Questions tagged [ipv6]

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

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IPv6 Subnetting

I was making an IPv6 exercise in which I had to configure two Router Interface: G0/0 and G0/1 G0/0 uses 2001:DB8:FADE:00FF::/64 and I have to use to next subnet for G0/1 This is the answer, but What ...
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743 views

6to4 - IPv6 tunnel address

http://packetlife.net/blog/2010/mar/15/6to4-ipv6-tunneling/ In order to configure a 6to4 tunnel on R2 router, you execute the following commands: R2(config)# interface tunnel0 R2(config-if)# tunnel ...
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1answer
279 views

Translation from unique local to global unicast address

is there NAT in IPv6 for private-to-public translation like in IPv4. I know that there is a protocol translation between v4 and v6 but did not find anything about same protocol translation . Thank ...
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Can we use prefix address as the host address in ipv6?

IPv6 I read somewhere that we can use the first and last ip address as host addresses in ipv6. Is it true?
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Are IP source and destination fields necessary on LAN?

When sending a packet from one computer to another over LAN, you send both an ethernet header and an IP header. The ethernet header has a source and designation MAC address, and the IP header has ...
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390 views

Why is space reserved for private ip addresses?

I just read that specific ranges of IPs have been set aside to be used to private ip addressing. But if we already distinguish between public and private IPs why do we need to reserve space? Why cant ...
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1answer
112 views

How to block outside initiated traffic in NPTv6?

NPTv6 does prefix translation between one IPv6 address to another. Is there a way to prevent outside initiated traffic to inside (preferably in A10 AX devices)?
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3answers
5k views

What is a valid public IP address?

What is a valid public IP address? When I was checking my ID to see if it was blacklisted, it came up with the above Amanda… "Please enter a valid public IP address,", so therefore my questions are: ...
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1answer
753 views

IPv6 Link-local addresses

RFC 4291 specifies that IPv6 link-local unicast addresses must have a high-order bit sequence of 1111111010, or fe80::/10. However, the same document specifies that the 54 bits following the first 10 ...
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What are common sizes to split a /29 - /32 IPv6 subnet?

As an LIR, you are getting a /29 to /32 network allocation by the RIPE, but I am a bit overwhelmed by the size of this subnet, and don't find a starting point to split this into common sizes. What we ...
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1answer
505 views

MAC Spoofing and EUI-64

I have two questions that both assume an attacker who has my MAC address: Suppose an attacker connects to the Internet before me, spoofing my MAC. I then connect and tell people to connect to my EUI-...
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IPv6 in PPP - should be an Interface Identifier negotiated FOR both ends of a link? Clarification of RFC 5072 needed

I am trying to implement IPv6 in an existing VPN PPP software, but having hard time of understanding some of the RFC 5072 sections meaning. Namely, section 4.1. Assumption 1: PPP interfaces do not ...
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OSPF - networks/links don't get advertised

In my Multiarea-OSPF configuration I can ping my neighbor, but nobody which is more than one hop away (for instance ABR2). Also traceroute just shows "1 * * * - 2 * * * - 3 * * *" Can ...
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What MAC address do I use to generate a IPv6 Pseudo-Random Global ID

I am setting up a virtual lab environment in the cloud to experiment with IPv6 networks. Bear with me please, I'm new to networking and my grasp of the whole IPv6 subject is quite shaky. Please ...
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1answer
203 views

IPv6 ACL in Packet Tracer - why doesn't it work?

I typed in this command: ipv6 access-list NO-SERVER-ACCESS permit ipv6 2001:db8:18::/48 host 2001:db8:18:6600::0010 eq 80 permit ipv6 2001:db8:18::/48 host 2001:db8:18:6600::0010 eq 443 permit ...
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979 views

OSPFv3 - Sample configuration (Dual Stack IPv4 and IPv6) - Cheat Sheet

When configuring OSPFv2 on a router, you type in router ospf 10 router-id 1.1.1.1 network 10.0.0.0 0.0.0.3 area 0 for example. That way the network can be advertised per LSAs. But in OSPFv3 it ...
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IPv4 shortage is now becoming a reality - what is needed for IPv6 to work?

Today I read that Microsoft has no more IPv4 addresses for its Azure cloud. Earlier this week I read that Latin America is out of IPv4 addresses as well. These are real - not predicted - IPv4 address ...
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1answer
729 views

IPv6 Testing Addressing Type Confusions

I'm new in the IPv6 Topic and Yesterday I was performing some testing on Cisco IOS and Cisco Routers of the addressing type in IPv6 with RIPng, i was testing the following: Global Unicast Address ...
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2answers
508 views

How to solve this IPv6 looping problem?

I have set up a 6in4 tunnel, namely "sit1", but I have discovered that if I traceroute non exist IP within the subnet, it will loop. What should I do to solve this? The routing table:
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326 views

Connect old device to IPv6

Hi I'm not an expert on networks and that's the reason why I'm posting this. My problem is that I have an old device (mediacenter box) that does not supports IPv6 to connect to Internet. Until now, ...
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1answer
2k views

Is there any difference between Link-local and Site-local scope in IPv6 world?

What is the difference between Node-Local-Scope, Site-Local-Scope and Link-Local-Scope ? What does it mean Link local (link only) ? Is it only for a Subnet ? Why do we need site-local address then ?...
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1answer
59 views

Automatically determining ipv6 prefix size to blacklist? [closed]

When writing blacklist automation for my network, is there a way to automatically determine the prefix size of the other party?
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1answer
440 views

Any router will automatically join at least two multicast groups on each interface. How do I see that on a Cisco router?

Any router will automatically join at least two multicast groups on each interface. How do I see that on a Cisco router? I know that they all join these two groups: all multicast nodes and all ...
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Do we need different VLANs on IPv6 network? [closed]

With IPv6 there's new train of thought around this technology than IPv4. Since this protocol does away with broadcasts, is creating different VLANs necessary? Some people will argue that you can apply ...
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1answer
108 views

IPv6 address scheme for network gear

I'm looking for best practice advice on how to IPv6 address your internal infrastructure network gear (routers, switches, etc). In my searching I've seen some people suggest using /127 like in a /30 ...
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2answers
258 views

Why subnetting is implemented if we can use Network Address Translation (NAT)

As in subnetting a block of IP adresses are allocated, which leads to consumption of those IP addresses. Then how come we don't use Network Address Translation (NAT) as it will only need one IP ...
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2k views

How to split an IPV6 nibble? [closed]

I've been tasked with assigning IPV6 addresses to be split into data centers in several different cities, in several different countries in several different continents. Part of the instructions is to ...
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1answer
2k views

Why the FF:FE in EUI-64?

EUI-64 IPv6 addresses are generated from MAC addresses by taking the network prefix (64 bits) and appending the first half of the MAC address, then FF:FE, then the second half of the MAC. Is there a ...
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2answers
669 views

IPv6: is it possible to use a /64 block when you have multiple routers?

I'm new to IPv6 and having some issues with a configuration that was really easy/common with IPv4. My setup looks like this: WAN (ISP managed router) <-> Router 1 ( my internal router ) <-&...
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1answer
39 views

How to know which IPv6 interface will be chosen by the router?

I would like to know how does the kernel decide through which interface it sends data to some IPv6 address, how is the calculation done based on the routing table information: destination, gateway and ...
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2answers
408 views

IPv6 link local address unicity on a routed network

Going through an exercise from the CCNA practice exam I encountered an example that required the configuration of link local addresses on all interfaces. On Router 1 all interfaces were set to FE80::...
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What is rdt_rcv(rcvpkt)/Λ in the given figure?

Please explain. I marked it in a red circle. It's rounded in red color.I got this from the book Computer networking a top down approach.Pg NUM 241. Section 3.4 Rdt 3.0
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Basic IPv6 Static Routing (Global Unicast Routing)

I have a topology like this: Every PC and router is configured with IPv6 addresses. -PING from PC1 to R1 is OK -PING from PC2 to R2 is OK -PING from PC3 to R3 is OK -PING from PC4 to R4 is OK ...
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3answers
2k views

How is NAT a hack?

Forgive me if this sounds a little amateurish, or if this is the wrong stackexchange, but...most of my entirely life I've had ipv4 behind a NAT router. I've been told that this was a hack; simply ...
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5answers
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Why do we need IPv6?

This will be a kind of newbie question but I am not quite sure why we really need IPv6. AFAIK, the story is as follows: In the olden days, when computers were not plentiful, 32 bit IP addresses were ...
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2answers
730 views

Configure tunnel between IPv6 enabled server and local IPv4 network

I am newbie here and also for IPv6 network. I have one debian installed server which is able to send IPv6 traffic. Now in my local network, ISP not supporting IPv6 traffic. I want to configure tunnel ...
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1answer
577 views

IPv6 ULA vs. Global addresses for private (intra entity) peering

I am working on converting my core to IPv6. My current addressing scheme includes the VLAN in the IPv6 address: VLAN1511: XXXX:XXXX:XXXX:1511::1/64 However I have some VLAN overlap (the same VLAN ...
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1answer
52 views

Authentication header doubt

In a book by Forouzan (https://www.amazon.com/Data-Communications-Networking-McGraw-Hill-Forouzan/dp/0072967757) I've read that the sequence number of the authentication header doesn't get repeated ...
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1answer
659 views

IPv4 and IPv6 gateway subnet differences

I understand why for IPv4 the host and the gateway should be part of the same subnet, but for IPv6 I am a little bit confused. There are several types of IPv6 address assignment, but IPv6 requires the ...
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2answers
156 views

IPv6 built-in security?

At one time IPv6 was supposed to have built-in security. I don't know how it was supposed to be implemented, but my guess is that perhaps, if your stack and application supported it, you could simply ...
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2answers
3k views

Host IPv6-only website and allow access to IPv4-only clients

Lets say site.example.com runs only with AAAA records, and I wish to access that site from IPv4-only network, and I don't want to do tunneling neither other protocols that masquerades IPv4 over IPv6 ...
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1answer
5k views

Method for assigning IPv6 ULA addresses to LAN

I'm finally embarking on the voyage that is IPv6. I am not sure however, on the best way of assigning a unique local address (ULA) to each host in my LAN. For IPv4 I prefer to have a DHCP server ...
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1answer
233 views

Cisco 3560G not passing IPv6 RA when VLAN without IPv6 address

Problem: When having VLAN without IPv6 address on L3 enabled switch, no RA is passed through VLAN unless there is IPv6 address assigned to the VLAN. Static assigments however are reachable fine. ...
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2answers
398 views

Do NDP and Link Local addresses remove the need for a router to have multiple routable IP addresses?

I'm trying to get my head round IPv6. I've stumbled on something which surprised me, and I'm looking to understand this better in terms of networking: Do Link Local addresses remove the need for a ...
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1answer
412 views

IPv6 default route

The IPv4 default route in CIDR notation is 0.0.0.0/0 translated to IP: 0.0.0.0 mask: 0.0.0.0 For IPv6 the default route in CIDR is ::/0. How is this transated ? Is it as below ? IP: :: mask: ::
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1answer
126 views

Doubt on handling mutable fields in IP header when computing digest or authentication data

I read RFC 4302, IP Authentication Header, Section 3.3.3, Integrity Check Value Calculation. In page 13, it is mentioned that the fields which are mutable during transit, like TTL or hop count, are ...
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1answer
538 views

How to configure a VLAN for all its client to get stateful IPv6 through a DHCPv6 server in the network on a Cisco C891F router?

Alright, so I've been trying this without any luck the whole day. How to configure a VLAN for all its client to get stateful IPv6 through a DHCPv6 server in the network on a Cisco C891F router? My ...
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3answers
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How does multihoming work with ipv6?

What are the differences between multihoming in IPv4 versus IPv6? Can an enterprise request a provider-independent IPv6 address space from its RIR/LIR which can be advertised to multiple upstream ...
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1answer
817 views

Cisco IPv6 BNG Radius Attributes

I am trying to push out IPv6 unnumbered to an interface via radius. I am trying to do it in a similar fashion to how you would for IPv4: Cisco-AVPair += "ip:vrf-id=vrf-name", Cisco-AVPair += "ip:ip-...
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1answer
76 views

Would two hosts with arbitrary IPs communicate with /0 mask in the same subnet? [closed]

I'm studying for my networking finals and this thought experiment crossed my mind. I was told that as long as two hosts are in the same subnet they can communicate by using only ARP requests skipping ...

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