DHCP problems

[Welsh Pete]

Hey,

In the office we have a network setup running 5 PC`s permanently and upto 4 more laptops getting random access. Wireless is working fine and this problem doesnt seem to effect it.

We have a Draytek Vigor 2820vn on the latest firmware which provides the routing. We have this running on DSL, as it has the option for 2 WAN`s. We have this uplinked to a netgear FS752TPS network switch, which provides PoE to the office IP phones, and we also have a siemens HiPath 2030 PBX connected on a static IP.

We also have an IPsec tunnel provided over VPN to the bosses house to provide the VoIP link, and this is tunnelled to another 2820vn at his house.

Setting this lot up took a while, but it works.

While everything works fine, and there are never any problems with the VPN, VoIP and wireless, every now and then at random intervals the office clients seem to stop working on the internet. A refersh of the IP fixes this.

Does anyone know why this is?

Phones, network cabling, fibre and PC`s I can fix but this has me a bit confused. As far as I can see the router is all kosher and there are no obvious problems in the config...

HELP

[stimpy]

What is the lease time on the assigned IPs? It could be expiring if a reset of the IP fixes it.

[Welsh Pete]

According to XP its a 3 day lease...and its similar on each PC...still drops randomly through the day though.

[tombott]

According to XP its a 3 day lease...and its similar on each PC...still drops randomly through the day though.

What's it set to on the router though?

Maybe easier to change the DHCP scope on the router to start higher

I.e

xxx.xxx.xxx.100

Then use xxx.xxx.xxx.010 - xxx.xxx.xxx.099 on your PC's

[tawny]

Is it just internet connectivity that they lose? What DNS settings are you using?

[Welsh Pete]

I cant see a lease expiry setting on the router...also all PC`s are dynamically assigned in the range xxx.xxx.10.10 - xxx.xxx.10.254. Only the PBX, switch and IP phones (5 of them) are statically assigned and I beleive these are using 10.2 through 10.9

[Welsh Pete]

Is it just internet connectivity that they lose? What DNS settings are you using?

Yeh, appears to be just internet connection as the network printer still responds fine.

I presume the defaut DNS from plusnet are in use as the WAN or LAN setup on the Draytek dont ask for DNS!

[Over Carl]

They do ask for dns but it's in a funny place - threw me at first - sorry I'm quite snowed under atm, can post relevant screen shots when I get home.

Personally for a small/not very dynamic office, I prefer assigning static ip's by reserving them in the vigor.

[tawny]

Yeh, appears to be just internet connection as the network printer still responds fine.

I presume the defaut DNS from plusnet are in use as the WAN or LAN setup on the Draytek dont ask for DNS!

Maybe worth you finding the setting on the Draytek to assign the PlusNet DNS server IP's to your clients. I've used the very model of Draytek at a lot of my Satellite offices in the past and I cant fault them. Had the configured overseas to come in to my UK only MPLS network.

[Over Carl]

Sorry to go off topic - MPLS = exponential e?

If so, do you mind if I create another thread on them as at work, we're on the verge of signing up for their 100Mb service.

[tawny]

Sorry to go off topic - MPLS = exponential e?

If so, do you mind if I create another thread on them as at work, we're on the verge of signing up for their 100Mb service.

Hi mate, i dont mind. I used Star Internet but we do use Exp E at my current job and have there 100mb next gen networking service. It's a good service once they ironed out the few glitches that hampered our bandwidth initially. They sorted it straight away though so cant knock them. I cant really tell you much about them really as it was pretty much in place when I started except for one site. As we hadn't gone live on it when I started my boss let me test the bandwidth by any means necessary! I had fun on Newsgroups that day

[Welsh Pete]

They do ask for dns but it's in a funny place - threw me at first - sorry I'm quite snowed under atm, can post relevant screen shots when I get home.

Personally for a small/not very dynamic office, I prefer assigning static ip's by reserving them in the vigor.

Yeh the screenies would be great, cheers mate

[Over Carl]

Edit: I thought I figured this out previously, although looking now for you has just made me realise something I had horribly wrong!

Okay, I'm looking at a 2820 running 3.3.1.2, go to wan... internet access out of the options on the left hand side.

If changing wan1, click wan1, then the MPoA (RFC1483/2684) tab at the top and you should see two dns servers at bottom right.

If changing wan2, click wan2, then Static or Dynamic IP tab at the top, then you will find the dns server addresses.

If you want to change the servers specified to clients by dhcp leases, click lan... general setup... and you will see them in the bottom right.

However, I think you've just helped me realise something. I remember previously thinking if we fill in everything for wan1 on the PPPoE/PPPoA tab, and the first thing I see under MPoA is Disable selected, then surely the setting was irrelevant. However, I remember knocking off internet on a site by entering invalid settings there (I did ipconfig/all to check I hadn't messed with the dhcp leases). But checking now, the dns servers mentioned in online status don't match the ones we've entered which baffles me.

Looking at this page http://www.beusergroup.co.uk/technot...tek_Vigor_2820 makes me think the only way of doing it is by entering all the settings on the MPoA page. Think I may have to look this up myself.

[Welsh Pete]

Hi.

Sorry I`ve been so long in responding but been busy.

I have specified the dns servers for plusnet but the problem is still there. If anything its more frequent. We even rewrote the router config but that is doing exactly the same...

Help!!!

[Over Carl]

Just wondering, when you say you specify the plusnet dns servers - I take it you mean you are changing the dhcp leases but the router still is using the isp's under the online status page?

I contacted the company that supplies us our draytek and they concurred that MPoA page is only way to change dns servers the router actually uses.

Had an interesting brief conversation with another draytek reseller who said he wouldn't sell draytek to anyone with 10+ users. Didn't get to speak for long, hopefully will be taking him out for a drink in the near future (probably will be about 2-3 weeks) and will report back what I find.