Kitz Forum
Computers & Hardware => Networking => Topic started by: gobuddy on February 06, 2016, 04:15:20 PM
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To get decent wireless coverage I've been trying to find a way to get my HH5 router near the middle of the house while having my main wired PC near the master socket.
I've got a solution which involves plugging the LAN and WAN sockets on the router into the same switch - there is then a single cable to another switch which is connected to the Openreach modem and a PC.
So something like this (hope ASCII art works OK for you)
Openreach---switch-----switch|------WAN socket on HH
| |------LAN socket on HH
|
PC
It seems strange connecting two sockets on the router to the same switch, but as I understand it one of them is on the WAN network and one on the LAN and the Homehub box itself has different networks on different sockets and doesn't route - but the switch allows you to combine them.
It seems to work - but am I doing something wrong, is there a clash somewhere on my network which will cause problem at some point?
Any thoughts much appreciated
Thanks
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It seems to work
Sounds good.
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Hello gobuddy. Welcome to the Kitz forum. :)
I must admit, I have never thought of using that type of configuration. At the moment, I am having difficulty understanding how it is working. ??? Perhaps if you were to run Wireshark (https://www.wireshark.org/) on the PC and look at the traffic "passing by", it might help understanding the mode of operation? :-\
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what prevents the pc taking the ip provided by the modem and being directly on the net with no firewall? thats what would concern me.
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Is there a DHCP server on the Openreach modem? If so is there a way to turn it off?
At the moment the PC has the gateway and IP address hard coded into the Windows config - which will beep it safe won't it?
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The Openreach modem [1] is a pure bridge between VDSL2 and Ethernet protocols.
There has to be a PPPoE client, the router, to establish the higher level connection.
I think I would be happier with a separate run of Ethernet cable . . . failing that, using physical splitters at each end of the existing Ethernet cable, using four of the wires for the modem's LAN1 port to the router's WAN port and the other four wires for on of the router's LAN ports to the PC.
[1] Huawei HG612 or ECI B-FOCuS /r ?
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It's the Huawei HG612. The PC has it's IP and gateway coded into the Windows config.
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I ran a similar setup for a while with no problems. In fact, it was a bit more complex with 2 HG612's connected to a switch along with everything else and the load-balancing router upstairs on a different switch ;)
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It's the Huawei HG612.
Thank you.
The PC has it's IP and gateway coded into the Windows config.
I shall read that as confirmation that the PC has a statically defined IPv4 address and that its DHCP client is turned off.
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That's right.
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Depending on the switches you could run two VLANs, with a trunk between the switches.
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This is a weird setup that, at first glance, shouldn't work. But it obviously does work, so deserves thinking about. So I did...
The first issue is that the interface between the WAN socket of the HH and the modem involves PPPoE, and isn't an IP protocol in the standard way of thinking. It doesn't use IP addresses, so doesn't use those to find Ethernet MAC addresses.
I think what is happening is that the router makes use of PPPoE discovery to find the modem. This involves broadcast packets at the Ethernet MAC level. Once discovered, the router and modem communicate directly with MAC-addressed Ethernet frames (not IP-addressed frames). With switches in between, the packets should only be seen on the appropriate ports (modem, HH WAN port, and the inter-switch trunk).
Traffic from the PC to the router is with IP-based packets. The IP layers of the software stack uses ARP to convert from IP addresses to Ethernet MAC addresses; the switches ensure that these packets on go through the appropriate ports (PC, HH LAN port, and the inter-switch trunk).
I think this answers @loonylion's concern. The modem isn't accessible to an IP network layer, so the PC can't masquerade with the modem's IP address ... it doesn't have one.
The Openreach modem, in bridge mode, doesn't have a DHCP server.
If there are security concerns, then "smart" switches with minimal management features could be used to create two VLANs. One VLAN with just the HH WAN port and the modem will keep the PPPoE frames entirely separate from IP packets.
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This is a weird setup, which I have no problem with. Is so no reason why it shouldn't be absolutely fine, it just saves on Ethernet cable that's all.
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I was pondering why we considered it weird, and came to the conclusion that we've had things too easy recently. For most of us, LAN networking is IP and Ethernet, with little distinction.
In reality, IP needs glue to wed it to Ethernet, and Ethernet is capable of carrying other protocols too, in parallel with IP.
Where we see TCP/IP as ubiquitous, it was a relatively slow burner. NetWare, NetBIOS, LAN Manager, Banyan Vines and Xerox all had different ways of providing LAN services in the past, and getting a TCP/IP stack was hard!
If we worked with a few more of these, we'd probably be very used to multiplexing different protocols over Ethernet.
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. . . NetWare, NetBIOS, LAN Manager, Banyan Vines and Xerox all had different ways of providing LAN services . . .
Five names that ring dim and distant bells, especially Banyan Vines. ;) I seem to remember that there were some good features but TCP/IP was much more promising! :D
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Do you have a block of IP's from your ISP ?.
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I do have a block of IPv4 addresses, a /26 (64). I also have an IPv6 /48 of which I am using two /64s currently.
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I do have a block of IPv4 addresses, a /26 (64). I also have an IPv6 /48 of which I am using two /64s currently.
Yes I know you do.
I was asking the OP (gobuddy ) :o
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My Apol guys. Many drugs, misunderstood
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My Apol guys. Many drugs, misunderstood
:)
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Hi
Sorry to be off topic slightly, but please could I ask weaver why he needs that many IPv4 addresses and what do you use them for.
You don't have to answer sorry and sorry for taking it off topic slightly
Many thanks
John
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[PM sent]
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It just occurred to me that a variation of that configuration could allow stats to be collected from a DSL modem with only one Ethernet port used for both IP management and PPPoE.