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The graceful Routing Engine switchover (GRES) feature enables a device with redundant Routing Engines to continue forwarding packets, even if one Routing Engine fails. GRES preserves interface and kernel information. Traffic is not interrupted. However, GRES does not preserve the control plane. Any updates to the primary Routing Engine are replicated to the backup Routing Engine as soon as they occur.
To preserve routing during a switchover, you must configure GRES with either of the following:
| Product / Application | Software | Introduced Release |
|---|---|---|
| ACX7332 | Junos OS Evolved | 25.4R1 |
| EX2300-C | Junos OS | 15.1X53-D50 |
| EX3400-VC | Junos OS | 15.1X53-D50 |
| EX4100 | Junos OS | 22.2R1 |
| EX4100-F | Junos OS | 22.2R1 |
| EX4100-H-12MP | Junos OS | 24.4R1 |
| EX4100-H-24F | Junos OS | 24.4R1 |
| EX4100-H-24MP | Junos OS | 24.4R1 |
| EX4100 Multigigabit | Junos OS | 22.2R1 |
| EX4300-VC | Junos OS | 13.2X50-D10 |
| EX4300 Multigigabit | Junos OS | 18.2R1 |
| EX4400 | Junos OS | 21.1R1 |
| EX4400 Multigigabit | Junos OS | 21.2R1 |
| EX4400-24X | Junos OS | 23.1R1 |
| EX4650-48Y | Junos OS | 19.3R1 |
| EX9200 | Junos OS | 21.1R1 |
| MX150 | Junos OS | 17.3R1 |
| MX240 | Junos OS | 12.2R1 |
| MX240 | Junos OS | 10.0R2 |
| MX240 | Junos OS | 9.0R1 |
| MX304 | Junos OS | 22.2R3 |
| MX480 | Junos OS | 12.2R1 |
| MX480 | Junos OS | 10.0R2 |
| MX480 | Junos OS | 9.0R1 |
| MX960 | Junos OS | 12.2R1 |
| MX960 | Junos OS | 10.0R2 |
| MX960 | Junos OS | 9.0R1 |
| MX2008 | Junos OS | 15.1F7 |
| MX2010 | Junos OS | 12.3R2 |
| MX2020 | Junos OS | 12.3R1 |
| MX10003 | Junos OS | 17.3R1 |
| MX10004 | Junos OS | 25.2R1 |
| MX10008 | Junos OS | 25.2R1 |
| MX10016 | Junos OS | 19.2R1 |
| vMX | Junos OS | 16.1R3 |
| Next Generation Port Extender | Junos OS | 25.4R1 |
| PTX3000 | Junos OS | 13.2R2 |
| PTX5000 | Junos OS | 12.1X48R1 |
| PTX10004 | Junos OS Evolved | 24.4R1 |
| PTX10004 | Junos OS Evolved | 24.2R2 |
| PTX10004 | Junos OS Evolved | 20.4R1 |
| PTX10008 | Junos OS Evolved | 24.4R1 |
| PTX10008 | Junos OS Evolved | 24.2R2 |
| PTX10008 | Junos OS Evolved | 20.3R1 |
| PTX10008 | Junos OS Evolved | 20.2R1 |
| PTX10016 | Junos OS Evolved | 21.2R2 |
| QFX5110 | Junos OS | 15.1X53-D210 |
| QFX5120-48Y | Junos OS | 19.3R1 |
| QFX5120-32C | Junos OS | 20.3R1 |
| QFX5120-48T | Junos OS | 20.2R1 |
| QFX5120-48YM | Junos OS | 20.4R1 |