On 03/12/2013 03:33 PM, Edward Ned Harvey (lopser) wrote:
The default is to replicate once per hour within a site, and once
every 180 minutes inter-site. There are lots of articles out there
describing how to architect your replication toplogy, and all the
reasons why, and they all boil down to conserving bandwidth.
In my mind, AD replication is a tiny amount of data, and I think I
would like to tweak the replication frequency to absolute maximum
speed. (Which is 4 times per hour within a site, and once every 15
minutes inter-site.)
That's actually not how intra-site replication works. Within a site
replication runs constantly (mostly). When a chance is made the
information is pushed almost immediately to other DCs within the site.
(It waits a few seconds to try to batch things.) A write-up for Windows
2003 is available at
http://technet.microsoft.com/en-us/library/cc728010%28v=ws.10%29.aspx.
(I don't believe the process has changed with 2008 or 2012.)
As you mentioned inter-site replication uses a different process that by
default runs every 3 hours, but can be turned to as frequently as every
15 minutes with the default settings. If you want to make replication
happen more frequently between sites you can enable change notification
to make inter-site replication behave like intra-site replication. (This
can be done on a per-site-link basis.) See
http://blogs.msdn.com/b/canberrapfe/archive/2012/03/26/active-directory-replication-change-notification-amp-you.aspx
for details on how to do that.
I browsed around and found a list of ports & protocols used in AD
replication, and there are a ton. LDAP, Kerberos, Ping (ICMP Echo),
RCP, etc. Sure I *can* create a wireshark capture to view that
traffic, but it would be a huge massive capture filter, very
complex.
So my question is:
Does anybody know any way to measure the bandwidth used by AD
replication? I am looking to test my assumption that it's a tiny
amount of traffic, basically irrelevant in the modern age where the
slowest connection is 3 Mbit.
Unfortunately I don't have any good details about actual traffic
volumes, but
http://blogs.technet.com/b/askds/archive/2013/01/21/configuring-change-notification-on-a-manually-created-replication-partner.aspx
implies it's not as necessary today as it used to be. It also looks like
perfmon has some counters available to measure replication traffic:
http://technet.microsoft.com/en-us/library/bb742457.aspx#ECAA (That's
for Windows 2000. I don't currently have access to a Windows
2003/2008/2012 DC to test if those counters still exist there.)
--
Thanks
Jefferson Cowart
[email protected]
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