eG Help

The Client Access Server manages client connections through redirection and proxy functionality. The Client Access server authenticates client connections and, in most cases, will proxy a request to the Mailbox server that houses the currently active copy of the database that contains the user's mailbox. In some cases, the Client Access server might redirect the request to a more suitable Client Access server, either in a different location or running a more recent version of Exchange Server.

Many CAS protocols / services are proxy enabled - for e.g., Autodiscover, Outlook Web App, Exchange ActiveSync, EAS, ECP, etc.

If a user accessing a proxy-enabled service on CAS complains of a slowdown, then Exchange administrators should be able to identify the exact service that is being affected, and where the CAS processing is bottlenecked – during authentication? When proxying? When making MailboxServerLocator calls? When connecting to the Mailbox server? The Exc2013HttpProTest test provides answers to these questions.

This test auto-discovers the proxy-enabled services on CAS and reports the time spent by CAS at various stages of processing the requests to each service. In the process, the test accurately pinpoints the latent service and what is causing the latency.

Measurement	Description	Measurement Unit	Interpretation
Avg_act_lat	Indicates the average latency of AD requests made by CAS for this proxy-enabled service.	Secs	Compare the value of this measure across services to know which service experienced the maximum latency when interacting with Active Directory.
Avg_auth_lat	Indicates the average time spent by CAS when authenticating requests to this service over the last 200 samples.	Secs	By comparing the value of this measure across services, you can pinpoint that service for which CAS took too much time to perform authentication.
Avg_client_lat	Indicates the time spent by CAS processing requests to this service.	Secs	This processing time does not include proxying time. Compare the value of this measure across services to identify that service for which processing was delayed.
Avg_mail_lat	Indicates the time taken by CAS for proxying requests to this service.	Kbytes	Compare the value of this measure across services to know which service was delivered slowly to users owing to bottlenecks in proxying.
Avg_tenant_lat	Indicates the average time required to resolve tenants over the last 200 samples. This includes Global Locator Service (GLS) lookups. (Applicable For Exchange Online Only).	Secs	Compare the value of this measure across services to know which service was delivered slowly to users owing to bottlenecks in tenant resolution.
Byte_in_sec	Indicates the rate at which data was received by CAS for this service.	KB/sec
Byte_out_sec	Indicates the rate at which data was sent by CAS for this service.	KB/sec
Mail_pro_rate	Indicates the percentage of connectivity failures that occurred between CAS and the Mailbox server when processing requests for this service.	Percent	A high percentage is a cause for concern. In the event of a slowdown in proxying, a very high value for this measure could indicate that connectivity failures are reason for the delay in proxying.
Mail_avg_lat	Indicates the time taken by CAS to make MailboxServerLocator calls for this service.	Secs	Compare the value of this measure across services to know which service was delivered slowly to users owing to bottlenecks in MailboxServerLocator calls.
Mail_cal_sec	Indicates the rate at which CAS made MailboxServerLocator calls for this service.	Calls/Sec
Mail_fai_rate	Indicates the percentage of failed MailboxServerLocator calls over the last 200 requests for this service.	Percent	By comparing the value of this measure across services to know which service suffered the most owing to MailboxServerLocator call failures.
Mail_cal_lat	Indicates the latency of the last MailboxServerLocator call for this service.	Secs
Mail_ret_rate	Indicates the percentage of MailboxServerLocator calls that were retried for this service over the last 200 requests.	Percent	By comparing the value of this measure across services to know which service suffered the most owing to retried MailboxServerLocator calls.
Out_pro_req	Indicates the number if concurrent outstanding proxy requests for this service.	Number	A high value is a cause for concern as it indicates too many proxy requests are pending processing. You can compare the value of this measure across services to know which service has the maximum number of outstanding proxy requests.
Pro_req_sec	Indicates the number of proxy requests processed each second for this service.	Reqs/Sec	A consistent drop in the value of this measure for any service is indicative of bottlenecks in processing proxy requests.
req_sec	Indicates the number of requests processed each second for this service, which may not involve proxying to a Mailbox server.	Reqs/Sec