North American Network Operators Group

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Re: intranet

  • From: Hank Nussbacher
  • Date: Fri Aug 21 03:38:14 1998

At 07:44 AM 8/20/98 PDT, Vince Fuller wrote:

You might want to check out:
Enabling Enterprise Multihoming
with Cisco IOS Network Address
Translation (NAT)
as well as:


>> At 05:43 PM 8/18/98 +0800, [email protected] wrote:
>> >Proposed Solution:
>> >
>> >The 7010 router will be connected to the 2 ISPs.  The 7010 will be upgraded
>> >to an IOS that supports NAT; all IP address behind the 7010 will be treated
>> >as internal IP addresses (to reduce reconfiguration).  IP address subnets
>> >from both ISPs will be NAT-mapped to internal IP addresses over the 7010,
>> >including the DNS server and the mail server.
>> >
>> >The DNS will be configured to use their DNS as the primary name server.
>> >The 2 ISPs' name servers will be used as secondary name servers.
>> >
>> >The mail server will be configured to have 2 IP address, one actual and one
>> >virtual IP address using the network card.  The DNS will have an MX 10 and
>> >an MX 20, each pointing to one IP addresses for the network card.
>> >
>> >
>> >Is this solution possible?  Will it work?  Did I forget anything?  Any tips?
>> That is one way to do it .. another and I think a BETTER way would be to
>> only use 1 set of ip's ( a set that is "portable" ) and talk bgp with both
>> providers. This way you can move the traffic in the most efficient way . If
>> you take routes from both of em you may get a better path to site X from
>> provider a and a better path to site Y from provider B . 
>> This way if provider a goes down the BGP will move trafic of the link that
>> is still  "GOOD" 
>The NAT approach has the obvious advantage of being more "CIDR-friendly"
>to the "global Internet". It is probably somewhat more complicated, but if
>implemented correctly, it should provide reasonable redundancy and load-
>sharing just like a "portable" address space solution.
>	--Vince