Virgin has Poor dhcp?

I seem to keep coming across a problem with a cisco router not being able to allocate an ip address by dhcp on a virgin connection. It happens every time the connection drops and has been doing this since the router was installed. But I don't think its our problem since it works again after we get virgin to reset something.

Full details of this are available here

What do you think?

years ago i bought a Linksys router which is Cisco and had the same issue. The Ip lease would drop after 24hrs and wouldnt reissue a lease in the end i give up and took it back and bought a Netgear which ive stuck with Netgear ever since with no problems.

Have u tried a firmware update?

It seems a common problem when looking at Virgin's support forums.
In my case I cannot renew my firewall's IP address and have to do a release then discover at intervals to keep my connection working. In Virgin's defense it appears to be a problem with the linux drivers for one Intel NIC chipset and the problem affects users on other cable systems worldwide.

In reply to a post by JimKirk363:

years ago i bought a Linksys router which is Cisco and had the same issue. The Ip lease would drop after 24hrs and wouldnt reissue a lease in the end i give up and took it back and bought a Netgear which ive stuck with Netgear ever since with no problems.

Have u tried a firmware update?

The firmware version I am using works is known to works with 4 other isp's who all present Ethernet

It also works fine with win 2003, 2008 and linux dhcpd servers as well as other router dhcp servers and many more things.

The fact it works when they reset something on their end should really rule out an issue with the firmware on the site end of things.

I think you're probably asking on the wrong forum!

Without seeing the contents of the DHCP discover the Cisco is sending out and the offer it rejects I don't have enough information to comment.

I have never experienced DHCP issues, while I would say it's clearly an incompatibility I would suggest it's a peculiarity of the Cisco device, if it were Virgin's issue it would affect everyone asking for a DHCP lease.

Given Cisco appear unable to obey their own standard (WCCP) properly it's not a huge leap to think they struggle to obey DHCP's RFCs.

When I was on cable, I always used to notice something a bit quirky.

If I have a router with mac address A connected to the cable modem and I power on the cable modem, and then the router, the router would normally DHCP shout and have no problems being allocated an IP.

If I then disconnect that router, and connect another completely different router, with mac address B, and let it try and DHCP, it would fail (it just wouldn't get any responses from its DHCP shouts). Only if I turn the cable modem off and back on would router B then be given a new IP via DHCP (the network responds as normal to the shouts). The IP is usually completely different, as this is a new mac address the network hasn't seen before.

I've seen this behaviour time and time again on cable, and it really puzzles me. I don't really understand what's going on but it certainly ain't normal, and it seems to me to be some weird side affect of the whole cable infrastructure that causes this. Maybe you can explain? Might be indirectly upsetting the Cisco, but this is purely speculation.

It's certainly normal for cable. Unplugging the router presumably doesn't break the modem connection to the CMTS.

to save time a dhcp renew on the router will also do the trick.

It seems qirky. Because its evident VM's dhcp server communicates with the router and not the modem, so the modem itself needing a reboot is odd.
Also if I use the clone mac feature on the dir615 router, then on every dhcp renewal (once a week) the connection will drop until dhcp is manually renewed.

In reply to a post by Chrysalis:

its evident VM's dhcp server communicates with the router and not the modem

It certainly allocates the IP (and so the lease) based on the MAC of the device plugged into it. I'm pretty much certain that I had to reboot the modem if I swapped routers or it wouldn't work.

On a kind of related note, and as you seem to understand things a little better can you answer this.

I have a pfsense router/firewall and it's WAN interface get the public IP via the modem.
On first boot of the modem, the router broadcasts for a DHCP server and it picks up the IP as expected from a DHCP server with a (from memory) 62.x.x.x address.

Come renewal time, the router tries repeatedly to renew with the server @ 62.x.x.x and gets no response for about 7 days then finally it gives up and tries a broadcast for a DHCP server, at which point the same 62.x.x.x server replies with the renewed lease. Is this normal?