RE: Load balancing outgoing mail relay
Hello:
-Original Message-
From: [EMAIL PROTECTED] [mailto:owner-freebsd-
[EMAIL PROTECTED] On Behalf Of freebsd
Sent: Wednesday, January 17, 2007 2:34 AM
To: FreeBSD Questions
Subject: Load balancing outgoing mail relay
Hi
I have a simple question but googling does not lead to a valid/usable
answer.
I need to load balance OUTGOING emails. I have serveral smart hosts. I
need
my internal SMTP server to send mail using ALL of the smart hosts
together,
making some kind of load balancing (no need for wheighted one).
Someone pointed out to use a name for the smart host, and have DNS to
resolve that name to the IP of all the relays (multiple A records) but
this
turned out in doing failover, not load balancing.
Anyone has a *working* idea for solving this apparently simple
problem?
Thanks
PF will definitely do what you want via its round-robin and redirect
features. You would redirect all inbound traffic on port 25 to your
smart host group/table which would then load balance across all of your
servers. In pf.conf, something like the following, with the
understanding that there are other things you may need to do first
before a pf config will work:
$int_if=em1 # replace with the interface name from your machine
$ext_if=em0 # replace with the interface name from your machine
$smart_host_01=192.168.1.1
$smart_host_02=192.168.1.2
$smart_host_03=192.168.1.3
$mail_server_01=10.1.1.1
table smtp_roundrobin persist { \
$smart_host_01, \
$smart_host_02, \
$smart_host_03 \
}
rdr on $int_if proto tcp from $mail_server_01 to any port 25 -
smtp_roundrobin round-robin
The configuration can become more granular (complex) by including NAT
and ALTQ if you want to do rate-shaping.
Regards,
Mike
___
freebsd-questions@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-questions
To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Load balancing outgoing mail relay
freebsd wrote: Hi I have a simple question but googling does not lead to a valid/usable answer. I need to load balance OUTGOING emails. I have serveral smart hosts. I need my internal SMTP server to send mail using ALL of the smart hosts together, making some kind of load balancing (no need for wheighted one). Someone pointed out to use a name for the smart host, and have DNS to resolve that name to the IP of all the relays (multiple A records) but this turned out in doing failover, not load balancing. Anyone has a *working* idea for solving this apparently simple problem? Thanks ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED] This (multiple A records) works for me, at least approximately. Both Bind and MS DNS will round robin when multiple A records exist for the same hostname. What is your setup? Charlie ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Load balancing outgoing mail relay
This (multiple A records) works for me, at least approximately. Both Bind and MS DNS will round robin when multiple A records exist for the same hostname. What is your setup? FreeBSD 6.2 with Sendmail (initially) and now postfix. MS DNS with round robin (and TTL set to 0 on the records). Resolving with nslookup gives something like: smarthost.domain.tld 192.168.0.1, 192.168.0.2, 192.168.0.3 If I kill 192.168.0.1 then it goes on the second one. But this is failover, and I need (approximately) load balancing. I understand this is related to the MTA and not to the OS, but hopefully someone solved this problem using Sendmail or Postifx that are both used on FreeBSD. Thanks ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Load balancing outgoing mail relay
FreeBSD 6.2 with Sendmail (initially) and now postfix. MS DNS with round robin (and TTL set to 0 on the records). Resolving with nslookup gives something like: smarthost.domain.tld 192.168.0.1, 192.168.0.2, 192.168.0.3 If I kill 192.168.0.1 then it goes on the second one. But this is failover, and I need (approximately) load balancing. Postfix will always internally shuffle equal-weight MX records (or multiple A records if there is no MX). I think sendmail does this also. This will not give strict round-robin use of the smarthosts, but over thousands of messages will give an equal share to each host. It sounds as if the host has primary/secondary MX records and you haven't disabled MX lookups for the relayhost. Use in main.cf relayhost = [smarthost.domain.tld] As documented, the brackets are required to disable MX lookups. You may want to adjust initial_destination_concurrency_limit and default_destination_concurrency_limit if your smarthosts will allow more than the default 20 connections. If sending small amounts of mail, postfix connection caching may interfere with observed load sharing. You may want to turn off smtp_connection_cache_on_demand if sending small amounts of mail, but leave it on if sending thousands of messages at a time. -- Noel Jones ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Load balancing outgoing mail relay
freebsd wrote: This (multiple A records) works for me, at least approximately. Both Bind and MS DNS will round robin when multiple A records exist for the same hostname. What is your setup? FreeBSD 6.2 with Sendmail (initially) and now postfix. MS DNS with round robin (and TTL set to 0 on the records). Resolving with nslookup gives something like: smarthost.domain.tld 192.168.0.1, 192.168.0.2, 192.168.0.3 If I kill 192.168.0.1 then it goes on the second one. But this is failover, and I need (approximately) load balancing. I understand this is related to the MTA and not to the OS, but hopefully someone solved this problem using Sendmail or Postifx that are both used on FreeBSD. Thanks What happens if you do multiple dig/nslookups for smarthost.domain.tld. Are the records returned in a different order each time? If not the problem may be at the NS. Charlie ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Load balancing outgoing mail relay
On 1/17/07, Charles Trevor [EMAIL PROTECTED] wrote: What happens if you do multiple dig/nslookups for smarthost.domain.tld. Are the records returned in a different order each time? If not the problem may be at the NS. Nope. Postfix shuffles equal-weight MX records internally, so it doesn't matter what order the NS presents them. Multiple A records without an MX record (or when MX lookups are suppressed) are treated as equal-weight MX records per RFC. This is likely a postfix configuration problem. The original poster should seek further help on the postfix-users list. http://www.postfix.org/DEBUG_README.html#mail -- Noel Jones ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
