Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?

 
 

Preparing for a Unified ISSU in an MX Series Virtual Chassis

Starting in Junos OS Release 14.1, you can perform a unified in-service software upgrade (unified ISSU) in an MX Series Virtual Chassis. Before you begin such an upgrade, perform the following tasks to help ensure its success.

Note:

For recommended settings on MX Virtual Chassis devices, please consult Maximizing Scaling and Performance for MX Series Virtual Chassis on the Juniper Networks Knowledge Base.

To prepare for a unified ISSU in a two-member MX Series Virtual Chassis:

  1. Back up the existing system software to each member router’s hard disk so you can roll back to it if necessary.

    Isssue the request system snapshot all-members command to archive data and executable areas for all members of the Virtual Chassis configuration.

  2. Make sure enhanced IP network services is configured.
  3. Verify that both graceful Routing Engine switchover (GRES) and nonstop active routing (NSR) are enabled.
  4. Make sure the router is configured to delay for 180 seconds (3 minutes) before removing access routes and access-internal routes for DHCP and PPP subscriber management after a graceful Routing Engine switchover takes place.
  5. Ensure that the router is configured to use a hold-time value of 300 seconds when negotiating a BGP connection with the peer.
  6. Stop all CPU-intensive periodic operations running on the Virtual Chassis in order to conserve system resources.

    Examples of such CPU-intensive operations include, but are not limited to, periodic SNMP Get and SNMP Walk requests, isssuing Junos OS operational mode commands with detailed or extensive output, and runnning Stylesheet Language Alternative Syntax (SLAX) operational scripts that monitor device status or network events.

  7. (Aggregated Ethernet interfaces only) If you are using aggregated Ethernet interfaces, make sure each interface is configured to use a slow interval (every 30 seconds) for periodic transmission of Link Aggregation Control Protocol (LACP) packets.
  8. (IS-IS interfaces only) If you are using IS-IS interfaces configured with the iso protocol family, make sure the link-state PDU lifetime value (lsp-lifetime) is set to 65317 seconds.
Best Practice:

For additional information about unified ISSU, consult our Knowledge Base.

Change History Table

Feature support is determined by the platform and release you are using. Use Feature Explorer to determine if a feature is supported on your platform.

Release
Description
14.1
Starting in Junos OS Release 14.1, you can perform a unified in-service software upgrade (unified ISSU) in an MX Series Virtual Chassis.