Quote:
Originally Posted by Ubermik
Firstly I dont quite get the relevance of what layer DHCP might be, its a one time deal which would have been completed before a packet is even attempted to be sent to the internet
That aside the router will wrap or try to wrap wan aimed packets with the gateway address and will then not send it because it fails the validity check or having established the gateway was flawed at setup will just not be routing at all
The modem on the other hand IS just that, it doesnt attempt to route or wrap the packets and does just act as a bridge leaving the routing to the router as far as I'm aware
|
yes but the packet is already encapsulated with the next hop (ie gateway address) at the pc wether or not it is connected to a router if this is not valid there is no reason for the modem to look at it as "interesting traffic" and would ignore it?
Quote:
Originally Posted by Ubermik
As for what happens when I "do it", thats already outlined in the original post
With the bogus gateway supplied by telewest I get absolutely no traffic to the modem from the router at all (I have a netgear router which shows packets to and from the modem on a statistics page), so theres no net access at all
|
now hang on a min.. the pc should recieve your router address as the gateway
address and by your reasoning if the modem just accepts packets from the pc encapsulated with the wrong gateway address and forwards them regardless
to the isp's ubr then after leaving the wan port of the router the packets from the router should "look" the same as the packets would look from the pc if it where using the modem directly! all the router does with the transmitted packets after NAT is encapsulate the packets in the same way as the pc would (source & destination)
so.. the fact the router has the wrong gateway address "should" have the same result as the pc with the wrong gateway address!
I am not having a go or anything
I spent 2 years getting my CCNA and another getting network+ if there is something I should understand but dont here I need to get my head round it
Quote:
Originally Posted by Ubermik
When I connect one of the PC's directly to the modem it picks up exactly the same IP information but works flawlessly and I have full internet access
If I manually enter the IP information with the correct gateway into either the PC or the router both still work perfectly
When you say a "wrong" gateway in your experiment what does that mean?
|
Some random but wrong one or an actual wrong one supplied by telewest but still part of their IP address pool? Because the first one I wouldnt expect to work with either the PC or the router connected to the modem, the second wont work with the router but will with the PC
I tried an assortment of gateway addresses in the same subnet as the correct gateway address and got the same result with 2 routers and 1 pc the routers I used btw where and old cisco 4000 series and a draytek 3300v
I really need to get my head round whats happening here!
Quote:
Originally Posted by Ubermik
I have the SB3100 modem, so its only an ethernet connection with no USB facility BTW
|
I dont actually know that modem but I will research it tomorrow
thanks and have a great weekend
Garry