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Assigned a /56 static, told I can only use 1/256th of it.

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NVTech
Occasional Visitor

Assigned a /56 static, told I can only use 1/256th of it.

Comcast support is now telling me that even though I have a /56 static, only the first /64 can be used.

 

Can anyone comment on this? Why would they assign a /56 then?

Accepted Solution

Re: Assigned a /56 static, told I can only use 1/256th of it.

What modem are you using? I can tell you for sure that the NetGear supports a /60 delegated from the /56 (although I don't think you can use the rest - I had issues that I never followed through on). With the Cisco I can't seem to use any IPv6 at all in passthrough mode, mine wants to assign SLAAC addresses directly from the modem, which won't work since my CPE is looking for a prefix delegation.  

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IPv8
New Member

Re: Assigned a /56 static, told I can only use 1/256th of it.

That does not sound right to me. Im still experimenting with my setup, so I have not tried anything larger than a /64. What is your modem model, and how are you requesting your prefixes from the modem? There are known issues with the WIDE DHCPv6 client and prefix != /64

ndb217
New Contributor

Re: Assigned a /56 static, told I can only use 1/256th of it.

What modem are you using? I can tell you for sure that the NetGear supports a /60 delegated from the /56 (although I don't think you can use the rest - I had issues that I never followed through on). With the Cisco I can't seem to use any IPv6 at all in passthrough mode, mine wants to assign SLAAC addresses directly from the modem, which won't work since my CPE is looking for a prefix delegation.  

NVTech
Occasional Visitor

Re: Assigned a /56 static, told I can only use 1/256th of it.

Yeah, I've got a Cisco as well. It will give a SLAAC, but I need to actually use at least 10 /64's, and ideally more.

NVTech
Occasional Visitor

Re: Assigned a /56 static, told I can only use 1/256th of it.

I'm trying to use static, so I shouldn't be requesting prefixes. 

However, when I did request them, I was trying to get the /56 I've been assigned.  

ndb217
New Contributor

Re: Assigned a /56 static, told I can only use 1/256th of it.

You can use static from a PD, that's what I had been doing with my netgear. I was unable to utilize more than the /60 I was delegated, but I had a segment that was not SLAAC enabled and I was statically assigning the host addresses. When i used addresses outside of that /60 I saw administratively denied errors, but admittely that was like 9 months ago. Also, no matter what you request, you'll get whatever the DHCP service is configured to hand you. I was originally requesting a /64 and receiving a /60. I never really understood the purpose of the hint. 

gguldens56
New Member

Re: Assigned a /56 static, told I can only use 1/256th of it.

I have an understanding that you are assigned a /56 and feel like you need to have the entire address space available to you for use.  I have static IPv4 and was assigned a static /56 IPv6 as well.   On my Netgear FVS318Gv2 firewall, I received a /64 delegation from which I allocated a DHCPv6 pool and a set of static addresses.

 

So, my question to you is this.  What makes you think you need more than (in my case anyway) the /64 worth of IPv6 addresses wich turns out to be 18,446,744,073,709,551,616 (in words that is eighteen quintillion, four hundred forty-six quadrillion, seven hundred forty-four trillion, seventy-three billion, seven hundred nine million, five hundred fifty one thousand, six hundred and 16) for your network?  A single /64 is the ENTIRE  32 bit IPv4 address space squared!

NVTech
Occasional Visitor

Re: Assigned a /56 static, told I can only use 1/256th of it.


gguldens56 wrote:

I have an understanding that you are assigned a /56 and feel like you need to have the entire address space available to you for use.  I have static IPv4 and was assigned a static /56 IPv6 as well.   On my Netgear FVS318Gv2 firewall, I received a /64 delegation from which I allocated a DHCPv6 pool and a set of static addresses.

 

So, my question to you is this.  What makes you think you need more than (in my case anyway) the /64 worth of IPv6 addresses wich turns out to be 18,446,744,073,709,551,616 (in words that is eighteen quintillion, four hundred forty-six quadrillion, seven hundred forty-four trillion, seventy-three billion, seven hundred nine million, five hundred fifty one thousand, six hundred and 16) for your network?  A single /64 is the ENTIRE  32 bit IPv4 address space squared!

 

What make me think that? Well, the RFCs from the people that designed IPv6 make me think that.

RFC 5375 explains that a /64 is the subnet size per broadcast domain, or VLAN. I have 10 VLANs at my main site, plus over 30 VPN tunnels to remote sites. That means I need at least 40 /64 subnets.

RFC 6177 says I should be getting a /48 as a business cusomter. As you point out, that is a lot of subnets, so I can be OK with a /56, even though that isn't following the standard. HOME users are to be assigned a /56, but Comcast normally does a /60.
Again, those are reasonable for most people, so I can live with that, even though, I shouldn't have to.

 

RFC 7421 explains why the /64 subnet bountry was chosen.

If you think you know better than the people that wrote these RFCs, go write your own RFC and explain why they're not as smart as you. Maybe you'll change their mind.

Until that point, I'll take the IPs I'm pay for and I'm entitited to, thank you very much. 

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