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setting ip

sol2k
sol2k asked
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hi i have a qustion for setting a getway ip
let say i have a small network and the router (hardware) ip is eg 192.228.128.20 <--- provide by ISP any my getway is 198.1.1.254 <----- .my question is is it the gateway ip is fix??? i mean 198.1.1.254 ...the 254 is fix????or we can change it to another ip like 198.1.1.115 ??????
acctualy i'm not very well in ip so i hope anyone can give some explaination /;0:) thnak you
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Les MooreSr. Systems Engineer
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Top Expert 2008

Commented:
Your router is your gateway. If your router's IP address is 192.228.128.20, then your gateway should be 192.228.128.20.

Commented:
To clarify on that a bit - your router likely has two addresses - one on the LAN side, and the other on the WAN side (connecting to the ISP).  For a workstation on the LAN, the gateway address is the IP address on the router interface connected to the LAN.  The router will also have a gateway address, and it will be the address of the interface on the router at the ISP that connects to your router.  Basically, each device needs to know the IP address of another device that can get packets off of the current network.  This is the gateway address.
>>To clarify on that a bit - your router likely has two addresses

It has to have at least two, thats why its called a router.  It routes traffic between two or more networks.  

Just think of the gateway as your way to get outside your network. The gateway will only be used when the address specified cannot be found on the local network.

Commented:
Not every router has two addresses.  If you are familiar with the IP unnumbered command on a Cisco router, it allows you to have a point to point network that does not have addresses.  It instead uses an already existing address from another interface.  Many smaller routers that people get with DSL service etc or from an ISP work on this principle and do not have WAN side addresses and instead just have an Ethernet address.

Therefore, it is likely it has two, but this is not necessarily the case.

Also if you want to get really technical - by Cisco's definitiion, moving a packet from interface to interface is actually the process of switching.  Routing is the process of learning about the network and using a table of information to decide switching paths.
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Computer101
Community Support Moderator

Commented:
I tend to mainly agree with above, except that I miss seeing specific answer, so I try. First, look at above comments for the general rules, and explanaitons since you say:
>"acctualy i'm not very well in ip "

For specific question, I think the answer is a qulified 'yes'. Where you use IP address to internet, that you may not change. The internet needs it to find you.

But the address on your side of this router/gateway, can be anything in the available private subnets. This is numbering your own network any way you see fit. While the range of 256 possibles can go from 0-255, the first and last ones are reserved. That still leaves from 1-254. Many use 254, the last choice. We use 1, the first choice. Both have similar value, where either case leaves the reminder of address range contiguous.

But I am not well versed on specific routers. What you would need to do is to have the router reconfigured to do that other, the alternative 'internal' or 'local' address (not the 'internet' one). For it is the one that has to know, and it is the one that has to map from one network group to another. So yes, sure you can do it, roll up your sleeves if you are in control of it, go ahead and take control.

Answer: No.

Still, there remains support issue. So if you admit you are not well versed, there is another problem, when asking for help or assistance. Quite often a help desk (ISP?) will begin with standard answers and assumptions, and it is possible that this address will be among their assumptions. If so, then changing address may confuse them when (if) they try to provide help for something else. So I propose that although you may be able to change it, you may not want to. Depending on situation, you may also have issues with allocated range and subnetting, and you'd need to be able to manage that well. So IMO, might be best to leave well enough alone, except in theory.

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Commented:
Computer101
i don't know how to give the feeback.u do it for me .cos i don't know which one is the answer :0 thank you for all experts
sol2k:
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sol2k,
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sol2k,
The answer to your question is the IP does NOT have to be fixed, in the sense that the IP on the gateway MUST be 254.  As long as the following two conventions are met, you can have AnY ip on that interface of the router:
1. The address you assign to the router interface is part of the network.
2. The address assigned to the router interface is used as the gateway on the PC's on the lan side of the network
So, as an example:
Your lan has addressing of 192.168.1.XXX with a subnet mask of 255.255.255.0.  The "gateway" will be the address used by the machines on this network to talk to a computer that is NOT on the local net.  So, if you try to connect to an address of 192.168.2.XXX 255.255.255.0, that's on a different subnet, so the machine sends the request to the gateway.  What the address of that gateway is, doesn't matter, as long as it's in the 192.168.1.XXX 255.255.255.0 address range.
Les MooreSr. Systems Engineer
CERTIFIED EXPERT
Top Expert 2008

Commented:
>Accept CleanupPing's answer ????
How about PAQ/no refund. Asker never provided feedback for over 2 months- no refund.
Original question was asked and answered -
Q: can I make my default gateway any arbitrary number that I want, or is it fixed?
A: NO, it is fixed, you must use what the ISP gives you.
He's asking if the _LAN_ side has to be fixed to the .254 address, which it does NOT.  you can make the gateway any address on the subnet, as long as the router has the address that the machines on that subnet are using as their default gateway (gateway of last resort)....
Les MooreSr. Systems Engineer
CERTIFIED EXPERT
Top Expert 2008

Commented:
True, if it is the LAN side, and IF he has configuration control of the router. In that case, then yes, you can set the router LAN IP to anything you want.
The question is worded so that it can be intrepteted as the router is provided by the ISP. In that case, all bets are off and I would stick with what is provided.

>the router (hardware) ip is eg 192.228.128.20 <--- provide by ISP
Which interface? LAN or WAN? Did the ISP provide the router?

>provide by ISP any my getway is 198.1.1.254
If ISP provided the configuration and user does not have control of the router....then the default gateway on a client PC cannot be anything other than this..


BTW, really appreciate your cleanup efforts and help!!
Thanks for the BTW!  Anyway, The if is does he have control of the router...which is unknown, and given that he hasn't responded to the umpteen posts of late, it should be delete/no ref. Just read what I wrote above...silly powerpost goofed me..I'm changing the rec.
sol2k,
No comment has been added lately (24 days), so it's time to clean up this TA.
I will leave a recommendation in the Cleanup topic area for this question:

RECOMMENDATION: PAQ/ No Refund

Please leave any comments here within 7 days.

-- Please DO NOT accept this comment as an answer ! --

Thanks,

scott_renton
EE Cleanup Volunteer
sol2k,
No comment has been added lately (24 days), so it's time to clean up this TA.
I will leave a recommendation in the Cleanup topic area for this question:

RECOMMENDATION: PAQ/ No Refund

Please leave any comments here within 7 days.

-- Please DO NOT accept this comment as an answer ! --

Thanks,

scott_renton
EE Cleanup Volunteer
PAQed per request/recommendation - No Refund

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