Cross-Site Interconnect lets you establish reliable, high-bandwidth Layer 2 connectivity between your on-premises network sites by using Google's global network.
You can use Cross-Site Interconnect to expand your connectivity globally, or add redundancy or capacity to your network.
Before you use Cross-Site Interconnect
Ensure that you meet the following requirements:
- Be familiar with Cloud Interconnect terminology.
- Your network must physically meet Google's network in a colocation facility. You must provide your own routing equipment. Your on-premises router is typically located in the colocation facility. However, you can also extend your connection to a router outside of the colocation facility.
In the colocation facility, your network devices must support the following technical requirements:
10-Gbps circuits, single mode fiber, 10GBASE-LR (1310 nm), or 100-Gbps circuits, single mode fiber, 100GBASE-LR4
802.1Q VLANs, for cross-site networks that contain wire groups in VLAN mode
How does Cross-Site Interconnect work?
For Cross-Site Interconnect, you provision Cross-Site Interconnect connections between Google's network and each of your on-premises networks.
The following diagram shows an example of two Cross-Site Interconnect connections between Google's network and two on-premises networks.
For the basic setup shown in the diagram, a Cross-Site Interconnect connection is provisioned at each site between Google's network and the on-premises router in a common colocation facility. Your setup might be different if your on-premises router isn't in the same colocation facility as your Cross-Site Interconnect connection.
You can use these connections to create cross-site networks between your sites. The diagram shows a cross-site network with a wire group of type single-wire.
For more information, see the example configurations for wire group topologies and network topologies.
Components
Cross-Site Interconnect uses the following components to connect your on-premises networks to each other:
| Component | Description |
|---|---|
| Cross-Site Interconnect connections | The physical connections between Google and your on-premises network sites. A connection exists in a colocation facility where your on-premises network and Google's network meet. You create separate Cross-Site Interconnect connections for each on-premises network site. |
| Wires | Individual wires transport layer 2 traffic between Cross-Site Interconnect connections. Wires belong to a wire group. |
| Wire group | Defines the configuration of the wires that connect Cross-Site Interconnect connections. Wire groups belong to a cross-site network. A wire group has the following key properties:
|
| Cross-site network | A container for logically grouping related wire groups together. Represents the network that connects your on-premises network sites to each other over Cross-Site Interconnect connections. |
Traffic modes
The following table describes the traffic modes that Cross-Site Interconnect supports. The traffic mode is a setting of a wire group.
| Traffic mode | Description | Supported wire group topologies |
|---|---|---|
| Port mode |
Port mode lets you send all traffic to the same destination regardless of any VLAN tags that are present, which simplifies the configuration but limits you to one wire per connection. Port mode also supports the following features:
|
|
| VLAN mode | VLAN mode lets you create multiple virtual networks (VLANs) on a single connection. You can use VLAN tags to isolate and prioritize traffic for enhanced security and flexibility. VLAN tags must be the same for both endpoints of a wire. |
|
Wire bandwidth
You configure wire bandwidth, in Gbps, by using the unmetered bandwidth setting when creating a wire group.
Consider the following when setting the unmetered bandwidth:
| Property | Description |
|---|---|
| Bandwidth allocation per wire | The unmetered bandwidth that you configure when creating a wire group applies to each wire in the group. Consider an example in which you have a redundant wire group with a bandwidth setting of 10 Gbps:
Ensure that your bandwidth usage doesn't exceed the capacity of an individual wire. In the preceding example, maintaining a bandwidth usage of less than 10 Gbps helps to avoid packet loss by ensuring sufficient capacity in a failover scenario. |
| Quotas and limits |
The following quotas and limits apply to wire bandwidth: For more information, see Quotas and limits. You must check these quotas and limits before you begin provisioning Cross-Site Interconnect as described in Check bandwidth quotas and limits. |
| Connection capacity | You must ensure that the sum of unmetered bandwidth across all wires that use the same Cross-Site Interconnect connection is less than or equal to the capacity of the connection. Google Cloud doesn't return an error if the connection is over provisioned. |
| Bandwidth per direction | Bandwidth is measured separately for each direction of traffic. For example, consider a single wire topology with 10 Gbps of unmetered bandwidth. Traffic from metro A to metro B has 10 Gbps of bandwidth, and traffic from metro B to metro A has a separate 10 Gbps of bandwidth. |
MTU
The MTU for Cross-Site Interconnect is 9000 bytes. This value isn't configurable.
Encryption options
The following encryption options are available for wire groups in port mode:
You can use MACsec for Cloud Interconnect to help you secure traffic on Cross-Site Interconnect connections, specifically between your on-premises router and Google's edge routers. For more information, see MACsec for Cloud Interconnect overview.
All Cross-Site Interconnect connections are MACsec capable.
You can implement end-to-end encryption between your on-premises routers by using a protocol of your choice. However, this configuration might introduce a large flow that can't be load balanced. Keep in mind that your traffic is subject to the limit for Maximum bandwidth per traffic flow on a wire. For more information, see Limits.
Regardless of which option you choose, you can still use other higher-level network security protocols, such as Internet Protocol Security (IPsec) and Transport Layer Security (TLS).
Connection capacity
For Cross-Site Interconnect, physical connections are available in two sizes: 10 Gbps or 100 Gbps.
Provisioning
To provision Cross-Site Interconnect, you start by deciding where you want Cross-Site Interconnect connections and checking that you have the necessary quota. Then, you order Cross-Site Interconnect connections for each site that you want to connect so that Google can allocate the necessary resources and send you a Letter of Authorization and Connecting Facility Assignment (LOA-CFA). After you receive the LOA-CFA, you need to submit it to your vendor so that they can provision the connections between Google's network and your network.
You then need to configure and test the connections with Google before you can use them. After the connections are ready, you can create a cross-site network over the connections.
For detailed steps to provision Cross-Site Interconnect, see the Cross-Site Interconnect provisioning overview.
Pricing
For information about pricing, see Cloud Interconnect pricing.
Wire group topologies
This section describes the topologies that you can configure for wire groups in cross-site networks.
You can create wire groups with the following topologies. To view example configurations for each topology, see its corresponding section.
- Single-wire topology: best for non-critical uses that can tolerate some downtime.
- Redundant topology: recommended for wire groups in port mode. Offers increased reliability and helps minimize downtime.
- Box-and-cross topology: recommended for wire groups in VLAN mode. Helps to ensure maximum uptime for critical applications.
Single-wire topology
The single-wire topology includes the following resources and settings:
- Two Cross-Site Interconnect connections, one connection in one metropolitan area (metro) and one connection in another metro.
- One wire between the connections.
Example configuration
The following example configuration shows two Cross-Site Interconnect
connections in two different metros: ord-zone1-7 and iad-zone1-1, with
a single wire between the metros.
Redundant topology
The redundant topology includes the following resources and settings:
Four Cross-Site Interconnect connections, two connections in one metropolitan area (metro) and two connections in another metro. Connections that are in the same metro must be placed in different edge availability domains (metro availability zones).
If the connections don't meet the preceding requirements, Google Cloud returns an error when you attempt to create a redundant wire group over the connections.
Two wires between the connections, with one wire connecting one pair of corresponding availability zones in each metro and another wire connecting the other pair of corresponding availability zones.
Example configuration
The following example configuration shows four Cross-Site Interconnect
connections in two different metros and different edge availability domains:
ord-zone1-7, ord-zone2-7, iad-zone1-1, and iad-zone2-1. There is
one wire between ord-zone1-7 and iad-zone1-1, and another wire between
ord-zone2-7 and iad-zone2-1.
Box-and-cross topology
The box-and-cross topology includes the following resources and settings:
Four Cross-Site Interconnect connections, two connections in one metropolitan area (metro) and two connections in another metro. Connections that are in the same metro must be placed in different edge availability domains (metro availability zones).
If the connections don't meet the preceding requirements, Google Cloud returns an error when you attempt to create a box-and-cross wire group over the connections.
Four wires between the connections, where there is one wire from each connection to both connections in the opposite metro.
Example configuration
The following example configuration shows four Cross-Site Interconnect
connections in two different metros and different edge availability domains:
ord-zone1-7, ord-zone2-7, iad-zone1-1, and iad-zone2-1. There are
four wires:
- One wire between
ord-zone1-7andiad-zone1-1 - One wire between
ord-zone2-7andiad-zone2-1 - One wire between
ord-zone1-7andiad-zone2-1 - One wire between
ord-zone2-7andiad-zone1-1
Network topologies
While a given wire group can only connect two sites, you can create a cross-site network that connects more than two sites by adding multiple wire groups. This section describes example configurations for connecting three sites: Site A, Site B, and Site C.
If you configure wire groups in VLAN mode, you can use the same Cross-Site Interconnect connections to create multiple wire groups.
Hub and spoke topology
The following example configuration shows a basic hub and spoke topology that includes three sites. In this topology, Site B is the hub and Sites A and C are spokes. This example configuration includes the following:
- One redundant wire group between Site A and Site B
- One redundant wire group between Site B and Site C
You can add more spokes to this topology by adding a wire group between Site B and each additional site that you want to connect.
Ring topology
The following example configuration shows a ring topology that connects three sites directly with each other. This example configuration includes the following:
- One redundant wire group between Site A and Site B
- One redundant wire group between Site B and Site C
- One redundant wire group between Site A and Site C
What's next
- See colocation facilities for Cross-Site Interconnect
- Get an overview of provisioning Cross-Site Interconnect