DHCP WAN renewal

Bugs
1

I’ve recently transitioned to using VyOS on commodity hardware after years on Ubnt EdgeOS, and things have been going well, except for an issue with DHCP renewal for the WAN.

My WAN connection is on ETH5, and my ISP is Verizon Fios, which has a DHCP lease time of 2 hours. I’ve observed that my internet goes down around the time the lease expires. When I check show dhcp client leases, it indicates that DHCP was renewed successfully with the same IP and gateway. However, internet traffic fails to go through. Manually executing renew dhcp interface eth5 seems to resolve the issue almost instantly.

Not seeing any DHCP logs.

I’m running VyOS version 1.1.8.

admin@vyos# show interfaces ethernet eth5
 address dhcp
 duplex auto
 firewall {
     in {
         name WAN_IN
     }
     local {
         name WAN_LOCAL
     }
 }
 hw-id ee:00:c3:00:ab:00
 smp_affinity auto
 speed auto
[edit]
2

I don’t know where you got this version; it was EOL several years ago.
Do not create bugs for EOL versions; it makes no sense.

2 Likes
3

Oh interesting…
I got it from official vyos support - Legacy LTS Release.

It mentions “ Modified on Wed, 18 Oct 2023 at 11:39 AM”

Figured it is stable but guess not. Will try the new release. Thanks for the heads up.

4

Updated to the latest version

VyOS 1.5-rolling-202401210026

But the problem remains. Any idea where I should be looking?

5

Might be worthwhile to share some logs - it certainly seems odd that it dies when the lease expires yet a manual lease renewal fixes it.

6

Unfortunately during the time of failure there are no logs. Nothing.

I did a fresh install with two subnets and WAN for testing.

Verizon Fios —-> VyOS —-> computer

Verizon issues 2 hour DHCP lease. About an hour or so the lease is renewed successfully. In exactly 2 hour mark - from the time first lease was issued- internet drops. New DHCP lease has exact same ip / gateway etc as first lease. Issuing renew manually brings it online.

I did further testing and everything works fine with another router. Everything works fine with another router in front of VyOS (fios → another router → VyOS → computer)
This behavior seems to be only when Verizon fios connects to VyOS directly. Looking through forms seeing other people with similar situation however those posts are a few years old. Best bet will prob be to get a new gateway from Verizon but will keep poking around some more.

Any insight anyone has would be helpful.

7

I would suggest running a tcpdump on the WAN interface for the period of time, but just grabbing DHCP traffic only (otherwise you’ll have a massive log!) and then checking the resulting capture to see what the difference is. Does the Vyos box GET a renew request? Does it respond? What’s different about a manual renew?
This isn’t going to immediatly resolve the problem, but it will help pinpoint where the issue is.

What if you clone the MAC of your Vyos FIOS box on your WAN Interface, does that make a difference?

1 Like
8

Thank for the tip. Finally had some time to run packet capture and turns out my XCP-NG was configured to request DHCP on the same interface. Turned it off and now works like a charm.

1 Like
9

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