Establishing a BGP Connection and Announcing PI Prefix

Selectel clients who want to use their own provider-independent, official public IP addressing can announce their PI subnet in two options:

  • Establishing BGP Connection if the client has their own PI subnet and Autonomous System (AS);
  • Announcing PI Prefix if the client only has a PI subnet.

Glossary

Terms Definition
Region Data center locations
BGP A global dynamic routing protocol between autonomous systems (AS)
RIPE Database
RIPE DB
A public database containing information about which organization owns blocks of IP addresses, AS numbers, etc.
Learn more at ripe.net/manage-ips-and-asns
AS (Autonomous System) A unique identifier that defines a group of routers announcing a common address space that maintain a single management policy.
The AS number is a key part of the BGP configuration.
This object is registered in the RIPE DB
AS-SET An object used to describe the group of autonomous systems and the entire address space announced via BGP.
This object is registered in the RIPE DB
Route object A RIPE database object that is a combination of the IPv6 prefix and the AS number from which this prefix is announced.
The route object is required for creating route filters on the border equipment of BGP routers on the Internet
Routing policy Describes the rules of interaction between BGP routers and affects the subnet announcement and passing the route both from the AS and to it.
There are three options available:
- default route only
- full-view
- default route only + full-view
PI (Provider Independent) Provider independent IP addresses.
Belong to the end user (individual or legal entity), and not the telecom operator that the user is connected to.
When changing a telecoms operator or connection point, the addresses are retained by the user
Next-hop An IP address from the public subnet allocated to the user and assigned to the user’s equipment.
Specifies the next network node on the path of an IP packet to the destination subnet
Neighbor An IP address for establishing a BGP session
Static route A form of routing in which routes are explicitly defined by the admin in the router settings.
When setting a static route, the following parameters are specified:
- destination subnet (to which traffic is routed);
- next-hop (node address) that facilitates further routing
BGP community A BGP protocol attribute used for tagging routes and their subsequent special processing.
List of Selectel BGP community:
- for Saint Petersburg
- for Moscow

Establishing a BGP Connection

The following is required to use the BGP connection service:

  1. A dedicated VLAN (network), learn more about VLAN in the Networks instructions.
  2. An IP address to be specified as neighbor only from a dedicated subnet in the corresponding location (IPv4 or IPv6, depending on the announced PI).
  3. A hardware or software router managed by the client of the PI IP subnet (minimum size /24 for IPv4 and /48 for IPv6).
  4. Use the registered public AS number.
  5. Create a route object of the existing PI subnet in RIPE DB, specifying your AS number in the origin field.
  6. Optionally specify the AS-SET name: if the client’s AS is transit, check the I already have AS-SET box.
  7. When connecting, select one of the three possible options for routing policies:
    • default route only — only route 0.0.0.0/0;
    • full-view — the entire global routing table (requires significant resources from the router);
    • default route only + full-view — both route 0.0.0.0/0 and the entire global routing table.

Scheme of Connecting a Client’s Router via BGP

The client’s router is on L2 VLAN 1000 with the 1.1.1.2/29 IP address. The 1.1.1.1/29 IP address is configured as a gateway on the Selectel router. The client’s router establishes two multihop BGP sessions on Selectel border routers with the 2.2.2.2 and 3.3.3.3 IP addresses.

Please note that a subnet from the Selectel address subspace must be used.

To configure a session with the Selectel border routers, the following must be configured on the client’s router:

  1. One of the options for static routing:
    • static default route through the next-hop 1.1.1.1;
    • two static routes — 2.2.2.2/32 and 3.3.3.3/32 through the next-hop 1.1.1.1.
  2. TTL: you need to set a value of at least 10 for the BGP session to always remain operational regardless of the Selectel network topology.

Enabling the Service

To establish BGP connection in the Control panel:

  1. Go to the Services tab in the Network subsection of the Servers and colocation section.
  2. Click Establish BGP connection.
  3. Fill in the required fields in the new window.
  4. Specify the IP address from the dedicated VLAN (from the Selectel range).
  5. Select the routing policy.
  6. Specify the AS number.
  7. Specify the payment period and check the total cost.
  8. Click Pay.

In the ticket, you will receive a notification that the connection is established.

Announcing PI Prefix (IPv4 and IPv6)

You can choose to announce the PI prefix according to the direct or static scheme.

If the service is enabled for IPv6 addresses, IPv6 blocks are announced only using static-route or via a BGP connection. For IPv4 subnets, the direct scheme is used by default.

The following is required to order and use the Announcing PI prefix service:

  1. A dedicated VLAN (network), learn more about VLAN in the Networks instructions.
  2. PI IP subnets (minimum size /24 for IPv4 and /48 for IPv6).
  3. Create a route object of the announced PI network in RIPE DB, specifying the AS number in the origin field, depending on the region:
    • Saint Petersburg — AS49505
    • Moscow — AS50340
  4. Optional: if using static-route, select and inform next-hop by checking the Use my router as a gateway box when enabling the service. Only an IP address from a dedicated subnet can be used as the next-hop in the corresponding location.

PI Direct Scheme

A gateway on the client’s equipment is not required.

PI Static Scheme

The client’s equipment acts as a gateway for the subnet. There must be a subnet from the Selectel address subspace.

Enabling the Service

To enable the PI prefix announcement in the Control panel:

  1. Go to the Services tab in the Network subsection of the Servers and colocation section.
  2. Click Announce PI Prefix.
  3. Select subnet type in the new window: IPv4 or IPv6.
  4. If IPv4 was selected, specify PI subnet in CIDR notation.
  5. Check the Use my router as a gateway box, if necessary.
  6. Select the location. Subnet will be available for all resources in this location. Please note that you can’t move the subnet to another location.
  7. If IPv6 was selected, specify PI subnet in CIDR notation and next-hop. Please note that to use your router as a gateway, you need to order an IPv6 subnet from the Selectel range.
  8. Specify the payment period and check the total cost.
  9. Click Pay.

In the ticket, you will receive a notification that the connection is established.