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Understanding Junos Fusion Ports

 

In a Junos Fusion topology, cascade, uplink, and extended ports are components that play key roles. Figure 1 and Figure 2 show sample Junos Fusion topologies, which serve as points of reference for this discussion of cascade, uplink, and extended ports.

In the Junos Fusion topology shown in Figure 1, two aggregation devices and two satellite devices are deployed. The aggregation devices are connected to each other through a multichassis link aggregation group (MC-LAG). Each satellite device is connected to its respective aggregation device through one or two links.

In the Junos Fusion Data Center topology shown in Figure 2, four aggregation devices and four satellite devices are deployed. The four aggregation devices form an EVPN core fabric wherein each satellite device is multihomed to each aggregation device. Also, in this topology, some hosts are single-homed to a satellite device, and other hosts are multihomed to two satellite devices.

On the aggregation devices in each illustration, each link is connected to a cascade port (for example, CP1 on Aggregation device 1), while on the satellite devices, each link is connected to an uplink port (for example, UP1 on Satellite device 1). Hosts 1 through 4 are connected to Satellite device 1 through extended ports EP1 through EP4, and so on.

Figure 2: Cascade, Uplink, and Extended Ports in a Junos Fusion Data Center Topology With Four Aggregation Devices and EVPN
 Cascade, Uplink, and
Extended Ports in a Junos Fusion Data Center Topology With Four Aggregation
Devices and EVPN

This topic provides the following information:

Understanding Cascade Ports

A cascade port is a physical interface on an aggregation device that provides a connection to a satellite device. A cascade port on an aggregation device connects to an uplink port on a satellite device.

On an aggregation device, you can set up one or more cascade port connections with a satellite device. For example, in the Junos Fusion topology shown in Figure 1, Aggregation device 1 has one cascade port connection (CP1) to Satellite device 1, and Aggregation device 2 has two cascade port connections (CP2 and CP3) to Satellite device 2. In the Junos Fusion Data Center in Figure 2, where EVPN multihoming is implemented, each aggregation device is connected to each satellite device through one cascade port. For example, on Aggregation device 1, cascade port CP1 is connected to the leftmost satellite device, cascade port CP2 is connected to the next satellite device, and so on.

When there are multiple cascade port connections to a satellite device, as shown in Figure 1, the traffic handled by the ports is automatically load-balanced. For a packet destined for a satellite device, the cascade port over which to forward the packet is chosen based on a per-packet hash that is computed using key fields in the packet. To select the key fields to be used, you can specify the hash-key statement in the [edit forwarding-options] hierarchy or the enhanced-hash-key statement in the [edit forwarding-options], [edit logical-systems logical-system-name routing-instances instance-name forwarding-options], and [edit routing-instances instance-name forwarding-options] hierarchies.

Note

The 802.1BR tag is not included in the load-balancing hash computation for cascade ports.

In addition, a cascade port can handle the traffic for all extended ports on a particular satellite device. However, you cannot specify that a particular cascade port handle the traffic for a particular extended port.

After you configure an interface as a cascade port (for example, by issuing set interfaces xe-0/0/1 cascade-port), you cannot configure the interface as a Layer 2 interface (for example, by issuing set interfaces xe-0/0/1 unit 0 family bridge) or a Layer 3 interface (for example, set interfaces xe-0/0/1 unit 0 family inet). If you try to configure a cascade port as a Layer 2 or Layer 3 interface, you receive an error message.

On a cascade port, you can configure class-of-service (CoS) policies.

Understanding Uplink Ports

An uplink port is a physical interface on a satellite device that provides a connection to an aggregation device. An uplink port on a satellite device connects to a cascade port on an aggregation device.

After a cascade port is configured on the aggregation device end of a link, a corresponding uplink port is automatically created on the satellite device. From the aggregation device, you can monitor port and queue statistics for uplink ports. However, we do not recommend that you configure Layer 2 or Layer 3 forwarding features on uplink ports.

On a satellite device, you can set up one or more uplink port connections to an aggregation device. For example, in the Junos Fusion topology shown in Figure 1, Satellite device 1 has one uplink port (UP1) to Aggregation device 1, and Satellite device 2 has two uplink ports (UP2 and UP3) to Aggregation device 2. In the Junos Fusion Data Center in Figure 2, where EVPN multihoming is implemented, each satellite device is connected to each aggregation device through an uplink port. For example, on the leftmost satellite device, uplink port UP1 is connected to Aggregation device 1, uplink port UP2 is connected to Aggregation device 2, and so on.

When a satellite device has multiple uplink ports to an aggregation device, the traffic from the extended ports is automatically load-balanced among the uplink ports. For example, in the Junos Fusion topology shown in Figure 1, the traffic from extended ports EP5 through EP8 is load balanced between uplink ports UP2 and UP3 to reach Aggregation device 2. In this situation, each packet is examined, and if an IPv4 or IPv6 header is found, a load-balancing algorithm chooses the uplink port based on the header (source and destination IP addresses, and source and destination TCP/UDP ports). If an IPv4 or IPv6 header is not found, the load-balancing algorithm chooses the uplink port based on the Layer 2 header (destination and source MAC addresses, Ethertype, and outer VLAN ID) of the packet.

Understanding Extended Ports

An extended port is a physical interface on a satellite device that provides a connection to servers or endpoints. To an aggregation device, a satellite device appears as an additional Flexible PIC Concentrator (FPC) and the extended ports on the satellite device appear as additional interfaces to be managed by the aggregation device.

On aggregation devices, you can configure extended ports by using the same Junos OS CLI and naming convention used for Junos OS interfaces on standalone routers and switches. The only difference is that when you specify an extended port name, the FPC slot number must be in the range of 100 through 254 in Junos OS Release 14.2 and in the range of 65 through 254 in Junos OS Release 16.1 and later.

For example, for the four extended ports shown on Satellite device 1 in Figure 1 and the leftmost satellite device in Figure 2, the FPC slot number could be 100, the PIC slot number could be 0, the first extended port could be 1, the second extended port could be 2, the third extended port could be 3, and the fourth extended port could be 4. The complete 10-Gigabit Ethernet extended port names could be as follows:

xe-100/0/1

xe-100/0/2

xe-100/0/3

xe-100/0/4

You can configure the following features on extended ports:

  • Layer 2 bridging protocols

  • Integrated routing and bridging (IRB)

  • Firewall filters

    Note

    In a Junos Fusion Data Center with EVPN wherein VXLAN encapsulation is used, firewall filters with next-interface or next-ip actions are not supported.

  • CoS policies