What happens when you disable DHCP - apart from not being able to see router?

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Hatch

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#70791 30-Oct-2010 23:16

I'm having problems experimenting with my home network (if you didn't know this is my third post relating to these issues)

Cascading networks (i.e. multiple routers), home servers, wireless.

Trying to disable DHCP results in the router becoming unaccessible, looking at network connections for a router shows no default gateway, subnet mask.

Aside from my lack of expertise in this area, what must I do to be able to access the router via admin?

I did this on my WRP400 and couldn't access internet or the admin console but VOIP was still working.

What am I missing? Must the connecting laptop be on a static IP in the range of the original settings before disabling DHCP server?

richms

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#397911 30-Oct-2010 23:27

If you dont have another DHCP on the network to assign an IP, then yes you will need to statically assign one, but if you dont have another DHCP server, then there is no reason to disable the one you have, the thing you cant have is MULTIPLE routers with DHCP on the same network segment.

Richard rich.ms

Hatch

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#397961 31-Oct-2010 08:52

Ah I get it now, the problem is that the device is not being assigned an ip address by the primary router.

I'm using a Draytek modem/router as the primary router, do you have any idea what options/settings must I enable to ensure the second router (where DHCP is disabled) will be assigned an ip address by the Draytek?

I have DHCP server enabled but nothing else.

Cheers

sbiddle

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#397974 31-Oct-2010 10:09

If you don't have DHCP enabled on the Draytek then the router that has DHCP enabled needs a static IP address.

webwat

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#398194 31-Oct-2010 20:09

The Draytek primary router is the one you want to be assigning DHCP addresses for the rest of the network? Or is it just the gateway with another DHCP server?

You need to understand that enabling DHCP server tells that router to be the machine allocating IP addresses. Enabling DHCP client is the normal setting where a machine can pickup its own IP address automatically from the network.

So if you want the primary router to only be the gateway (and presumably will be a NAT firewall to separate the network from internet), then another machine needs to be the DHCP server. If you want the gateway to also allocate IP addresses, then that router needs to enable DHCP server.

All of the machines need DHCP client on the LAN enabled except for the DHCP server, which needs a static IP outside the range that is being allocated automatically. If you have double NAT, then you need a good reason to be making things difficult and treat each side of the router as a separate LAN with its own DHCP server.

Time to find a new industry!

Hatch

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#398254 31-Oct-2010 21:58

webwat: The Draytek primary router is the one you want to be assigning DHCP addresses for the rest of the network? Or is it just the gateway with another DHCP server?

You need to understand that enabling DHCP server tells that router to be the machine allocating IP addresses. Enabling DHCP client is the normal setting where a machine can pickup its own IP address automatically from the network.

So if you want the primary router to only be the gateway (and presumably will be a NAT firewall to separate the network from internet), then another machine needs to be the DHCP server. If you want the gateway to also allocate IP addresses, then that router needs to enable DHCP server.

All of the machines need DHCP client on the LAN enabled except for the DHCP server, which needs a static IP outside the range that is being allocated automatically. If you have double NAT, then you need a good reason to be making things difficult and treat each side of the router as a separate LAN with its own DHCP server.

Hi, I understand the notion of the DHCP server, however I am not capable of setting Draytek as Primary router AND DHCP server to WRP400 as secondary and wireless access point only.

I was told the WRP400 is not capable of acting as an AP, however I´m not sure if these are one and the same but all I want to do is to disable DHCP on the WRP400 and do all the routing (DHCP etc) from the Draytek, which will directly connected to my Windows Home Server.

I.e. disable NAT and DHCP on the WRP400 so all the routing is done at the Dratek.

The Draytek´s have quite advanced admin settings such as DHCP relay agent which I have no clue about.

Everytime I disable DHCP on the WRP400 I can't ¨find¨ the WRP400, network settings show no IP address or default gateway and therefore no internet access, VOIP works however. I take from this that the DHCP server on the Draytek isn't working, or I haven't configured it properly.

What I attempted:

Draytek set to 192.168.1.1, starting IP server (DHCP) 192.168.1.2.
WRP400 IP address changed to 192.168.1.255.
Disable DHCP in the WRP400.

I followed the principles in this article (and others) in regards to the ¨disabling 2nd router¨ section only.
http://www.smallnetbuilder.com/lanwan/lanwan-howto/24431-howtotworoutersharing?tmpl=component&print=1&layout=default&page=

I was a bit confused about connecting via Lan ports as opposed to ¨Uplink ports¨ but regardless of how I connected the 2 devices I could never get any internet connection on the WRP400 nor any IP address visable in Network Connection properties.

I am using Windows 7 and only have experience assigning static IPs for PCs and opening ports but this exercise goes far beyond that.

HELP!

webwat

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#399036 2-Nov-2010 11:27

Ahhh right. You dont want the main gateway router to be a relay, since its the server. If you cant set your wifi router to just be an access point then relay everything on the WRP400 might be another way to make it into an access point.

The uplink port there is what other routers call a WAN port, useful if the router can do dhcp relay itself or you want it acting as a firewall. Otherwise you might want to connect a LAN port with the WRP400s DHCP Server disabled. If the LAN port doesn't detect the cable (being 100baseTX), then try a crossover cable. These things aren't really designed to be an access-point behind an ADSL router, so we have these kind of workarounds to achieve the same result.

Which reminds me, another solution is to turn off all the routing functions of your ADSL box by setting to half-bridge mode, and use the Linksys as the primary router, gateway and DHCP server. If you give up getting DHCP the way you want it, you can check plenty of previous threads about that as well.

Time to find a new industry!

Regs

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Snowflake

#399097 2-Nov-2010 13:45

richms: the thing you cant have is MULTIPLE routers with DHCP on the same network segment.

you can run as many DCHP servers as you like... just need to make sure that they all server the same subnet (assuming no subnet routers) and that the "default gateway" they dish out is the correct one. you would also probably want to make sure they also dont have overlapping address pools too

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webwat

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#399593 3-Nov-2010 13:33

Regs:
richms: the thing you cant have is MULTIPLE routers with DHCP on the same network segment.

you can run as many DCHP servers as you like... just need to make sure that they all server the same subnet (assuming no subnet routers) and that the "default gateway" they dish out is the correct one. you would also probably want to make sure they also dont have overlapping address pools too

if multiple servers allocate the same range of IP addresses they would create IP conflicts and everything would randomly stop working properly. If they are on different subnets then probably you don't want the subnets to talk to each other directly, but subnets still need valid gateway addresses to get any internet.

Time to find a new industry!

richms

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#399968 4-Nov-2010 08:29

If they dont overlap and have the same gateway it will work, but I have had many problems with PCs flip-flopping between ranges when I have tried that in the past.

Richard rich.ms