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Questions tagged [ipv6]

For questions about Internet Protocol version 6 (IPv6); as specified in RFC2460.

58
votes
7answers
16k views

Why are IPv4 addresses running out?

I understand that we are running out (or ran out already?) of IPv4 addresses, but I don't really understand why that is. Right now, every home has its own IPv4 address (dynamically assigned, but still,...
14
votes
6answers
21k views

How are IP addresses mapped to MAC addresses?

I've been reading about the differences between MAC and IP addresses, and why we need both of them. To summarize, MAC addresses are physical unchangeable unique IDs for every single device while IP ...
13
votes
1answer
1k views

What happened to IPv5?

I hear/read much about IPv4 and IPv6 and nothing about IPv5. Where did it get lost in the discussion?
89
votes
12answers
27k views

IPv6 address space layout best practices

I'm comfortable with IPv4 address space allocations. By which I mean: Given services to plan for, or an organization to network, I have a good grasp of how to plan IP address space usage. (or at least,...
41
votes
4answers
43k views

Why is fe80::/10 reserved for link local addresses when fe80::/64 is actually used?

I understand that IPv6 reserves the fe80::/10 prefix for link local addresses, and that hosts select an address with a /64 prefix. Why is the reserved space so much larger than what is actually used ...
13
votes
4answers
1k views

Possible (bit) patterns of a netmask

Given a prefix Y, it's easy to calculate the corresponding netmask: Put Y times a set bit, and then fill up "to the right" with zeros until one has 32 bits (IPv4) in total. Example: Prefix 24, thus ...
8
votes
2answers
15k views

IPv6 link-local vs unique local

When do you use link-local or unique local in IPv6 networks? (Cisco doesn't manage to explain it properly in their online material.)
14
votes
5answers
9k views

Duplicate IP Address - which one wins?

If there's a duplicate IP address, which one "wins"? First, last, flaps, neither?
4
votes
0answers
758 views

Juniper SRX IPv6-PD update-router-advertisement issues

I'm trying to get some sweet prefix delegation working on my SRX. My provider offers DHCPv6-PD and gives out /56 addresses. I have done setups using cisco routers and am trying to replicate it onto a ...
3
votes
1answer
377 views

Finding Subnet Ranges of IPv6

I need to find a single subnet range to cover 10,000 IP addresses (hosts), given the IPv6 Address 2405:1300:c5c1:322::/108 (for example) I am aware of how to do subnet in IPv4 but cannot grasp the ...
10
votes
3answers
3k views

Selecting IPv6 Unique Local Addresses (ie, choosing least-sig 40 bits)

We started with fec0::/10 for site-local addresses -- but that is now deprecated. Instead, we now have fc00::/7 reserved, with fd00::/8 dedicated to /48 nets for Unique Local Addresses. What's the ...
5
votes
3answers
734 views

In networking, is there a word for the first n bytes of an IP address?

I have two IP addresses. They share an IP address to the nth byte. Is there a word that effectively says that they have the same IP address up to the nth byte? Are there different words depending on ...
4
votes
1answer
2k views

MAC address can be used to generate an IPv6 link local address

MAC address can be used to generate an IPv6 link local address. What is the process of using MAC address to derive an IPv6 address ? What are the problems that can be caused due to process of using ...
3
votes
1answer
628 views

IPv6 Link-local addresses

RFC 4291 specifies that IPv6 link-local unicast addresses must have a high-order bit sequence of 1111111010, or fe80::/10. However, the same document specifies that the 54 bits following the first 10 ...
3
votes
3answers
3k views

IPv6 NAT with Link-Local Address

It's more than usual to find NAT translating IPv4 private addresses (such as 192.168.0.0/16 or 10.0.0.0/8) to non private addresses. Is it possible that NAT translates even IPv6 link-local addresses (...
2
votes
3answers
690 views

What is IP address management ? Why its needed ? How does the vendors like Bluecat Networks and Infoblox solves the IPAM problem? [closed]

Recently I heard a term IPAM i.e IP Address management. Theoretically I got the definition from Wikipedia, but couldn't understand its actual need. Since for that we have DHCP then What is the need ...
2
votes
1answer
402 views

MAC Spoofing and EUI-64

I have two questions that both assume an attacker who has my MAC address: Suppose an attacker connects to the Internet before me, spoofing my MAC. I then connect and tell people to connect to my EUI-...
1
vote
1answer
83 views

Unsecured devices and IPv6

I'm currently starting to read up on IPv6, and as soon as I heared that every device can/will have a public accessible adreess i got a little freaked out. There are a lot of horror stories about ...
1
vote
2answers
178 views

Link Local Address using in NDP (IPv6)

How is using of link local address in NDP. We can discover neighbor by using global address. So why we need link local address in NDP?