Questions tagged [ipv6]

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

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141 views

Is Path MTU Protocol more beneficial for IPv6

Should Path MTU Discovery (PMTUD) be implemented over fragmentation regardless of whether it is IPv4 or IPv6? Or should it just be implemented in ipv6 due to fragmentation now being handled through ...
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1answer
65 views

IPv6 address abbreviateion

Given IPv6 address 2001:0000:0000:0000:1111:0000:0000:0000, should it be abbreviated as: 2001::1111:0:0:0 or 2001:0:0:0:1111::? It seems I didn't see any specification talking about it.
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221 views

Can you keep DHCP addresses from your ISP

I have my modem configured for bridge mode. I get one IPv4 for my router and one goes to my server for public access. If I static assigned these IPv4 address would I keep them as long as no one else ...
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139 views

Will an asa pass traffic that matches a crypto map entry if Phase 2 is not completed?

I have two ASAs that have publicly routable ipv6 addresses, and a /56 at each site. Since we're going to be rolling out ipv6 internally at some point for all users, I'd really like to prevent packets ...
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710 views

router advertisement packet

Networking beginner here, trying to understand the output of the tcpdump tool using a captured router advertisement packet. tcpdump -i wlp4s0 -nn -t -c1 -vvv -X -s0 Based on what I've found online, ...
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226 views

Question about Duplicate Address Detection with VLANS?

Consider the case of a Router-on-a-Stick topology with multiple vlan tags, when a new computer joins the network. Will the DAD Neighbor Solicitation message be tagged with a VLAN? Will all the ...
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1answer
271 views

What is the purpose of “Process name” in RIP for IPv6 on Cisco Routers

I was going through Cisco documentation to configure RIP for IPv6. One of the steps says Enables the specified IPv6 RIP routing process on an interface. But they do not go into detail about this ...
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2answers
392 views

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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193 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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144 views

How can IPv6 host know default router's IPv6 address using RA?

I know an IPv6 host will send Router Solicitation (RS) messages, and a router on the link will reply Router Advertisement (RA) messages. In the RA message, there is the Source Link-Layer Address and ...
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3answers
2k views

My first IPv6 ping fails

I have some dual stack websites. When I open my websites they connect using IPv4 the first time, and then IPv6. If I ping the IP address directly, the first ping fails for IPv6 and then works fine. ...
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121 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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60 views

Misbehaving host always uses the gw's MAC as destination: Violation of standard?

We have an appliance that always uses the IPv6 gateway's MAC address as the link layer destination address for all its outgoing IPv6 packets, even when the receivers IPv6 address is on the same subnet....
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2answers
4k views

IPSec in IPv4 and IPv6

I'm getting a little confused in understanding the differences in IPSec in IPv4 and IPv6... Are the principles of IPsec the same in v6, but instead of it being optional it is now mandatory for it to ...
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557 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
47 views

What is the command line to inspect the IPv6 discovery cache?

I can't seem to find a command for this, only configuration commands are listed in the documentation and show ipv6 nd destination does not work on my system This is on Cisco vIOS 15.2 Edit: ...
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181 views

How to verify whether two devices can communicate

In IPv4, we had to find the Network Address using the IP address and the subnet mask. With IPv6 there's already the Network Prefix in the IP address. Suppose I have an IP address A: 2001:db8:a0b:12f0::...
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191 views

IPV6 Neighbor Advertisement (NA) not recieved

I'm trying to make a project to detect NAs in an inter-vlan IPv6 environment via trunk line. I know that NAs are sent in multicast so it would be possible to see the NA messages using a trunk line. ...
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1answer
88 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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2answers
2k views

no default-router option in dhcpv6?

I'm learning how to program a Cisco router with dhcpv6 and i saw that they never configure the default gateway address in the dhcpv6 configuration . Then how can the pc know what it's gateway address ...
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1answer
115 views

IPv6 VPNs source address selection

Say I have the following IPv6 prefix assigned to me by my ISP : 2a01:1000:1000::/48 with 2a01:1000:1000::1/48 assigned to my VPN server. I set up a VPN with a /64 from that block to assign to my ...
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1answer
65 views

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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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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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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598 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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1answer
352 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 ...
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1answer
495 views

Max hosts of subnet IPv6

When a interface takes an IPv6 address it does the DAD mechanism. A NS will be sent to the multicast address "solicited node multicast group address". If there is another interface in this multicast ...
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1answer
207 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
521 views

Juniper EX IPv6 outside LAN isn't working

JunOS version: 12.3R11.2 Juniper EX switch with 2 VLANs: vlan 0: IPv4: 10.0.0.6/20 This vlan is used for private IP space vlan 1: IPv4: X.X.X.254/24 IPv6: XXXX:XXXX:X:XXX::ffff/64 This vlan is ...
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162 views

How do I generate ESP trafic (IPv6)?

I have this topology: I only have moon and sun. After the connection was successfully established, I need to generate ESP packets for wireshark capture. How do I generate ESP packets? When I use ...
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1answer
2k views

Calculate networking bits for IPv6

I can get the networking bits for IPv4 addresses like 17 for 255.255.128.0. Similarly, how should I calculate it for IPv6 addresses? Say, if I have a subnet mask of ffff:ffff:ffff:ffff:0:0:0:0 or ...
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86 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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2answers
2k views

pfSense: ICMP Ping allowed, but not possible

I have a pfSense 2.2.6 box that is connected with a WAN link that supports native IPv6. IPv6 is working great, and my clients can access IPv6 services on the Internet and also on the local network. ...
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1answer
768 views

IPV6 Client Device not sending Router Solicitation upon expiry of Router lifetime [closed]

we have a test case from the operator that upon expiry of router lifetime the client device supposed to send Router solicitation message to the router. But this is not happening. is this because of ...
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1answer
101 views

ICMPv6 RA to make it as default gateway in the Network

Hey guys if you are familiar with ICMPv6, i have a problem right now considering RA. I am trying to come up with a mitigation for last hop router attack, so i thought of how about sending a packet ...
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1answer
95 views

How long does an IPv6 neighbour table entry last?

I've been looking around in manuals and Cisco Books, but nowhere have I found how long an entry lives in the IPv6 Neighbour table. If that depends on the implementation, what is it for Cisco?
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3answers
2k views

IPv4 & IPv6 IPSec differences

I am an undergraduate student where I decided to develop a firmware that would eliminate the security vulnerabilities that exist within the current technologies used. such as tunneling, translation ...
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1answer
49 views

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 ...
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1answer
47 views

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 ...
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1answer
27 views

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 ...
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96 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 ...
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1answer
422 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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1answer
37 views

Is it possible that IPv6 multicast address is shown in the “IPv6 Address” column of the “show ipv6 neighbors” command in Junos?

Is it possible that IPv6 multicast address(i.e address from ff00::/8 address block) is shown in the "IPv6 Address" column of the "show ipv6 neighbors" command in Junos?
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76 views

ISATAP configuration not working when adding hosts

I am trying to make an ISATAP configuration where two ipv6 hosts connected to dual stacked routers can communicate to each other. I have the following configuration: I have configured RIP across ...
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1answer
224 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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1answer
399 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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514 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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2answers
288 views

How do I determine the IPV6 address added to VXLAN when interface is set to up? [closed]

Setup: Currently working on a machine with Red Hat 7.2 (Red Hat Enterprise Linux Server release 7.2 (Maipo) to be exact.) I have a vxlan interface configured: # ip link add test.123 type vxlan dev ...
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2answers
496 views

How does data encapsulation work in the TCP/IP stack?

As a UDP segment traverses down the stack, each layer adds a header. What occurs for this to happen? Does the kernel do a bunch stuff then add the header? I am particularly interested in the ...
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1answer
805 views

How does address resolution work with multicast, specifically IPv6?

If I want to send an IPv6 UDP multicast message, how does L3 to L2 address resolution occur? I think I understand ARP and how this same idea applies to unicast, but I am struggling to grasp the idea ...

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