<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman,new york,times,serif;font-size:12pt"><br><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;">> It is very typical. /48 to every customer, no exceptions. If a customer<br>> wants less, assign them a /48 anyway and only tell them the first part<br>> of the prefix. When they get wiser, tell them the /48 that you <br>> "reserved" for them. <br><br>Depends on what kind of customers you have.<br>If the bulk of your customers are residential, and you expect to assign<br>them prefixes dynamically, then it is very likely you will only assign<br>them a prefix of whatever length is hinted in their DHCPv6 request.<br>You still have the policy decision of "what is the largest prefix request<br>I will honor?" but that's a
different question.<br><br>If many of your customers are dial-up, you may decide that multiple<br>subnets are unlikely, and default to a /64.<br><br>For customers with statically-assigned prefixes, do whatever you want.<br>Nibble-boundary prefixes are recommended (so you can delegate<br>reverse DNS), and multiple /64s are encouraged. So, between /48 and<br>/60, but you might make it easier on yourself to pick a prefix length and<br>use the same for everyone.<br><br>> Don't gamble on this. ARIN expects you to assign a /48 to everyone, and<br>> if you use less then you are only punishing yourself by increasing the<br>> complexity of your network and your management processes.<br><br>s/expects/allows<br><span><a target="_blank" href="https://www.arin.net/policy/nrpm.html#six54">https://www.arin.net/policy/nrpm.html#six54</a></span><br><p>The following guidelines may be useful (but they are only
guidelines):</p>
<ul><li>/64 when it is known that one and only one subnet is
needed</li><li>/56 for small sites, those expected to need only a few subnets
over the next 5 years.</li><li>/48 for larger sites</li></ul>and<br>Subsequent IPv6 allocations, based on HD-Ratio in units of /56
assignments.<br><br>Lee<br><br></div></div>
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