iperf speed test

I am tired of  using ftp to test upload and download speed.  Some guys said that FTP has limitation in case the bandwidth of the broadband line is large. I have to explore the use of  iperf to find out if the download and upload speed are accurate.

As my home PC is riding on an internal IP address, it can act as a client to perform upload test.  However, for download test, the internal host must act as a server.  Hopefully, I am able to set up a virtual server on my WiFi router and forward connection for port 50001 from the WAN side to the host on the LAN side.


IPv6 subnet prefix

The following sketch might be useful to help determine which position of an IPv6 address to play with in order to set a subnet prefix. I just copy it from a website so the background colour remains.

IPv6 Subnets

      ||| |||| |||| |||| |||| |||| ||||
      ||| |||| |||| |||| |||| |||| |||128
      ||| |||| |||| |||| |||| |||| ||124
      ||| |||| |||| |||| |||| |||| |120
      ||| |||| |||| |||| |||| |||| 116
      ||| |||| |||| |||| |||| |||112
      ||| |||| |||| |||| |||| ||108
      ||| |||| |||| |||| |||| |104
      ||| |||| |||| |||| |||| 100
      ||| |||| |||| |||| |||96
      ||| |||| |||| |||| ||92
      ||| |||| |||| |||| |88
      ||| |||| |||| |||| 84
      ||| |||| |||| |||80
      ||| |||| |||| ||76
      ||| |||| |||| |72
      ||| |||| |||| 68
      ||| |||| |||64
      ||| |||| ||60
      ||| |||| |56
      ||| |||| 52
      ||| |||48
      ||| ||44
      ||| |40
      ||| 36


RFC 3901 - DNS IPv6 Transport Operational Guidelines

Some colleagues in the Government want to supplement native IPv6 connection to their serving websites but their ISPs told them that nameservers are not yet equipped with IPv6 transport. My colleagues are quite frustrated worrying that IPv6 only hosts will not be able to access the websites because of an IPv6 brokenness in DNS path.

Actually, the ISPs do not quite understand the issue. IETF has published "RFC 3901 - DNS IPv6 Transport Operational Guidelines". In order to preserve name space continuity in the transition to IPv4, the essential points to note are :

- All recursive name servers should be IPv4 only or dual stack hosts.
- All zones should be served by at least one authoritative IPv4 capable host.

IPv6 only hosts will access a dual-stack resolver to find the nameservers and the nameservers do not need to be served with IPv6 transport. So long as nameserves can return AAAA records to resolvers, IPv6 only client hosts can receive the information and hence there is no brokenness in the name resolution process.

I recall that I have answered the same question at least twice.


List of IPv6 home routers

I am preparing a list of IPv6 home/SOHO routers which will be posted in the coming “IPv6 In Action” website, the domain name of which  is not decided yet. The website will be managed by the Internet Society Hong Kong.  It is for general end users in Hong Kong to be aware of IPv4 exhaustion and get prepared for the IPv6 era.

My source of information is mainly from the IPv6 Forum and I do a search for routers that have been awarded the “IPv6 Ready” Logo.  I only sorted out the common brand names such as Linksys, Netgear and D-Link and their products are commonly available in Hong Kong with reasonable price.  I tended not to give products from Japan, New Zealand, China and UK etc as I am not sure whether these products would be sold in Hong Kong.

Just when I thought the list was OK, I mistakenly missed out one important item, Apple Airport Extreme.  I checked IPv6 Forum again and noticed that Apple submitted its Airport Extreme base station as host device for getting IPv6 Ready Logo but not as a router.  What a crazy move. 

After the “IPv6 in Action” website is launched, I intend to update the list on a monthly basis.  Hopefully, the workload is not heavy.


Brainstorming on IPv6 Address Space

I did a bit of googling on the number of times IPv6 address space over IPv4. In simple math, it is :

2^128 divided by 2 ^32 = 2 ^96 which should be 79228162514264337593543950336.

Surprisingly, many websites quote the wrong math calculations like 4 billion times, 40 billion times and 16 trillion times. There are some that say "79 Octillion times the IPv4 address space" which should be correct.

Of course, "79 Octillion times" can not be understood in English and can hardly be translated into Chinese. It seems meaningless to quote how many times IPv6 address space over IPv4. To convey a clear message on huge address space, we can just simply say :

IPv4 can only provide approximately a total of 4 billion addresses while the number of  available addresses of IPv6 is up to 3.403 x 10^38.