Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?

Configure Service Chaining With PNF

 

This section shows how to create Layer 3 PNF service chains for inter-LR traffic.

Service Chaining Using a PNF

Service Chaining provides security control and enforcement through a physical firewall on traffic between virtual networks that are attached to logical routers. By default, virtual networks attached to the same logical router can communicate only using Layer 3 routing. Virtual networks connected to different logical routers cannot communicate. Service chaining using a firewall (a physical network function) between the logical routers allows virtual networks on separate logical routers to communicate and to communicate in a secure way.

For CEM service chaining you insert a physical network function (PNF) device between two logical routers on a border spine or border leaf device. The PNF device allows for Layer 3 communication between the logical routers. Only Juniper SRX Services Gateways are supported as PNF devices.

Figure 1 shows a logical view of service chaining. VLANs provide connectivity between the logical routers and the PNF device. EBGP advertises routes between the logical routers and the PNF.

Figure 1: Logical View of Service Chaining
Logical View of Service
Chaining

In a topology that uses border leaf devices, attach the PNF to the border leaf devices as shown in Figure 2.

Figure 2: PNF in Topology with Border Leaf
PNF in Topology with Border Leaf

Service Chaining Configuration Overview

In this example we are configuring service chaining In the following topology to provide inter-LR routing on the blue and green networks as shown in Figure 3. SRX4k and SRX5k Services Gateways are supported as PNFs. Our PNF is an SRX5400 Services Gateway.

Figure 3: Inter-LR Service Chaining
Inter-LR Service Chaining

The virtual networks show in Figure 3 have already been configured. See Configure Virtual Networks for Multi-tenant Service Operations. We are adding PNF service chaining so that devices on each network can communicate with each other as shown with the purple line.

To configure service chaining for inter-LR traffic:

  1. Onboard an SRX device as the PNF device connected to an existing fabric—you can connect the PNF device to a border spine or a border leaf.
  2. Assign PNF service chaining device role to the PNF device and to the border spines or border leaf devices that connect to the PNF device.
  3. Connect the PNF to the fabric using a PNF service template.
  4. Connect the right and left LRs by configuring VLANs and EBGP peering between the PNF and the LRs using a PNF service instance.

Onboard an SRX Services Gateway as the PNF Device

This section shows how to use Contrail Command to integrate an SRX device into our data center fabric to serve as a PNF device.

This configuration assumes that you have already created your fabric. You must use the Brownfield Wizard to onboard the PNF device. You can’t onboard a PNF using the Greenfield Wizard.

SRX clusters are not supported for PNF service chaining.

To selectively onboard an SRX Series router as a PNF device onto an existing fabric:

  1. Select Fabrics, and then select the fabric to which you want to add the SRX Series gateway.
  2. Select Action > Brownfield Wizard.
  3. On the Create Fabric screen, configure the Management subnet, then select Additional Configuration, and enter the PNF ServiceChain subnets.

    In this example, we are assigning 10.102.70.215/32 as the Management subnet and 10.200.0.0/24 as the PNF ServiceChain subnet. The Management subnet is used to search for the device. The PNF ServiceChain subnet is used to establish the EBGP session between the PNF device and the spine.

    Name

    DC1

    Overlay ASN

    64532

    Node Profile

    Select the SRX device

    VLAN-ID Fabric-Wide Significance

    Check box

    Management subnets

    (used to search for the device)

    10.102.70.215

    PNF ServiceChain subnets (subnet used to establish EBGP session between the PNF device and the spine.

    10.200.0.0/24

  4. Click Next, and then click Finish.

Assign Device Roles for Spines or Border Leaf Devices

In this procedure we will assign the PNF service chaining role for the spine or border leaf devices that connect to the PNF.

To assign roles:

  1. On the Fabric Devices summary screen, select Action>Reconfigure Roles.
  2. Next to the spine or border leaf devices, select Assign Roles.
  3. Assign the PNF-Servicechain role to the SRX device and click Assign.

Create a PNF Service Template

The service template provides Contrail Command with information about how the PNF device attaches to the spine or border leaf device. In our example, we are using the following interface numbers:

To create a PNF service template:

  1. Click Infrastructure>Services>Catalog.

    The VNF Service Instances page is displayed.

  2. Click the PNF tab.

    The Create PNF Service Template page is displayed.

  3. Click Create.
  4. Select Instance (with Template) from the list that appears.

    The Create PNF Service Instance page is displayed.

  5. Enter the following information in the PNF Service Template pane and click Create.

    Field

    Value

    Name

    PNF

    PNF Device

    DC2-PNF

    PNF Left Interface

    xe-2/2/1

    PNF Left Fabric

    DC2

    PNF Left Attachment Points (Attachment points on the spine or border leaf.)

    Specify how the spine or border leaf device attaches to the left interface of the PNF device:

    Physical Router—DC2-Spine1

    Left Interface—xe-0/0/34:0

    PNF Right Interface

    xe-2/2/2

    PNF Right Fabric

    DC2

    PNF Right Attachment Points (Attachment points on the spine or border leaf.)

    Specify how the spine or border leaf device attaches to the right interface of the PNF device:

    Physical Router—DC2-Spine2

    Right Interface—xe-0/0/34:0

Create a PNF Service Instance

A PNF service instance defines how logical routers are interconnected and how BGP reachability is exchanged between the PNF and the logical routers. The configuration includes VLANs that arne created between the PNF and the logical routers along with EBGP peering.

Figure 4: Completed PNF Configuration
Completed PNF Configuration

To create a PNF Service Instance:

  1. Navigate to Services > Deployments, and select the PNF tab.

    The PNF Service Instances screen displays.

  2. Select Create Instance.

    Configure the screen as shown here:

  3. Enter the following information in the PNF Service Template pane and click Create.

    Field

    Value

    Name

    Spine-to-PNF

    Service Template

    PNF template

    PNF eBGP ASN

    65231

    Left Tenant Logical Router

    LR1

    PNF Left BGP Peer ASN

    64512

    Left Service VLAN (VLAN between the PNF and the LR1)

    201

    Right Tenant Logical Router

    LR2

    Right BGP Peer ASN

    64512

    Right Service VLAN (VLAN between the PNF and LR2)

    202

Verify Service Chaining

  1. To check that inter-LR traffic is working, ping from a server on one virtual network to a server on another virtual network. Here we are running ping from BMS1 to BMS4.
  2. Run traceroute from BMS1 to BMS4.
  3. On the PNF, show that BGP peers are up.
  4. Show the BGP routing information being advertised to 10.200.0.5 and 10.200.0.13.
  5. Display routing information received from 10.200.0.5 and 10.200.0.13