Questions tagged [ipv6]

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

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1answer
168 views

How can IPv6 host know default router's IPv6 address using RA?

I know an IPv6 host will send Router Solicitation (RS) messages, and a router on the link will reply Router Advertisement (RA) messages. In the RA message, there is the Source Link-Layer Address and ...
7
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1answer
1k views

How to break apart an IPv6 /56 6rd delegated prefix from ISP into multiple /64 VLANs for use with SLAAC EUI-64? [Cisco]

I have CenturyLink Internet service, and they have a 6RD IPv6 deployment where they hand out an IPv6 delegated prefix /56 block to me and allow me to use it as I wish. My Cisco ISR router receives the ...
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2answers
90 views

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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5answers
12k views

Why is the U/L bit inversed in EUI64?

This inversion is bijective, so I can't figure out what is it's use.
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1answer
899 views

IPv6 default route not being installed from RA

Platform: Juniper SRX300 Version: JUNOS 15.1X49-D160.2 ISP: Midco I currently have an issue where the IPv6 default route is not being installed from the CMTS RA. Try as I might, I cannot get ...
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1answer
89 views

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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2answers
316 views

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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3answers
11k views

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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2answers
415 views

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
186 views

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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0answers
44 views

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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3answers
6k views

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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6answers
30k 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 ...
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0answers
43 views

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
39 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
396 views

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
100 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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1answer
76 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" ...
2
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1answer
94 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 ...
2
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2answers
305 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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0answers
87 views

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 ...
13
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3answers
4k views

Should a router use SLAAC for IPv6 address assignment?

I am a little confused by the following 2 RFCs relating to IPv6: RFC 4862 (IPv6 Stateless Address Autoconfiguration) RFC 7084 (IPv6 CE Router Requirements) RFC 4862 states: The autoconfiguration ...
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1answer
133 views

Is there a method to modify bits in IP packets with OpenFlow? [closed]

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
695 views

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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2answers
4k views

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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1answer
108 views

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 ...
2
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4answers
174 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 ...
3
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1answer
93 views

Global Unicast in IPv6 Neighbor Discovery

I have a very small pcap file in which Neighbor Discovery is performed for Global Unicast Addresses. That is, IPv6 addresses of both neighbors as I can see in Wireshark start from 2001:. Both IPv6 ...
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2answers
922 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?
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1answer
106 views

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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1answer
38 views

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
80 views

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 ...
4
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2answers
496 views

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
571 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 ...
2
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1answer
71 views

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 ...
3
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2answers
297 views

IPv6 tunneling over IPv4

I am willing to build a program that simulates the routing process of IPv6 packets over an IPv4 overlay network (tunnel). From what I have read so far I have understood that the IPv4 tunnel packets ...
2
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2answers
121 views

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 ...
3
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2answers
6k views

pfSense IPv6 NAT

I know many of you said that IPv6 has no NAT, but my server provider told me, that it is possible. I have no idea how... I have a pfSense Server as my Firewall (Not the router!). I have a /28 IPv4 ...
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2answers
13k views

Is it true that the fd00::/8 address range (ULA) in ipv6 is for machines that you NEVER want to speak with anything on the Internet?

Is it true that the fd00::/8 address space (User Local Addresses) in ipv6 is for machines that you NEVER want to speak with anything on the Internet? I was just reading that here and rather surprised ...
2
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3answers
147 views

Do extension headers in IPv6 increase the header length

I was reading about IPv6. It says the header is of a fixed size i.e. 40 bytes, then how come is it able to accommodate extension headers. Doesn't this alter the size of headers. Please help, cant ...
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3answers
451 views

How to do subnetting on IPV6 for non nibble boundaries?

As I was reading this article on How to: calculating IPv6 subnets outside the nibble boundary https://blog.apnic.net/2018/08/10/how-to-calculating-ipv6-subnets-outside-the-nibble-boundary/ The author ...
5
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1answer
205 views

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
34 views

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
169 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
61 views

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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0answers
28 views

Can a Neighbor Advertisement response packet trigger the transition from STALE to DELAY?

I think the title is pretty descriptive. I cannot seem to find anything in the standard about what kind of packets could trigger the transition from the state STALE to the state DELAY, in the ...
0
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1answer
95 views

Ping error ipv6

I am able to ping a PC1 to R1, Pc2 to r2 and PC3 to R3. All routers can ping each other. PC's can also ping themselves but I can't ping different PC's, I also cannot ping a PC to their own Gateway. ...
1
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1answer
64 views

Remote Host Neighbor Cache Entry State after Neighbor Solicitation request

When a Host A sends for the first time a NS request to another Host B, host B answers with a NA. In Host A Neighbor Cache, the state Entry for host B gets from INCOMPLETE to REACHABLE, when NA comes ...
1
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1answer
80 views

Assign a new public and static IP to a router behind my main router [closed]

What can you suggest to bring a second public and static IPv4 so I can configure my WAN-A interfase with my primary and an additional secondary IP settings so I can route all the traffic from the ...
9
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2answers
60k views

Stateful vs Stateless IPv6?

What's the difference here? Are stateful IPv6 entries retained in the DHCPv6 server?

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