how to route ipv6?

[BashedRoot]

So I'm all new to IPv6, just got a small block from ARIN and quite honestly, I hate numbers and I don't know how to route IPv6 on my Cisco 3750 switch. Please explain in laymen terms. I'm fine with IPv4, but IPv6 is too confusing to me.

Cisco 3750G (WS-C3750G-24T-S)
Cisco IOS 12.2(55)SE5 (IPSERVICESK9)

It's a /32 IPv6 block.

How would one compare a /32 IPv6 block to IPv4 equivilant? For example, a /24 is 256 hosts (253 usable).

Based on online calculators, a /32 block is 79,228,162,514,264,340,000,000,000,000 IP addresses. What the heck? Am I rich? :)

[Kunal Gandhi]

If I correctly understood your question.. you are looking for how the host address is calculated, how to use it in network.

In IPv6 you have total 8 blocks & each blok is 16 bit
XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX = 128 bit
As ARIN gave you /32 means first two blocks are network portion & remaining 6 blocks are host portion
here is a simple maths = 6(blocks)X16(bits per blocks) = 96 & now 2^96 is 79,228,162,514,264,340,000,000,000,000.

You can create small prefix like /64 or /96 & use it in your network like you use to do it in ipv4 if you get /8 from ARIN & configure it in your network
Keep in mind that this are globaly routable address.

As far as routing is concern,
you have to use ipv6 unicast-routing, give address to the interfaces & use whichever rouring protocol you want to use ( even static if you are fine with it)
IGP for IPV6 are - RIPng, OSPFv3 & EIGRPv6
for internal communication you can use ULA range FC00::/7

Hope this answer you query.

[Joseph W. Doherty]

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Posting

A /32 block, eh?  Reminds me when they used to give class A addresses out like candy.  100 years from now, they will say, what were they thinking giving out /32s.

Basically you route IPv6 like you do IPv4, except the network prefixes are 4x the size and the look "funny" being in hex and with colons.

On a 3750, you'll want to enable one of the IPv6 SDM templates, but they all split TCAM resources in half, which can result in performance issues for IPv4.

[Jon Marshall]

A /32, as Joe alludes to, is not a small block, a /48 is more common for an organisation but that is from an ISP.

You can't really compare with IPv4 because the scale is so different.

IPv6 is actually easier in some respects because you don't use host bits for the subnet ie.the prefix size is recommended to be a /64 and /64 bits for hosts (note some use /127 on loopbacks and P2Ps but even here many recommend 64s).

So with your block you have 2^32 for subnets or to put it another way the size of the entire IPv4 address space just for subnets.

And each subnet has 2^64 available IP addresses in it which is a huge number.

You actually design the size of your subnets pretty much as you do now but you just have a lot of unused IPs in each subnet (and I do mean a lot).

You have to just get used to the fact that an awful lot of IPs are never used which coming from IPv4 and public addressing seems a waste but IPv6 was designed to make sure we don't run out of addressing any time soon.

As the others have said routing is pretty much the same but address allocation to end devices can be different and the behaviour of end devices with IPv6 addresses can also be different.

You may also want to post in the IPv6 forum because there are guys there who are using IPv6 and they will know the things you need to watch out for.

Jon