Manage Cache Groups

After you have provisioned the CDN, you may need to add cache groups to the CDN, modify existing cache groups, or configure additional features that you can not configure using the CDN Wizard, such as backup Edge cache groups. From the Cache Groups tab of the Provisioning > Edit CDN window you can edit all of the Mid, Edge, and Origin cache groups that you have in your environment and you can create new cache groups.

From the Cache Group tab you can add a new cache group, including Origin server cache groups, and change the following settings of a cache group:

  • Short name

  • Latitude

  • Longitude

  • Parent and Secondary Parent Cache Group for Edge cache groups and Mid cache groups

  • Configure fallback settings for backup Edge cache groups


Note
To assign cache servers and Origin Servers to a group, you must go to the Provisioning > Edit CDN > Servers tab. To delete a Mid cache group or Edge cache group, you must go to Provisioning > CDN Overview.

Note
If you are running OMD Director in an HA configuration, you can only make configuration changes from the Primary OMD Director instance. To perform the steps in this chapter, make sure you are logging into the Primary OMD Director instance.

This chapter describes how to perform these configuration tasks.

This chapter includes the following topics:

Add a Edge Cache Group

Edge caches provide edge caching, content streaming, and download to subscriber IP devices. Traffic routers redirect client requests to edge caches based on geolocation, server availability, server load, and server cache content to provide efficient system-wide load balancing. Edge caches are organized into cache groups. You configure each edge cache group with a primary mid-tier parent cache group and optionally a secondary mid-tier parent cache group for failover.

To add a new Edge cache group to the CDN, follow these steps:


Note
For information on Origin cache groups, see Create Origin Server Cache Groups.

Procedure

Step 1

Choose Provisioning > > Edit CDN. From the CDN Name drop-down list above the tabs, make sure the correct CDN is selected.

Step 2

Click the Cache Groups tab.

Step 3

Next to the Cache Group Name drop-down list, click the + icon to create a new Edge cache group.

Step 4

In the New Cache Group Window that appears, enter the following information for the new group:

  • Name: Enter a descriptive name for the group. This is the name that appears in the OMD Director Drop-Down menus. The name should begin with EDGE (in any upper case or lower case combination) so you can easily identify the type of the group.

  • Short Name: Enter an additional descriptive name. This name is not currently used in OMD Director, but it is a required field. The Short Name can be the same as the Name.

  • The Geo Magnetic Latitude and Geo Magnetic Longitude: These parameters define the geolocation of the cache group. For cache groups, the geolocation is used by the CDN system to help redirect user clients to the most optimal cache. Enter the latitude and longitude that geolocation should use for this group.

    Note 
    For more information on how the Traffic Router determines which cache group should service a request, see the Manage Client Routing section.

  • Type: Choose EDGE_LOC.

    Edge caches provide edge caching, content streaming, and download to subscriber IP devices. Traffic routers redirect client requests to edge caches based on geolocation, server availability, server load, and server cache content to provide efficient system-wide load balancing. Edge caches are organized into cache groups. You configure each edge cache group with a primary mid-tier parent cache group and optionally a secondary mid-tier parent cache group for failover.

  • Parent Cache Group: Choose the Mid cache group to use as a parent.

  • Secondary Parent Cache Group: To provide failover in case the Mid caches in the Parent Cache Group are unavailable, you can optionally assign a secondary cache group to use. When the Mid caches in the Parent Cache Group are unavailable, the mid caches in the Secondary Parent Cache Group are used as a backup.

Step 5

Click Add to add the group.

Note 

To add a server to a cache group, edit the cache server properties. For more information see Edit an Existing Origin Server.

Step 6

When the cache group has been successfully added, the “Processing” status in the title bar will disappear and you will see a green check mark for every action in the Status column. Click OK to close the status window.

Note 

After an Edge Cache group is created, you can configure the Edge cache group to use backup Edge cache groups. Backup edge cache groups are used when there are no caches available in the original Edge cache group selected by the Traffic Router for the client request. For more information on how this feature works and how to configure it, see Backup Edge Cache Groups.

Backup Edge Cache Groups

Backup Edge cache groups are used when there are no caches available in the original Edge cache group selected by the Traffic Router for a client request. The Traffic Routers use the CZF file and the Fallback configuration on the Edge cache group to support backup Edge cache groups.

When no Edge caches are available from the original cache group that is matched in the CZF file, the Traffic Router uses the processes described in the following sections, "Process When Geo Limit is Set to CZF Only" and "Process When Geo Limit is Set to CZF + Country Codes or None", to determine which Edge cache group to use, if any, as a backup.


Note

CZF File explains how to configure the CZF file to support backup Edge cache groups and provides an example of a CZF.

Process When Geo Limit is Set to CZF Only

The Traffic Router checks the CZF file for a cache group with a subnet match to the client request. If a cache group is found, the Traffic Router then chooses an Edge cache from that group based on cache availability, cache load, and cache content. If there is no available Edge cache for the cache group that was matched, the Traffic Router uses the following process to look for a backup Edge cache group:

  • When the original cache group has fallback cache groups assigned:

    1. The Traffic Router checks the list of fallback cache groups in the order listed, to find an available cache.

    2. If there are no Edge caches available from the fallback cache groups, the Traffic Router checks the "Fallback Enable" setting of the original Edge cache group that was matched:

      • If the Fallback Enable setting is set to No, no further searches are performed and no cache is returned. The client is redirected to the bypass location listed in the Bypass FQDN field of the Delivery Service. If the Bypass FQDN field is empty, the client will receive a 503 Service Unavailable message.

      • If the Fallback Enable setting is set to Yes, the Traffic Router looks for the next closest cache group to the original group, based on the latitude and longitude configured in the CZF file. The Traffic Router then chooses an Edge cache from that group based on cache availability, cache load, and cache content. If no Edge cache is available in the backup Edge cache group, or if there are no latitude and longitude settings in the CZF file for any of the other caches assigned to the Delivery Service used for the client request, the client is redirected to the bypass location listed in the Bypass FQDN field of the Delivery Service. If the Bypass FQDN field is empty, the client will receive a 503 Service Unavailable message.

  • When the original cache group does not have fallback cache groups assigned:

    1. The Traffic Router looks for the next closest cache group to the original group, based on the latitude and longitude configured in the CZF file. The Traffic Router then chooses an Edge cache from that group based on cache availability, cache load, and cache content. If no Edge cache is available in the backup Edge cache group, or if there are no latitude and longitude settings in the CZF file for any of the other caches assigned to the Delivery Service used for the client request, the client is redirected to the bypass location listed in the Bypass FQDN field of the Delivery Service. If the Bypass FQDN field is empty, the client will receive a 503 Service Unavailable message.


Note

The list of fallback cache groups and the Fallback Enable setting are configured on the Edge Cache group. For more information on configuring these settings, see Configure Backup Edge Cache Groups.

Process When Geo Limit is Set to CZF + Country Codes or None

The Traffic Router first checks the CZF file for a cache group with a subnet match to the client request. If a cache group is found, the Traffic Router then chooses a cache from that group based on cache availability, cache load, and cache content. If there is no available cache for the cache group that was matched, the Traffic Router uses the following process to look for a backup Edge cache group:

  • When the original cache group has fallback cache groups assigned:

    1. The Traffic Router checks the list of fallback cache groups in the order listed, to find an available cache.

    2. If there are no Edge caches available from the fallback cache groups, the Traffic Router checks the "Fallback Enable" setting of the original Edge cache group that was matched:

      • If the Fallback Enable setting is No, no further searches are performed and no Edge cache is returned. The client is redirected to the bypass location listed in the Bypass FQDN field of the Delivery Service. If the Bypass FQDN field is empty, the client will receive a 503 Service Unavailable message.

      • If the Fallback Enable setting is Yes, the Traffic Router looks for the next closest Edge cache group to the original group, based on the latitude and longitude configured in the CZF file. It then chooses an Edge cache from that group based on cache availability, cache load, and cache content.

    3. If the Fallback Enable setting is Yes and no Edge cache is available in the backup Edge cache group selected by the CZF file, or if there are no latitude and longitude settings in the CZF file for any other caches assigned to the Delivery Service being used for the client request, the Traffic Router uses geolocation to find an Edge cache group. The Traffic Router checks the geolocation database to determine the latitude and longitude of the IP address in the client request and compares that latitude and longitude to the latitude and longitude configured for each cache group (in the Cache Group settings) to find the geographically closest cache group. The Traffic Router then chooses an Edge cache from that group based on cache availability, cache load, and cache content.

    4. If no Edge cache is available from the Edge cache group based on the geolocation look up, the client is redirected to the bypass location listed in the Bypass FQDN field of the Delivery Service. If the Bypass FQDN field is empty, the client will receive a 503 Service Unavailable message.


      Note

      If coordinates for the client request are not available using geolocation, the Geo Miss Default Latitude and Geo Miss Default Longitude settings of the Delivery Service are used to determine the closest cache group to use. The Traffic Router then chooses a cache to use from that group based on cache availability, cache load, and cache content. If no edge cache is available from that group, the client will receive a 503 Service Unavailable message.

  • When the original cache group does not have fallback cache groups assigned:

    1. The Traffic Router looks for the next closest Edge cache group to the original group, based on the latitude and longitude configured in the CZF file. It then chooses an Edge cache from that group based on cache availability, cache load, and cache content.

    2. If no Edge cache is available in the backup Edge cache group selected by the CZF file, or if there are no latitude and longitude settings in the CZF file for any other caches assigned to the Delivery Service being used for the client request, the Traffic Router uses geolocation to find an Edge cache group. The Traffic Router checks the geolocation database to determine the latitude and longitude of the IP address in the client request and compares that latitude and longitude to the latitude and longitude configured for each cache group (in the Cache Group settings) to find the geographically closest cache group. The Traffic Router then chooses an Edge cache from that group based on cache availability, cache load, and cache content.

    3. If no Edge cache is available from the Edge cache group based on the geolocation look up, the client is redirected to the bypass location listed in the Bypass FQDN field of the Delivery Service. If the Bypass FQDN field is empty, the client will receive a 503 Service Unavailable message.


      Note

      If coordinates for the client request are not available using geolocation, the Geo Miss Default Latitude and Geo Miss Default Longitude settings of the Delivery Service are used to determine the closest cache group to use. The Traffic Router then chooses a cache to use from that group based on cache availability, cache load, and cache content. If no edge cache is available from that group, the client will receive a 503 Service Unavailable message.


Note

The list of fallback cache groups and the Fallback Enable setting are configured on the Edge Cache group. For more information on configuring these settings, see Configure Backup Edge Cache Groups.

Configure Backup Edge Cache Groups

To configure an Edge cache group to use backup cache groups when none of the caches in the primary Edge cache group are available, perform the following steps:

Procedure

Step 1

Choose Provisioning > > Edit CDN. From the CDN Name drop-down list above the tabs, make sure the correct CDN is selected.

Step 2

Click the Cache Groups tab.

Step 3

From the Cache Group Name drop-down list, choose the Edge cache group for which you want to configure backup Edge cache groups.
Step 4

From the Fallback Enable drop-down list, choose either Yes or No, to determine whether the CZF file should be used to find a backup cache group:

  • Yes: If there are no cache groups entered in the "Fallback Cache Group" field or if there are no caches available from any of the backup groups listed, the Traffic Router will look for a backup cache group using the latitude and longitude configured in the CZF file for the cache groups.

  • No: If there are no caches available from any of the backup groups listed, the Traffic Router will not check the coordinates in the CZF file so the request will fail. The client is redirected to the bypass location listed in the Bypass FQDN field of the Delivery Service. If the Bypass FQDN field is empty, the client will receive a 503 Service Unavailable message.

Note 

When there are no Fallback cache groups assigned in the Fallback Cache Group field, the Fallback Enable setting is always considered to be Yes, regardless of what is set in the Fallback Enable field.

Step 5

From the Fallback Cache Group field, choose the Edge cache groups to use for backup. The Traffic Router will check these groups in the order in which they are listed.

The following is an example of the Cache Groups tab:

Step 6

Click Save to save the settings.

CZF File

To enable the Traffic Router to find a backup cache to use in the CZF file when the “Fallback Enable” setting of the mapped Edge cache group is set to “Yes”, you must add the longitude and latitude parameters for the backup cache groups in the CZF file.

To add the longitude and latitude settings for a cache group in the CZF file, you must add a "coordinates"section inside the cache group that contains a "longitude"and "latitude" setting, as shown in the following example: 

{
    "coverageZones":
    {
        "Edge-West1":
        {
           "network6":
           [
               "1234:5704::/64",
               "1234:5705::/64",
               "1234:5706::/64"
           ],
           "network":
           [
               "192.168.4.0/24",
               "192.168.5.0/24",
               "192.168.6.0/24",
               "192.168.7.0/24",
               "192.168.8.0/24",
               "192.168.9.0/24"
           ],
           "coordinates": 
           {
               "longitude": -118,
               "latitude": 34
           }
        },
        "Edge-West2":
        {
           "network6":
           [
               "1234:5710::/64",
               "1234:5711::/64",
               "1234:5712::/64"
           ],
           "network":
           [
               "192.168.10.0/24",
               "192.168.11.0/24",
               "192.168.12.0/24",
               "192.168.13.0/24",
               "192.168.14.0/24",
               "192.168.15.0/24"
           ],
           "coordinates": 
           {
               "longitude": -122,
               "latitude": 47
           }
        },
        "Edge-West3":
        {
           "network6":
           [
               "1234:5720::/64",
               "1234:5721::/64",
               "1234:5722::/64"
           ],
           "network":
           [
               "192.168.20.0/24",
               "192.168.21.0/24",
               "192.168.22.0/24",
               "192.168.23.0/24",
               "192.168.24.0/24",
               "192.168.25.0/24"
           ],
           "coordinates": 
           {
               "longitude": -117,
               "latitude": 32
           }
        },
        "Edge-West4":
        {
           "network6":
           [
               "1234:5730::/64",
               "1234:5731::/64",
               "1234:5732::/64"
           ],
           "network":
           [
               "192.168.30.0/24",
               "192.168.31.0/24",
               "192.168.32.0/24",
               "192.168.33.0/24",
               "192.168.34.0/24",
               "192.168.35.0/24"
           ],
           "coordinates": 
           {
               "longitude": -105,
               "latitude": 40
           }
        }
    }
}

Add a Mid Cache Group

Mid caches provide content ingest and storage functionality. When an edge cache does not contain the content requested by the client, the edge cache will proxy the request to a mid-cache server, based on the parent cache group assigned to the edge cache. If the mid-cache server does not contain the content, it is responsible for fetching the content from the Origin Server. Mid-tier caches are also organized into cache groups. Mid-tier cache groups may serve (be a parent to) multiple edge cache groups.

To add a new Mid cache group, follow these steps:


Note
For information on Origin cache groups, see Create Origin Server Cache Groups.

Procedure

Step 1

Choose Provisioning > > Edit CDN. From the CDN Name drop-down list above the tabs, make sure the correct CDN is selected.

Step 2

Click the Cache Groups tab.

Step 3

Next to the Cache Group Name drop-down list, click the + icon to create a new Mid cache group.

Step 4

In the New Cache Group Window that appears, enter the following information for the new group:

  • Name: Enter a descriptive name for the group. This is the name that appears in the OMD Director drop-down menus. The name should begin with MID (in any upper case or lower case combination) so you can easily identify the type of the group.

  • Short Name: Enter an additional descriptive name. This name is not currently used in OMD Director, but it is a required field. The Short Name can be the same as the Name.

  • The Geo Magnetic Latitude and Geo Magnetic Longitude: These parameters define the geolocation of the cache group. For cache groups, the geolocation is used by the CDN system to help redirect user clients to the most optimal cache. Enter the latitude and longitude that geolocation should use for this group.

    Note 
    For more information on how the Traffic Router determines which cache group should service a request, see Client Routing Overview.

  • Type: Choose MID_LOC.

  • Parent Cache Group: If MSO is being used and specific Origin Servers should be assigned to this Mid cache group, choose the Origin Server group that contains those Origin Servers. For more information on MSO and how to configure it, see Multi Site Origin.

  • Secondary Parent Cache Group: If MSO is being used and a different origin cache group is configured for your backup Origin Servers, choose that origin cache group as the secondary parent cache group. For more information on MSO and how to configure it, see Multi Site Origin.

Step 5

Click Add to add the group.

Step 6

When the cache group has been successfully added, the “Processing” status in the title bar will disappear and you will see a green check mark for every action in the Status column. Click OK to close the status window.

Note 

To add a server to a cache group, edit the cache server properties. For more information see Edit an Existing Origin Server.

Edit an Existing Cache Group

To edit an exiting cache group, follow these steps:

Procedure

Step 1

Choose Provisioning > Edit CDN. From the CDN Name drop-down list above the tabs, make sure the correct CDN is selected.

Step 2

Click the Cache Group tab.

Step 3

From the Cache Group Name list, choose the group you want to edit.

Step 4

If needed, change the short name, latitude, or longitude of the cache group. If you are editing an Edge or Mid cache group, you can also change the parent cache group and secondary parent cache group.

Note 
The Latitude and Longitude define the geolocation of the cache group. The geolocation is used by the CDN system to help redirect user clients to the most optimal cache. Enter the latitude and longitude that geolocation should use for this group.
Step 5

If you are editing an Edge cache group, you can also change the Fallback settings to configure backup edge cache groups. For more information on backup edge cache groups, see Backup Edge Cache Groups.

Note 
To add a server to a cache group, edit the server settings. For more information, see Edit an Existing Origin Server.
Step 6

When you have finished making your changes, clickSave. The Processing window will appear. This window displays the progress of the cache group being updated, including the status of each action involved. For example, the following shows the process of a server being added to the cache group.

Step 7

When the cache group has been successfully updated, the “Processing” status in the title bar will disappear and you will see a green check mark for every action in the Status column. The following is an example:

Step 8

Click OK to close the status window and return to the CDN Overview page.

Delete a Mid Cache Group


Note
If you are running OMD Director in an HA configuration, you can only make configuration changes from the Primary OMD Director instance. To perform the steps in this section, make sure you are logging into the Primary OMD Director instance.

To delete a Mid cache group, follow these steps:


Note

You cannot delete a Mid cache group if it is the parent of any Edge cache groups.

Procedure

Step 1

Choose Provisioning > > CDN Overview. From the CDN Name drop-down list above the tabs, make sure the correct CDN is selected.

Step 2

In the Mid Cache Groups section, click the Delete icon (trashcan) for the Mid cache group that you want to delete.

Note 

If you try to delete a Mid cache group that has servers assigned to it, you will receive an error message letting you know that the group was not deleted. You cannot delete a Mid cache group if there are any Cache servers assigned to the group.

If the word “updating” appears instead of the Delete icon (trashcan), this indicates that the Mid Cache Group has been modified and is in the process of being updated. To delete the Mid Cache Group, you will need to wait until it has finished updating.

Step 3

In the Deleting Cache Group confirmation window that appears, click Yes to confirm that you want to delete the Mid cache group.

Step 4

When the Cache Group has been successfully deleted, the “Processing” status in the title bar will disappear and you will see a green check mark for every action in the Status column. Click OK to close the status window.

Delete an Edge Cache Group


Note
If you are running OMD Director in an HA configuration, you can only make configuration changes from the Primary OMD Director instance. To perform the steps in this section, make sure you are logging into the Primary OMD Director instance.

To delete an Edge cache group, follow these steps:

Procedure

Step 1

Choose Provisioning > > CDN Overview. From the CDN Name drop-down list above the tabs, make sure the correct CDN is selected.

Step 2

In the Edge Cache Groups area, click the Delete icon (trashcan) for the Edge cache group that you want to delete.

Note 

If you try to delete an Edge cache group that has servers assigned to it, you will receive an error message letting you know that the group was not deleted. You cannot delete an Edge cache group if there are any Cache servers assigned to the group.

If the word “updating” appears instead of the Delete icon (trashcan), this indicates that the Edge Cache Group has been modified and is in the process of being updated. To delete the Edge Cache Group, you will need to wait until it has finished updating.

Step 3

In the Deleting Cache Group confirmation window that appears, click Yes to confirm that you want to delete the Edge cache group.

Step 4

When the Cache Group has been successfully deleted, the “Processing” status in the title bar will disappear and you will see a green check mark for every action in the Status column. Click OK to close the status window.