Unified ISSU System Requirements

This section contains the following topics:

• Unified ISSU JUNOS Software Release Support
• Unified ISSU Platform Support
• Unified ISSU Protocol Support
• Unified ISSU Feature Support
• Unified ISSU PIC Support
• Unified ISSU DPC Support

Unified ISSU JUNOS Software Release Support

In order to perform a unified ISSU, your router must be running a JUNOS software release that is ISSU capable for the specific platform. See Unified ISSU Platform Support. You can use unified ISSU to upgrade from an ISSU-capable software release to a newer software release. To downgrade from an ISSU-capable release to a previous software release (ISSU-capable or not), use the request system add command. See the JUNOS Software Installation and Upgrade Guide for details.

Note: Unified ISSU does not support extension application packages developed using the Juniper Partner Solution Development Platform (PSDP) SDK.

Unified ISSU Platform Support

Table 12 lists the platforms on which a unified ISSU is supported.

Table 12: Unified ISSU Platform Support

Unified ISSU Protocol Support

Unified ISSU is dependent on nonstop active routing. Table 13 lists the protocols that are supported during a unified ISSU.

Table 13: Unified ISSU Protocol Support

Unified ISSU Support for Layer 2 Control Protocol Process (L2CPD)

Unified ISSU supports the Layer 2 Control Protocol process (L2CPD) on MX-series Ethernet Services routers. In a Layer 2 bridge environment, spanning tree protocols share information about port roles, bridge IDs, and root path costs between bridges using special data frames called Bridge Protocol Data Units (BPDUs). The transmission of BPDUs is controlled by L2CPD. Transmission of hello BPDUs is important in maintaining adjacencies on the peer systems. The transmission of periodic packets on behalf of L2CPD is carried out by periodic packet management (PPM), which, by default, runs on the Routing Engine. However, you can configure the JUNOS software to run PPM on the Packet Forwarding Engine by including the delegate processing statement at the [edit routing-options ppm] hierarchy level. When the delegate processing statement is included in the configuration, L2CPD uses distributed PPM (PPMD) to move the responsibility of sending hello BPDUs to the Packet Forwarding Engine. PPMD in the Packet Forwarding Engine ensures that the BPDUs are transmitted even when the L2CPD control plane is unavailable, and keeps the remote adjacencies alive during unified ISSU.

Unified ISSU enhancements and nonstop active bridging support for L2CPD ensure that the new master Routing Engine is able to take control during unified ISSU without any disruptions in the control plane and minimize the disruptions in the Layer 2 data plane during unified ISSU.

Unified ISSU Feature Support

Unified ISSU supports most JUNOS software features in JUNOS Release 9.0. However, the following constraints apply:

• Link Aggregation Control Protocol (LACP)—Link changes are not processed until after the unified ISSU is complete.
• Automatic Protection Switching (APS)—Network changes are not processed until after the unified ISSU is complete.
• Ethernet Operation, Administration, and Management (OAM) as defined by IEEE 802.3ah and by IEEE 802.1ag—When a Routing Engine switchover occurs, the OAM hello times out, triggering protocol convergence.
• Ethernet circuit cross-connect (CCC) encapsulation—Circuit changes are not processed until after the unified ISSU is complete.
• Logical Systems—On routers that have logical systems configured on them, only the master logical system supports unified ISSU.

Unified ISSU PIC Support

The following sections list the Physical Interface Cards (PICs) that are supported during a unified ISSU.

• PIC Considerations
• SONET/SDH PICs
• Fast Ethernet and Gigabit Ethernet PICs
• Channelized PICs
• Tunnel Services PICs
• ATM PICs
• Serial PICs
• DS3, E1, E3, and T1 PICs
• Enhanced IQ2 Ethernet Services Engine (ESE) PIC

Note: For information about FPC types, FPC/PIC compatibility, and the initial JUNOS software release in which an FPC supported a particular PIC, see the PIC guide for your router platform.

PIC Considerations

Take the following PIC restrictions into consideration before performing a unified ISSU:

• Unsupported PICs—If a PIC is not supported by unified ISSU, at the beginning of the upgrade the software issues a warning that the PIC will be brought offline. After the PIC is brought offline and the ISSU is complete, the PIC is brought back online with the new firmware.
• PIC combinations—For some PICs, newer JUNOS services can require significant Internet Processor ASIC memory, and some configuration rules might limit certain combinations of PICs on particular platforms. With a unified ISSU:
  • If a PIC combination is not supported by the software version that the router is being upgraded from, the upgrade will be aborted.
  • If a PIC combination is not supported by the software version to which the router is being upgraded, the in-service software upgrade will abort, even if the PIC combination is supported by the software version from which the router is being upgraded.
• Interface statistics—Interface statistics might be incorrect because:
  • During bootup of the new microkernel on the Packet Forwarding Engine (PFE), host-bound traffic is not handled and might be dropped, causing packet loss.
  • During the hardware update of the Packet Forwarding Engine and its interfaces, traffic is halted and discarded. (The duration of the hardware update depends on the number and type of interfaces and on the router configuration.)
  • During a unified ISSU, periodic statistics collection is halted. If hardware counters saturate or wrap around, the software does not display accurate interface statistics.
• CIR oversubscription—If oversubscription of committed rate information (CIR) is configured on logical interfaces:
  • And the sum of the CIR exceeds the physical interface's bandwidth, after a unified in-service software upgrade is performed, each logical interface might not be given its original CIR.
  • And the sum of the delay buffer rate configured on logical interfaces exceeds the physical interface's bandwidth, after a unified in-service software upgrade is performed, each logical interface might not receive its original delay-buffer-rate calculation.

SONET/SDH PICs

Table 14 lists the SONET/SDH PICs that are supported during a unified ISSU.

Table 14: Unified ISSU PIC Support: SONET/SDH

Fast Ethernet and Gigabit Ethernet PICs

Table 15 lists the Fast Ethernet and Gigabit Ethernet PICs that are supported during a unified ISSU.

Note: Starting with JUNOS 9.2, new Ethernet IQ2 PIC features might cause the software to reboot the PIC when a unified ISSU is performed. For information about applicable new Ethernet IQ2 PIC features, refer to the release notes for the specific JUNOS release.

Table 15: Unified ISSU PIC Support: Fast Ethernet and Gigabit Ethernet

Channelized PICs

Table 16 lists the channelized PICs that are supported during a unified ISSU.

Table 16: Unified ISSU PIC Support: Channelized

Tunnel Services PICs

Table 17 lists the tunnel services PICs that are supported during a unified ISSU.

Table 17: Unified ISSU PIC Support: Tunnel Services

ATM PICs

Table 18 lists the ATM PICs that are supported during a unified ISSU. This includes support on Enhanced III FPCs.

Table 18: Unified ISSU PIC Support: ATM

Serial PICs

The 2-port EIA-530 serial PIC ( PB-2EIA530) is supported during a unified ISSU on M320 routers with Enhanced III FPCs and on M120 routers.

DS3, E1, E3, and T1 PICs

Unified ISSU supports the following PICs on M120, M320, and T320 routers; T640 and T1600 routing nodes; and the TX Matrix routing platform:

• 4-Port DS3 PIC (PB-4DS3)
• 4-Port E1 Coaxial PIC (PB-4E1-COAX)
• 4-Port E1 RJ48 PIC (PB-4E1-RJ48)
• 4-port E3 IQ PIC (PB-4E3-QPP)
• 4-Port T1 PIC (PB-4T1-RJ48)

Enhanced IQ2 Ethernet Services Engine (ESE) PIC

Unified ISSU supports the enhanced IQ2 ESE PICs listed in

Table 19: Unified ISSU Support: Enhanced IQ2 Ethernet Services Engine (ESE) PIC

Unified ISSU DPC Support

Unified ISSU as of JUNOS Release 9.4 supports all Dense Port Concentrators (DPCs) on the MX-series Ethernet Services routers. For more information about DPCs, see the MX-series Ethernet Services Router DPC Guide.