So software isn't using the standard DHCP renewal of 24 hours then?

What would explain the pattern in the original post, which was broken this morning?

In reply to a post by hk11:

Yes - http://helpforum.sky.com/t5/Fibre/Static-IP-should-b...

Maybe. I asked them a couple of weeks ago and they said after I signed up they might be able to offer one :-/

Sounds to me as though they just wanted your order. I take it you have nothing in writting?

The DHCP lease is provided by the server. Here is an extract from my log (on a Q Hub) that shows a lease time of 3600 seconds and the Q Hub attempting to renew in about half that.

Nov 24 23:03:38 syslog: Lease renewed 3600 ip 94.194.5.246
Nov 24 23:36:54 syslog: Lease renewed 3600 ip 94.194.5.246
Nov 25 00:03:18 syslog: Lease renewed 3600 ip 94.194.5.246
Nov 25 00:30:23 syslog: No lease renewal received
Nov 25 00:45:37 syslog: No lease renewal received
Nov 25 00:55:46 syslog: No lease renewal received
Nov 25 00:59:56 syslog: No lease renewal received
Nov 25 01:01:34 syslog: No lease renewal received
Nov 25 01:03:22 syslog: No lease renewal received
Nov 25 01:03:22 syslog: DHCP lease expired. -> DISCOVERY 3600
Nov 25 01:03:28 syslog: DDNS update successful
Nov 25 01:03:29 syslog: ptm0.1 - WAN link UP.
Nov 25 01:03:29 syslog: Received valid DHCP lease from server. Connection UP.
Nov 25 01:03:29 syslog: Connection Up. SNO/MAC/IP/SWVER: [XXXXXXXXXXXXXX/XXXXXXXXXXXX/151.224.186.18/2.01.1850.R]
Nov 25 01:03:30 syslog: Send out NTP request to ntp1.isp.sky.com
Nov 25 01:03:30 syslog: Received NTP Sync Reply from ntp1.isp.sky.com
Nov 25 01:03:30 syslog: System time is up to date
Nov 25 01:36:38 syslog: Lease renewed 3600 ip 151.224.186.18
Nov 25 02:10:30 syslog: Lease renewed 3600 ip 151.224.186.18
Nov 25 02:40:29 syslog: Lease renewed 3600 ip 151.224.186.18

In this case the lease was not renewed at 00:30 so the Q Hub then made further requests are reducing intervals until the lease expired at 01:03 (exactly 1 hour after the last valid lease renewal).

At this point the Q Hub could no longer use the IP address and had to submit a request for a new IP that it got at 01:03.

So it seems Sky's lease time is 1 hour.

On SKY FTTC, on my line, lease is for 3600 seconds = 60 mins = 1hr. But the renewal process actually happens every 1/2hr (see below). I am assuming SKY are using this 30min update as a router "ping I am up" type message. For IPv6 there are no logs around change of IP address, so what happens there is invisible.

The network time NTP is checked every 2+hrs. I find if the NTP has to adjust the time, then the WAN link is torn down and restarted, causing a mini outage on my line. My daughter hates that, and I always get the blame.

Dec 10 02:53:33 syslog: Received NTP Sync Reply from ntp1.isp.sky.com
Dec 10 02:54:54 syslog: [ 156.410000] Line 0: VDSL2 link down
Dec 10 02:54:56 syslog: [ 158.045000] Line 0: xDSL G.994 training
Dec 10 02:54:56 syslog: Clear IP addresses. IP connection DOWN.
Dec 10 02:55:04 syslog: [ 166.055000] Line 0: VDSL G.993 started
Dec 10 02:55:21 syslog: [ 183.535000] Line 0: VDSL2 link up, Bearer 0, us=4681, ds=19999
Dec 10 02:55:28 syslog: ptm0.1 - WAN link UP.
Dec 10 02:55:28 syslog: Received valid DHCP lease from server. Connection UP.
Dec 10 02:55:28 syslog: Connection Up. SNO/MAC/IP/SWVER: [xxxxxxxxxx0053/xxxxxxxxxx08/188.221.7.xxx/2.01.1860.R]
Dec 10 03:23:00 syslog: Lease renewed 3600 ip 188.221.7.xxx
Dec 10 03:47:00 syslog: Lease renewed 3600 ip 188.221.7.xxx
Dec 10 04:17:16 syslog: Lease renewed 3600 ip 188.221.7.xxx
Dec 10 04:42:46 syslog: Lease renewed 3600 ip 188.221.7.xxx
Dec 10 04:55:33 syslog: Send out NTP request to ntp1.isp.sky.com
Dec 10 04:55:33 syslog: Received NTP Sync Reply from ntp1.isp.sky.com
Dec 10 04:55:33 syslog: System time is up to date
Dec 10 05:09:44 syslog: Lease renewed 3600 ip 188.221.7.xxx
Dec 10 05:38:14 syslog: Lease renewed 3600 ip 188.221.7.xxx
Dec 10 06:08:13 syslog: Lease renewed 3600 ip 188.221.7.xxx
Dec 10 06:39:05 syslog: Lease renewed 3600 ip 188.221.7.xxx
Dec 10 07:08:47 syslog: Lease renewed 3600 ip 188.221.7.xxx
Dec 10 07:08:47 syslog: Send out NTP request to ntp1.isp.sky.com
Dec 10 07:08:48 syslog: Received NTP Sync Reply from ntp1.isp.sky.com
Dec 10 07:08:48 syslog: System time is up to date

In reply to a post by iand:

On SKY FTTC, on my line, lease is for 3600 seconds = 60 mins = 1hr. But the renewal process actually happens every 1/2hr (see below). I am assuming SKY are using this 30min update as a router "ping I am up" type message. For IPv6 there are no logs around change of IP address, so what happens there is invisible.

This is normal, but a lease time of 1hour is quite short. Probably because Sky need to reclaim IPv4 from devices that are powered off, as IPv4 has run out. IPv6 doesn't typically use DHCP, which is why you don't see a DHCP renewal. (Look up RADV for one alternative).

Other ISPs don't use DHCP directly, they use PPP (either Over ATM on ADSL or Over Ethernet on VDSL) but Sky is different not using PPP encapsulation. This is generally because they don't have to host other ISPs on their infrastructure. (similar to virgin media)

The network time NTP is checked every 2+hrs. I find if the NTP has to adjust the time, then the WAN link is torn down and restarted, causing a mini outage on my line. My daughter hates that, and I always get the blame.

That sounds like a bug in the router firmware

Edited by jchamier (Mon 12-Dec-16 21:47:35)

In reply to a post by hk11:

No, not really.

A standard renew time of 24 hours would normally result in a new IP every 12 hours, if I have read up correctly.

As others have said you can have a renew every minute if they want - a static IP is just that.

In reply to a post by Eeeps:

So it seems Sky's lease time is 1 hour.

You think this is across the board?

A previous poster said 24hrs and I have had the same IP for several days now: just a fluke?

In reply to a post by hk11:

A previous poster said 24hrs and I have had the same IP for several days now: just a fluke?

A lease time of 24 hours does NOT mean you get a new IP, it means there is the option for the DHCP server to give you a new IP.

On a network I ran I had the same IP for 4 years, even though the lease time was 3 days.

I realise my IP may not change, but just odd it changed every 24 hrs for several days in a row, but hasn't changed now for several days.