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Ethernet routing to a second subnet from a wintel machine

Started by Didi January 31, 2011
The problem I have is that while the wintel pc (xp) has acquired its
IP & subnet via dhcp from my ISP it won't route packets to another
subnet (e.g. 192.168.100.xx). I set manually an ARP entry to the
(DPS) machine it has to route to but no banana, it still wastes
the packets down the gateway of the ISP-s subnet. Now why have
MS made this not to work is beyond me, my DPS systems will
route down the gateway only if no such entry found in the ARP
table (obviously they won't initiate an ARP search for routable
IP addresses).

Is there a solution to that at all? I mean without adding another
NIC to the stupid wintel machine, all I need it to do is to set the
destination MAC address its output Ethernet packets to the one I have
manually set in its ARP table (what good is that arp -s at all???).

To make sure I am clear, all the wintel and the DPS machines I
want to communicate are on the "same wire" (same broadcast domain,
i.e. plugged in a plain ethernet switch, no physical issues
whatsover).

Thanks,

Dimiter

------------------------------------------------------
Dimiter Popoff               Transgalactic Instruments

http://www.tgi-sci.com
------------------------------------------------------
http://www.flickr.com/photos/didi_tgi/sets/72157600228621276/
In article <4b7652e1-7c26-4532-8cdb-dc84ea392a3b@y26g2000yqd.googlegroups.com>,
Didi  <dp@tgi-sci.com> wrote:
>The problem I have is that while the wintel pc (xp) has acquired its >IP & subnet via dhcp from my ISP it won't route packets to another >subnet (e.g. 192.168.100.xx). I set manually an ARP entry to the >(DPS) machine it has to route to but no banana, it still wastes >the packets down the gateway of the ISP-s subnet. Now why have >MS made this not to work is beyond me, my DPS systems will >route down the gateway only if no such entry found in the ARP >table (obviously they won't initiate an ARP search for routable >IP addresses).
No, you need to add an IP route.
>Is there a solution to that at all? I mean without adding another >NIC to the stupid wintel machine, all I need it to do is to set the >destination MAC address its output Ethernet packets to the one I have >manually set in its ARP table (what good is that arp -s at all???).
Won't help a bit if you don't add an IP route.
>To make sure I am clear, all the wintel and the DPS machines I >want to communicate are on the "same wire" (same broadcast domain, >i.e. plugged in a plain ethernet switch, no physical issues >whatsover).
Are they on the same IP subnet? -- mrr
Didi <dp@tgi-sci.com> wrote:
> The problem I have is that while the wintel pc (xp) has acquired its > IP & subnet via dhcp from my ISP it won't route packets to another > subnet (e.g. 192.168.100.xx).
Does your 'wintel' machine have an address on that network, or an interface route to it through the correct interface?
> I set manually an ARP entry to the (DPS) machine it has to route to but no > banana, it still wastes the packets down the gateway of the ISP-s subnet.
I'm not sure why you need a static ARP entry. If your host has an address in the correct network and a route to it, ARP will just happen in the background. Actually, even just a static route would do, provided you didn't expect to get any traffic back. - Philip -- Philip Paeps Please don't email any replies philip@paeps.cx I follow the newsgroup. BOFH Excuse #79: Look, buddy: Windows 3.1 IS A General Protection Fault.
On Jan 31, 7:40=A0pm, Philip Paeps <philip+use...@paeps.cx> wrote:
> Didi <d...@tgi-sci.com> wrote: > > The problem I have is that while the wintel pc (xp) has acquired its > > IP & subnet via dhcp from my ISP it won't route packets to another > > subnet (e.g. 192.168.100.xx). > > Does your 'wintel' machine have an address on that network, or an interfa=
ce
> route to it through the correct interface?
I don't think it has, it only has the IP address acquired via dhcp from my ISP. I am not familiar with wintel systems, this is why I ask if there is a way - although if there were one I would expect it to be obvious enough to me.
> > > I set manually an ARP entry to the (DPS) machine it has to route to but=
no
> > banana, it still wastes the packets down the gateway of the ISP-s subne=
t.
> > I'm not sure why you need a static ARP entry.
Well that is straight forward enough. On my DPS machines, outbound packets will route according to an entry (or "subnet", ARP table entries are maskable) in the ARP table; if no routing entry is found in the ARP table, the packet will go down its respective subnet gateway if it belongs there; if it is on the same subnet and there was no ARP entry for it, a network ARP query will be initiated. I expected similar behaviour from windows; but no, the manually set ARP entry is ignored.
> Actually, even just a static route would do, provided you didn't expect t=
o get
> any traffic back.
Nope, does not work on windows. Dimiter ------------------------------------------------------ Dimiter Popoff Transgalactic Instruments http://www.tgi-sci.com ------------------------------------------------------ http://www.flickr.com/photos/didi_tgi/sets/72157600228621276/
On 31.1.11 7:07 , Didi wrote:
> The problem I have is that while the wintel pc (xp) has acquired its > IP& subnet via dhcp from my ISP it won't route packets to another > subnet (e.g. 192.168.100.xx). I set manually an ARP entry to the > (DPS) machine it has to route to but no banana, it still wastes > the packets down the gateway of the ISP-s subnet. Now why have > MS made this not to work is beyond me, my DPS systems will > route down the gateway only if no such entry found in the ARP > table (obviously they won't initiate an ARP search for routable > IP addresses). > > Is there a solution to that at all? I mean without adding another > NIC to the stupid wintel machine, all I need it to do is to set the > destination MAC address its output Ethernet packets to the one I have > manually set in its ARP table (what good is that arp -s at all???). > > To make sure I am clear, all the wintel and the DPS machines I > want to communicate are on the "same wire" (same broadcast domain, > i.e. plugged in a plain ethernet switch, no physical issues > whatsover). > > Thanks, > > Dimiter > > ------------------------------------------------------ > Dimiter Popoff Transgalactic Instruments > > http://www.tgi-sci.com > ------------------------------------------------------ > http://www.flickr.com/photos/didi_tgi/sets/72157600228621276/
You're probably asking for more than the XP is able to fill in. To route packets from the ISP's net to a local subnet and back needs NAT (Network Address Translation), which is Internet Connection Sharing in windowspeak. I'm not sure if XP is able to associate two different networks with one physical interface. Linux calls it IP Alias. You would need one static address and one DHCP on the same Ethernet card, and this is probably Greek to Windows. I'd buy a second interface card, if it is mechanically possible. -- Tauno Voipio tauno voipio (at) iki fi
On Jan 31, 7:59=A0pm, Tauno Voipio <tauno.voi...@notused.fi.invalid>
wrote:
> .... > You're probably asking for more than the XP is able to fill in. > > To route packets from the ISP's net to a local subnet and back > needs NAT (Network Address Translation), which is Internet Connection > Sharing in windowspeak.
No-no, I am not asking for that. I just want the packets originating from the windows machine to go to the DPS machine on the same wire, I am not expecting windows to route incoming IP traffic to the DPS machine, nor to do NAT for the DPS machine and route its IP traffic out to the Internet. I am just after a local connection without disconnecting the wintel machine from the Internet. What I do now is manually set the windows IP address to 192.168.100.something and access the 192.168.100.something_else machine; I did not have to do that until recently but my ISP began to give me via dhcp addresses from _different_subnets_ over the same cable modem (yes, they are morons and I wish I had options), and lately began limiting the number of addresses they give me (used to give me 5 with no problem for years - before a takeover took place...). Dimiter ------------------------------------------------------ Dimiter Popoff Transgalactic Instruments http://www.tgi-sci.com ------------------------------------------------------ http://www.flickr.com/photos/didi_tgi/sets/72157600228621276/
On Mon, 31 Jan 2011 10:12:19 -0800 (PST), Didi <dp@tgi-sci.com> wrote:

>On Jan 31, 7:59&#2013266080;pm, Tauno Voipio <tauno.voi...@notused.fi.invalid> >wrote: >> .... >> You're probably asking for more than the XP is able to fill in. >> >> To route packets from the ISP's net to a local subnet and back >> needs NAT (Network Address Translation), which is Internet Connection >> Sharing in windowspeak. > >No-no, I am not asking for that. I just want the packets originating >from the windows machine to go to the DPS machine on the same wire, >I am not expecting windows to route incoming IP traffic to the DPS >machine, nor to do NAT for the DPS machine and route its IP traffic >out to the Internet. I am just after a local connection without >disconnecting the wintel machine from the Internet. What I do now >is manually set the windows IP address to 192.168.100.something >and access the 192.168.100.something_else machine; I did not have >to do that until recently but my ISP began to give me via dhcp >addresses from _different_subnets_ over the same cable modem >(yes, they are morons and I wish I had options), and lately >began limiting the number of addresses they give me (used to >give me 5 with no problem for years - before a takeover >took place...).
Is adding a NAT router an option? The router would pick up the ISP's DHCP info while your Windows and DPS machines would both be on the same local non-routable network.
On Jan 31, 8:22=A0pm, Char Jackson <n...@none.invalid> wrote:
> On Mon, 31 Jan 2011 10:12:19 -0800 (PST), Didi <d...@tgi-sci.com> wrote: > >On Jan 31, 7:59=A0pm, Tauno Voipio <tauno.voi...@notused.fi.invalid> > >wrote: > >> .... > >> You're probably asking for more than the XP is able to fill in. > > >> To route packets from the ISP's net to a local subnet and back > >> needs NAT (Network Address Translation), which is Internet Connection > >> Sharing in windowspeak. > > >No-no, I am not asking for that. I just want the packets originating > >from the windows machine to go to the DPS machine on the same wire, > >I am not expecting windows to route incoming IP traffic to the DPS > >machine, nor to do NAT for the DPS machine and route its IP traffic > >out to the Internet. I am just after a local connection without > >disconnecting the wintel machine from the Internet. What I do now > >is manually set the windows IP address to 192.168.100.something > >and access the 192.168.100.something_else machine; I did not have > >to do that until recently but my ISP began to give me via dhcp > >addresses from _different_subnets_ over the same cable modem > >(yes, they are morons and I wish I had options), and lately > >began limiting the number of addresses they give me (used to > >give me 5 with no problem for years - before a takeover > >took place...). > > Is adding a NAT router an option? The router would pick up the ISP's > DHCP info while your Windows and DPS machines would both be on the > same local non-routable network.
It is an option of desperation, of course, but adding another box only because windows cannot do the correct lookup in its ARP table is what it is... :-) . Actually I could make the DPS machine behave as a router and all that - will do it before too long - but there should be a way devices on the same wire to communicate with each other... Then I prefer that window machine to be with a real IP address, it keeps a listening VNC viewer to accept support connections from customers etc. Port forwarding will do most if not all of what my current needs are but I still cannot accept that a purely software issue - a very simple to solve one - will force me to add hardware etc. Dimiter ------------------------------------------------------ Dimiter Popoff Transgalactic Instruments http://www.tgi-sci.com ------------------------------------------------------ http://www.flickr.com/photos/didi_tgi/sets/72157600228621276/
On 31.1.11 8:12 , Didi wrote:
> On Jan 31, 7:59 pm, Tauno Voipio<tauno.voi...@notused.fi.invalid> > wrote: >> .... >> You're probably asking for more than the XP is able to fill in. >> >> To route packets from the ISP's net to a local subnet and back >> needs NAT (Network Address Translation), which is Internet Connection >> Sharing in windowspeak. > > No-no, I am not asking for that. I just want the packets originating > from the windows machine to go to the DPS machine on the same wire, > I am not expecting windows to route incoming IP traffic to the DPS > machine, nor to do NAT for the DPS machine and route its IP traffic > out to the Internet. I am just after a local connection without > disconnecting the wintel machine from the Internet. What I do now > is manually set the windows IP address to 192.168.100.something > and access the 192.168.100.something_else machine; I did not have > to do that until recently but my ISP began to give me via dhcp > addresses from _different_subnets_ over the same cable modem > (yes, they are morons and I wish I had options), and lately > began limiting the number of addresses they give me (used to > give me 5 with no problem for years - before a takeover > took place...).
So you're asking for an IP alias on the only NIC. I did not find such an option on my copy of XP. However, there are plenty of differently crippled XP editions, so some of the more capable editions may be able. -- Tauno Voipio tauno voipio (at) iki fi
On Jan 31, 10:03=A0pm, Tauno Voipio <tauno.voi...@notused.fi.invalid>
wrote:
> On 31.1.11 8:12 , Didi wrote: > > > > > On Jan 31, 7:59 pm, Tauno Voipio<tauno.voi...@notused.fi.invalid> > > wrote: > >> .... > >> You're probably asking for more than the XP is able to fill in. > > >> To route packets from the ISP's net to a local subnet and back > >> needs NAT (Network Address Translation), which is Internet Connection > >> Sharing in windowspeak. > > > No-no, I am not asking for that. I just want the packets originating > > from the windows machine to go to the DPS machine on the same wire, > > I am not expecting windows to route incoming IP traffic to the DPS > > machine, nor to do NAT for the DPS machine and route its IP traffic > > out to the Internet. I am just after a local connection without > > disconnecting the wintel machine from the Internet. What I do now > > is manually set the windows IP address to 192.168.100.something > > and access the 192.168.100.something_else machine; I did not have > > to do that until recently but my ISP began to give me via dhcp > > addresses from _different_subnets_ over the same cable modem > > (yes, they are morons and I wish I had options), and lately > > began limiting the number of addresses they give me (used to > > give me 5 with no problem for years - before a takeover > > took place...). > > So you're asking for an IP alias on the only NIC. I did not find > such an option on my copy of XP. However, there are plenty of > differently crippled XP editions, so some of the more capable > editions may be able.
So you are saying it can't work normally? I am not a lot more of a wintel user than the average office worker, hence my post to the community. Using some crippled version etc. will not be what I will try out, I'll rather keep on switching manually the IP address of the wintel pc until I solve it by adding functionality to the DPS side. Thanks, Dimiter ------------------------------------------------------ Dimiter Popoff Transgalactic Instruments http://www.tgi-sci.com ------------------------------------------------------ http://www.flickr.com/photos/didi_tgi/sets/72157600228621276/