BT 5 static IP's - pain in the ass.

[cava83]

Hi,

Have a small office, new router put in supplied by BT BT2700hgv.

Current configuration;

Router > Switch > PC's

Proposed configuration;

Router > Firewall > Switch > PC's

Information;

Therefore behind the router I have a Sonicwall 2040 pro firewall which will also be used for our office VPN's, connected to the LAN.

Need to give both the router firewall a static IP address. Not working properly, as BT's IP's are a bit weird.

Putting the router into bridge mode, and setup the PPPoE credentials on the firewall so the router acts as a modem. Still no luck.

Anyone else had similar? Looked on google but no solutions.

I have a spare cisco 1840 (might be just easier to set it up on this), but don't have a clue on how to configure these, specially in bridged mode.

Can anyone assist?

Really appreciated,

G.

 

[DMS]

Simple way would be to turn off NAT on the router, then give the WAN interface and the internal interface one IP address from the range each. Obviously don't use the network or broadcast addresses, but I'm assuming you already knew that?
Then give the external interface of the firewall another one of the addresses, enable NAT on the firewall and the inside interfaces of the firewall can then have private IP's as I'm assuming the rest of your network does / will.

Then, all you need to do when trying to VPN in is use the firewall's external public IP. BT will route the traffic to your internet connection and your router will know that the external IP of the firewall exists out of the internal interface on the router. Simples.

If you need any more info, post up your IP address range and I'll give a working example.

BTW. If BT say you've got 5 useable IP's, you've actually got 6.

 

[cava83]

DMS Hi

By disabling routing it automatically puts it into bridge mode which disables the NAT and DHCP Server.

Settings when I tried it in bridge mode where;

public IP Address: 217.40.130.254 (default gateway) 255.255.255.248 (subnet)
VPI : 0
VCI: 38
ATM Encapsulation: bridge llc
ATM PVC Search: enable = unticked
Upstream MTU : 1500
Diable Routing : Enable = unticked.

This in theory should work, as it just turns it into a modem.

In the firewall WAN, i tried both DHCP and PPPoE , the ip address I tried was 217.40.130.253 (one of the range)

Both DHCP and PPPoE didn't work

So quite confused.

Thanks,

Gabi.

 

[DMS]

Can't you just disable NAT without putting it into bridge mode? You still want it to be routing for my suggestion to work.

So .254 is the default gateway that gets assigned on the WAN interface of the router, making your entire IP range 217.40.130.248 - 217.40.130.255.
Obviously .248 is the network address and .255 is the broadcast address so these can't be used, and .254 is the default gateway, meaning you have .249, .250, .251, .252 and .253 useable.

If you can turn off DHCP and NAT without turning on bridging mode, try this:

Router WAN interface
IP: 217.40.130.249
Subnet mask: 255.255.255.248
Default Gateway: 217.40.130.254

Router internal interface
IP: 217.40.130.250
Subnet mask: 255.255.255.248
Default Gateway: (leave blank)

Create the following static routes:
217.40.130.252/32 > 217.40.130.251
217.40.130.253/32 > 217.40.130.251

The router should sort out the rest of the routing table by itself.

Firewall external interface
IP: 217.40.130.251
Subnet mask: 255.255.255.248
Default gateway: 217.40.130.250

The firewall should then be able to make use of .251, .252 and .253. I'm not sure with the SonicWall's whether or not you have to create sub-interfaces off the main WAN interface to use the other IP's or, if like on a Cisco device, you can simply configure services to use the IP's and it'll use them.

P.S. I'm going for lunch now and won't be back for an hour (just so you know I'm not being ignorant).

 

[Magic Johnson]

You forgot the switch, so there'd only be 4 host addresses useable?

 

[DMS]

You forgot the switch, so there'd only be 4 host addresses useable?

No, because the switch would be hanging off the inside interface of the firewall. In that scenario (above), you'd enable NAT on the firewall and use private address space off the internal interface (that's 10.x.x.x, 172.16.x.x, 192.168.x.x etc to you). The switch wouldn't have a public IP address at all.

I really am going for lunch now

 

[Magic Johnson]

Ah right. Cheers!

 

[Longy]

Bridge mode doesn't tend to work for DSL connections - you need to use half-bridge mode which only certain DSL modems can do (eg: Draytek, Zyxel). I've only used them when we have 1 static ip to use. However like has been mentioned if you have 5 then run a no-nat configuration and not a bridge mode.

 

[cava83]

Hi,

Thanks for you time to write back, hope you had a nice lunch would not think you are ignorant, don't be silly ...... people have things to do, so no biggy.

Anyhow, not sure how this would work, are these settings applicable for the T2700HGV?

For the public IP all I get as options are;

Router Address
Subnet Mask
Auto Firewall Option.

There is an option for static IP, but that does not work with our configuration ..........

There is no option to configure the router interface unless I am looking in the wrong place,

Shall I provide some screen grabs?

There is no place to turn off the nat as far as I can see, it can only be done via choosing the option to bridge the router

Thanks ever so much,

Gabi.

 

[Longy]

To run No-NAT mode you normally have to telnet into the router and do it from the CLI on alot of routers I've used. Not sure if you can do that on your BT Router.

I just googled that router model and got 1 result! popular router then?

 

[cava83]

Longy,

Well, s**t router to be honest but hey.

They turned off telnet I believe in a previous firmware version. What a pain.

Do you have any experience in setting up the cisco 1840?

Thank you all for your time,

Thanks,

Gabi.

 

[Longy]

Been awhile since I've used IOS, however:

http://www.petri.co.il/forums/showthread.php?t=24951

I know it's for a 857

 

[cava83]

Found the solution yesterday.

I tried a numerous amounts of ways and finally got it working.

Basically, don't use BT's 2 wire router, it's shite and you cannot turn off NAT properly, I also tried a Netgear DM111P - this is just a modem, this doesn't work either as you cannot turn off DHCP if it's in half bridged mode PPPOA.

Tried a Zyxel, no luck either (admitedly an old one) in the end, got it working with a DG834G.

The configuration isn't your standard in regards to the IP settings, I have drawn a diagram below to explain how I have set it up.

Basically, BT tell you to use the default gateway for the router, and that doesn't work, you need to use an IP from the block give to you (if you use multiple IP's)

Hope this helps someone in the future!!

Thanks,

G.

<a href="http://smg.photobucket.com/albums/v365/gabi_cavaller/?action=view&current=wickford2.png" target="_blank"><img src="http://img.photobucket.com/albums/v365/gabi_cavaller/th_wickford2.png" border="0" alt="Photobucket" ></a>

 

[cava83]

Might help if I do the right link