Questions tagged [ipv6]

For questions about Internet Protocol version 6 (IPv6); as specified in RFC 8200.

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How do I know when an AAAA record is required? [closed]

I'm trying to wrap my head around DNS. My biggest issue right now is understanding when an AAAA record is required. Recently, I was asked by a colleague to point a subdomain from Server A to Server B....
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IPv4 and IPv6 Source Address field

Both the IPv4 and IPv6 headers contain the source address field. What are the reasons for including this field? Is it for to trace which who sent this packet if it get's lost?
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How is ICMP Packet Too Big handled in IPv6?

I am trying to comprehend the way packets fragmentation works in IPv6. As far as I understand it, IPv6 routers never fragment packets: upon receiving a packet whose size is bigger than the MTU of the ...
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2answers
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Why does IPv6 NS not use unicast address but multicast

This is a follow up of Why not put unicast address in IPv6 packet containing NDP neighbor solicitation instead of solicited-node multicast address? The accepted answer makes no sense. It states the ...
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1answer
36 views

Brocade OSPFv3 Routes are not installed

I am trying to deploy OSPFv3 across our network. However a few routers do not install the OSPFv3 route's to their routing tables. For example, this router is able to ping a certain host on the network....
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Why is the IPv6 address I'm getting from whatismyipaddress.com wrong? [duplicate]

So I've portforwarded my machine using the graphical interface provided by my router. This interface also gives me a public IPv6 which I can use to communicate with my machine through the internet. ...
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1answer
38 views

ASSIGNED or AGGREGATED-BY-LIR status of IPv6 subnet used for Virtualisation

According to the RIPE NCC IPv6 Basics training slides the ASSIGNED status should be used for your own infrastructure and individual (large) assignments to customers. The AGGREGATED-BY-LIR status ...
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5answers
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How does the shortage of IPv4 public IPs influence existing firewalls?

I came to know recently IPv4 public IP address pools are going to be exhausted soon. If IPv6 addresses are fully in use, all device vendors like Cisco, Fortinet, Palo Alto have to redesign their ...
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1answer
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What are usecases for IPv6 link-scope anycast?

IPv6 Neighbor Advertisement messages have a flag called Override, see RFC4861. It toggles, whether the receiver of the message should remove other link-layer addresses for the same IPv6 target address ...
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Distance Command in OSPFv3

Does anyone know if there is a way to specify the distance of a specific neighbor in OSPFv3 in a Cisco router/switch? You seem to be able to do it for an entire area, but not for a specific neighbor ...
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Why is an IPv6 interface required to have a link-local address?

According to Link-local address on Wikipedia: In IPv4, link-local addresses are normally only used when no external, stateful mechanism of address configuration exists, such as the Dynamic Host ...
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1answer
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Extra IPv6 Addresses - where are they coming from? [closed]

I recently got assigned a block of IPv6 addresses by my ISP. I've set it up with prefix delegation and it works just fine. When I plug a NIC in on the network it quickly picks up an IPv4 address from ...
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IPV6 static Routing

I'm new to networking and I'm currently learning about IPv6 in static routing. I set up an environment in Cisco Packet Tracer like this: have connected two routers with serial medium , each router ...
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2answers
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What Does a Private IPV6 address look Like?

I'm doing a presentation on how the internet works, and I'm wondering if there is even such a thing as a private IPV6 address. If so, what does a private IPV6 address looks like?
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1answer
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What is the last usable address in an IPv6 network

IPv6 does not have broadcast, so is the last address usable? Besides it being long, is it bad practice to actually use it? For example: A:B:C:D::0/64 starts with A:B:C:D:0000:0000:0000:0000 and ends ...
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IPv6 Extension Headers and UDP/TCP/ICMPv6 Checksums

Should the checksum for IPv6 packets (UDP, TCP, ICMPv6, etc.) change if extension headers are present? For example, will a UDP packet without a Hop-By-Hop extension header have a different checksum ...
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IPv6 - link-locals mess

I am implementing IPv6 in my network and for now I have my own routable IPv6 /48 block, Cisco routers, Cisco switches, OSPF between them and several hosts. Its all working fine, but there is something ...
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Will IPv6 make private IP addresses become obsolete?

Will it still be useful to make use of private IP addresses with IPv6?
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ipv6 connectivity and ESx

what does it mean of "Verify that the network infrastructure provides IPv6 connectivity for the ESXi hosts, vCenter Server and external database if used" ? to install ipv6-only ESx environment, what ...
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If a server has both IPv4 and IPv6 addresses, how does the DNS determine which to return? See the following example [closed]

These Pings were done at different times of the same day: C:\Users\LPress>ping www.ucla.edu Pinging gateway.lb.it.ucla.edu [164.67.228.152] with 32 bytes of data: C:\Users\LPress>ping www.ucla.edu ...
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1answer
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IPv6 SLAAC and Static DAD

I started learning about IPv6 and I wonder what happens when you mix SLAAC and static addresses in the same /64. My current understanding is as follows: Machine A with a statically configured ...
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1answer
34 views

ipv6: I can ping only 1 interface within same network even with static route

This is how I set up a static route. R1(conf): ipv6 route 2004:DB8:2233:23::/64 2001:DB8:1122:12::2 With this, I can ping to 2004:DB8:2233:23::2 (S2/2 on R2) but not to 2004:DB8:2233:23::3 (S2/2 on ...
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2answers
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Can link local addresses be used for transit networks without breaking routability?

I am asking this because my ISP uses SLAAC/DHCPv6 to assign addresses to clients. Firewalls, no matter what brand/name/type get a link local IPv6 address complete with a link local gateway AND clients ...
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1answer
67 views

How Many Extension Headers Can an IPv6 Packet Have?

How many next-header extensions can an IPv6 packet contain? I read here that it can contains: None, one, or more. which isn't very informative. Below is a reference to an IPv6 packet I'm looking ...
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2answers
192 views

DAD and link local address

I'm a new guy in IPV6, and now I encounter a question, when ipv6 policy is Auto configuration, is it necessary to DAD on Link local address? my question is, since link local address is created from ...
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1answer
68 views

How can MLDv2 work according to the RFCs 3810 and 4606?

When IPv6 Stateless Address Autoconfiguration is happening, an interface/node has to join the all-nodes multicast address and the solicited-node multicast address AFTER forming a "tentative" ...
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OPNsense and IPv6

I've got two servers hosted at online.net. They give away 1 free /48 subnet per user and configure them using DUIDs. I'm using OPNsense as an VM (in combination with Proxmox) on each server to handle ...
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Difference between :: and ::1

I am confused about following netstat output. There are two kind of local ports. The first is: [::]8100 The second is: [::1]8100 I know that [::1] is a loopback address for IPv6. My question is: ...
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1answer
61 views

When is the source address of ICMPv6 message types 133, 135 and 136 other than unspecified(::/128) or link-local(fe80::/10)?

According to rfc4861 the source address for Router Solicitation(ICMPv6 type 133), Neighbor Solicitation(ICMPv6 type 135) and Neighbor Advertisement(ICMPv6 type 136) can be an address assigned to the ...
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Why does the IPv6 header not include a checksum?

It is stated in Wikipedia that an IPv6 header does not include a checksum. What are the reasons that were behind this decision?
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PVLANs/Port isolation in IPv6 networks

We're currently using port isolation to prevent communication between computers on the same vlan and use client isolation on our guest wifi. The reason for having this enabled is to prevent unwanted ...
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Ipv6 link-local/multicast issue [duplicate]

When you ping a link-local address why is the destination (in packet tracer) to the solicited-node multicast address of the host and not the (FE80) link local address ? I understand that it needs to ...
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1answer
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Is there a method to modify bits in IP packets with OpenFlow?

We've already known that ovs-ofctl provides many actions to modify packets like set_field, load, move... but I can't find a suitable action or action combination to modify a bit in the IP packet ...
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1answer
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Remotely Connecting an IPv6 Computer to a IPv6 Private Web Server

I have a private web server at my office, and I want to access that server remotely at my house via IPv6. My office has both IPv4 and IPv6 enabled, but my home has only IPv6. IPv4 works, but I have ...
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Why is the source / destination address ordering in IPv4 and IPv6 headers opposite of Ethernet source and destination MAC addresses? [duplicate]

Engineers always do things for a reason. I've noticed that in Ethernet frames, the ordering is destination MAC address first, and then the source MAC address. What's the reason for reversing the ...
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1answer
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Next Header field in IPv6 vs Protocol field in IPv4, any difference?

So I am new to the IPv6 concept, and I seen that the Protocol field seems to be replaced with Next Header, and I have a question. Question: Is Next Header a complete replace of Protocol, or is they ...
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4answers
113 views

Why not put unicast address in IPv6 packet containing NDP neighbor solicitation instead of solicited-node multicast address?

This is a follow-up question to Why is the NDP Neighbor Solicitation message sent to the solicited-node address?. Summary: say I would send an IPv6 packet and put the unicast address of the host I ...
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1answer
269 views

Fortigate and ipv6 routing

I have a Fortigate router and my ISP support ipv6. I'm getting a public ipv6 on the Fortigate and also on the computers on the lan (2a02:a18:9041....) I have not to much understanding of ipv6, but by ...
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1answer
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Confusion about IANA “Protocol Numbers” registery

In the IANA registery for "Protocol Numbers", there listed 2 IP protocol versions: IPv4 at #4 and IPv6 at #41. Their "protocol" column says IPv[46] Encapsulation, and "reference" column points to 2 ...
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Does network layer provide connection oriented service

I know that in TCP/IP model the data link layer provides connection less service. While reading IPv6 Header. 'The flow label is used for connection oriented servie'. How does TCP/IP model provide ...
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1answer
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Function of the P-bit flag in an IPv6 multicast

Currently I'm trying to learn (common) things about IPv6 and started with the address format and the address scopes. Finally I reached the multicast part where my problem with the definiton of the ...
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2answers
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Is the first address in an IPv6 subnet assignable?

I am working in a lab and have configured a series of /125 subnets between routers. Lets ignore the best practice for this discussion of using /64 for everything. When I assign fd00:f9a8:ffff::257 to ...
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1answer
310 views

Understanding EUI-64

I was reading Forouzan's book. It says following: In IPv4 addressing, there is not a specific relation between the hostid (at the IP level) and link-layer address (at the data-link layer) because ...
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2answers
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Why the first octet of a MAC address always end with a binary 0?

I stumbled upon a piece of code on GitHub: https://github.com/adeverteuil/bash-ula-generator/blob/master/gen-ula.sh # Generate an EUI64 from the MAC address # as described in RFC 3513 # https://tools....
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2answers
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Why is the IPv6 link-local address not /9?

According to this answer, it's because computers read addresses in binary. Fine. That explains why the fe80 address does not need to be /12 or /16--it's because everything after the 10th bit is a ...
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1answer
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configure IPv6 ACL on interface WS-C3750X-48

I am using  WS-C3750X-48 model switch. license is lanbase. I have activated cmd on my switch: sdm prefer dual-ipv4-and-ipv6 routing. Then i did reload. After that, i will able to config IPv6 on ...
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1answer
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What does NAT64 do which can't be done by deploying IPv6 + NAT444?

Why was NAT64 developed? What does it do that can't be done by deploying IPv6 + NAT444, and allocating your customers a (public) IPv6 and a (private) IPv4 address (behind a shared public IPv4 address)?...
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1answer
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How to assign an ipv6 address to router 2900 gigabitethernet 0/0/0 - 0/0/3 interfaces?

I am working with a cisco router model 2900 which has four gigabitethernet 0/0/0 - 0/0/3. They do accept ipv4 addresses, however they will not accept ipv6 address. I have tried to use svi (assigning ...
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3answers
106 views

Can u explain this representation of the IPv6 address 1001::1 64?

::1 is for loopback address. An IPv6 address contains 8 16-bit pieces. What do this representation 1001::1 64 mean (what is the full address with all 8 16-bit pieces)?
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1answer
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Packet Tracer 7.2.1 does not support eigrp for ipv6

I'm trying to enable eigrp for ipv6 in packet tracer but is seems to only have ospf and rip for ipv6. Is this a recent limitation?

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