 255.255.255.0 would be the same as a slash 24 prefix length. EX: 255.255.255 each 255 is 8 bits, adding up to 24 Hence the Subnet can also represented with /24

Cable or DSL Modem Configurations

Are usually done by the service provider's representative either on-site or remotely through a walkthrough with you on the phone. If you buy the modem, it will come with documentation for how to connect it to your service provider which will usually include contacting your service provider for more info.

Dynamic Addressing

Instead of manually configuring every device, you cantake advantage of implementing a Dynamic Host Configuration Protocol(DHCP) server. DHCP servers automatically assign IP addresses, simplifying the addressing process. Auto-configuring some of the IP addressing parameters also reduces chances of assigning duplicate/invalid IP addresses. Most host devices by default are configured to request IP addressing from a DHCP server. The default setting for Windows comps are: - Obtain an IP address automatically - Obtain DNS server address automatically. When a comp is set to auto-obtain IP addresses, all other IP addressing config boxes aren't available. This process is the same for wired or wireless NICs. A DHCP server can auto-assign the following v4 address config info to a host: - v4 Address - Subnet Mask - Default Gateway - Optional values, like a DNS server address. DHCP is also available to auto-assign v6 Address info.

Whitelisting and Blacklisting

Specifies which IP address is allowed or denied on your network. Similar to MAC addr filtering, you can manually configure specific IP to allow or deny into your network. On a router, it's usually done using an access list/access policy. Refer to your router's doc for specific steps, or search the net for a tutorial. Similar to MAC addr filtering, it can become burdensome, better solutions exist. Search the net for "Parental control software" and "content filters".

Basic Wireless Settings

1. View the WLAN defaults A wireless router provides wireless access to devices using a default wireless network name and pass OOB. Locate the basic wireless settings for your router to change these defaults. 2. Change the network mode Some wireless routers allow you to select which 802.11 standard to implement. Mixed means wireless devices connecting to the router can have a variety of wireless NICs installed. Today's wireless routers configured for mixed usually support 802.11a, 802.11n, and 802.11ac NICs. 3. Configure the SSID Assign an SSID to the WLAN. OfficeNet is The wireless router announces its presence by sending broadcasts advertising its SSID. This allows wireless hosts to auto-discover the name of the network. If the SSID broadcast is disabled, you must manually enter the SSID on each wireless device that connects to the WLAN. 4. Configure the channel Devices configured with the same channel within the 2.4GHz band may overlap and cause distortion, slowing down the wireless performance and potentially break network conns. he solution to avoid interference is to configure non-overlapping channels on the routers and access points that are near each other. Specifically, channels 1, 6, and 11 are non-overlapping. 5. Configure the security mode. Routers may have no WLAN security configured OOB. WPA2 with Advanced Encryption Standard(AES) encryption is currently the strongest security mode. 6. Configure the passphrase. WPA2 personal uses a passphrase to authenticate wireless clients. It is easier to use in SOHO because it doesn't require an authentication server. Larger orgs implement WPA2 enterprise and require wireless clients to authenticate with a username and password.

Basic Network Setup

1: Log into the router form a web browser. After logging in, a GUI opens. It will have tabs or menus to help navigate to various router config tasks. It's often necessary to save the settings before proceeding to another window/tab. At this point, it's best practice to make changes to the default settings. 2. Change the default password. To do so, find the admin portion of the router's GUI. This is where the router pass can be changed. On some devices, you can only change the pass, the username remains admin(or whatever the default username is) for the router you are configuring. 3. Log in with the new password. After saving the new password, the router will request authorization again. Enter the username and the new pass. 4. Change the DHCP IPv4 addresses. Change the default router v4 address. Best practice is to use private v4 addressing inside your network. Search the internet for "private ip addressing" to learn more. 5. Renew IP address. After clicking save, you will lose access to the wireless router temporarily. Open the cmd window and renew your IP address with the ipconfig /renew command. 6. Log in at the new IP address Enter the new router's IP address to gain access to the router config GUI. You're not ready to continue configuring the router for wireless access.

Demilitarized Zone(DMZ)

A network that provides services to an untrusted network. An email, web, or FTP server is often placed into it so that the traffic using the server Doesn't come inside the local network. This protects the internal network from attacks by this traffic, but doesn't protect the servers in the DMZ in any way. It's common for a firewall to manage traffic to and from the DMZ. You can create on on a router for one device by forwardeing all traffic ports from the net to a specific IP or MAC address. A server, game machine, or web camera can be in it so that the device can be accessed by anyone. However, the Web Server is exposed to attacks from hackers on the net, and should have firewall software installed.

IP Address

Allows devices to communicate with devices on other networks. Routers are used to forward messages between IP networks. IP addresses are assigned by network admins based on location within the network. If a device moves from one network to another, its IP address will most likely change. These days a computer probably has an IPv4 and and IPv6 address. Use the ipconfig /all function in the command line to find them. The creation of the IPv6 stems from a concern of running out of IPv4 network addresses, which led its invention by the Internet Engineering Task Force(IETF). IPv6 is currently operating alongside IPv4 and beginning to replace it. Notes: On a Windows PC, NIC = Ethernet Adapter MAC Address = Physical Address

Computer Technician

As a computer technician, one most be able to support the networking need of one's customers, therefore one most be familiar with Network Components and Network Design.

Port Forwarding

Hardware firewalls can be used to block TCP and UDP ports to protect unauthorized access in and out of a LAN. However, there's situations when specific ports must be opened so certain programs and apps can comm with devices on different networks. Port forwarding is a rule-based method of directing traffic between devices on a separate network. When traffic reaches the router, the router determines if the traffic should be forwarded to a certain device based on the port number found with the traffic. The rules determine which traffic is sent onto the LAN. EX: a router may be configured to forward port 80. When the router receives a packet with the destination port of 80, it forwards the traffic to the server inside the network that serves web pages.

IPv4 Addressing

Have four decimal numbers, separated by a decimal, with each representing eight bits for a total of 32 bits. They also have a 32-bit subnet mask, represented in the same dotted decimal notation. An IP address under this format has two parts, a network portion and a host portion. The subnet mask is used to differentiated these two parts, the ones in the subnet mask indicate the network portion, whereas the zeroes represent the host portion. EX: the three decimal 255s of 255.255.255.0, 24 one bits, indicate the network portion of the v4 address, and the decimal zero, or zero bits, indicate the host portion. 192.168.1.100 255.255.255.0 192. 168 .1 255.255.255 =Network .100 .0 =Host

Static Addressing

IN a small network, you can manually configure each device with proper IP addressing via assigning a unique IP address to each host within the same network. On a Windows comp, you can assign the following IPv4 address configuration info to a host: - IP address; IDs the device on the network - Subnet Mask; used to ID the network on which the device is connected. - Default gateway; IDs the router that the device uses to access the internet or another network. - Optional values; such as the preferred DNS server address and the alternate DNS server address.

More about IPv4

If a device prepares data to send out on the network, it must first determine whether to send data to the intended receiver or to a router. It will send it directly to the receiver if the receiver is on the same network, otherwise it sends it to a router, who then uses the network portion of the IP address to forward it to the other network. EX: The windows comp has data to send to a host at 192.168.200.28. It sends it directly to the host because it has the same prefix of 192.168.200. Should the destination be 192.168.201.28, then the window''s computer would send the data to a router.

IPv4 Link-Local Address

If a windows comp can't comm with a DHCP server to obtain a v4 address, then Windows auto-assigns an Automatic Private IP Addressing(APIPA) address. This link-local address is in the range of 169.264.0.0 to 169.264.255.255

Configure a Wireless Mesh Network(WMN)

In a SOHO, one wireless router may suffice to provide wireless access to all the clients. If a person wishes to extend the range beyond 45m(indoors) and 90m(outdoors) however, they can add wireless APs. Extending a WLAN in a SOHO has increasingly become easier. Manufacturers have made creating a WMN simpler through smartphone apps. Buy the sys, disperse the APs, plug them in, download the app, and configure your WMN in a few steps. Search the internet for "Best wifi mesh network sys" to find the reviews of current offerings.

Document Findings, Actions, and Outcomes

In the final step of the troubleshooting process, document your findings, actions, and outcomes.

Network Components

Includes wired and wireless NIC, and network devices such as switches, wireless APs, routers, multipurpose devices, and more.

Network Design

Involves knowing how networks are interconnected to support the needs of a business. For instance, the needs of a small business will differ greatly from a large business. EX: A small business with 10 employees has contracted you to connect their users. A home or small office wireless router could be used for such a small number of users, they are multi-purpose, and usually provide router, switch, firewall, and AP capabilities. Additionally, they tend to provide a variety of other services including DHCP. If the business were larger, then this kind of router wouldn't work. Instead, you'd consult with a network architect to design a network of dedicated switches, APs, firewall appliances, and routers. Installing network cards, connecting wired and wireless devices, and configuring basic network equipment are necessary knowledge regardless of network design.

IPv6 Link-Local Address

Like v4, v6 Link-Local Addresses enables a device to comm with other v6-enabled devices on the same network, and only that network. Unlike v4, every v6 enabled device is required to have a link-local address. v6 link-local address are in the range of Fe80:: to febf::. EX: say the links to other networks are down(not connected). However, all the devices on the LAN can still use link-local v6 addresses to comm with each other. Note: unlike v4 link-local addresses, v6 link-local addresses are used in a variety of processes including network discovery protocols and routing protocols.

Quality of Service(QoS)

Many SOHO routers have an option for configuring QoS. By doing so, you can guarentee certain traffic types(like voice and video) are prioritized over traffic that is not as time-sensitive(email and browsing). On some routers, traffic can also be prioritized on specific ports. You will usually find the QoS settings in the advanced menus. If you have a router available, investigate the QoS settings. It might also be listed under "bandwidth ctrl" or something similar. Consult the router's doc or search the net for "qos settings" for your router's make/model.

Logging into the Router

Most SOHO wireless routers are ready for service out of the box. They're preconfigured to be connected to the network and provide services. EX: the wireless router uses DHCP to auto-provide addressing info to connected devices. Your first priority should be to change these defaults for security reasons, because wireless router default IP addresses, usernames, and passwords can be easily found on the internet. Just enter the search phrase "default wireless router IP address" or "default wireless router passwords" to see a listing of many websites that provide this info.

IPv4 in action

Network 192.168.1.0 with the 255.255.255.0 mask Network 172.16.0.0 with the 255.255.0.0 mask Network addresses have all zeroes in the host portion. Both networks share the same subnet mask, so the network portion of their addresses are identical. Their host portions are unique. PC A has the first IP address, should it move to a different network, its IPv4 address will change, but still share the same subnet mask and the same network portion of its address, with all other devices on that network. PCA now has the address 172.16.3.0, with the subnet mask 255.255.0.0, meaning it's now part of the 172.16.0.0 network.

Identify the Problem

Network problems can be simple or complex, and can result from a combination of hardware, software, and connectivity issues. As a technician, one should develop a logical and consistent method for diagnosing network problems by eliminating problems one at a time. EX: assess the problem, determine how many devices are experiencing the problem. If there's a problem with one device, start with that device. If it's a problem with all of them, start the troubleshooting process in the network room where all devices are connected. Use open ended and closed ended questions to gather info from customers.

NAT for IPv4

On a wireless router, if you look for a page like the Status page, you will find the v4 addressing info that the router uses to send data to the internet. EX: 209.165.201.11 us a different network than the 10.10.10.1 address assigned to a nrouter's LAN interface. ALl the devices on the router's LAN will get assigned addresses with the 10.10.10 prefix. The 209.165.201.11 v4 address is publicly routable on the internet. Any address with the 10 in the first octet is a private v4 address and can't be routed on the internet, so the router will use NAT. Some ISPs use private addressing connect to customer devices. However, eventually, your traffic will leave the provider's network and be routed on the internet.

Wireless Router Configuration GUI

Open a web browser, then enter the default IP address of your router in the address field. The default IP address can be found in the documentation that came with the router, or you can search the internet. A security window will prompt for authorization to access the router GUI. The word admin is usually used as the default username and password. Check your documentation or search the internet to find out what your actual authorization access is.

User cannot use SSH to access a remote device

Probable Cause: -The remote device isn't configured for SSH access. -SSH isn't allowed from the user or a particular network. Possible Solutions: -Configure remote device for SSH access. -Allow SSH access from the user/network.

Windows Comp has a v4 address of 169.254.x.x

Probable Causes: -The network cable is unplugged -The router is powered off or the conn is faulty. -The DHCP server isn't operational. -The NIC is damaged. Possible Solutions: -Reconnect the network cable. -Ensure router is pwoered on and properly conn to the netwrk. Then release and renew th eIP on the comp. -restart the DHCP server. -Replace NIC

The comp can't Telnet into a remote computer.

Probable Causes: -The remote comp hasn't been configed to accept Telnet conns. -Telnet services aren't started on the remote comp. Possible solutions: -Config the remote comp to accept Telnet cons. -Start the Telnet service on the remote comp.

A device cannot access a specific HTTPS site

Probable Causes: -The site isn't on that computer's browser's list of trusted sites. Probably Solutions: -Decide whether to add the security certificate to the browser's list of trusted sites.

The network is func, but the w-device can't connect to the network.

Probable Causes: -The wireless capability of the device is turned off. -The device is out of wireless range. -There's interference from other wireless devices using the same frequency range. Possible Solutions: -Enable wireless capability of the device. -Move closer to the router/AP. -Change router to a different channel.

A device on one network can't ping a device on another network

Probable Causes: -There's a broken link between the two networks. -ICMP is blocked at the router. -ICMP is blocked at the Windows firewall. Possible Solutions: -Use tracert to locate which link is down and fix the broken link. -Config the router to allow ICMP echo reqs and echo replies. -Config Win firewall to allow ICMP echo req and echo replies.

A user can't access the FTP server

Probable causes: -FTP is being blocked by the firewall at the router. -FTP is being blocked by the Win firewall. -The max number of users have been reached. Possible solutions: -Ensure ports 20 and 21 are allowed through the router's outbound firewall. -Ensure ports 20 and 21 are allowed through the Win outbound firewall. -Increase the max number of simultaneous FTP users on the FTP server.

The ipconfig /release or ipconfig /renew cmd results in the following msg: "No operation can be performed on the adapter while the media is disconnected."

Probable causes: -The gateway IP is incorrect. -The network cable is unplugged. -The comp has ben configed with a statis IP addr. Possible solutions: -Config the correct gateway IP addr on the device or on the DHCP server. -Recoonect the network cable. -Reconfig the NIC to auto-obtain IP addressing.

Routers and Mac Addresses

Routers on an Ethernet LAN also have Ethernet NICs, meaning they will have their own Ethernet MAC address. A router's function is to connect to multiple networks. EX: Router D's Ethernet NIC, with an address ending in all Ds is only used to communicate with other devices on the same network with PCA, printer B, and server C. The same router with another Ethernet NIC an address ending in all E's is used to connect to another network, and can't be reached devices connected to other LANs, such as those connected to the address with all D's. If one of these devices wish to send a message to a device on another network, it sends it to the MAC address they're connected to, who forwards the message to the appropriate interface towards the destination device.

Updating an NIC

Sometimes manufacturers publish new driver software for an NIC. A new driver might enhance the functionality of the NIC, or ight might be needed for OS compatability. The latest drivers for all supported OS are avilable for download from the manufacturer's website. While installing new drivers, disable antiviral software to ensure they install correctly as some scanners detect driver updates as a possible virus attack. Only install one driver at a time, some updating processes may conflict otherwise. The best practice is to close all apps that are running so they aren't using any files associated with the driver update.

MAC Address Filtering

Specifies which device MAC addresses are allowed to/blocked from sending data on your network. Many routers only give you the option of allowing or blocking MAC addresses, but not both. Technicians usually configure allowed MAC addresses. The MAC address for your Win comp can be found with ipconfig /all., though one may need to search the net for where to find MAC addresses on specific devices. Finding them isn't always straightforward 'cause not all devices call it a MAC addr. Win calls it a "Phys Addr", and Iphones call it a "Wifi addr". Furthermore, your device may have two/more MAC addr. EX: PS4 has two MAC addr, one for wired, and one for wireless networks. Similarly, a Win PC may have multiple MAC addr. Finally, consider the fact that new devices might be added to the network at any time. You can see how the technician responsible for manually configuring all these MAC addr might be overwhelmed. Imagine having to manually enter/maintain duzens of MAC addr in th an interface. However, MAC addr filtering may be your only option. Better solutions, like port security, require purchasing a more expensive router or a separate firewall device.

Connecting Wired Devices to the Internet

Step 1: connect a network cable to the device. An ethernet cable is attached to the NIC port. Step 2: connect the device to a switch port. The other end of the cable is connected to an Ethernet port on the wireless router. In a SOHO network, the laptop most likely would connect to a wall jack which in turn connects to a network switch. Step 3: connect a network cable to the wireless router internet port. On the wireless router, connect an Ethernet cable to the port labled Internet. This port may also be labeled WAN. Step 4: connect the wireless router to the modem. Step 5: connect to the service provider's network. The modem is then connected to the service provider's network. Step 6: power all devices and verify physical connections. Turn on the broadband modem and plug in the power cord to ther outer. After the modem establishes a connection to the ISR, it will begin comms with the router. The laptop, router, and modem LEDs will light up, indicating comms. The modem enables the router to receive the network info necessary to gain access to the internet from the ISP. This info includes public v4 addresses, subnet mask, and DNS server addresses. With the depletion of public v4 addresses, many ISPs are also providing v6 addressing info as well. Note:

IPv6 in action

Two v6 networks 2001:db8:acad:100:97ef:100:a765:1 Prefix 2001:db8:acad:100, Host :97ef:100:a765:1 2001:db8:acad:200::365ab Prefix, 2001:db8:acad:200, Host ::365ab 2001:db8:acad:100::/64 2001:db8:acad:200::/64 All devices in both networks share the same prefix length, however their host portions are unique. PCA has the v6 host address 2001:db8:acad:100:77/64. If a PC moves to a different network, its v6 address will change, and perhaps its prefix link. Moving PCA to a new network, it now has the v6 address of 2001:db8:acad:200::77/64, meaning it's now part of the 2001:db8:acad:200::/64 network.

MAC Addressing

Used to ID a device. AKA a physical address, MAC addresses never change, and will be the same whenever the device it is tied to is located. Used by Ethernet LANs. Written in 48 bits and hard-coded into an NIC by the manufacturer. Has two parts, first 24 bits represent the organizattionally unique identifier, or OUI, and is the vendor/manufacturer portion of the address. EX: one OUI code associated with Cisco is 00-60-2F. The next 24 bits are assigned by the vendor, and unique to that particular OUI. EX: 3A-07-BC is unique to vendor code 00-60-2F. Usage ex: when a PC sends a message to a printer, it sends it to that printer's MAC address.

IPv6 Addressing

represented in hexadecimal notation, with each digit in four bits, meaning each segment of four hexadecimal digits will be 16 bits. There are eight 16bit segments with each segment separated by a colon, totaling 128 bits. Is usually represented in compressed format, done using two rules. 1: leading zeroes of any 16 bit segment can be omitted. 2: a single string of contiguous all-zero segments can be replaced by a single double colon. An IPv6 address can utilize only one double colon. EX: Rule-1 2001:0db8:acad:00a0:3700:0000:0000:a100 2001:- db8:acad:- -a0:3700:- - -0:- - -0:a100 2001:0db8:acad:00a0:3700:0000:0000:a100 2001:0db8:acad:00a0:3700:------------:a100 2001:0db8:acad:00a0:3700:0000:0000:a100 2001:- db8:acad:- -a0:3700:- - -0:- - -0:a100 2001:0db8:acad:00a0:3700:------------:a100 2001:db8:acad:a0:3700::a100 Similar to IPv4, v6 uses slash notation. The prefix length to indicate the network portion(the prefix), of the v6 address. EX: 2001:db8:acad:100:37ef:100:a765:1 2001:db8:acad:100: = 64 one bits :37ef:100:a765:1 = 64 zero bits, so can be represented with :/64. 2001:db8:acad:100::/64