Questions tagged [ipv6]
For questions about Internet Protocol version 6 (IPv6); as specified in RFC 8200.
478
questions
2
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1
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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 ...
0
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2
answers
1k
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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 ...
0
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0
answers
53
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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 ...
28
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3
answers
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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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0
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242
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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
...
5
votes
1
answer
514
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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 ...
1
vote
1
answer
67
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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 ...
2
votes
2
answers
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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 ...
1
vote
1
answer
686
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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 ...
2
votes
2
answers
696
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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 ...
2
votes
1
answer
117
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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" ...
13
votes
4
answers
7k
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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:
...
2
votes
1
answer
258
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 ...
38
votes
3
answers
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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?
4
votes
0
answers
215
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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 ...
0
votes
1
answer
242
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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 ...
0
votes
1
answer
2k
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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 ...
1
vote
1
answer
344
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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 ...
2
votes
4
answers
598
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 ...
0
votes
1
answer
2k
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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 ...
2
votes
1
answer
202
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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 "...
0
votes
1
answer
92
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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 ...
4
votes
1
answer
192
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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 ...
8
votes
2
answers
3k
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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 ...
0
votes
1
answer
2k
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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 ...
3
votes
2
answers
6k
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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....
2
votes
2
answers
324
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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 ...
2
votes
1
answer
101
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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 ...
5
votes
1
answer
251
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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)?...
0
votes
1
answer
91
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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 ...
-1
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3
answers
421
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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)?
0
votes
1
answer
65
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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?
1
vote
0
answers
40
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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 ...
1
vote
3
answers
784
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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 ...
0
votes
1
answer
140
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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
vote
1
answer
121
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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
vote
1
answer
122
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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 ...
0
votes
1
answer
993
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RDP on IPV6 using DS-Lite-Tunnel [closed]
I am trying to access one of my PCs from and external network using RDP on port 3389.
After realizing my ISP uses DS-Lite-Tunnel I gave up ipv4 and focusing on ipv6.
So far the only way I managed ...
1
vote
1
answer
37
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How to group 3 hosts in ACE Ipv6 statement
I know for ipv6 ACE there is no wildcard mask, so if I want to add three hosts in one statement, for example, which prefix should I use for that network? (network 2001:db8:cafe:1/64, ::1 reserved as ...
4
votes
1
answer
246
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Benefits for adopting ipv6 internally?
I have googled it, but the articles dealing with the question seem to be either several years old or very general.
What is the current status of ipv6 adoption in terms of usefulness?
Specifically, ...
8
votes
6
answers
5k
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Could IPv6 make NAT / port numbers redundant?
From what I can tell, each process could get its own IP address, with loads of IP's to spare.
What would the drawbacks be?
Essentially, your host would become a router and each process is a host (in ...
2
votes
1
answer
2k
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Setting Destination MAC address for RTP/UDP packets
I have a requirement where I have to send the UDP packet to a destination multicast IPv6 address. In addition to that the packets must also have corresponding destination multicast MAC address set. I ...
1
vote
1
answer
315
views
Does CSR1000v on AWS support IPv6?
I'm trying to implement Segment Routing IPv6 (SRv6) in Cisco CSR1000v on AWS. I'm having issues with IPv6 which gave the impression that IPv6 data plane does not work.
Similarly, I configured a ...
3
votes
1
answer
61
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How to handle IPv6 Extension Header Options with action = 01
RFC 8200 section 4.2 states that if a node does not recognize an option type, that node must do some action depending on the 2 higher order bits of the option type. When the higher order bits are 01, ...
2
votes
3
answers
259
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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 ...
3
votes
2
answers
531
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How to handle ICMP-in-IPv6 or ICMPv6-in-IPv4?
Since ICMP and ICMPv6 have different IP protocol numbers, it's technically possible for an IPv4 host to receive an ICMPv6 packet or for an IPv6 host to receive an ICMP packet. Is the host's behavior ...
2
votes
1
answer
462
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ipv6 dhcp pool option link-address
I'm learning to set up an ipv6 dhcp pool in Packet Tracer. And I'm stomped on what a link-address is as an option in a dhcp server ipv6. I've read this https://www.cisco.com/c/en/us/td/docs/ios-xml/...
5
votes
2
answers
271
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How to architect a globally distributed website, from an IP address perspective
I would like to have a website that is loaded fast from any point in the world. From my understanding, you need to take advantage of the data center "regions" at places like Google Cloud or AWS. That'...
2
votes
0
answers
71
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RPL: questions on routing mechanism
I'm studying RPL and two questions came to my mind:
1: Both in storing and non-storing modes, if a node wants to send a packet to another node via P2P communication paradigm, then how does the ...
9
votes
2
answers
2k
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Why do IPv6 unique local addresses have to have a /48 prefix?
According to RFC 4193, unique local addresses will always have a prefix of FD00::/8.. but according to Wikipedia:
The block fd00::/8 is defined for /48 prefixes, formed by setting the forty least-...