gateway address on a bridge ?

This makes me feel really dumb…

I’m setting up my first wireless bridge and while I understand the need for an IP/Subnet (strictly for management purposes I thought) I’m not real sure what to do with the gateway setting.

As I thought I understood the manual, with wireless bridges were you have a Master and Slave, they do not need an IP, Mask or gateway in order to do what they do, bridge. If it comes in the ethernet then send it out the radio and if it comes in the radio then send it out the ethernet.

I’m not sure what to set the gateway to though for management. I have two set up in the lab, Master / Slave .

Master :
IP: 192.168.1.251
Mask: 255.255.255.0
gateway: ?

Slave :
IP: 192.168.1.252
Mask: 255.255.255.0
gateway: ?


I’ve tried putting the IP of the other radio in as the gateway (didn’t make any sense to me but I can’t come up with what else it would need) and I’ve tried just 0.0.0.0 (it won’t let me NOT enter a gateway).

The radios appear to bridge just fine the problem is I can’t manage them unless I am directly connected to them. That is , if I connect to the master via the ethernet <Master>----<my laptop> then I can access and manage the master but I can not manage the slave. To manage the slave I have to connect to it (via ethernet) and then I can manage the slave but I can’t manage the Master.

They show connected, they pass data (bridge) but I can’t manage one from the other. This set will bridge to another
<Internet gateway>- <Master bridge 1> - <Slave bridge 1> - < Master birdge 2 > - <Slave bridge 2> - <AP> - <Subscribers>


I need to be able to manage these things without going out and and plugging into them.

Do I set the bridge of each radio to whatever the next hop from the ethernet interface is ?

E.G. <internet gateway IP 208.20.20.1> - < Master ethernet interface gateway ip set to 192.168.1.251 gateway points to 208.20.20.1 ><Master wireless interface linked to slave no ip info needed> < Slave radio interface linked to master no ip info needed> <Slave ethernet interface ip set to 192.168.1.252 gatway points to 192.168.1.253> — < Master of bridge 2 ethernet interface ip 192.168.1.253 is it’s gateway going to point back to the 192.168.1.252 ? >

Have you looked at the manual?

Jerry Richardson wrote:
Have you looked at the manual?


Yes, it says the IP's are for management purposes only.

When it comes to the part about setting them up it just explains what a gateway is, not if I need one or what I might use for the gateway or any logic for why it is there.

Typically the gateway is the router that is controlling the network.

Hey!

The gateway would typically be a router (or a gateway route through a big router, if that makes any sense; I’m so NOT a ‘big router’ guy), but I wanted to offer one sage piece of advice with regards to the IP scheme you’ve chosen: Change it.

The scheme you’re using there is the default IP address scheme for every (crappy) Linksys router in the world, and if you put 192.168.1.1 in for the BH gateway, your just begging for trouble from some silly client.

I would strongly recommend changing the IP scheme to something more off-the-wall (10.x.y.z) just so when a client router gets plugged in backwards (or just goes inexplicably nuts) it doesn’t start babbling at your infrustructure right out of the gate(way). :roll:

newcastle wrote:
Hey!

The gateway would typically be a router (or a gateway route through a big router, if that makes any sense; I'm so NOT a 'big router' guy), but I wanted to offer one sage piece of advice with regards to the IP scheme you've chosen: Change it.

The scheme you're using there is the default IP address scheme for every (crappy) Linksys router in the world, and if you put 192.168.1.1 in for the BH gateway, your just begging for trouble from some silly client.

I would strongly recommend changing the IP scheme to something more off-the-wall (10.x.y.z) just so when a client router gets plugged in backwards (or just goes inexplicably nuts) it doesn't start babbling at your infrustructure right out of the gate(way). :roll:


It won't matter the bridges. Or it shouldn't. It would be a problem if that was the IP scheme on the AP/CPE but this is about bridges. On the bridge the IP , I thought, is irrellevent and the bridge it's self doesn't have an ip, the IP is only there so you can manage the unit via telnet / http etc...

And that brings me full circle. Why is there a gateway. If I need a gateway then I need to know why it needs one as that will allow me to figure out what IP I need to give it.
Jerry Richardson wrote:
Typically the gateway is the router that is controlling the network.



I don't think that is the correct context . If I go with that, then what do you do for a gateway ip on the end of the bridge connected to a network that doesn't have a "router that is controlling the network" ? ANd why would the bridge care ?


Normally "gateway IP" means " If the destination isn't local (e.g. it's going to a different subnet) then it goes out here (here = gateway IP and here=first/one hop)


So I'm back to the start. Do you really need to enter a gateway IP (is it even used at all if you do ?) on the birdges ? If so , why ? What is it used for ?

Hi Farrell

Typically a gateway would be the router (or possibly server) on your network. Its main job is to connect your network to another network via its ethernet interfaces.

Your IP structure is 192.168.1.xxx (I agree with newcastle not the best one to use…I know cause I used to use it too!) so basically you communicate with your Canopy equipment on this network and subnet.

To monitor the equipment you need to be on the same network as this so the gateway should also be on the 192.168.1.xxx subnet.

We use a linux server to control our canopy net. The server/gateway has 3 network cards and has 3 different IP settings. Our canopy net is on 192.168.250.xxx and the gateway machine has a 192.168.250.xxx address to communicate with it.

So basically set the gateway to a non assigned IP in the 192.168.1.xxx (or if you have a dedicated machine on that subnet to monitor your radios then set the gateway to that machines IP address) and all should work.

Hope that helps

What router are you using?

Thanks for all the input.


Turned out to be a radio issue.

Gateway IP isn’t needed, don’ t know why it’s there. After I got them working I set the gateway to various oddball IP’s and subnets, didn’t change how it worked. Right now it’s set to 0.0.0.0 and works great. I am going to test later and see if I can access the radios (management interface) from outside my network with the gateway set to 0.0.0.0 . I’m thinking that if the gateway matters at all on the management interface then this will be were it matters, attempting to manage the units from outside my network.

mjcthepilot wrote:
Hi Farrell

Typically a gateway would be the router (or possibly server) on your network. Its main job is to connect your network to another network via its ethernet interfaces.

Your IP structure is 192.168.1.xxx (I agree with newcastle not the best one to use......I know cause I used to use it too!) so basically you communicate with your Canopy equipment on this network and subnet.

To monitor the equipment you need to be on the same network as this so the gateway should also be on the 192.168.1.xxx subnet.

We use a linux server to control our canopy net. The server/gateway has 3 network cards and has 3 different IP settings. Our canopy net is on 192.168.250.xxx and the gateway machine has a 192.168.250.xxx address to communicate with it.

So basically set the gateway to a non assigned IP in the 192.168.1.xxx (or if you have a dedicated machine on that subnet to monitor your radios then set the gateway to that machines IP address) and all should work.

Hope that helps


Ahh I see. You guys have your bridges on the same subnet as your AP/CPE's. I won't have this situation so it is a non-issue for me. Thanks for the input though.
So I'm back to the start. Do you really need to enter a gateway IP (is it even used at all if you do ?) on the birdges ? If so , why ? What is it used for ?


The short answer to this is "yes" and "no". As you touched upon in a more recent post, if you wish to manage/view the radio interfaces from a subnet other than the subnet the radio interfaces are on (192.168.1.0/24) then yes, you will need to specify a gateway IP address. If you plan on plugging in directly to the PIDUs, or the equipment that the PIDU's terminate to every time you wish to view the radio interfaces, then no you do not need to specify a gateway IP address.

My assumption would be that setting the gateway to 0.0.0.0 will not allow you to get into the management interface from a remote network. I am actually surprised that the radio interface allowed that as proper input.

You may have described this in an earlier post, but what does your physical setup look like, including IP addresses?

You’ll definitely need the gateway to manage from outside the immediate network. Think of a gateway from the perspective of the equipment you’re setting it on:

<says to self>Okay, I’ve got a packet here. Is it in the same network as I am? (checks netmask) Yes it is, I just throw it out the ethernet port and I’m done, arp takes it from there…

Here’s the next packet going out… Netmask says it’s not in my network. Now I throw it to my gateway address and the router handles it from there.
</says to self>

So, if your radios are bridging, and you don’t ever want to be able to manage them, none of the IP settings matter, all traffic flows through as if both ethernet ports are on the same switch.

To manage them, however, the radios need to understand their context in the network, so that they can decide how to send packets out. A packet destined for the same network gets the MAC address of the destination machine and goes out on the wire. A packet destined for another network gets the MAC of the router, and the router, um… routes it. :slight_smile:

So if you don’t put the correct gateway in the radios (both will use the ame gateway if they are bridging, by the way…), the management packets will get to the radios, but the response packets will not make it back to you.

Clear as mud?

The gateway is not needed if you are on the same network/subnet. Hence the reason when you program your laptop for 169.254.1.10 with a /24 netmask and you can program your new out of the box BH’s, SM’s and AP’s with no gateway defined.

The addressing scheme you use on the radios does not matter, whether you use 192.168.x.x, 10.0.x.x or 172.16.x.x, or even the least responsible of public routeable space. All you need to keep in mind is what network belongs to what devices.

A gateway is simply that, your opening to networks outside the network you are currently in. Gateway = Outbound Destinations, Routing = Inbounds Destinations.

In our network I use all 3 networks and almost a /20 of Allocated IP space, all SM’s BH’s and AP’s including CMM’s are on the 192.168.x.x Network, All customer Router Natted Assignments are on the 172.16.x.x Assignment and I use 10.0.x.x only for testing and when we buy another ISP temporarily for Network Migrations. I personally have opted for my least favorite network of 10.0.x.x because I had so many problems with my cable modem over the years I want nothing to do with any prefix allocated to the cable companies :roll:.

Canopy AP’s BH’s and SM’s are bridges unless otherwise configured, and “Dumb” Bridges at that.

To keep your customers that may be challenged from plugging in backwards to our network we use the protocol filtering tab in configuration on every SM in our network, this will keep people from getting a DHCP assignment from the closest DHCP server to them or at least the one that answers first, which is wrong.

–SDH