Questions tagged [ipv6]

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

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1answer
23 views

Is it possible to do SLAAC with Route Advertisement *without* default-route? [closed]

I have a router with IPv6-ULA networks. It's running Linux with Systemd-networkd if that matters. Now I'd like to auto-configure clients in one network so that they will have an address in one of the ...
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1answer
32 views

Why solicited-node multicast address while all-node multicast address can do the same thing?

Why bother plugging in the last 24 bits of the sender's unicast address into the solicited-node multicast address while all-node multicast address can achieve the same thing? In my view, this move is ...
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2answers
35 views

Does it require a DAD when generating link-local address in IPv6

In IPv4, link-local addresses are checked to be unique using an ARP request. But in IPv6, as it is generated by a EUI-64 or hash. It is assumed to be unique (I suppose). But does it require a DAD (...
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1answer
41 views

What is the reason behind not returning unused IP addresses? [closed]

There are several companies out there with one or more /8 IP addresses, for example: DoD has more than 200 million, HP has one /8 (>16 million), Apple has one /8, General Electric has one /8, IBM ...
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2answers
23 views

Calculating Checksum for ICMPv6 Packet

I have a packet that has a checksum of 0xffff, and a calculated checksum of 0x0000. I know in UDP, a checksum of 0x0000 is not allowed, and is instead replaced with 0xffff, thus the packet should be ...
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5answers
219 views

If IPv6 exists, why do we still pay for static IPv4 addresses?

Given that there is some ridiculous number of IPv6 addresses per every single person on the planet, why do ISPs still charge for IPv4 addresses? Why not just give the user an IPv6 address? Is it ...
4
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1answer
524 views

Which one right, UDP has 508 or 512 bytes payload limits?

We know the size guarantees the datagram won't be fragmented in IPv4 is maximum 576 bytes. But the size when use UDP header 8 bytes and if we take UDP payload 512 bytes and choose maximum header size ...
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1answer
36 views

Do IPv6 addresses have better persistence with DHCPv6?

I have a LAN with about 25 devices that occasionally grab each other's IP address via DHCPv4. I know there are certain lease time limits and it can be set to very long periods to work it around to an ...
3
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1answer
87 views

Are IPv4 type of service and IPv6 traffic class equivalent to each other or is traffic class IPv6 specific? [duplicate]

IPv6 has a traffic class field. According to the specification it is an IPv6 length, out of which first 6 bits are called code point or differential services code point (DSCP) and the last 2 bits are ...
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2answers
88 views

Is it possible for TCP can accept out of order segments?

TCP is connection-oriented protocol whereas IP isn't connection-oriented protocol. Any packets before sending into transport layer sorted operation must have been done in network layer. That's why we ...
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2answers
185 views

Why can IPv4 and IPv6 use strict source routing(in options field) and flow label respectively inspite of connectionless protocol?

In IPv4 option field one field option is source routing option this means packet will always be routed by router Or not. Packet can also be routed by source such routing is known as source routing. ...
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1answer
35 views

How to configure IPV6 /53 subnet on packet tracer?

I have tried configuring a Ipv6 subnet address 2001:0dce:0000:0000::1/53 into the router interface. It works but when the I tried setting the auto-configuration button on the PC connected to this ...
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4answers
99 views

IPv6 addresses plan and allocation

I read at several places that ISPs should allocate a /48 (or /56) IPv6 addresses blocks to end users Wikipedia for instance The RIRs assign smaller blocks to local Internet registries that ...
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1answer
127 views

Traffic sent to GRE Tunnel fails, but GRE Tunnel is up and OSPF adjacencies are formed

NEW INFO_7-12-21 R1#sho ipv6 rout 2001:db8:B2:200::2:2 Routing entry for 2001:db8:B2:200::2:2/128 Known via "static", distance 1, metric 0 Route count is 1/1, share count 0 Routing ...
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1answer
156 views

Static IPv6 Route on Ubiquiti EdgeRouter for my own /64

I am colocating some hardware in a local datacenter, and I'm trying to get IPv6 going. My datacenter has assigned me a /64, but they have given me a gateway address within that /64. The gateway (that ...
2
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1answer
45 views

EUI-64 on a loopback address

A loopback address does not have a MAC address. How then does a loopback interface get assigned an EUI-64 address? I ran an example on packet tracer, and the loopback interface successfully acquired a ...
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0answers
53 views

Why cant my network send packages but piv6 pings go through?

I have the following network: My routing is as follows: Device configuration for ISP: Building configuration... Current configuration : 1388 bytes ! version 15.1 no service timestamps log datetime ...
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2answers
39 views

How to create a mapping between TCP segments or IP packets or fragments and TCP Windows? [closed]

I am searching for a method how I practically can determine the segments within a TCP window both when sending and receiving them? I want to modify IP packets per TCP window. I already looked into the ...
2
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2answers
64 views

Unable to add an abbreviated IPv6 to a Cisco router

I am very new to networking and playing around with GNS3. I am trying to configure a router to have 2 IPv6 addresses in a single interface (as far as I understood, this is possible with IPv6) I ...
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1answer
22 views

why is the adress prefix for global unicast adresses in ipv6 considered 3 bits?

global unicast adresses in ipv6 always start with number 2 or 3, but 2 or 3 takes only 2 bits , and the whole adress is represented in hexadec which takes 4 bits not 3, so why the prefix is 3 bits ?
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1answer
277 views

I can't ping the gateway IP (fe80::1) from the internal port in my fortigate 60f firewall

I am using a fortigate 60f firewall. I have configured it for both ipv4 and ipv6. I have used the SD wan (by adding wan1 and wan2) for load-balancing. Moreover, I have configure a default static route ...
1
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1answer
69 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
24 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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1answer
33 views

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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0answers
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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 ...
3
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1answer
54 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
849 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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0answers
30 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
100 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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0answers
19 views

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
20 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
218 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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1answer
49 views

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
60 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
19 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
71 views

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
149 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
48 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
71 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 ...
1
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1answer
87 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
584 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
87 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
49 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
569 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
148 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 ...
1
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1answer
43 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
266 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. ...
0
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1answer
93 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
2k views

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 ...
3
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1answer
79 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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