Questions tagged [ipv6]

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

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4
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2answers
10k views

What does a switch do when the destination MAC address is unknown?

Say I just connected my computer to the internet through a home/office LAN network. I then proceed to ping google.com. Of course, the DNS converts google.com to the destination IP address, but how is ...
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1answer
5k views

Smallest IPv6 block advertised?

We've received a /48 allocation from ARIN, and want to advertise smaller blocks from different sites in our organization. I tried advertising a /56 from each site, but ISP is telling me they won't ...
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2answers
257 views

Are there limits to the number of global IPv6 multicast addresses in use at a time?

The address space for IPv6 multicast addresses is very large (something like 2^112) and so I'm imagining it might not be so hard to get my hands on a million or so of them at some point, and try using ...
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1answer
212 views

Using IPv6 for multihome ISP eBGP peering due to IPv4 public /24s no longer available

Problem: I have two routers, and two separate ISPs (two different public ASNs). I wish to accept full BGP routes in order for us to properly set up true reliable ISP failover in a way that allows ...
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1answer
89 views

Which fields in the IPv6 header are checked during an IP lookup?

I'll consider IPv6 headers for this question. I assume that the simplest IP lookup scheme implementation would just look at the 'Destination Address' field in the IP header of an incoming IP packet. ...
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4answers
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Does IPv6 remove the need for a VPN?

I know that a VPN may be used in lots of different ways for lots of different things, so I'm not suggesting that IPv6 removes the need for a VPN completely. I'm interested in one particular use-case: ...
10
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2answers
462 views

What is the proper name for hexadecimal like standard notation of an IPv6 address?

RFCs such as 5952 - "A Recommendation for IPv6 Address Text Representation" and 2373 - "IP Version 6 Addressing Architecture" each outline the commonly used hexadecimal and colon based notation that ...
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1answer
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MLD messages during IPv6 duplicate address detection

I was wondering if anyone can shed some light on when Multicast Listener Discovery (MLD) messages ought to be send during IPv6 Duplicate Address Detection. RFC4862 section 5.4.2 gives a detailed ...
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1answer
2k views

May every IPv6 address be written as an IPv4-mapped IPv6-address?

In RFC 5952 - section 5 it is stated that for some IPv6 addresses it is recommended to give the mixed notation, if it has a certain prefix. However, it is unclear which prefixes are used for this, ...
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4answers
923 views

OSI layer of Neighbor Discovery Protocol

NDP operates using ICMPv6 and, even though ICMPv6 messages are encapsulated in payload field of IPv6 datagram, ICMPv6 and ICMP are usually considered as network layer protocols. At least, on Wikipedia ...
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2answers
833 views

ipv6 Aggregatable global unicast addresses

Studying IPv6 addressing I haven't understood IPv6 aggregable global unicast addresses, I mean on RFC 4291 there is a generic scheme: | n bits | m bits | 128-n-m bits ...
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2answers
389 views

Two IPv6 global unicast addresses on the same interface (stateless and stateful)

Can I assign two global unicast address to the same interface, one obtained via stateful addressing (DHCPv6) and the other one via SLAAC (eui-64)? According to the RFC-4862: Both stateless address ...
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1answer
104 views

Why does Neighbor Discovery Protocol have to monitor upper-layer protocols?

While reading the RFC of NDP I wondered, why it is necessary to monitor upper layer traffic in order to know if a neighbor is reachable, e.g. a TCP ACK. I do get the IPv6 packet anyway, so I know it'...
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2answers
1k views

How does the TCP/IP stack handle UDP checksum errors?

RFC 2460, Internet Protocol, Version 6 (IPv6) Specification, Section 8.1 Upper-Layer Checksums, states the UDP checksum is mandatory and any IPv6 receivers must discard UDP packets containing a zero ...
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0answers
368 views

DHCPv6 - When is the Status Code Option added to the options field of an IA Address Option? [closed]

I was wondering if someone would be able to tell me when is the status code option (OPTION_STATUS_CODE) added to the options field of a OPTION_IAADDR or OPTION_IAPREFIX (RFC3633). The RFC seems to ...
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3answers
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Is there an renew after the lease-time or after the half of the lease-time in DHCPv6?

Is there an address renew after the lease-time or after the half of the lease-time in DHCPv6 ? I´m not sure about, and I didn´t find that answer inside the RFC of DHCPv6.
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1answer
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Why is the NDP Neighbor Solicitation message sent to the solicited-node address?

As I understand it, when Host Alice knows Host Bob's IPv6 address but not its MAC, Alice sends an NDP Neighbor Solicitation (NS) message to the solicited-node multicast address for Bob. Alice knows ...
3
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1answer
565 views

Is there any way to check if an IP address is a real IP address or private IP address?

Is there any way to check if an IP address is a real IP address or private IP address?
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1answer
3k views

Understanding the difference between EUI-64 and IPv6

I understand that Extended Unique Identifier (EUI-64) allows a host to automatically assign itself a 64-bit interface identifier IID for an IPv6 address. My question is: What is the purpose of using ...
2
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1answer
435 views

Do different nodes on a LAN share a public IPv6 address?

I looked up the public IPv6 addresses on google for two devices on my LAN, and the addresses are unique (only the first 64 bits match). I thought that the router connected to the internet has a ...
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1answer
119 views

Is NATing possible in case of IPV6 addressing mode anyway?

Setup: A(2001::1:123) <------> B(2001::1:124) <------> C(2001::1:125) where A,B and C are the systems.And apply rule of NAT(SNAT/DNAT) on system B for forwarding a packets from C to B,B to C,A ...
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1answer
107 views

Unsecured devices and IPv6

I'm currently starting to read up on IPv6, and as soon as I heared that every device can/will have a public accessible adreess i got a little freaked out. There are a lot of horror stories about ...
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1answer
579 views

Network Diagram for IPv6 LAN

From what I understand about IPv6 networks, since NAT was a hack to deal with a lack of IP addresses in IPv4, NAT is a possibility, but not a requirement in an IPv6 LAN. So taking this into account,...
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1answer
82 views

IPV6 ping, the pinged address is different from the once caught by wireshark

I'm trying to ping an ECU, both PC and ECU have static IPV6 address the problem is that the target address (ECU) pinged is different from the one caught by Wireshark subnet : 64 ping command $ ...
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5answers
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IPv6 address assigned to vlan interface of 3750 switch changes

When setting up my 3750 stacks, I enable IPv6 on the Vlan1 interface so that I can manage the stack over IPv6. The stacks are not doing any layer 3 routing. However, it seems that the IPv6 address ...
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1answer
83 views

Disadvantages or risks of leaving the the family inet6 configuration under interface configuration in Junos applied

I have a corner-case where I need to leave the family inet6 configuration under IFL present while hosts in that network should not use IPv6. This means, that the logical interface of a router will ...
3
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2answers
1k views

IPv6 can't ping host when static route configured with exit interface

I have the following topology (using IPv6) interfaces: I have the following static routes configured on it: R1#sh ipv6 route static IPv6 Routing Table - default - 9 entries Codes: C - Connected, L -...
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1answer
705 views

Why command “ipv6 dhcp relay” doesn't work at packet tracer?

I'm trying to enable dhcp for ipv6 with the "ipv6 dhcp relay dest" command but, I'm receiving an error and I'm trying both of these commands but none work. Router model: 2811 (config)# interface [...
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2answers
1k views

OSPFv3 (newer commands) not working in Cisco Packet Tracer

The command router ospfv3 1 is not working in the Cisco Packet Tracer (Router: 2811). Does it work somehow or are the IOS version just not up-to-date?
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2answers
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Why is Cisco enforcing X:X:X:X::X for link-local addresses when the standard says FE80:/10?

This document shows that you can use one of these options: interface type/number ipv6 address ipv6-prefix/prefix-length eui-64 ipv6 address ipv6-prefix/prefix-length link-local <------...
7
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1answer
332 views

Is the first address of the subnet a valid configurable address in case of IPv4 and IPv6 point to point networks?

Am I correct, that first address of the subnet is a valid addresses to configure in hosts/routers in case of IPv4 and IPv6 point to point networks? For example, in case of 192.0.2.0/31 one of the ...
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1answer
371 views

IPv4 to IPv6 one-to-one mapping for a whole Class A range

Are there any IPv6 technologies that support translating one-to-one mapping from IPv4 to IPv6 for the whole Class A range, like 10.0.0.0/8 network to a particular IPv6/40 range? Preferably for A10 AX ...
2
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1answer
660 views

What it means to configure two global ipv6 address on a single interface?

I have seen some network configuration files where a single interface is assigned with two different but similar ipv6 addresses, what is the significance of it, ex : interface te 0/1/0/10 ipv6 ...
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7answers
18k views

Why are IPv4 addresses running out?

I understand that we are running out (or ran out already?) of IPv4 addresses, but I don't really understand why that is. Right now, every home has its own IPv4 address (dynamically assigned, but still,...
5
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1answer
7k views

What is the use of the IPv6 scope ID?

In the structure struct sockaddr_in6, the field sin6_scope_id is declared. What is the use of this member? How can we know from the IPv6 address and the prefix length the scope that it should use?
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4answers
2k views

Using IP subnet at multiple datacenters

We control IPv4 and IPv6 subnets. Now we'd like to use a part of a /24 IPv4 subnet at one datacenter and another part at another datacenter. I know that announcing the subnet on the internet at ...
3
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1answer
718 views

NAT64 return translation doesn't work

I'm doing a NAT64 translation on cisco router. The translation from IPv6 to IPv4 work but the return isn't translated neighter in the NAT64 statistics. config: interface GigabitEthernet0/1 nat64 ...
4
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3answers
166 views

Native IPv6 load balancing

We have two software gateways (on Linux) for IPv6 that take fullviews from ISPs and announce our AS. And several nodes connected to Internet via the gateways. Something like at picture: And we ...
3
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1answer
95 views

Quagga router advertisement messages are wrong after an address change

I have a problem with Quagga OSPFv3 implementation. I have a Mininet topology with a host connected to a router. I assigned an IPv6 address to the router interface. And I enabled IPv6 ...
13
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3answers
24k views

What is Link-local addressing?

I noticed that IPv4 reserved 169.254.0.0/16 and IPv6 reserved fe80::/10 for link-local addressing. While I saw IPv6 uses both fe80::/10 address and my private IPv6 address fd00::12 to communicate with ...
4
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0answers
491 views

HSRP IPv6 configuration

Looking at the Cisco documentation for HSRP IPv6 configuration I noticed the use of 'standby 1 ipv6 autoconfig'. interface FastEthernet0/0 no ip address duplex auto speed auto ipv6 address 2020:...
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1answer
90 views

IPv6 source address selection: can the source address have a smaller scope than the destination address?

In RFC 6724 section 5 on "Source Address Selection" rule 2 says to "Prefer appropriate scope": If Scope(SA) < Scope(SB): If Scope(SA) < Scope(D), then prefer SB and otherwise prefer SA. ...
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1answer
88 views

Why are there IP collisions in my network? [closed]

So I have a switch connected to ethernet cable which has a static IP address configured on it for IPv4 / v6. there are 3 IPv4 static addresses on its subnet. I have 2 Anritsu callboxes connected to ...
2
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1answer
404 views

Does IPv6 Prefix Delegation work with SLAAC, without the need of a DHCPv6 server/client?

All the (cisco) documentation I found about this topic always uses a DHCPv6 server or client to configure Prefix Delegation. But I never read that this is a requirement. Can Prefix Delegation be ...
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0answers
65 views

Using IPv6 6in4 tunnel with multiple VLANs, or LAN Interfaces?

I have a pfSense router, and I've setup a Hurricane 6in4 IPv6 tunnel by following this guide: http://thirdinternet.com/wp-content/uploads/2017/11/Configure-6in4-Tunnel-in-pfSense.pdf It all seems to ...
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1answer
1k views

What is the use-case of including the IPv4 address in IPv6 address?

It is possible to include the IPv4 address into IPv6 address. For example, 2001:db8::c0a8:6301 where last 32 bits are IPv4 address 192.168.99.1. There is even a special notation of IPv6 address where ...
4
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2answers
6k views

How does computer in IPv4 network communicate with computer in IPv6 network

I have a Verizon cell modem that uses IPv6 addressing only. I can use it to access IPv4 addresses, like browsing the Internet. However, if I try to ping this IPv6 address on a cell modem from IPv4 ...
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1answer
55 views

How can know the subnet mask in IPv6 network?

How the host can know the subnet mask in the IPv6 network, in case the network does not use the default subnet mask which is /64. for example the subnet mask of the network is /88, How can the IPv6 ...
9
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2answers
5k views

Is TCP maximum segment size (MSS) “clamping” compatible with IPv6?

With IPv4, TCP MSS "clamping" (a network device editing the MSS value in a TCP header) can help when path maximum transmission unit discovery is not working. (e.g., when ICMP is being blocked ...
6
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1answer
529 views

How does router advertisement in IPv6 avoid IP conflict?

If a router advertisement sends the range of subnet, and the client can choose an IP from it, how is there no conflict with another client that has chosen the same address?

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