1. Look at the following IPv6 Address. Shorten it to its optimal length. 2001:ba
ID: 3605781 • Letter: 1
Question
1. Look at the following IPv6 Address. Shorten it to its optimal length. 2001:bac1:45df:0:0:0420:0:0001/64
2. Define the following terms for IPv6: a. Unicast b. Anycast c. Multicast When is each used?
3. With Stateless Address Autoconfiguration (SLAAC) how does a host obtain an IP Address? Be sure to detail all the steps involved.
4. EUI64 is a particular addressing process using IPv6. Explain the process of obtaining an EUI 64 address, and explain its purpose.
5. Describe the features of a link local IPv6 address. What unique portion is in this address? 6. What is an address that has the following prefix: FF02::/? When is it used?
Explanation / Answer
1. Look at the following IPv6 Address. Shorten it to its optimal length. 2001:bac1:45df:0:0:0420:0:0001/64
Answer: 2001:bac1:45df::420:0:1/64
-Continous section of zeros can be replaced with (::) double colon. In your case 0:0 is resplaced with (::).
-One or more leading zeroes from any hexadecimal digit group can be removed. so, 0420 can be 420 and 0001 will become 1.
2. Define the following terms for IPv6: a. Unicast b. Anycast c. Multicast When is each used?
Answer:
Unicast: - A Unicast address is used to represent a single host / single interface. It is used when you are suppose to send the data to a single destination. There are 3 groups of unicast in IPV6, Link-local, Site-local and Global Unicast Addresses. Used for One-to-One Communication.
Multicast: A Multicast address is used to represent a group of destinations/interfaces. It is used when you are suppose to send the data to a group of hosts/destination. Once you send the packet to multicast address, it will be delivered to all hosts that has joined that particular group.
Multicast addresses range is FF00::/8. Used for One-to-Many Communication.
Anycast: A Anycast address is used to represent a group of interfaces similar to Multicast address. But, a packet which is sent to anycast address will be delivered to the closest/random member of a group. The addresses of Anycast are taken from Unicast address scope itself.
3. With Stateless Address Autoconfiguration (SLAAC) how does a host obtain an IP Address? Be sure to detail all the steps involved.
Answer:
Step 1: The IPV6 Router sends RA (Router Advertisements) message to the host. It conains IPV6 prefix (Link-local scope), pefix lifetime information and other information.
Step 2: IPV6 Client will be istening for the local RA's from the router to form its unique IPV6 address. SLAAC is implemented in IPV6 Clients.
Step 3: IPV6 Client receives RA message from Router which contains IPV6 Network prefix of length 64 bits. Now, SLAAC will dynamically generate a host identifier which is 64 bits long and will be suffixed with the network prefix sent by IPV6 Router. SLAAC uses EUI-64 to generate a unique host identifier.
4. EUI64 is a particular addressing process using IPv6. Explain the process of obtaining an EUI 64 address, and explain its purpose.
Answer: EUI64 is a addressing scheme used in IPV6 to generate Unique IPV6 addresses (Host part) by clients.
For Example, Assume IPV6 Router sends RA message with IPV6 Network prefix of 2000:1234:5678::/64.
Now, Once the IPV6 Client receives this RA message, It starts generating the host identifier of IPV6 address using EUI 64 scheme. It performs the following:
Assume MAC address of IPV6 client is 0200:1234:5678
1. The first step of EUI-64 is to divide the MAC address into half and add FF:FE in the middle, which results in 0200:12FF:FE34:5678.
2. Second step is, Seventh (7th) bit will be flipped. In our example, first 8 bits are 00000010 (for 02). After flipping seventh bit, the value will be 00000000. So Now, address looks like 0000:12FF:FE34:5678.
3. At last, The generated host identifier will be merged with the network prefix from RA message. i.e, 2000:1234:5678:0000:0000:12FF:FE34:5678, which can be shortened to 2000:1234:5678::12FF:FE34:5678.
In this way, EUI 64 is used to generate unique IPV6 address for clients. It uses MAC address of client to generate unique IPV6 address.
5. Describe the features of a link local IPv6 address. What unique portion is in this address?
Answer: Link-local IPV6 address is used for local communication. These addresses are used by devices for communicating with other nodes on same link. The scope of this address is limited to local link.
These addresses cannot be routed to public networks (like internet) and is limted to local network. These are auto-configured / auto-generated stateless addresses.
The Unique portion of this address is, All IPV6 Link-local address starts with FE80 (hexadecimal). the address block fe80::/64 is reserved as link-local unicast addresses in IPV6.
6. What is an address that has the following prefix: FF02::/? When is it used?
Answer: IPV6 Multicast addresses begin with FF00::/8. After first 8 bits, follows 4-bits of flag and then 4-bits of Scope (Which indicates scope of multicast traffic).
Scope vaoues:
1 - Interface Local
2- Link Local
4 - Admin Local
5 - Site Local
E - Global
etc.
So, the IPV6 addresses that start with FF02:: /16 are multicast addresses which is intended to stay on link local.
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