I have a short question. I am using router pentagram cerberus: WAN: ADSL RJ-11 LAN: 4X ethernet RJ-45 Wireless Access point
I changed ISP and now I have internet connection via ethernet. I am wondering if i am able to use my router. I am wondering if it is possible to connect ISP ethernet to LAN RJ-45, and set up router AP as simple reapeter. I want to have wireless connection, i don't need to connect more PC's. Please help me if it possible, or i should bay new router with ethernet WAN port.
Jacek Ptaszyñski wrote in news: firstname.lastname@example.org m:
In case you do, you *must* disable your routers DHCP server. Otherwise your setup will screw up the ISPs whole network.
Your wireless router, connected to the internet by a LAN ethernet port, will function as an AP - not a repeater - but you *must* disable the DHCP server!
The other LAN ethernet ports will function as a switch. So you will also be able to connect your PC by cable, and if your account comes with more than one public ip-address, you will be able connect up to
3 PCs by cable, and as many as the wireless can handle, to the internet, up the number of public ip-addresses provided for you by the ISP.
They work quite well, as long as you understand you are trading bandwidth for range. Unlike repeaters which retrans on a different frequency, wifi repeaters use the same frequency. So, if you wifi net is 25% saturated, you will be 50% saturated with a repeater.
Why? As I said, they work very well as long as you know how they work and what your network utilization is. I used one in a rural campus environment (actually a ranch), where it wasn't possible to do a direct line of sight between two buildings about 2000' apart.
There was a third building that both buildings could see, roughly in the middle (think triangle). We put a repeater there and everything worked fine.
As I understand it, you have a new DSL internet connection and want to connect a computer to it via wireless.
Very simply done. A standard Linksys WRT54G for under $60 available almost anywhere will work. The built in discovery process will make it very easy. Simply connect the DSL modem's ethernet jack to the Linksys' WAN jack. The wireless connection will be functionally identical to the four LAN ports.
Axel's response about turning off the DHCP server is incorrect. Granted if you were to connect one of the four DHCP'ed LAN ports of a hub or switch directly to the DSL modem, it will create some problems for you (it would not create a problem on the DSL network as the DSLAM ports are on a switch to protect their network from such problems).
Notice he said "you must disable your routers DHCP server". That means he's talking about a router, which be definition would have a WAN port connected to the ISP's network and at least one LAN port, which can most certainly be driven by a DHCP server.
He did bring up the point about an ISP selling you multiple IP addresses as a profit avenue, but that was over ten years ago, before consumers discovered they could use a router to connect multiple computers to their DSL (or cable modem) service.
Robert Blass added brought up repeaters. Generally speaking, we can define that four ways.
1) A two way radio system repeater receives a signal on one frequency and transmits it back out on a different frequency in real time.
2) A consumer grade wireless device that receives a chunk of data and stores it, then turns off the receiver and turns on the transmitter and transmits it on the same frequency. Store and forward repeaters cut your overall speed in half.
3) A commercial grade wireless device that uses both a transmitter and separate receiver for full duplex operation without halving your connection speed.
4) A generalized non-specific description that technically uninformed people use to describe transmitting, connecting, sending, etc. any sort of signal.
Robert Neville described a consumer grade store-and-forward wireless repeater that operate on e single frequency. Commercial grade wireless repeaters use two frequencies.
I partly agree. It's very unlikely to cause a problem for the ISP, but will drive the user side nuts. The ISP is protected because the typical configuration is the user looking at a router port, not an ethernet switch or hub. DHCP operates on the MAC layer and must "see" other machines MAC addresses in order to work. You can't see the other machines backwards through a router port. All you can see is the one router port MAC address. So, there's no danger of an extra DHCP server assigning addresses to the ISP's desktops or other customers attached to other ports.
Try it. Connect a PC to the DSL modem directly (no router) and run: arp -a Try pinging a few things and run it again. It should be the same. All you'll ever "see" is the MAC address of the default gateway (i.e. the router port). (Well, if you're lucky, you might see some logging devices or sniffers, but those usually use static IP's).
However, having more than one DHCP running on any LAN is going to cause problems. If you have two DHCP servers running (one at the ISP, the other in the access point), a connecting computah will have to guess which DHCP server to trust and obtain its IP's from. It's basically a crap shoot. A PC could use either, probably at random. Bad idea.
There's also a problem about connecting to such an arrangement. Most ISP's allow only one routeable IP address per connection. If you have a wireless access point connected to the DSL modem, it will deliver exactly one IP address from the ISP's server, thus allowing exactly one client computah to connect. It will work, but is not my idea of useful.
In general, its a lousy idea to have more than one DHCP server running on a given LAN segment. There are provisions for running more than one in a backup-DHCP server configuration, but that's handled with a shared DHCP lease table. You don't have that with the proposed arrangement. It probably will not affect the ISP.