BGP Community Services Plugin

The BGP Community Services Plugin allows the 128T router to create services based on the community strings of prefixes learned via BGP from remote routers. The plugin allows you to configure a profile containing mappings of application names to community strings. A router can be assigned one profile, which will allow it to create application identification information to associate learned prefixes to application names. These application names can then be configured within a service definition in order to appropriately populate the routers FIB. The primary use case for this plugin was to identify Microsoft Office 365 application traffic for customers using ExpressRoute. However, there may be other use cases where it is desirable for prefixes identified by a BGP community string to be mapped into a service dynamically.

note

The instructions for installing and managing the plugin can be found here.

Configuration Snippet

One or more BGP community profile objects can be configured at the authority level of the configuration. These profiles are then assigned to the individual routers.

BGP Community Services Profile Configuration

An example configuration is shown below, which shows the standard community strings for Microsoft Office 365 over ExpressRoute. The application-name values are completely user configurable. The bgp-community is a list object to allow for scenarios where you may want to associate multiple community strings with a single application.

config
authority
bgp-community-services-profile O365
name O365
application ExchangeOnline
application-name ExchangeOnline
bgp-community 12076:5010
exit
application SharePointOnline
application-name SharePointOnline
bgp-community 12076:5020
exit
application SkypeForBusiness
application-name SkypeForBusiness
bgp-community 12076:5030
exit
application OtherO365
application-name OtherO365
bgp-community 12076:5100
exit
exit
exit
exit

In order to place prefixes learned for these applications in the FIB of a router, services must be created that reference the application-name values chosen above. Example services that correspond to the previously configured O365 profile are shown below.

config
authority
service MSEX
name MSEX
application-name ExchangeOnline
access-policy lan
source lan
exit
exit
service MSSP
name MSSP
application-name SharePointOnline
access-policy lan
source lan
exit
exit
service MSSK
name MSSK
application-name SkypeForBusiness
access-policy lan
source lan
exit
exit
service MSOT
name MSOT
application-name OtherO365
access-policy lan
source lan
exit
exit
exit
exit

Before the router can leverage the application identification module for BGP community services, you must assign a profile to the router as shown below.

config
authority
router router1
name router1
bgp-community-services-profile O365
exit
exit
exit
important

In order for the router to use the prefix values calculated for each application, the application-identification mode module MUST be enabled on the router as shown below.

config
authority
router router1
name router1
application-identification
mode module
exit
exit
exit
exit

Troubleshooting

Pillar Generation

When the plugin is installed on the conductor, each commit triggers a script called generate_pillar to auto-generate pillar data for each node of each router. Please check the following locations on the conductor for debugging information.

  • Logs for the pillar generation for each commit can be found here
/var/log/128technology/plugins/bgp-community-services-generate-pillar.log
  • The actual pillar data containing mappings of application name to community strings can be found here
/var/lib/128technology/plugins/pillar/bgp-community-services/<asset name>.sls

Router Application Identification Module Configuration

If a BGP Community Services Profile has been assigned to the router, the 128T-bgp-community-services router package should be installed on all nodes of the router via Salt. In addition, a configuration file should be generated and a symlink should be created to enable the application module.

  • The configuration for the plugin module, directly generated from pillar data can be found here
/var/lib/128technology/plugins/bgp-community-services/config.json
  • A symlink to the bgp-community-services executible should exist as shown below
# cd /etc/128technology/application-modules/
# ll
total 0
drwxr-xr-x 2 root root 45 Jun 29 23:28 app_module_utils
lrwxrwxrwx 1 root root 70 Jun 30 00:44 bgp-community-services -> /etc/128technology/application-modules/defaults/bgp-community-services
drwxr-xr-x 2 root root 86 Jun 29 23:28 defaults
lrwxrwxrwx 1 root root 21 Jun 29 20:30 office365.py -> defaults/office365.py
#

Application Identification Output

Once the application identification module is setup correctly and a configuration exists, it will begin to generate JSON data in an application module file. If this file does not exist, or if it is not being updated periodically, ensure that application-identification mode module is configured on the router.

  • The application module file is located here
/var/run/128technology/application-modules/bgp-community-services.json

The contents of this file should show a JSON mapping of the user defined application names to a list of prefixes. If the module had any difficulties producing the data, it should generate an error message that can be used to help in determining the reason for the failure. The failure will also indicate which application and community string the module was processing when it encountered a failure. This may be useful in determining if the failure happened initially with the first application/community or later in the processing of the dta. Some examples are shown below.

  • This error indicates that the routingManager API was not available to be queried. Please ensure the correct 128T software version is running on the router with this capability.
{
"module-name": "bgp-community-services",
"duration": 60,
"continue-file-watch": true,
"services": {},
"error": "URLError: [Errno 111] Connection refused on application ExchangeOnline and community 12076:5010"
}
  • This error indicates that the routingManager API was available but returned an error.
{
"module-name": "bgp-community-services",
"duration": 60,
"continue-file-watch": true,
"services": {},
"error": "HTTPError: 502 Bad Gateway on application ExchangeOnline and community 12076:5010"
}
  • This error indicates that routingManager did not return the expected data. Check to ensure BGP is configured correctly on the router.
{
"module-name": "bgp-community-services",
"duration": 60,
"continue-file-watch": true,
"services": {},
"error": "AttributeError: 'str' object has no attribute 'get' on application ExchangeOnline and community 12076:5010"
}
  • An empty result like this indicates that no match was found for the configured BGP community strings. Please check the received prefixes to ensure you are getting the communitie strings you expect.
{
"module-name": "bgp-community-services",
"duration": 60,
"continue-file-watch": true,
"services": {}
}

Azure Express Route O365 Profile Definition

The output here is provided in flat format to facilitate copy/pasting into an existing 128T conductor or router. This can be used to create a proile named O365 which can be assigned to specific routers. It will define application-names ExchangeOnline, SharePointOnline, SkypeForBusiness, and OtherO365 which can each be used in the application-name field to define a service.

config authority bgp-community-services-profile O365 name O365
config authority bgp-community-services-profile O365 application ExchangeOnline application-name ExchangeOnline
config authority bgp-community-services-profile O365 application ExchangeOnline bgp-community 12076:5010
config authority bgp-community-services-profile O365 application SharePointOnline application-name SharePointOnline
config authority bgp-community-services-profile O365 application SharePointOnline bgp-community 12076:5020
config authority bgp-community-services-profile O365 application SkypeForBusiness application-name SkypeForBusiness
config authority bgp-community-services-profile O365 application SkypeForBusiness bgp-community 12076:5030
config authority bgp-community-services-profile O365 application OtherO365 application-name OtherO365
config authority bgp-community-services-profile O365 application OtherO365 bgp-community 12076:5100
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