Category: IPv6

IPv6 Link-Local Address (Follow up)

This article is a small follow up on the IPv6 Link-Local address article some time ago and based on a question in one of the comments:


How you will convert 0008.209a.081b in link-local address. First step is ok where u insert FFFE i.e. 0008.20FF.FE9a.081b
issue is 2nd step, how to convert 0008 to binary?
I have done reverse engineering from link-local address
link-local address is FE80::208:20FF:FE9A:81B

when u convert 208 to binary it comes 10000001000. So my question is how to convert 0008 to 10000000000 (this comes to 400 in HEX)

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IPv6 at Home (Part III – Followup)

As mentioned in the last article about PPPoE, I had to do a redesign within my home network to support IPv6 and SSL VPN Connections. With the old layout the ASA didnt allow anything initiated from the outside, it just did NAT it to the router no matter what it was. Also I wasn’t able to map a static one-to-one NAT statement onto my single outside interface IP address after I upgraded to 8.3(2).
In this article, I gonna show the configuration for both the router and the ASA, even though the configuration itself is way easier now than it was before o_O

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IPv6 at Home (Part II – Configuration)

In this article Im going to show on how to configure the Cisco ASA and the Cisco 1700 Router to have IPv6 connectivity at home and also gonna explain on why I had to use an ASA and a Router.

As written in the first article, my ISP does not offer IPv6 to its (private) customers, so to get IPv6 at home I had to use an IPv6 Tunnelbroker which is providing the IPv6 connectivity over a an 6in4 Tunnel. And that’s also the reason why an ASA without a router will not work in that scenario, its plain and simple, ASAs do not support tunnel Interfaces today..

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IPv6 at Home (Part I – Peparation)

Something I really wanted to do for quite some time now is to play with IPv6 at home. And well, finally Im able too :)
I now got my “own” routable /48 IPv6 range I can play with and get used to the IPv6 subnetting and a lot of other stuff to play with.

The topic will be split into two articles. The first article will describe on how to get an IPv6 Range and Tunnel endpoint from a Tunnel Broker, while the second article will show how I configured my IPv6 access using a Cisco ASA5505 with a base licence and a Cisco 1700 Router.

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IPv6 universal/local bit

Muslimtech posted the following question on the IPv6 Link-local article:

“hi man

i want ask you Q About U\L Bit

i read that in Bsci

Universal/Local (U/L)
The seventh bit in an IPv6 interface identifier is referred to as the universal/local bit, or U/L bit. This bit identifies whether this interface identifier is universally or locally administered.

If the U/L bit is set to 0, the address is locally administered. The network administrator has overridden the manufactured address and specified a different address.
If the U/L bit is set to 1, the IEEE, through the designation of an ISP, has administered the address

i cant understand How U\L Bit = 0 i want Ex; About that

and whene he say “locally administered” mean
i use command to change mac address for interface ??
or what”

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IPv6 Summarization

Summarizing IPv6 addresses is quite similar to the summarization of IPv4 addresses. The only real differences are:

  • IPv6 is 128bit while IPv4 only has 32 bits
  • IPv6 is written in HEX while IPv4 is written in decimal

If we take those two differences into account the summarization is the same.

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IPv6 Link-Local Address

Link-local addresses only have a scope of the link they are used on, they will not be used or even reachable from another link.
The link-local address of an interface is a mix between the BIA (Burned In Address) and some static IPv6 stuff. The “dynamic” part is also know as modified EUI-64 addressing.
First of all, every link-local address in IPv6 is generated from FE80::/10, so if you ever see a address starting with FE80 you know thats a link-local address :)

Over a sh int you see your BIA:

R1#sh int fa 0/0
FastEthernet0/0 is up, line protocol is up
Hardware is AmdFE, address is cc00.0bfc.0000 (bia cc00.0bfc.0000)

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