Couple of other options that come to mind would be dependent on the number of ISPs you have as well as the exact goal of what you want to accomplish. Typically, as Mark points out, you can use DNS round-robin techniques to specify a host in the east and a host in the west (or multiples) all with the same domain name. You could go so far as to have two different ISP's; one in the east and one in the west each hosting the network connectivity and possibly the DNS records (they need to be identical) for your domain with the goal to be redundant or at least fault tolerant mail delivery. Keep in mind that the mailstore of the recipient has to be available for this to really mean something, but what you describe is possible and a normalized way of architecting a national solution (or even international for that matter). This type of thinking may also lead to redundancy/failover concepts at the mailstore level (i.e. geoclustering, etc.) You probably want to look at the RFC 821/822 and 2821/2822 as well as relevant DNS rfc's to see what the thinking is around the DNS round robin approach. Also, have a look for documents that describe web hosting datacenter architecture as they are very similar in concept to what you are trying to do. If you have any other questions, feel free to contact offline. Al -----Original Message----- From: Shevill, Mark M SITI-ITDCE22 [mailto:Mark.Shevill@xxxxxxxxx] Sent: Wednesday, September 17, 2003 1:55 AM To: [ExchangeList] Subject: [exchangelist] RE: Enterprise Email Architecture (Distributed Datacentre vs. Single Datacentre) http://www.MSExchange.org/ Not too sure on what you mean by entry points? If this is mail coming from external to internal, then there are a number of ways that this could be done. Setting up front end servers in a DMZ with a cname entry for the servers on the internet would allow fault tolerance. Have mail server setup in the east and one in the west. The number of front end servers would depend on the amount of mail you expect to receive. I think ISA is another option to have in there also but we haven't used this although plenty in this forum appear to have. Mark Shevill IMG Messaging Technical Lead Shell Information Technology International Limited Rowlandsway, Wythenshawe, Manchester M22 5SB, United Kingdom Tel: +44 161 435 8709 Fax: +44 161 933 3502 Other Tel: +44 7932 625510 Email: Mark.Shevill@xxxxxxxxx Internet: http://www.shell.com <http://www.shell.com/> _____ From: Wakelin, Frank [mailto:fwakelin@xxxxxxxxxxxxx] Sent: 16 September 2003 23:58 To: [ExchangeList] http://www.MSExchange.org/ I was wondering if any national/multi-city organizations out there could share a little info with me, or if you know of any "best practises" resources out there point me in the right direction. I'm looking for case-studies or best practices in setting up multiple email entry points within an organization; the main justification being fault-tolerance. I'm trying to justify multiple entry points from cities in the east to cities in the west, as opposed to a simply 1 or 2 entry points in the east. Emails would be received by servers distributed in data-centres from east to west running identical email gateway software and configurations (anti-spam/content filtering/anti-virus). Does anyone have any resources or stories to share? Any help would be greatly appreciated... ____________________ FRANK WAKELIN NETWORK ANALYST tel: (604) 640-4096 (direct) fax: (604) 687-1415 Email: fwakelin@xxxxxxxxxxxxx BORDEN LADNER GERVAIS LLP Vancouver Office ------------------------------------------------------ List Archives: http://www.webelists.com/cgi/lyris.pl?enter=exchangelist Exchange Newsletters: http://www.msexchange.org/pages/newsletter.asp Exchange FAQ: http://www.msexchange.org/pages/larticle.asp?type=FAQ ------------------------------------------------------ Other Internet Software Marketing Sites: Leading Network Software Directory: http://www.serverfiles.com No.1 ISA Server Resource Site: http://www.isaserver.org Windows Security Resource Site: http://www.windowsecurity.com/ Network Security Library: http://www.secinf.net/ Windows 2000/NT Fax Solutions: http://www.ntfaxfaq.com ------------------------------------------------------ You are currently subscribed to this MSExchange.org Discussion List as: Mark.Shevill@xxxxxxxxx To unsubscribe send a blank email to $subst('Email.Unsub') ------------------------------------------------------ List Archives: http://www.webelists.com/cgi/lyris.pl?enter=exchangelist Exchange Newsletters: http://www.msexchange.org/pages/newsletter.asp Exchange FAQ: http://www.msexchange.org/pages/larticle.asp?type=FAQ ------------------------------------------------------ Other Internet Software Marketing Sites: Leading Network Software Directory: http://www.serverfiles.com No.1 ISA Server Resource Site: http://www.isaserver.org Windows Security Resource Site: http://www.windowsecurity.com/ Network Security Library: http://www.secinf.net/ Windows 2000/NT Fax Solutions: http://www.ntfaxfaq.com ------------------------------------------------------ You are currently subscribed to this MSExchange.org Discussion List as: al.mulnick@xxxxxxxxxx To unsubscribe send a blank email to $subst('Email.Unsub')