Re: TCP/IP gurus, please help! Can this be a valid gateway address?

From: HisNameWasRobertPaulson (kalis_anon_at_hotmail.com)
Date: 09/12/03 

Date: 12 Sep 2003 10:35:47 -0700

Okay, but you are reffering to a ppp connection. Even though I am not
clear on how the 32 bit netmask works, can this apply to a cable
connection?
Even then, the netmask in my case is NOT 255.255.255.255

I still do not see how a packet can reach other networks WITHOUT a
router (gateway) on it's local network to route the packets there...

or am I in left field?

-Mike

Clifford Kite <kite@see.signature.id> wrote in message news:<uahsjb.503.ln@corncob.inetport.com>...
> David Efflandt <efflandt@xnet.com> wrote:
> > On 11 Sep 2003, HisNameWasRobertPaulson <kalis_anon@hotmail.com> wrote:
> >> I am stumped by this one so, I will get right to it:
> >>
> >> Ip address: 68.2.20.180
> >> Netmask: 255.255.252.0
> >> Gateway: 68.14.232.1
> >>
> >> Can this be a valid gateway? I say no, simply because this gateway
> >> (host) does not reside on this network. But, my buddy has cable and
> >> says that this is his current working configuration... how can this
> >> be?
>
> > A gateway does not have to be in the same network. My adsl ISP uses a
> > netmask of 255.255.255.255, so there is no local network on that
> > connection, just local IP and remote IP (gw). It is just that if you do
> > that with static IPs, you need to set a host route to the gw IP before
> > you can use it as a gw:
>
> >> /sbin/ifconfig ppp0
> > ppp0 Link encap:Point-to-Point Protocol
> > inet addr:68.20.32.39 P-t-P:68.20.39.254 Mask:255.255.255.255
> > UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1492 Metric:1
> > RX packets:556982 errors:0 dropped:0 overruns:0 frame:0
> > TX packets:623069 errors:0 dropped:2 overruns:0 carrier:0
> > collisions:0 txqueuelen:3
> > RX bytes:144034347 (137.3 Mb) TX bytes:54424260 (51.9 Mb)
>
> >> /sbin/route -n
> > Kernel IP routing table
> > Destination Gateway Genmask Flags Metric Ref Use Iface
> > 68.20.39.254 0.0.0.0 255.255.255.255 UH 0 0 0 ppp0
> > 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
> > 0.0.0.0 68.20.39.254 0.0.0.0 UG 0 0 0 ppp0
>
> Here is an example of how to add a gateway to a non-PPP, non-local network:
>
> corncob:~# route add 172.16.16.16/32 dummy0
> corncob:~# route
> Kernel IP routing table
> Destination Gateway Genmask Flags Metric Ref Use Iface
> 172.16.16.16 * 255.255.255.255 UH 0 0 0 dummy0
> 192.168.0.0 * 255.255.255.0 U 0 0 0 dummy0
> 127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
>
> corncob:~# route add default gw 172.13.13.13 dummy0
> corncob:~# route -n
> Kernel IP routing table
> Destination Gateway Genmask Flags Metric Ref Use Iface
> 172.16.16.16 0.0.0.0 255.255.255.255 UH 0 0 0 dummy0
> 192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 dummy0
> 127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
> 0.0.0.0 172.13.13.13 0.0.0.0 UG 0 0 0 dummy0
>
> corncob:~# ifconfig
> dummy0 Link encap:Ethernet HWaddr 00:00:00:00:00:00
> inet addr:192.168.0.1 Bcast:192.168.0.255 Mask:255.255.255.0
> UP BROADCAST RUNNING NOARP MTU:1500 Metric:1
> RX packets:0 errors:0 dropped:0 overruns:0 frame:0
> TX packets:1 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:0
>
> lo Link encap:Local Loopback
> inet addr:127.0.0.1 Mask:255.0.0.0
> UP LOOPBACK RUNNING MTU:16436 Metric:1
> RX packets:1135 errors:0 dropped:0 overruns:0 frame:0
> TX packets:1135 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:0

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