Finalizing previous update. Adding Acrolinx changes to troubleshooting article. Adding troubleshooting article to TOC

Author: sbdoroff

articles/frontdoor/TOC.yml

@@ -354,6 +354,8 @@
       items:
       - name: Troubleshooting Front Door issues
         href: troubleshoot-issues.md
+      - name: Troubleshooting Front Door performance issues
+        href: troubleshoot-performance-issues.md
       - name: Allowed certificate authorities
         href: https://ccadb-public.secure.force.com/microsoft/IncludedCACertificateReportForMSFT
       - name: File compression

articles/frontdoor/troubleshoot-performance-issues.md

@@ -14,15 +14,15 @@ ms.author: stdoroff
 
 # Azure Front Door Performance 
 
-Performance issues can originate in several potential areas.  This guide will assist in identifying which hop along the data-path is most likely the root of the issue and how to resolve.  As a brief overview, the issue could be at the Azure Front Door (AFD), the origin, the requesting client or the path between any of these hops.
+Performance issues can originate in several potential areas.  This guide  in identifying which hop along the data-path is most likely the root of the issue and how to resolve.  As a brief overview, the issue could be at the Azure Front Door (AFD), the origin, the requesting client or the path between any of these hops.
 
 ## Check for Known Issues
 
 Before beginning, be sure to check for any [known issues on the AFD platform](https://azure.status.microsoft/status), any known ISPs in the path or on the requesting client's ability to connect and retrieve data.
 
 ## Scenario 1: Investigate the Origin
 
-If one of the origin servers are slow then the first request for an object via the AFD will also be slow.  Further, if the content is not being cached at the AFD's Point of Presence (POP), every request will be forwarded to the origin, negating the benefit of the POP's proximity to the requesting client, and relying on the origin's performance.
+If one of the origin servers are slow, then the first request for an object via the AFD is slow.  Further, if the content isn't cached at the AFD's Point of Presence (POP), requests are forwarded to the origin.  Serving from the origin negates the benefit of the POP's proximity and local delivery to the requesting client, and, instead, rely on the origin's performance.
 
 ### Scenario 1 | Environment Information Needed
 
@@ -40,7 +40,7 @@ If one of the origin servers are slow then the first request for an object via t
     > To check response headers, utilize your browser's Developer Tools (F12), select the *Networking* tab, then the relevant file to be investigated, then the *Headers* tab. ***If the file is missing*** the page need to be reloaded with Developer Tools (F12) open.
      
     - The initial response should have an *x-cache* header with *TCP_MISS* value
-    - Requests with this value are being forwarded by the AFD's POP to the origin and returning on that same path to the requesting client
+    - Requests with this value are forwarded by the AFD's POP to the origin and returning on that same path to the requesting client
     - Examples
       - TCP_MISS
 
@@ -99,15 +99,15 @@ If one of the origin servers are slow then the first request for an object via t
          ```
 
 1. Continue to request against the endpoint until the *x-cache* header has a *TCP_HIT* value
-1. ***If the performance issue is resolved***, then the issue was based on the origin's speed, and is not the of the AFD's performance.  The AFD's cache settings or the origin will need to be address by it's owner to resolve the performance issue.
+1. ***If the performance issue is resolved***, then the issue was based on the origin's speed, and isn't the AFD's performance.  The AFD's cache settings or the origin need to be address by it's owner to resolve the performance issue.
 1. ***If the issue persists***, then the issue may be with the client requesting the content or the AFD  
   A. Move to Scenario 2 to identify
 
-## Scenario 2: A Single Client or Location (ie. ISP) is Slow
+## Scenario 2: A Single Client or Location (example: ISP) is Slow
 
-This could happen if there is a bad network route between the requesting client and the AFD POP.  Any bad route should be ruled out as it will affect the distance to the POP, removing the AFD POP's proximity benefit.
+A single client or location being slow can happen if there's a bad network route between the requesting client and the AFD POP.  Any bad route should be ruled out as it affects the distance to the POP, removing the AFD POP's proximity benefit.
 
-This could be because of an ISP issue, the customer is using a VPN or they are a part of a corporate network that runs all traffic through a central, remote point.
+High latency, or low bandwidth, could be because of an ISP issue, the customer is using a VPN or they're a part of a dispersed corporate network.  A corporate network can run all traffic through a central, remote point.
 
 ### Scenario 2 | Environment Information Needed
 
@@ -130,24 +130,26 @@ This could be because of an ISP issue, the customer is using a VPN or they are a
     ```
 
 1. Determine if the traffic is taking a path that would add time or travel to a distant region
-   - Look for IP, city or country codes that do not take a reasonable route based on the customer’s geography (ie. a customer in Europe getting routed to the United States), or excessive number of hops
+   - Look for IP, city or region codes that don't take a reasonable route based on the customer’s geography (example: a customer in Europe getting routed to the United States), or excessive number of hops
 1. Test from a different requesting client in the same region
-1. **If additional hops or remote regions are identified**, the issue will be with the client accessing the AFD POP and not with the AFD itself.  This will need to be addressed by the connectivity or VPN provider.
-1. **If additional hops or remote regions are not identified** AND the content is being served from cache (x-cache: TCP_HIT), the issue will likely be with the AFD and a Support Request may need to be created.  Include a reference to this troubleshooting article and steps taken.
-   - ***Note***: If the content is being served from the origin (x-cache: TCP_MISS), see Scenario 1<insert link when available>
+1. **If additional hops or remote regions are identified**, the issue is with the client accessing the AFD POP and not with the AFD itself.  Hops between endpoints needs to be addressed by the connectivity or VPN provider.
+1. **If additional hops or remote regions are not identified** AND the content is being served from cache (x-cache: TCP_HIT), the issue is with the AFD and a Support Request may need to be created.  Include a reference to this troubleshooting article and steps taken.
+   - ***Note***: , when the content is being served from the origin (x-cache: TCP_MISS), see Scenario 1 above
 
 ## Scenario 3: A Website Loads Slowly
 
-There are some scenarios where there is ***not*** an issue with a single file but the performance of the whole, AFD proxied, webpage is unsatisfactory.  This will usually be revealed by a webpage performance tool and will show under performance compared to the webpage outside of AFD.
+There are some scenarios where there is ***not*** an issue with a single file but the performance of the whole, AFD proxied, webpage is unsatisfactory.  Site performance is revealed by a webpage performance tool and shows under performance compared to the webpage outside of AFD.
 
-A webpage will often consist of many files.  The way the AFD offers benefit for the webpage is if each file in the webpage is being served from the origin linked to the AFD and the AFD is configured to optimize the delivery of that file.  For example:
+A webpage often consists of many files.  The way the website benefits from the AFD is only if each file in the webpage is being served from the AFD.  Additionally, the AFD must be configured to maximize the benefit.  For example:
 
 - Origin: origin.contoso.com
 - AFD Custom Domain: contoso.com
 - Page customer attempts to load: https://contoso.com
-- **Explanation**: When the page loads, the initial file at the "/" directory calls other files which build the page.  These are images, javascript, text files and more.  If those files are not called via the AFD hostname, *contoso.com*, the AFD will ***not*** be utilized.  So, if one of the file requested by the website is *http://www.images.fabrikam.com/businessimage.jpg* the file will ***not*** benefit from the use of the AFD.  Instead, the file will be requested directly, from the *images.fabrikam.com* server, by the browser on the requesting client .
+- **Explanation**: When the page loads, the initial file at the "/" directory calls other files, which build the page.  These files are images, JavaScript, text files and more.  If those files aren't called via the AFD hostname, *contoso.com*, the AFD is ***not*** being utilized.  So, if one of the file requested by the website is *http://www.images.fabrikam.com/businessimage.jpg* the file is ***not*** benefiting from the use of the AFD.  Instead, the file is being requested directly, from the *images.fabrikam.com* server, by the browser on the requesting client.
 
-   :::image type="content" source="..." alt-text="Example of multiple, differently sourced files for a singular website and how it affects AFD performance":::
+   :::image type="complex" source="media/troubleshoot-performance-issues/AFDCDNPerformance.jpg" alt-text="Example of multiple, differently sourced files for a singular website and how it affects AFD performance":::
+
+   :::image-end:::
 
 ### Scenario 3 | Environment Information Needed
 
@@ -157,19 +159,19 @@ A webpage will often consist of many files.  The way the AFD offers benefit for
   - Origin Hostname
     - Geographical location of the origin
 - Full URL of Affected Webpage
-- Tool and metric which is measuring performance
+- Tool and metric, which is measuring performance
 
 ### Scenario 3 | Troubleshooting
 
-1. Review the metric which is showing the slower performance  
+1. Review the metric, which is showing the slower performance  
    > [!IMPORTANT]
    > If it is based on a third part tool, Microsoft cannot discern what is being measure by tools not owned by Microsoft
 1. Pull up the AFD webpage in a Browser with Developer Tools (F12) enabled
    > [!NOTE]
    > Developer tools in your browser can be used to determine the source of the files being served
 1. Note the source of files
-1. Identify which files are utilizing the AFD hostname and which are not
-  A. Example: From the above example, an AFD hosted image would be something like https://www.contoso.com/productimage1.jpg and that which is not would be something like http://www.images.fabrikam.com/businessimage.jpg
+1. Identify which files are utilizing the AFD hostname and which aren't
+  A. Example: From the above example, an AFD hosted image would be something like https://www.contoso.com/productimage1.jpg and that which wouldn't is something like http://www.images.fabrikam.com/businessimage.jpg
 1. Once gathered test performance for file being served from AFD, its origin and, if applicable, the testing webpage
    > [!IMPORTANT]
    > If the origin or testing webpage is served from a geographical region closer to the tool testing performance, a tool or requesting client may need to be used in another region to examine the AFD POP's proximity benefit  
@@ -181,7 +183,7 @@ A webpage will often consist of many files.  The way the AFD offers benefit for
    > Any files served from outside the AFD's hostname will not be able to benefit from it and the webpage may need to be redesigned to do so
  
 1. **If the collected data shows that files are being issued from servers outside the AFD's hostname or performance is better at the AFD**, the AFD is working as expected  
-  A. This may require a change in webpage design, for assistance in optimizing your website to leverage an AFD, connect with your website design team or our [Microsoft Solution Providers](https://www.microsoft.com/solution-providers/home)
+  A. Slowly loading websites may require a change in webpage design, for assistance in optimizing your website to use an AFD, connect with your website design team or our [Microsoft Solution Providers](https://www.microsoft.com/solution-providers/home)
    > [!NOTE]
-   > This issue could take time to review based on the complexity of a website's design and it's file calling instructions
+   > Slowly loading websites issue could take time to review based on the complexity of a website's design and it's file calling instructions
 1. **If the collected data shows that performance is ***not*** better at the AFD**, a Support Request is likely required for further investigation.  Include a reference to this troubleshooting article and steps taken.