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Google Networking Best Practices for Large Deployments User Manual

Page 15

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Network Evaluation

15

1. Open the sample list

text file hosted on the apps-deployments code site

. (Note that

this is a sample only, not a complete list.)

2. Save the sample .txt file in the directory where you will be using the test commands:

a. Click View raw file.

b. Right-click the page, and choose Save As.

3. Run the following command to test DNS resolution:

% dig +all +trace -f GoogleAppsDomains.txt

ICMP Connectivity Test

Ensure that clients in your network can reach the hostname

mail.google.com

, by testing

ICMP connectivity from all your network locations to Google Apps. Test that your users can
reach Google Apps, especially from all users’ VLANs.

% ping -s 512 -c 400 -n mail.google.com

If you see slow or failed connections on your ping requests, this may indicate a loss of
connectivity. Investigate each step of your connection to identify the source of the problem.

TCP/UDP Reliability Test

Ensure that clients in your network can reliably establish and maintain a connection to Google
Apps servers. Use the

Hping

tool to test link reliability over a period of time. Run the following

command:

% time hping3 -S mail.google.com -p 443 --fast -c 1000

If there is time, run this test for each domain listed in the

GoogleAppsDomains.txt

file

mentioned above.

Note:

TCP/UDP reliability tests are intrusive and can affect network performance. Run these

tests during off-hours to gather data while causing the minimum possible the impact to
your network.

Available WAN Bandwidth Assessment

Use the

iperf

tool to assess the amount of bandwidth available from each location to its

network egress point. This test is run on both the client and the network egress point.

This test is intended to assess bandwidth within your WAN network. It is not suited for testing
bandwidth between your network and Google Apps servers.

On each remote location that is connected over a WAN network, run this command:

% iperf -c CLIENT IP ADDRESS -d

On the network egress location, run this command: