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Chapter 05
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Atualizámos a nossa política de privacidade de modo a estarmos em conformidade com os regulamentos de privacidade em constante mutação a nível mundial e para lhe fornecer uma visão sobre as formas limitadas de utilização dos seus dados.
Pode ler os detalhes abaixo. Ao aceitar, está a concordar com a política de privacidade atualizada.
Obrigado!
Ver política de privacidade atualizada
Encontrámos um problema, por favor tente novamente.
Hi,
First, let me offer a little background. I'm working on my Network+ cert, and I'm reading a book on the subject, and I'm up to the chapter on IPv6. I'm a former netadmin, who's been away from the industry for a good many years, and I thought that this cert would be a good refresher course for me. However, I have some questions related to IPv6 notation, particularly the short-cuts involved in typing in IPv6 addresses, and I felt that the book wasn't very clear on this. Therefore, I'm going to present what I know to be the case (and please correct me, if I'm wrong here), and then, I'll present what I'm unclear on. Also, please understand that the addresses listed below were all used as examples in this the aforementioned book.
Example #1: I understand that 2001:0000:0000:3210:0800:200c:00cf:1234 is a valid address, which can be rewritten as 2001:0:0:3210:800:200c:cf:1234. I also understand that this can be further reduced to 2001::3210:800:200c:cf:1234, b/c pairs of colons can be used to represent a string of consecutive groups w/ a value of zero.
However, double colons is where this tends to go off the rails for me a bit. For instance:
Example #2: fe80:0000:0000:0000:00cf:0000:ba98:1234 is a valid IPv6 address. This was then reduced to fe80::cf:0:ba98:1234. The only commentary given here was the following: "We can’t use a second :: to represent the third-to-last group of four zeroes—only one :: is allowed per address. The reason for this rule is that if more than one :: was used, we wouldn’t be able to tell how many sets of zeroes were in each group."
My problem here is if the first three hextets of zeroes are removed and replaced w/ a single colon, how am I to know that this represents three hextets instead of only two? From example #1, I see that two hextets of zeroes were replaced by two colons. If that address were 2001:0000:0000:0000:0000:0000:0000:0000, could it be rewritten as 2001::, and I would be led to understand that the address must be 2001:0000:0000:0000:0000:0000:0000:0000, since an address must have eight hextets? Therefore, in example #2, e80::cf:0:ba98:1234 would have to be fe80:0000:0000:0000:00cf:0000:ba98:1234, since the only way to make this address valid would be to add in three hextets of zeroes, correct?
Any help w/ this would be of great assistance. Thank you!
How long is a IPv6 address and how many possiblities are there? Ipv6 is a 128-bit address allowing up to 2^128 (3.4x10^38) addresses. What is one advantage of IPv6 IPSec is a standard part of every IPv6 stack meaning every packet sent from a NIC is encrypted. Also provides more efficient routing scheme by using aggregation Give an example of an IPv6 address and explain the
structure 2001:0000:0000:3210:0800:200C:00CF:1234 IPv6 addresses can be hard to read, what is a way to simplify them? Leading zeroes can be shortened to '::'
- Quartet/Hextet = each group of numbers
- Numbers between 0000:FFFF
- Eight groups of 4 characters
2001:0000:0000:3210:0800:200C:00CF:1234
now becomes
2001:0:0:3210:800:200C:CF:1234
and can now become
2001::3210:800:200C:CF:1234
NOTE: '::' can only be used to represent the zeroes once
FEDC:0000:0000:0000:00CF:0000:BA98:1234
becomes
FEDC::CF:0:BA98:1234
What is the IPv6 loopback address
How does one determine an IPv6 address is link-local
The first 64 bits will start with FE80::/10 followed by 54 zero bits.
FE80:0000:0000:0000
The second 64 bits are the 'Interface Identifier' and is generated by either
- Systems post-vista or OSX, and linux will generate a random number
- Legacy systems
like XP will use the MAC
How does subnetting happen in IPv6 and who passes them out?
Because the last 64 bits are generated by the NIC, the subnet mask is a maximum /64
IANA passes out /48 subnets to big ISPs, and /16 for smaller ISPs who will then pass out /64 subnets
Define unicast address (IPv6)
This is the systems link-local address
Define Multicast address (IPv6)
a set of reserved addresses designed to go only to certain systems. Individual addresses are assigned to specific applications.
What address is used to encapsulate IPv6 multicast packets
What is the function of the address FF02::1
Waht is the function of the address FF02::2
What is the function of the address FF02::1:FFxx:xxxx
Where does a DNS server keep the IP addresses of the root servers
Starts by giving a number of computers the same IP address. Routers use BGP to determine which computer or cluster is closest. The router then send the packet to the closest root DNS server.
How does a system get on the internet with IPv6
It needs a Global Unicast address and is only given out by the default gateway
Explain the process, in detail, of getting a Global Unicast Address
1. Computer sends out a solicitation message on boot
2. IPv6 Router sends prefix to computer
3. Computer adds interface identifier or EUI64 to prefix
4.
tells the router to go upstream and get a prefix to hand out to clients
Define no-default routers
tier-one routers that connect to other tier one routers. They can not have a default route
Every router underneath one router uses a subset of that routers existing routes.
Give the formula for a IPv6 address
48 bit from upstream router + 16-bit from default gateway + 64 bit unique number
What are the two modes that DHCPv6 uses?
Stateful - passes out IPv6 addresses, subnet masks, and defualt gateways, DNS, and TFTP server addresses.
Stateless - passes out only optional information (default)
How does a DNS server store a IPv6 record
Storing it in a record type of AAAA
encapsulating IPv6 traffic into a IPv4 tunnel
Enables IPv6 traffic to use the IPv4 internet. Generally used to connect two routers.
- Always start with 2002::/16
-
192.88.99.1 is the 6to4 anycast address
one of two tunneling protocols that can go through a NAT
IPv6 tunneling protocol
Start with 2001:0000:/32
Built into windows
Open source version of Teredo for linux
Define Intra-site automatic tunnel addressing protocol
ISATAP
Designed to work within an IPv4 network by adding IPv4 address to an IPv6 prefix.
ex. 2004:DB8::98CA:200:131.107.28.9
Tunnel Setup Protocol and Tunnel Information and Control are used to take advantage of automatic configuration
enables two IPv6 netowrks to connect over an existing IPv4 infrastructure
What ius a manual tunnel used for
Creates a simple point to point connectionbetween the two IPv6 networks
How does a IPv6 multicast fiffer from broadcasts
Both broadcasts and multicasts are sent to all network nodes but in multicast only the destination nodes process the incoming packets