SRX 3400 and SRX 3600 Hardware Capabilities and Limitations

The following list describes the hardware capabilities and limitations for the SRX 3400 and SRX 3600 series devices:

• For SRX 3400 and SRX 3600 series devices, each Input/Output Card (IOC) Flexible PIC Concentrator (FPC) or IOC slot has only one Physical Interface Card (PIC), which contains either two 10-Gigabit or sixteen 1-Gigabit Ethernet ports. Table 218 shows the maximum number of cards and ports allowed in an SRX 3400 and SRX 3500 device.

  Table 218: Available NPCs and IO Ports for SRX 3400 and SRX 3600 Devices

  System	IOCs	IO Ports	NPCs
  SRX 3600	7	108 (16 x 6 + 12)	3
  SRX 3400	5	76 (16 x 4 + 12)	2

  Note: The number of ports the Network Processing Unit (NPU) needs to handle may be different than the fixed 10:1 port to NPU ratio for 1G IOC, or the 1:1 ratio for the 10G IOC that is needed on the SRX 5600 and SRX 5800 devices, leading to oversubscription on the SRX 3400 and SRX 3600 devices.

• SRX 3400 and SRX 3600 series devices allow you to install up to three Network Processing Cards (NPC). In a single-NPC configuration, the NPC has to process all of the packets to and from each IOC. However, when there is more than one NPC available, an IOC will only exchange packets with a pre-assigned NPC. You can use the set chassis ioc-npc-connectivity CLI statement to configure the IOC-to-NPC mapping. By default, the mapping is assigned so that the load is shared equally among all NPCs. When the mapping is changed, for example, an IOC or NPC is removed, or you have mapped a specific NPC to an IOC, then the device has to be restarted. For more information, see the JUNOS Software Administration Guide.
• For SRX 3400 and SRX 3600 series devices, the IOC supports the following hierarchical scheduler characteristics:

  Level 1- Shaping at the physical interface (ifd)

  Level 2- Shaping and scheduling at the logical interface level (ifl)

  Level 3- Scheduling at the queue level

  Note: Interface set (iflset) is not supported for the SRX 3400 and SRX 3600 devices.

• Shaping at the port level—In SRX 5600 and SRX 5800 devices, an NPC supports 32 port-level shaping profiles at level 1, such that each front port can have its own shaping profile.

  In SRX 3400 and SRX 3600 devices, an NPC supports only 16 port-level shaping profiles in the hardware, including two profiles that are predefined for 10-Gbps and 1-Gbps shaping rates. The user can configure up to 14 different levels of shaping rates. If more levels are configured, then the closest match found in the 16 profiles will be used instead.

  For example, assume that a system is already configured with the following rates for ifds:

  10Mbps, 20Mbps, 40Mbps, 60Mbps, 80Mbps, 100Mbps, 200Mbps, 300Mbps, 400Mbps, 500Mbps, 600Mbps, 700Mbps, 800Mbps, 900Mbps, 1Gbps (predefined), 10Gbps (predefined)

  Each of these 16 rates is programmed into one of the 16 profiles in the hardware, then consider the following two scenarios.

  1. If the user changes one port’s shaping rate from 1Gbps to 100Mbps, which is already programmed in one of the 16 profiles, the profile with 100Mbps shaping rate will be used by the port.
  2. If the user changes another port’s shaping rate from 1Gbps to 50Mbps, which is not in the shaping profiles, the closest matching profile with 60Mbps shaping rate will be used instead.

  When scenario 2) happens, not all of the user-configured rates can be supported by the hardware. If more than 14 different rates are specified, only 14 will be programmed in the hardware. Which 14 rates are programmed in the hardware depends on many factors. For this reason, we recommend that you plan carefully and use no more than 14 levels of port-level shaping rates.

• Weighed Random Early Discard (WRED) at the port level—Each NPU has 512 MB of frame memory. Also, 10-Gigabit Ethernet ports get more buffers than the 1-Gigabit Ethernet ports. Buffer availability depends on how much bandwidth (number of NPCs, ports, 1-Gigabit or 10-Gigabit, and so forth) the device has to support. The more the bandwidth that the device has to support, the less buffer is available. When two NPCs are available, the amount of frame buffer available is doubled.