The Deutsche Telekom AS3320 Internet network ("AS3320") provides the following BGP community based routing services to IP transit customer networks. A customer network can use these communities to influence routing decisions and manipulate traffic streams within AS3320. There are two general categories of communities:

• Signalling communities that are sent by a customer network to request certain routing services from AS3320.
• Informational communities that AS3320 sends to provide additional information about routes that is not available via other BGP attributes.

2 - Signalling Communities

2.1 - Blackholing

A customer network may request blackholing to defend against Denial of Service (DoS) and Distributed DoS attacks. Blackholing results in AS3320 discarding all traffic to the particular address space. Authorization by AS3320 backbone engineering is required to ensure the affected address space truly belongs to the customer network.

2.2 - NOPEER

This is the recently IETF defined community NOPEER[1]. A customer network can use this to restrict propagation of its routes to AS3320 peers.

2.3 - Local Preference

A customer network can control the route priority within AS3320 for its advertisements by using the following Local Preference communities. Currently, AS3320 assigns the (standard) Local Preference value of 100 by default.

2.4 - Restrict Route Propagation

A customer network may use these communities to restrict propagation of its routes to AS3320 peers. However, the well known community NOPEER should be employed instead of these where appropriate.

2.5 - AS Path Prepending

AS path prepending is a common way of making routes less attractive since AS path length is usually one of the BGP path selection criteria. A customer network may use these communities to selectively request AS3320 to insert additional copies of the AS number 3320 when propagating the customer routes to neighbors.

3 - Informational Communities

3.1 - Route Classification

As information to customer networks, AS3320 sends region and country origins on the routes it advertises and indicates whether the route is imported from a customer, peer or upstream provider.

Route Classification by Region

Route Classification by Country

Route Classification by Neighbor Type