It'll be interesting to watch the complaints roll in on social media. There are only 254 connections available on any one router, I think
Common misconception this. Let me try and explain it a little. Each host on a network gets it's own unique IP Address for that device. A little like how your house in a street has a door number. Much the same concept.
It depends on how the router is configured. Lets assume the router is using a 192.168.1.x / 255.255.255.0 Subnet Mask. This is commonly known as a Class C or /24 Subnet. This is standard configuration for nearly all domestic and small business networks. This allows for 254 hosts on the same network. Of which 1 host is the Default Gateway / The Router Itself. Depending on the configuration on the router side that would allow 253 client hosts on the same network.
However you can configure most routers to use Class B and Class A Subnets also.
It's rather technical but I will try and explain it in the best way I can.
| | Subnet Class | | | Private IP Space Format | | | Number of Usable Hosts | | | Subnet /XX Format | | | Full Subnet Mask | |
| | Class C | | | 192.168.1.x | | 254 | | /24 | | 255.255.255.0 |
| | Class B | | | 172.16.x.x | | 65,534 | | /16 | | 255.255.0.0 |
| | Class A | | | 10.x.x.x | | 16,777,214 | | /8 | | 255.0.0.0 |
Each network subnet has 2 Reserved IP Addresses for Broadcast and Subnet ID. These I will call reserved IP Addresses as they cannot be used for hosts on the network. These IP Addresses are always the
FIRST and
LAST IP Addresses in the subnet network.
So if you look at a Class C Subnet which is used on the majority of BTHomeHubs, Virgin SuperHubs etc. The "192.168.1." part
ALWAYS remains the same. The part after the last . can be any number from 1 - 254 inclusive. As 192.168.1.0 and 192.168.1.255 are our reserved IP Addresses these cannot be used. So you select IP 192.168.1.1 for your router. A host could have any IP from 192.168.1.2 - 192.168.1.254
NO HOST can share the same IP AddressA Class B subnet the "172.16." parts remain the same. So the part after the second . can both be selected at random with the exception of IP address 172.16.0.0 and 172.16.255.255 as these are the reserved addresses. So lets put our router on 172.16.0.1 This leaves us with another 65,533 addresses to choose from. So we could have 172.16.43.125 and 172.16.150.234 allocated to 2 seperate hosts.
As with Class C Subnets. A host cannot share the same IP address as another host.
Finally Class A Subnets. These are "10.x.x.x" so the first part "10." remains the same. That allows use to chose any number from 0 - 255 for the subsequent parts of the IP Address. So the reserved IP Address are 10.0.0.0 and 10.255.255.255 so these cannot be used. Our router goes to 10.0.0.1 that leaves the remaining 16,777,213 IP Addresses for our client hosts.
Lets assume you want to run 2 seperate networks on the same infrastructure. A host on say 192.168.150.x network wanted to communicate with a host on 192.168.125.x network. As these are 2 different subnets. You would need a device called a Router or Bridge. That would allow these 2 seperate networks to communicate with each other. This would allow you in theory to have a network of 506 hosts that could all communicate with each other. On 2 seperate 254 host networks. That is what your router in essence does. Allows your computer to find a path to the Public IP Address Space for the likes of Google etc.
So lets look at it in this way. I want to get from my computer in an Internet Cafe to Google.
| Location | IP Address |
| My Laptop | 192.168.1.73 |
| Cafe Router | 192.168.1.1 |
| Google | 173.194.112.95 |
My Computer asks the Router if I can have a path to Google. The Router searches it's networks and finds another router that has the ability to go to Google. Eventually after Several Routers route me across the network. I arrive at my destination of 173.194.112.95
Explanation over. Hope you can have some understanding of it. Please do PM me for clarification and I will do my best to explain it rather than clutter this thread. Once I have made my explanations I will make a seperate post accordingly
Having now managed to get on an
FGW▸ Service with WiFi for a time period long enough to do some investigating. I can confirm the subnet mask available on the FGW WiFi is a /24 255.255.255.0 Subnet for 254 IP Addresses. With 192.168.101.1 being the Router on the Wireless Access Point. It's reasonably safe to assume there are 253 IP Lease Addresses available via something called DHCP. This is a service that gives any device an IP Address should it request one to communicate with other devices on the Network and the Internet.
I am yet to establish if this subnet is for the whole train or just per carriage. I am in the Buffet and currently hold an IP Address of 192.168.101.118 So when the train stops at Taunton I will walk all the way down to Coach A and see if I get a different IP Address or different Subnet in Coach A.
A tracert command shows traffic passing through the a router with 10.225.200.0 as an IP Address. This is perfectly normal for Cell Modems to use an Internal /8 Subnet with mass NAT (Network Address Translation). NAT is a function that allows Private IP Address Space (192.168.1.x / 172.16.x.x / 10.x.x.x) to communicate with Internet IP Addresses (such as 8.8.8.8 and 8.8.4.4 for Google
DNS▸ )
What I have noticed is the DHCP Lease time Allocation is for 20 minutes. So if the device using the WiFi after 20 minutes does not request a renewal of it's IP Address. The IP Address returns to the allocation pool to be issued to someone else.
So for a maximum of 20 minutes after I get off this train. The IP Address will be reserved for me to reconnect. If I don't then it can be issued to someone else
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