Citrix SD-WAN

Zones

March 12, 2021

Contributed by:

S C

You can configure zones in the network and define policies to control how traffic enters and leaves zones. By default, the following zones are created:

Internet_Zone
- Applies to traffic to or from an Internet service using a Trusted interface.
Untrusted_Internet_Zone
- Applies to traffic to or from an Internet service using an Untrusted interface.
Default_LAN_Zone
- Applies to traffic to or from an object with a configurable zone, where the zone has not been set.

You can create your own zones and assign them to the following types of objects:

Virtual Network Interfaces (VNI)
Intranet Services
GRE Tunnels
LAN IPsec Tunnels

The following illustration displays the three zones pre-configured. Additionally, you can create your own zones as required. In this example, the zone “ZoneA_Intranet” is a user created zone. It is assigned to the Virtual Interface of the bypass segment (ports 1 and 2) of the SD-WAN appliance.

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The source zone of a packet is determined by the service or virtual network interface a packet is received on. The exception to this is virtual path traffic. When traffic enters a virtual path, packets are marked with the zone that originated the traffic and that source zone is carried through the virtual path. This allows the receiving end of the virtual path to make a policy decision based on the original source zone before it entered the virtual path.

For example, a network administrator may want to define polices so that only traffic from VLAN 30 at Site A is allowed to enter VLAN 10 at Site B. The administrator can assign a zone for each VLAN and create policies that permit traffic between these zones and blocks traffic from other zones. The screenshot below shows how a user would assign the “ZoneA_Intranet” zone to VLAN 10. In this example, the “ZoneA_Intranet” zone was previously defined by the user in order to assign it to Virtual Interface “VirtualInterface-2”.

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The destination zone of a packet is determined based on the destination route match. When a SD-WAN appliance looks up the destination subnet in the route table, the packet will match a route, which has a zone assigned to it.

Source zone
- Non-Virtual Path: Determined through the Virtual Network Interface packet was received on.
- Virtual Path: Determined through source zone field in packet flow header.
- Virtual network interface - the packet was received on at source site.
Destination zone
- Determined through destination route lookup of packet.

Routes shared with remote sites in the SD-WAN maintain information about the destination zone, including routes learned through dynamic routing protocol (BGP, OSPF). Using this mechanism, zones gain global significance in SD-WAN network and allow end-to-end filtering within the network. The use of zones provides a network administrator an efficient way to segment network traffic based on customer, business unit, or department.

The capability of SD-WAN firewall allows the user to filter traffic between services within a single zone, or to create policies that can be applied between services in different zones, as shown in figure below. In the example below, we have Zone_A and Zone_B, each of which has a LAN Virtual network interface.

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Screenshot below displays the inheritance of zone for a Virtual IP (VIP) from its assigned Virtual Network Interface (VNI).

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Zones

March 12, 2021

Contributed by:

S C

March 12, 2021

Contributed by:

S C

Zones

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