'ip mobile arp' is what allows that device to communicate with the local router interface. Without that command you'll never end up with an entry for the errant device in the ARP table of the router. Without an entry in the ARP table no communication will occur.
'ip proxy-arp' is there to allow the router to act as a proxy default gateway. The errant device currently has a default gateway configured that exists elsewhere in the network. Before it can communicate with the default gateway it will ARP for its MAC address because the device doesn't realize that it isn't really on the same segment as the configured default gateway. The router knows this, and if you have proxy arp configured the router will answer this ARP request with its own MAC address. So far we still haven't done anything to the routing table, so the static route is necessary so that the local router knows that there is a /32 host on that LAN that doesn't belong there. Redistribution into the routing protocol allows the rest of the network to become aware of this host route. John ----- Original Message ----- From: "Zsombor Papp" To: Sent: Friday, August 01, 2003 8:17 PM Subject: Re: Friday Follies #1 [7:73370] > Why do you need the 'ip mobile arp' command? I would think the static route > (with the default 'ip proxy-arp', if its a broadcast interface) would > provide local connectivity and redistributing the static route into the IGP > will provide global connectivity (well, except connectivity to devices that > are on the subnet where the misconfigured router thinks it is). > > Also, in the solution I suggested above the looback interface is not needed > if the gateway has a route to the IP address the misconfigured router thinks > the gateway is, or if the link to the misconfigured router is a > point-to-point one. > > Thanks, > > Zsombor > > John Neiberger wrote: > > > > Jason gave the answer I was looking for: Local Area Mobility. > > > > On the interface to which the device is connected add the > > following two > > lines: > > > > ip proxy-arp > > ip mobile arp > > > > Then add: > > > > ip route a.b.c.d 255.255.255.255 (interface) > > > > Where a.b.c.d is the IP address of the device. This creates a > > /32 host route > > in the routing table. Redistribute this into your routing > > protocol and you > > have local and remote connectivity to this single host even > > though it is not > > on the correct LAN subnet. > > > > John > > > > ----- Original Message ----- > > From: "Jason Viera" > > To: > > Sent: Friday, August 01, 2003 1:53 PM > > Subject: Re: Friday Follies #1 [7:73370] > > > > > > > Depending upon the topology you may be able to use Local Area > > Mobility, > > and > > > this is a stretch unless you have the right topology Mobile > > IP?? Just a > > > guess! Need to take the edge off before my first lab attempt > > on Monday!! > > > Thanks for keeping us thinking! > > > Jason > > > ""John Neiberger"" wrote in message > > > news:[EMAIL PROTECTED] > > > > You have a device that is reachable only via telnet or > > console that > > you've > > > > preconfigured with an IP address, subnet mask, and default > > gateway and > > > > subsequently shipped out to a remote location to be > > installed. Once the > > > > device was in place you realized that you've configured it > > with the > > wrong > > > > addressing information. The subnet you used actually exists > > at another > > > > location so this device is currently unreachable via IP. If > > you could > > > > somehow reach the device you'd be able to correct your > > mistake without > > > > having someone ship the device back to you. > > > > > > > > What can you do to restore IP connectivity to this device > > in its current > > > > location and make it reachable from both the local router > > and remote > > > > routers? > > > > **Please support GroupStudy by purchasing from the > > GroupStudy Store: > > > > http://shop.groupstudy.com > > > **Please support GroupStudy by purchasing from the GroupStudy > > Store: > > > http://shop.groupstudy.com > **Please support GroupStudy by purchasing from the GroupStudy Store: > http://shop.groupstudy.com > FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=73403&t=73370 -------------------------------------------------- **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
