5 Replies Latest reply: May 4, 2012 3:58 AM by Daniel RSS

    Deafault route / Gateway of last resort


      Hi, i built this little PT to demonstrate to me and show me how Default route works,  it does work like i had hoped

      i took two routers and using no routing protocols i only used    "  ip route

      and i can ping end to end accross the network, this is cool...

      I would like to hear comments on the use of this type of command....




      ps i am uploadig the PT file.

        • 1. Re: Deafault route / Gateway of last resort
          learning cookie monster

          A better term would be a default route as this is layer 3 mechanism. That statement basically says, if I have not more specific matching route in my table, send this traffic to next hop


          a little clarifciation as there is a command ip default-gateway which will let a layer 2 only device know where to send anytnig that is not on a local subnet.





          • 2. Re: Deafault route / Gateway of last resort



            Please excuse if the comment is a lil off target for I am unable to view your file from where I am. I'm still learning but, assuming your link between routers is a serial link wouldn't you be able to ping anyway since HDLC is enabled by default?

            • 3. Re: Deafault route / Gateway of last resort

              thanks for your reply, yes HDLC is on by default but without the ip route 0.0.0 command you cannot ping accross the network.

              HDLC High-Level-Data-Link-control, allows and provides a way for data to pass accross the serial linkHDLC defines the framing, HDLC frame has Flag byte, address byte control bit data field,type field and FCS field, HDLC performes error detection,

              but without the default route there will only be the two connected networks in the routing table, by adding the default route you create a static route to the next hop router so the packet can go through..

              • 4. Re: Deafault route / Gateway of last resort
                Rajiv Kumar

                I want to know if you can connect to the internet using all of ur devices thru ur default-route. I have default route set but it is not working from all of my devices.

                • 5. Re: Deafault route / Gateway of last resort



                  The default route can be used to put all traffic not destined for your local lan out to the internet. But if it's not working it means your routing tables are incorrect somewhere. Usually the ip route xxx.xxx.xxx.xxx command is used at the boarder router separating your LAN from internet.


                  It can be used internally as well but remember that for a device to have full connectivity it must have a destination path and a return path. So interconnecting two devices like this - only using default route will work since they will both send every packet they don't know where it exists - to the other router.


                  Meaning, if you ping the remote network it will be sent to the other router because of the default route....next router knows where the network is....return path goes the same way back because of the default route.


                  ...i know this is rather old but try to accomplish the same thing with three routers interconnected like a triangle and see if you can get it to work .