Citrix SD-WAN

BGP

The SD-WAN BGP routing functionality enables you to:

  • Configure the autonomous system (AS) number of a neighbor or other peer router (iBGP or eBGP).
  • Create BGP policies to be applied selectively to a set of networks on a per-neighbor basis, in either direction (import or export). An SD-WAN appliance supports eight policies per site, with up to eight network objects (or eight networks) associated with a policy.
  • For each policy, users can configure multiple community strings, AS-PATH-PREPEND, MED attribute. Users can configure up to 10 attributes for each policy.

Note

Only local preference and the IGP metric for path selection and manipulation is allowed.

Configuring Neighbors

To configure eBGP, an extra column to the existing BGP neighbors section is added to configure the neighbor AS number. The existing configurations are pre-populated to this field with the local AS number when you import the previous configuration using the SD-WAN 9.2 configuration editor.

The neighbor configuration also has an optional advanced section (expandable row) where you can add Policies for each neighbor.

Configuring Advanced Neighbors

With this option, you can add network objects and add a configured BGP policy for that network object. This is similar to creating a route map and ACL to match certain routes and configuring BGP attributes for that neighbor. You can specify the direction to indicate if this policy is applied for incoming or outgoing routes.

The default policy is to <accept> all routes. Accept and reject policies are defaults and cannot be modified.

You have the ability to match routes based on Network address (destination address), AS Path, Community string and assign a policy and select direction for the policy to be applied.

  1. Go to Monitoring > Routing Protocols > Dynamic Routing Protocols to monitor the configured BGP policies and neighbors for the DC or Branch site appliance.

You can enable debug logging and to view log files for routing from the Monitor > Routing Protocol page. The logs for the routing daemon are split into separate log files. The standard routing information is stored in dynamic_routing.log while dynamic routing issues are captured in dynamic_routing_diagnostics.log which can be viewed from monitoring of routing protocols.

BGP Soft Reconfiguration

Routing policies for BGP peer include configurations such as route-map, distribute-list, prefix-list, and filter-list that might impact inbound or outbound routing table updates. When there is a change in the routing policy, the BGP session must be cleared, or reset, for the new policy to take effect.

Clearing a BGP session using a hard reset invalidates the cache and results in negative impact on the operation of the networks as the information in the cache becomes unavailable.

The BGP Soft Reset Enhancement feature provides automatic support for dynamic soft reset of inbound BGP routing table updates that are not dependent upon stored routing table update information.

Troubleshooting

To view the BGP parameters, navigate to Monitoring > Routing Protocols > select BGP State from the View field.

BGP state 1

You can observe theDynamic routing logs to see if there is any issue with BGP Convergence.

BGP state 2

BGP