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6 posts

Wannabe Geek

#304550 14-May-2023 15:52
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Hi all,


I'm facing a minor issue (ie it it doesn't significatly impact my service) on my ORCON fibre connection.


I am running a dual stack IPv4/ IPv6 network and it is generally working very well.


However, the minor issue is with DHCP lease times I'm receiving from Orcon. 


On my WAN side the IPv4 and IPv6 lease times I'm receiving are 5 minutes . This seems to contradict the info on this forum suggesting that lease times should be 1 day (86400 seconds) by default.


I'm using my own Fortigate router and it is possible I have missed something in the WAN config there- but for both IPv4 and Ipv6 "suggesting" longer lease times in Fortigate config doesn't appear to have any impact.


I have raised a support ticket to Orcon- but the response just suggested to use DHCP for IPv4 and IPv6. It didn't really address the lease time (I suspect it needed some second line support perhaps).


Does anyone have any suggestions or has seen this knd of behaviour before?


Kind Regards,





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26749 posts

Uber Geek


  #3076107 14-May-2023 16:50
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What is the problem with the short lease time causing you?



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6 posts

Wannabe Geek

  #3076111 14-May-2023 17:03
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Hi Richard,


The short answer is- not much. As I said in the post it’s a pretty minor issue in the scheme of things.


But, the very helpful guide posted in this forum suggested that 1 day lease time was standard. That makes me rather “non-standard”. So I’d like to know why that is the case.


It does add a little overhead, and it means the router advertisements I use inside the network (subnets from the delegated IPv6 block) have to be advertised much more regularly than they otherwise might (in case they change in 5 minutes time- always possible given it is not a static IPv6 block).


Kind Regards,





  #3076116 14-May-2023 17:49
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I am also with Vocus and my lease time is 5 mins as well with the change happening without my noticing anything. No impact on ipv4 services on my end, in fact I've been assigned the same ipv4 address for several months so their system seems to just roll over the ipv4 lease. I had some issues with ipv6 services a few months ago and had switched off ipv6 but not sure if it is related to this. Using Microtik gear.


Unless there's any specific issues then it looks like DHCP is working as it intended.


You raise an interesting question about the IPv6 RAs though and I do recall that when I had ipv6 enabled vocus would randomly cycle my ipv6 prefix even though it never did that with ipv4. I tried to get away with using a IPv6 public server on my LAN but the occasional change of IPv6 prefix put a stop to that. That as back when the lease time was longer -- not sure if it was 1 day though but certainty more than 5mins.


6 posts

Wannabe Geek

  #3076121 14-May-2023 18:10
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Hi KiwiSurfer,


Thanks for your feedback. 


It’s good to know that you are seeing the same lease times- it certainly suggests it has been an intended change rather than something specific to me.


Yes- it would be good to have a static IPv block too. In practice mine doesn’t seem to change a great deal- but if you can’t rely on it being static it it’s hard to use it for internet accessible services. I guess I could try looking for an IPv6 DDNS service- but in practice I don’t have a particular application just at the moment.


Anyway, thanks again for your comments. I think I’ll park this topic for now given your feedback.


Kind Regards,





171 posts

Master Geek


  #3076155 14-May-2023 19:12
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I'd hazard a guess that the low lease time is due to the consolidation work going on currently. Where 2degrees is behind the scenes migrating customers on the various backend systems inherited via the vocus/2degrees and related companies merger. Onto the one system they intend to keep long term.



When backend changes are being made it is useful to have dhcp lease times set low to ensure that clients pickup changes quickly. I don't know if we'd get any official word from orcon/2degrees on the matter. As I suspect exactly what is going on with the internal migrations as they consolidate the backends most likely to be considered commercially sensitive.

2052 posts

Uber Geek

Lifetime subscriber

  #3076163 14-May-2023 19:37
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FYI: Zeronet uses 15 min leases.

Please keep this GZ community vibrant by contributing in a constructive & respectful manner.

1096 posts

Uber Geek

  #3076215 15-May-2023 00:23
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One possible reason for using low DHCP/DHCPv6 lease times is to allow for the use of different routers by the customer.  There have been people in the past who have switched routers and then found that they can not connect on the new router until the old lease time expired, so they had to wait for a day and it suddenly started working.  The cause for this may be that the DHCP server is registering the MAC address of the router and ignoring requests coming from a different router.  If the leased addresses are not actually changing, then it should not cause any problems.  If the leased IPv6 addresses do change, then the router should automatically be propagating that by sending a new Router Advertisement packet, and if I remember the rules correctly, it should send three RAs to make sure one of them is seen.  If it does not, then that should be reported as a bug in the router.


BTW The very idea that assigned IPv6 addresses would be changed is anathema to the design of IPv6 and should not be happening - IPv6 is designed so that there are plenty of addresses to go around and the only time they should change is if the topology of Internet connection changes, for example if the ISP merges with another ISP and they align their IPv6 addresses, or you change to a different ISP.

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