Questions tagged [ipv6]

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

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1answer
54 views

How does a device receive default gateway IP address?

When and how does a device get information about default gateway in LAN? I know you can define default gateway statically, but which protocol is used when it is not statically defined? Is it from ...
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1answer
20 views

Can servers derive the user IPv6 block of an address?

Internet Service Providers (ISPs) assign users large IPv6 blocks (~/64) containing millions of IPv6 addresses. If a user was to ping a server using 2 different IPv6 addresses from his given IPv6 block,...
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Why does a Cisco router advertise a prefix with NDP RA when it has an address in that range?

If I write interface Vlan1 ... {ipv4 config} ... ipv6 address 2001:DB8:5432:101::/64 eui-64 ipv6 address FDAA:DB8:5432:101::/64 eui-64 ipv6 enable ipv6 nd prefix 2001:DB8:5432:101::/64 ipv6 nd ...
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Can I route DHCPv6 & Router-Advertisements through another router? [closed]

I have asked this question on Super-User, though I'm not sure, it's the best place. 1 I believe this Exchange is a more appropriate place to ask: I have a dual router setup (two routers behind each ...
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1answer
42 views

Recommended IPv6 prefix size for PPP to a single host?

I am using PPP to create a IPv6 connection to a remote host. What is the recommended IPv6 prefix size for a single host at the other end of the PPP connection? Should it be /128, because there is ...
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2answers
683 views

Can a client-side outbound TCP port be reused concurrently for multiple destinations?

Can a client-side outbound TCP port be reused concurrently for multiple destinations? If it's possible, this would let NAT gateways milk an IP Address much more, and make it practically impossible to ...
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29 views

ECT Marked ICMP Responses

For ongoing research I'm conducting, I'm measuring the modification of ECT fields of the IPv[46] header. To do this I'm relying on ICMP quotations to inspect what packets 'look like' as they traverse ...
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2answers
65 views

IPv6 Prefix Delegation & propagation through an organisation

IPv6 Prefix delegation is designed to allow an ISP to give an organisation a block of addresses to issue throughout their network. However, enterprise networks extend beyond a single tier of devices, ...
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Why did we not run out of IPv4 adresses yet? [duplicate]

I know how IP addresses work and I also understand the reasons why there is a natural limit to those addresses, as well as the solution to that problem. Officially, we have ran out of IPv4 addresses ...
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1answer
16 views

Ping6 replies go to a different interface [closed]

Server A has two interfaces (i1 and i2) with the same IP on them, say fd11:1111:1111:1111::1/48. Server B has the same two interfaces with the same IP on them, say fd11:1111:1111:1111::2/48. When ...
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1answer
184 views

Why DNS services Like google public DNS and Cloudflare 1.1.1.1 has ipv6 versions?

I understand the need for ipv6 as we ran out of ipv4 but dns resolvers like google and cloudflare already have ipv4 addresses for resolving dns and i don't see compatibility as a reason either because ...
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Need a little clarification with NAT and IPv6

I understand NAT exists to not exhaust all the ipv4 addresses so there is no need for it with ipv6. So with ipv6 having an unimaginable amount of addresses, will every device have its own public ...
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1answer
39 views

Confusion regarding possible IPv6 Link Local address prefixes

I have trouble understanding how many alternative link local IPv6 address prefixes may exist. I know that the prefix is fe80::/10 which implies that the first 10 bits must be static as: | 10 ...
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0answers
15 views

Segment Routing Encapsulation on Client Interface? [closed]

I wanted to test SRv6. Always between two clients (client 1 <-> client 2). If I do the encapsulation on the client everything works smooth as expected. Client 1 (encap SRv6 Tunnel) <- 2001::/...
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2answers
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Is NAT66 a Viable Option to Protect Client?

Due to the addressing scheme of IPv6, each client now is able to get and directly use Globally-Routable Address (GUA) from the ISP. But that poses bigger security threat because attacker can directly ...
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2answers
93 views

Why cant't IPSec's Transport Mode ESP be used in NAT64 although ESP doesn't sign the new IP header?

In RFC6146 stated: Any protocols that protect IP header are incompatible with NAT64. This implies that end-to-end IPsec verification will fail when the Authentication Header (AH) is used (both ...
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1answer
25 views

Why does CLAT in 464XLAT architecture use Stateless NAT64 instead of Stateful?

As of my understanding, stateless NAT is using 1:1 translation, meaning it needs one IPv4 address for one IPv6 address vice versa, thus not preserving IPv4. Since the CLAT is supposed to be router/...
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1answer
61 views

BGP unnumbered on P2MP link

I'm wondering what will happen if BGP unnumbered session is configured on a link that has multiple routers on the other side which are both IPv6-capable and will both reply on RS and produce RA ...
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1answer
41 views

GNS3 can not ping from ethernet interface to serial interface

So I am doing a Lab for one of my classes involving ipv6 and routing using EIGRP. When I set-up the network and assign the router interfaces with IPV6 address I get an issue pinging the whole network. ...
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2answers
279 views

General: What is a dynamic gateway, how does it work, where is it used?

I saw this option in my OPNsense gateway configuration, and was hoping someone could shed light on what it is, exactly: Dynamic gateway policy: [YES/NO] This interface does not require an ...
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1answer
31 views

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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1answer
44 views

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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1answer
382 views

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
95 views

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
40 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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1answer
214 views

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
74 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
76 views

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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1answer
108 views

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
84 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
87 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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2answers
328 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
168 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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257 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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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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0answers
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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
38 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
330 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
92 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
283 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
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" ...
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4answers
3k views

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
89 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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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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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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1answer
116 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
628 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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