Quote:
Originally Posted by Ubermik
Garry, the reason for that is twofold
The first part of the reason, why the router doesnt seem to even try and send packets is because its a layer 3 router
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now please feel free to correct me but..
dhcp is a layer 2 protocol
Quote:
Originally Posted by Ubermik
Either it will just decide to not bother routing any LAN traffic to the modem because the gateway is wrong or the actual act of routing the packets itself will fail due to not having a valid destination on each attempt although the effects will be identical in that no traffic will get from the lan to the WAN side of the router,
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well we agree so far as the packets will exit the wan port of the router their destination ip address will be wrong and thus will be discarded at the isp's router
but afaik the modem isn't exactly that.
it infact is a dsu/csu & performs protocol conversion as well as the act of modulation/demodulation..
now what you are saying here is perfectly correct when using USB
but when using ethernet the packets should be sent to a valid gateway address
if you are right in your explanation that means that all the modem actually is infact is a bridge!
even then I am surprised and the ntl modem must work differently
I have just tested this by connecting a windows host directly via ethernet to my cable modem and unless I specified the correct gateway address in the os
I had no connectivity!
as soon as I correctly specified the gateway address connectivity was restored!
I am using an anbit modem here btw
Quote:
Originally Posted by Ubermik
the only real difference being that one will be due to each individual packet being discarded and the other will be due to it simply ceasing to route due to the lack of a valid gateway which will depend on how the firmware is written for the router
The reason it WILL work when connected directly to the modem is because the modem isnt a router so it wont wrap any routing information around the packets, that will instead be done by Telewests routers who dont rely on the packets routing information for the gateway but which use their own routing tables which will contain the real gateway for each subnet meaning it will carry on its way merrily
---------- Post added at 01:37 ---------- Previous post was at 01:34 ----------
So basically the information the router and PC get are identical, but the router being a router is what means it doesnt work
If you connect the PC directly to the modem and then do an ipconfig or ipconfig /all you will see the information thats tendered by the DHCP server is still just as wrong and will be identical to that the router obtains when its connected between the PC and the modem
I hope that clears it up
Mike
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fascinating.. I would really be interested if you could try this in the way I did and post the results
I mean REALLY interested!!
what midem are you using?
sorry if I sound a little shouty (if there is such a word) but it's my work we are talking about here and if I am wrong I need to know
thanks a lot for your explanation; I look forwards to hearing your results and what type of modem you are using!
thanks again
Garry