[Wiltshire] Fwd: Re: IPV6
guy at wiltshire-it.co.uk
Wed Mar 9 09:36:22 UTC 2011
John has most of the pertenant points covered here. The most
imprtant thing he says is about compatibility addresses, this had to be
the case or it will all fall over. I will add further to the early
windows scare (MS cockup, they did know about IPV6) and remind you that
those running very old red hat, debian, slackware etc, servers that just
sit in a corner and hum away will also need some attention.
-------- Original Message --------
Subject: Re: [Wiltshire] IPV6
Date: Tue, 8 Mar 2011 15:02:11 +0000 (GMT)
From: John Larkworthy <john_larkworthy at yahoo.co.uk>
Reply-To: wiltshire at mailman.lug.org.uk
To: Wiltslug <wiltshire at mailman.lug.org.uk>
Let me talk complete rubbish. I am sure someone will correct me if I am wrong.
If you currently run a server of any description with an IP4 address this need
not change. The IP6 address includes a compatability ip4 address range so the
DNS record can point to this. The older Win PC people will be the ones to
suffer as they cannot access sites like ip6.google.com because a) early MS win
software is IP4 only b) no DNS lookup for ip6 addresses, c) ISP does not route
IP6 addresses and finally d) the home router does not support IP6.
I know ip6.google.com is not a loss with www.google.com accessible via IP4 but I
quote it as an example. The real problem will be when you need to connect with
a website which is IP6 only (probably in China).
How does IP6 work:
Basically it works as IP4 used to work. Each subscriber will get a 48 or 56 bit
subnet for their own use.
Each interface will have multiple addresses - local address, internet address
and respond to targeted multicast addresses. You may need more but this is the
minimum starting point for an internet connected host.
The local address must be unique within the network. With IP4 this is done by a
random number in the subnet 18.104.22.168/16 but with IP6 the use of the MAC
address is recommended but either way a broadcast or multicast request is used
to establish that it is unique within the LAN.
Internet addresses are currently assigned to the WAN/LAN router in an IP4
network and use NAT to convert between LAN and WAN but in IP6 the addresses
will be directly assigned by the gateway. The gateway will broadcast a routing
prefix. The remainding bits must be unique within the subnet. There are various
policies for remaining part of the address i.e. MAC address (or part of), user
set, random number, etc. The MAC address would be useful for machines expecting
to plug and go,. User set may be more help for servers at specific addresses.
Finding a specific service on the network is expected to be done using the
service discovery protocols like Avahi, uPnP, SLP, or Bonjour.
The simplest policy in IP6 is to use the MAC address for all addresses and
simply change the prefix for local and internet address. The multicast
addresses will then be derived from these. There are security issues with
allowing all hosts to have internet addresses but there is no reason a host
should have an internet address. The home gateway may very well provide an
opportunity for a fire wall.
If the idea of allowing the hosts to magic up their own addresses does not
apeal then DHCP v6 can be used in a manner similar to IP4.
Hope all my ramblings helps.
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