Re: [lwip-users] PING request not answered

[David Empson]

You can't simply pick a fixed IP address like 192.3.1.254, use it in 
multiple devices, and expect to use it when plugged into any network.

1. Nobody will be able to communicate with your device unless they 
reconfigure the router and/or computers on their network to access your 
device.

2. You can't have two of your devices connected to the same network, as 
devices on the same network must have unique IP addresses.

3. That is a public IP address and it is assigned to some organisation. If 
someone does reconfigure their network to enable access to your device, they 
will be unable to access the computer on the Internet which has been 
assigned that IP address, and probably several similar IP addresses (unless 
your device is used on a completely private network which is isolated from 
the Internet).

4. Most enterprise IT departments have policies on allocation of IP 
addresses, which you must comply with in order to connect a device to their 
network. You have to use DHCP, or use a static IP address, subnet mask and 
gateway assigned by the IT department.

This means you must have a mechanism which allows your device's IP address, 
subnet mask and gateway to be configured by the end customer or an agent, or 
be prepared to supply a pre-configured device with custom IP configuration 
to every customer, and be able to change that configuration on request. A 
static IP configuration would typically be stored in nonvolatile memory in 
the device.

You must also have a unique and properly assigned Ethernet MAC address for 
every device (based on an Organisationally Unique Identifier purchased from 
IEEE, or a smaller block of MAC addresses). This is typically hard-coded or 
stored in nonvolatile memory for each device, and cannot be changed by the 
end user. Some enterprise customers may want to assign their own private MAC 
addresses as well, but I expect this is very rare (we haven't allowed for it 
in our devices).

----- Original Message ----- 
From: "Alexandre Malo" <address@hidden>
To: "Rick Culver" <address@hidden>; "Mailing list for lwIP users" 
<address@hidden>
Sent: Saturday, August 29, 2009 3:25 AM
Subject: Re: [lwip-users] PING request not answered


> Its because we dont have a CLI on our uC and we wanted to avoir having to
> compile the uC each time when changing it's location...
>
> The agent is recieving the ping, but is not replying.. Thats why I'm
> thinging of something implemented in LWIP which block the reply.
>
> Alex
>
>
> ----- Original Message ----- 
> From: "Rick Culver" <address@hidden>
> To: "Mailing list for lwIP users" <address@hidden>
> Sent: Friday, August 28, 2009 9:40 AM
> Subject: Re: [lwip-users] PING request not answered
>
>
> > Alex,
> > I think what Mike meant was to change the IP address of your uC to the
> same
> > subnet group as your PC.  For example your PC is apparently set to
> > 172.27.37.70 so trying setting the IP of your uC to 172.27.37.75 or
> similar.
> > You should then be able to ping the uC either through a switch or with a
> > crossover cable.
> > Rick
> >
> > ----- Original Message ----- 
> > From: "Alexandre Malo" <address@hidden>
> > To: "Mailing list for lwIP users" <address@hidden>
> > Sent: Friday, August 28, 2009 8:04 AM
> > Subject: Re: [lwip-users] PING request not answered
> >
> >
> > >I tried to put three gateway on the uC (which doesnt reply)
> > >
> > >      127.0.0.1
> > > and None. ( I tought none would put a good default address...)
> > > and the uC own ip address
> > > and 255.255.255.255 (Broadcast)
> > >
> > > I tried the following mask on the uC
> > >
> > >        255.255.255.0
> > > and  255.255.255.255
> > >
> > > Of course if I put my comp and the uC in the same subnet, the ping
> work...
> > >
> > > Alex
> > >
> > >
> > >
> > >
> > > ----- Original Message ----- 
> > > From: "Mike Kleshov" <address@hidden>
> > > To: "Mailing list for lwIP users" <address@hidden>
> > > Sent: Friday, August 28, 2009 1:15 AM
> > > Subject: Re: [lwip-users] PING request not answered
> > >
> > >
> > >> 2009/8/28 Alexandre Malo <address@hidden>:
> > >> > My pc must use the following ip addresses:
> > >> > ip = 172.27.37.70
> > >> > mask = 255.255.224.0
> > >> >
> > >> > My uC (MCF5282) must use the following ip addresses:
> > >> > ip = 192.3.1.254
> > >> > mask = 225.225.224.0
> > >>
> > >> So they are on different IP subnets? Then the packets must be routed
> > >> through a gateway. In your explanation, a gateway is never mentioned.
> > >> Choose your IP addresses from the same subnet to remove this
> > >> complication. Once you get it working, you can try different subnets.
> > >>
> > >>
> > >> _______________________________________________
> > >> lwip-users mailing list
> > >> address@hidden
> > >> http://lists.nongnu.org/mailman/listinfo/lwip-users
> > >>
> > >
> > >
> > > _______________________________________________
> > > lwip-users mailing list
> > > address@hidden
> > > http://lists.nongnu.org/mailman/listinfo/lwip-users
> > >
> >
> >
> >
> > _______________________________________________
> > lwip-users mailing list
> > address@hidden
> > http://lists.nongnu.org/mailman/listinfo/lwip-users
>
>
>
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