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Unified ISSU System Requirements

Unified ISSU Junos OS Release Support

To perform a unified ISSU, your device must be running a Junos OS release that supports unified ISSU 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. However, note that:

• The unified ISSU process is aborted if the Junos OS version specified for installation is a version earlier than the one currently running on the device. To downgrade from an ISSU-capable release to a previous software release (ISSU-capable or not), use the request system add command. Unlike an upgrade using the unified ISSU process, a downgrade using the request system add command can cause network disruptions and loss of data. For more information about the use of the request system add command, see the Installation and Upgrade Guide.
• The unified ISSU process is aborted if the specified upgrade has conflicts with the current configuration, components supported, and so forth.
• Unified ISSU does not support extension application packages developed with the Junos SDK.

Unified ISSU Platform Support

Table 1 lists the platforms on which a unified ISSU is supported.

Unified ISSU Protocol Support for M, MX, and T Series Routers

Unified ISSU depends on nonstop active routing. Table 2 lists the protocols that are supported during a unified ISSU.

Unified ISSU Support for the Layer 2 Control Protocol Process

Unified ISSU supports the Layer 2 Control Protocol process (l2cpd) on MX Series 3D Universal Edge Routers. In a Layer 2 bridge environment, spanning tree protocols share information about port roles, bridge IDs, and root path costs between bridges that use special data frames called Bridge Protocol Data Units (BPDUs). The transmission of BPDUs is controlled by the l2cpd process. Transmission of hello BPDUs is important in maintaining adjacencies on the peer systems.

The transmission of periodic packets on behalf of the l2cpd process is carried out by periodic packet management (PPM), which, by default, is configured to run on the Packet Forwarding Engine. The PPM daemon (ppmd) process on the Packet Forwarding Engine ensures that the BPDUs are transmitted even when the l2cpd process control plane is unavailable, and keeps the remote adjacencies alive during unified ISSU. However, if you want the distributed ppmd process to run on the Routing Engine instead of the Packet Forwarding Engine, you can disable the ppmd process on the Packet Forwarding Engine by including the no-delegate-processing statement at the [edit routing-options ppm] hierarchy level.

Note: The delegate-processing statement at the [edit routing-options ppm] hierarchy level, which was used to enable the ppmd process on the Packet Forwarding Engine in Junos OS Release 9.3 and earlier, has been deprecated. The ppmd process is enabled on the Packet Forwarding Engine by default in Junos OS Release 9.4 and later.

Unified ISSU enhancements and nonstop active bridging support for the l2cpd process ensure that the new master Routing Engine is able to take control during unified ISSU without any disruptions in the control plane. The ISSU enhancements also minimize the disruptions in the Layer 2 data plane during unified ISSU.

Unified ISSU Protocol Support for PTX5000 Routers

Table 3 lists the protocols that are supported during a unified ISSU on PTX5000 routers.

Unified ISSU Feature Support

• Link Aggregation Control Protocol (LACP)—Link changes are not processed until after the unified ISSU is complete.

  Note: When you configure ISSU on the T4000 Core Router, you can also configure the LACP protocol. However, LACP periodic fast mode is not supported. If you configure LACP periodic, set it to slow mode at both sides before initiating an ISSU. If fast mode is configured, the configuration can be committed without any commit or system log error messages, but you might notice that a larger than expected amount of traffic drops because of the LACP links going down during an ISSU.

  Note: LACP is not supported on the PTX5000 during ISSU.

• 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 message 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 devices 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 IQ PICs
• Enhanced IQ2 Ethernet Services Engine (ESE) PIC

Note: For information about FPC types, FPC/PIC compatibility, and the initial Junos OS Release in which an FPC supported a particular PIC, see the PIC guide for your platform.

PIC Considerations

• 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 OS 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 device is being upgraded from, the upgrade will be aborted.
  • If a PIC combination is not supported by the software version to which the device is being upgraded, the in-service software upgrade will abort, even if the PIC combination is supported by the software version from which the device 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 device 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 4 lists the SONET/SDH PICs that are supported during a unified ISSU.

Fast Ethernet and Gigabit Ethernet PICs

Table 5 lists the Fast Ethernet and Gigabit Ethernet PICs that are supported during a unified ISSU.

Note: Starting with Junos OS Release 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 OS release.

Channelized PICs

Table 6 lists the channelized PICs that are supported during a unified ISSU.

Tunnel Services PICs

Table 7 lists the Tunnel Services PICs that are supported during a unified ISSU.

ATM PICs

Table 8 lists the ATM PICs that are supported during a unified ISSU. The table includes support on Enhanced III FPCs.

Serial PICs

• PB-2EIA530 on M320 routers with Enhanced III FPCs, and on M120 routers
• PE-2EIA530 on M10i routers

DS3, E1, E3, and T1 PICs

• 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)

Note: Unified ISSU is also supported on 4-Port DS3 PIC (PB-4DS3) and 4-port E3 IQ PIC (PB-4E3-QPP) on the TX Matrix Plus router.

• 2-Port DS3 PIC (PE-2DS3)
• 4-Port DS3 PIC (PE-4DS3)
• 4-Port E1 PICs (PE-4E1-COAX and PE-4E1-RJ48)
• 2-Port E3 PIC (PE-2E3)
• 4-Port T1 PIC (PE-4T1-RJ48)
• 4-Port E3 IQ PIC (PE-4E3-QPP)

Enhanced IQ PICs

• 1-Port Channelized OC12/STM4 enhanced IQ PIC (PB-1CHOC12-STM4-IQE-SFP)
• 1-Port nonchannelized OC12/STM4 enhanced IQ PIC (PB-1OC12-STM4-IQE-SFP)
• 4-Port Channelized DS3/E3 enhanced IQ PIC (PB-4CHDS3-E3-IQE-BNC)
• 4-Port nonchannelized DS3/E3 enhanced IQ PIC (PB-4DS3-E3-IQE-BNC)
• 4-Port nonchannelized SONET/SDH OC48/STM16 Enhanced IQ (IQE) PIC with SFP (PC-4OC48-STM16-IQE-SFP)

Unified ISSU supports 1-port Channelized OC48/STM16 Enhanced IQ (IQE) PIC with SFP (PB-1CHOC48-STM16-IQE-SFP) on MX Series routers.

Enhanced IQ2 Ethernet Services Engine (ESE) PIC

Unified ISSU supports the enhanced IQ2 ESE PICs listed in Table 9.

Unified ISSU FPC Support on T4000 Routers

In the FPCs on T4000 routers, interface-specific and firewall filter statistics are preserved across a unified ISSU. During the unified ISSU, counter and policer operations are disabled.

To preserve statistics across a unified ISSU on T4000 routers with FPC/PIC interfaces, the router stores the statistics data as binary large objects. The router collects the statistics before the unified ISSU is initialized, and restores the statistics after the unified ISSU completes. No statistics are collected during the unified ISSU process.

To verify that statistics are preserved across the unified ISSU, you can issue CLI operational commands such as show interfaces statistics after the unified ISSU completes.

• T4000 FPC5 (Model Numbers—T4000-FPC5-3D and T4000-FPC5-LSR)
• Enhanced Scaling FPC4-1P (Model Number—T640-FPC4-1P-ES)
• Enhanced Scaling FPC4 (Model Number—T1600-FPC4-ES)
• Enhanced Scaling FPC3 (Model Number—T640-FPC3-ES)
• Enhanced Scaling FPC2 (Model Number—T640-FPC2-ES)

Unified ISSU Support on MX Series 3D Universal Edge Routers

The following sections list the Dense Port Concentrators (DPCs), Flexible PIC Concentrators (FPCs), Modular Port Concentrators (MPCs), and Modular Interface Cards (MICs) that are supported during a unified ISSU on MX Series routers.

• Unified ISSU DPC and FPC Support on MX Series Routers
• Unified ISSU MIC and MPC Support on MX Series Routers
• Unified ISSU Limitation on MX Series Routers

Unified ISSU DPC and FPC Support on MX Series Routers

Unified ISSU supports all DPCs except the Multiservices DPC on MX Series routers. Unified ISSU also supports FPC type 2 (MX-FPC2) and FPC type 3 (MX-FPC3) on MX Series routers. For more information about DPCs and FPCs on MX Series routers, go to https://www.juniper.net/techpubs/ en_US/release-independent/junos/ information-products/pathway-pages/mx-series/.

Unified ISSU MIC and MPC Support on MX Series Routers

Unified ISSU supports all the Modular Port Concentrators (MPCs) and Modular Interface Cards (MICs) listed in Table 10 and Table 11. Unified ISSU is not supported on MX80 routers or in an MX Series Virtual Chassis.

In the MPCs on MX Series routers, interface-specific and firewall filter statistics are preserved across a unified ISSU. During the unified ISSU, counter and policer operations are disabled.

To preserve statistics across a unified ISSU on MX Series routers with MPC/MIC interfaces, the router stores the statistics data as binary large objects. The router collects the statistics before the unified ISSU is initialized, and restores the statistics after the unified ISSU completes. No statistics are collected during the unified ISSU process.

To verify that statistics are preserved across the unified ISSU, you can issue CLI operational commands such as show interfaces statistics after the unified ISSU completes.

Note: Note that unified ISSU is supported only by the MICs listed in Table 11.

Unified ISSU Limitation on MX Series Routers

Unified ISSU is currently not supported when clock synchronization is configured for Synchronous Ethernet, Precision Time Protocol (PTP), and hybrid mode on MX80 routers and on the MICs and MPCEs on MX240, MX480, and MX960 routers.