Virgin Media Community

[kelv1n]

Hey All

I posted about this earlier, but now this is absolutely driving me crazy.

I've always run my Hub in Modem mode, I'm lucky to own a PA Firewall. Periodically I get an issue after restarting the Hub, the Firewall is unable to pick-up the Public IP. Historically rebooting the Hub 1 or 20 times fixes this, but for the past several months, this has not been happening.

After doing some more testing, with 2 different laptops and another router, I've come to the conclusion it works fine when a new mac-address is seen, it just issues a new public IP, but if its a previously (and recently) seen IP, it just doesn't work.

I've called VM Support 5 times this morning, 1 time they put me through to "Gadget Help", this is an issue with Virgins DHCP service, so that is no use - Then the other 4 times the "Tier 2" team in India just hung up on me!

Anybody got any ideas? Any of the VM Forum team able to assist?

[kelv1n]

I slight correction: if its a previously seen mac-address (I wrote IP last time), it just doesn't work, no public IP is isssued.

[tehwolf]

when presenting a different MAC address to the hub (whether new-new or previously seen) the hub needs to be switched off for a couple of minutes before being switched back on.  The sequence of events is also important, your palo alto should be fully booted and ready before switching the hub on.. 

there's a detailed breakdown (written by another customer) of how dhcp works when using modem mode here that you may find useful.

i know next to nothing about PA devices, but is it possible that it's sending a dhcp-requested-address argument when it initiates the dhcp conversation? this is all speculation on my part, but it could be confusing the VM dhcp servers i guess? it could be that it's sending the requested-address argument, being offered something different by the hub and then sending a NAK to say that it doesn't want that address - you might have to do some tcpdumps to get the detail of what's happening in that conversation..

[Adduxi]

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@kelv1n wrote:

I slight correction: if its a previously seen mac-address (I wrote IP last time), it just doesn't work, no public IP is isssued.

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Which Hub and have you tried a full factory reset, i.e. pinhole for 60 seconds and do NOT reboot, just let the Hub do it's thing.  It's a strange one, as I've never come across this before, and I've always used the Hub's in Modem mode.

[kelv1n]

Thanks - I'll take a look at this and work through it.

Unfortunately, whilst I work in networking my experience with DHCP is limited, but I can replicate the issue with other devices.

[kelv1n]

@adduxi - I've experienced this issue persistently for the past 6 months, I had it 2 different Hub v3's, and yesterday my Hub 4 arrived, and the problem continues with that.

[Adduxi]

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@kelv1n wrote:

@adduxi - I've experienced this issue persistently for the past 6 months, I had it 2 different Hub v3's, and yesterday my Hub 4 arrived, and the problem continues with that.

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In that case, it sounds like an issue with your networking kit as I've had the VM Superhub, Superhub 2 and Hub3, all without issues in Modem mode.

[tehwolf]

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@kelv1n wrote:

Thanks - I'll take a look at this and work through it.

Unfortunately, whilst I work in networking my experience with DHCP is limited, but I can replicate the issue with other devices.

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what other devices have you replicated it with? similarly to @Adduxi, I've been running in modem mode for years and never experienced the issue - granted, i don't tend to offer up different MAC addresses on a regular (or even semi-regular) basis, or indeed reboot my network kit unnecessarily to trigger this behaviour, but it's been very reliable for me.. which kinda makes me think that maybe it's the way your PA device is requesting an address that is a problem - though again, DHCP is pretty robust/standard, so unless the PA device is explicitly NAK'ing the address that's offered, i don't really understand why there would be a problem.. 

[kelv1n]

@Adduxi .. How do I reply with quote on this dam forum... 😄

I don't discount it, given "what is the common factor?", as I do have a Unifi Switch between the Firewall and Hub - But this happens even if I plug a new device such as a laptop directly into the Hub. IP issued when it's first seen, if I then disconnect and reconnect it, it fails.

That blog post that was linked too earlier is pretty much what I'm experiencing, so I'll work through that.

[tehwolf]

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@kelv1n wrote:

@Adduxi .. How do I reply with quote on this dam forum... 😄

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Click the quote button - fourth one in from the left above the text input box 🙂

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@kelv1n wrote:

I don't discount it, given "what is the common factor?", as I do have a Unifi Switch between the Firewall and Hub - But this happens even if I plug a new device such as a laptop directly into the Hub. IP issued when it's first seen, if I then disconnect and reconnect it, it fails.

That blog post that was linked too earlier is pretty much what I'm experiencing, so I'll work through that.

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The unifi switch.. i take it that this is managed and that it itself is not requesting an IP address of any sort? is there anything else plugged into the switch, or just the hub and the PA device?