From: Leigh Harrison (ccileigh@gmail.com)
Date: Tue Aug 22 2006 - 11:50:54 ART
Hey there fella,
We also had another customer, who shall remain nameless, but is in the
finance sector and backs onto the hotel on George Street in Edinburgh ;-)
We remotely looked after their network and we had a bag of nat'd
addresses on an interface. As and when we put in static nat's, the
switch would proxy arp and we'd keep monitoring...
LH
Skinner, Stephen wrote:
> Leigh ,
>
> Thanks for the detailed explanation .
>
> I was reading the old Cisco CCIE lab workbook ( the 6 lab variant) .
>
> And I noticed in lab 3 ,under the NAT section , it mentioned that I would
> need proxy arp to complete the scenario .
>
> I want to sure why , but after Mr Comer and yourself , I now understand why
> it the natting would work without proxy arp .
>
> Thanks again
>
>
> Stephen Skinner
>
> -----Original Message-----
> From: Leigh Harrison [mailto:ccileigh@gmail.com]
> Sent: 22 August 2006 15:13
> To: Skinner, Stephen
> Cc: Cisco certification
> Subject: Re: Scenario examples for proxy arp
>
> *** WARNING : This message originates from the Internet ***
>
> Hey there Stephen,
>
> I've used this recently for a customer.
>
> They moved their european datacentre to a new location and liked the idea of
> having a routed LAN. They were aloso looking to migrate from their old IP
> address ranges to new ones. The users changed straight away, but the
> servers needed to stay on the old address range and the customer was quite
> uncomfortable changing anything on the servers, default gateway included.
>
> This was a bit of a problem, as they had a single switch in the top of each
> rack and at the old datacentre they had a single vlan for the servers. My
> first thought was to run mobile ip with eigrp or ospf, but only standard
> image switches were put in, so I only had rip to play with.
>
> I built the whole thing routed, meaning that each switch was in it's own
> L3 network, for the server switches I put in static routes, effectively
> advertising what servers they had connected to that switch. There were 10
> server switches in all, all holding the same IP address, so that the servers
> didn't have to change the default gateway. Static routes were redistributed
> into rip to advertise which servers lived where and proxy arp played the
> main role, telling the server that it knew where the box it was after lived,
> even though logically it was a few hops away, the server switch thought it
> was on the same network.
>
> The customer was very happy as it meant they could shift over 1 server at a
> time is they wanted to.
>
> Try it out with this scenario:-
>
> PC 10.0.0.2/24 - - - - 10.0.0.1/24 | ROUTER1 | 11.0.0.1/24 - - - -
> 11.0.0.2/24 | ROUTER2 | 10.0.0.1/24 - - - - 10.0.0.3/24 PC
>
> If you put a route on router 1 saying that 10.0.0.3 lives on router 2 and
> vice versa, the 2 pc's will be able to ping eachother - the magic of proxy
> arp ;-)
>
> Hope that helps,
> LH
>
>
> Skinner, Stephen wrote:
>
>> Gents.
>>
>> I have been recently been reading the Proxy Arp section of TCP/IP
>> protocols (5th edition) by Comer.
>>
>> And I was wondering if anyone can think of some scenario's in which
>> this could be used .?
>>
>> Many thanks
>>
>>
>> Stephen Skinner
>>
>>
>>
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