Network Enlightenment

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Network Enlightenment

Nigel Verity
Hi

I have arrived at a situation where I have 2 routers in my home network.

Router A provides the connection back to my iSP while router B serves purely as a wireless access point. B is connected to A.

I connect wired devices to router A through powerline adaptors and wireless devices talk to router B.

There is no real need for the wired and wireless devices to talk to each other, so the fact that they don't have sight of each other is not a problem.

I recently discovered that my Dell laptop routinely had both wired and a wireless interfaces active. This means it was accessing both routers simultaneously.

The wireless connection on the Dell is now switched off, but I can't say I've noticed any change to internet performance for better or worse. The route duplication seems to have been managed perfectly well without any explicit configuration on my part.

For my own enlightenment can anybody with more networking knowledge than me (which is practically everyone) suggest how my internet traffic is likely to have been routed across these two connections? I would have expected contention at the very least.

I doubt that it's relevant in this instance but the Dell runs Ubuntu Mate 15.04

Thanks

Nige

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Re: Network Enlightenment

Simon Greenwood
I found due to a similar query recently that wired connections take precedent over wifi connections in Network Manager so all traffic should have been going across the wired connection.

s/

On 17 November 2015 at 14:24, Nigel Verity <[hidden email]> wrote:
Hi

I have arrived at a situation where I have 2 routers in my home network.

Router A provides the connection back to my iSP while router B serves purely as a wireless access point. B is connected to A.

I connect wired devices to router A through powerline adaptors and wireless devices talk to router B.

There is no real need for the wired and wireless devices to talk to each other, so the fact that they don't have sight of each other is not a problem.

I recently discovered that my Dell laptop routinely had both wired and a wireless interfaces active. This means it was accessing both routers simultaneously.

The wireless connection on the Dell is now switched off, but I can't say I've noticed any change to internet performance for better or worse. The route duplication seems to have been managed perfectly well without any explicit configuration on my part.

For my own enlightenment can anybody with more networking knowledge than me (which is practically everyone) suggest how my internet traffic is likely to have been routed across these two connections? I would have expected contention at the very least.

I doubt that it's relevant in this instance but the Dell runs Ubuntu Mate 15.04

Thanks

Nige

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Re: Network Enlightenment

Colin Law
In reply to this post by Nigel Verity
On 17 November 2015 at 14:24, Nigel Verity <[hidden email]> wrote:

> Hi
>
> I have arrived at a situation where I have 2 routers in my home network.
>
> Router A provides the connection back to my iSP while router B serves purely
> as a wireless access point. B is connected to A.
>
> I connect wired devices to router A through powerline adaptors and wireless
> devices talk to router B.
>
> There is no real need for the wired and wireless devices to talk to each
> other, so the fact that they don't have sight of each other is not a
> problem.
>
> I recently discovered that my Dell laptop routinely had both wired and a
> wireless interfaces active. This means it was accessing both routers
> simultaneously.
>
> The wireless connection on the Dell is now switched off, but I can't say
> I've noticed any change to internet performance for better or worse. The
> route duplication seems to have been managed perfectly well without any
> explicit configuration on my part.
>
> For my own enlightenment can anybody with more networking knowledge than me
> (which is practically everyone) suggest how my internet traffic is likely to
> have been routed across these two connections? I would have expected
> contention at the very least.

There won't be any contention issues as the wired and wifi interfaces
on the PC will have different ip addresses.  The PC could route route
through either interface and all would be well.  I suspect that Simon
is right in that it will prefer the wired i/f when available, but I
don't know.

Colin

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Re: Network Enlightenment

Matt Wheeler-2
In reply to this post by Nigel Verity
On 17 November 2015 at 14:24, Nigel Verity <[hidden email]> wrote:

> Hi
>
> I have arrived at a situation where I have 2 routers in my home network.
>
> Router A provides the connection back to my iSP while router B serves purely
> as a wireless access point. B is connected to A.
>
> I connect wired devices to router A through powerline adaptors and wireless
> devices talk to router B.
>
> There is no real need for the wired and wireless devices to talk to each
> other, so the fact that they don't have sight of each other is not a
> problem.

Are you sure they don't have sight of each other?

I assume your network looks something like this:

                                  v---(wired devices)
internet <--- (x.x.x.x :router A: 192.168.0.1) <--- (192.168.0.2
:router B: 192.168.1.1) <--- (wireless devices)


You're right that the wired devices can't see the wireless ones, but
the wireless ones in this configuration *can* "see" the wired devices.

The default route advertised by router B's DHCP will be itself, so all
non-local-subnet traffic from wireless devices will go there.
Devices attempting to connect to a device in 192.168.0.0/24 will send
the packets via the default route,
Router B knows its external interface is in 192.168.0.0/24 so it will
happily send packets directly out via the local subnet, and they will
reach the wired devices there.

What won't happen is autodiscovery of SMB/CIFS or zeroconf type things
between the two subnets, but your wired devices aren't really
protected from the wireless ones any more than if your router simply
advertised different subnet ranges to wireless
clients.

> I recently discovered that my Dell laptop routinely had both wired and a
> wireless interfaces active. This means it was accessing both routers
> simultaneously.

One or other (either the one that was connected first or maybe the
wired one, as Simon mentions) of those connections should end up
having a better "metric" which means it will be selected first for
routing requests.

As the two interfaces are on different subnets they will have
different addresses, so even if for some reason the metrics were wrong
and wireless was selected things would still just work, but maybe just
slower.

There wouldn't be any contention at any point, just 2 different possible routes.

> The wireless connection on the Dell is now switched off, but I can't say
> I've noticed any change to internet performance for better or worse. The
> route duplication seems to have been managed perfectly well without any
> explicit configuration on my part.
>
> For my own enlightenment can anybody with more networking knowledge than me
> (which is practically everyone) suggest how my internet traffic is likely to
> have been routed across these two connections? I would have expected
> contention at the very least.

Try running traceroute 192.168.0.1
*(assuming that's your router A's internal IP address)
with each of wired and wireless interfaces connected on its own, that
should show you the different routes taken, but it will probably look
something like:

(wired)
$ traceroute 192.168.0.1
 1  gateway (192.168.0.1) ....

(wireless)
$ traceroute 192.168.0.1
 1  gateway (192.168.1.1) ....
 2  192.168.0.1 (192.168.0.1) ....

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Re: Network Enlightenment

Stuart Ward

On 17 November 2015 at 16:34, Matt Wheeler <[hidden email]> wrote:
internet <--- (x.x.x.x :router A: 192.168.0.1) <--- (192.168.0.2
:router B: 192.168.1.1) <--- (wireless devices)


What you should do is turn off DHCP and NAT on router B and give that router a fixed IP address on Router A, Then all your devices will be on the same subnet.

Router A 
IP 192.168.1.1
DHCP on addresses 192.168.1.10-192.168.1.254

Router B
IP 192.168.1.2
DHCP off

Stuart

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Re: Network Enlightenment

Matt Wheeler-2


On 17 Nov 2015 18:55, "Stuart Ward" <[hidden email]> wrote:
> What you should do is turn off DHCP and NAT on router B and give that router a fixed IP address on Router A, Then all your devices will be on the same subnet.

Except Nigel seems to *want* the subnets split, based on his mail, and was just asking questions about how it worked.

Also bear in mind that if you do want to use 2 home routers on the same subnet like that you need to connect one LAN port from each router together, which is not what he or I described (WAN port of router b connected to a LAN port on router a).


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Re: Network Enlightenment

Neil Greenwood-2
In reply to this post by Stuart Ward


On 17 November 2015 18:55:16 GMT+00:00, Stuart Ward <[hidden email]> wrote:

>On 17 November 2015 at 16:34, Matt Wheeler <[hidden email]> wrote:
>
>> internet <--- (x.x.x.x :router A: 192.168.0.1) <--- (192.168.0.2
>> :router B: 192.168.1.1) <--- (wireless devices)
>>
>>
>What you should do is turn off DHCP and NAT on router B and give that
>router a fixed IP address on Router A, Then all your devices will be on
>the
>same subnet.
>
>Router A
>IP 192.168.1.1
>DHCP on addresses 192.168.1.10-192.168.1.254
>
>Router B
>IP 192.168.1.2
>DHCP off
>

To get this working properly, you might need to configure Router B to forward the DHCP packets to Router A, rather than just disabling DHCP.

That's what I had to do with my very similar configuration.


Neil

>Stuart

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