🛡️ Juniper SRX340 vs SRX345

The SRX340 and SRX345 are sibling appliances at the top of Juniper's SRX300-series branch line, and the practical difference is incremental rather than architectural. The SRX345 delivers around 6% more stateful firewall throughput (5 Gbps vs 4.7 Gbps), 25% more IPS throughput (1 Gbps vs 800 Mbps), a third more concurrent sessions (512K vs 384K) and two additional Mini-PIM slots. Both run the same Junos OS image, expose the same 16 onboard GE ports and plug into the same Security Director management plane, so day-to-day operations are identical.

The SRX345 earns its premium in two specific scenarios. First, branches that need richer WAN diversity — multiple xDSL, T1/E1, serial or LTE Mini-PIMs alongside the onboard copper — benefit from the extra two expansion slots. Second, sites that want on-box logging or local event retention can fit the optional SSD, which the SRX340 does not support. The higher IPS ceiling also gives more headroom if a UK branch terminates full SSL inspection plus IDP on a single appliance.

The SRX340 remains the more sensible buy where the workload sits comfortably under 4 Gbps with IPS enabled, fewer than four WAN modules are needed, and logging is sent off-box to Security Director, JSA or a SIEM — which is how most UK enterprises run their branches anyway under GDPR and NCSC logging guidance. At list price, the gap between the two does not always justify itself if the extra capacity will sit idle.

Recommendation: choose the SRX345 if you are sizing for 150–250 users, want Mini-PIM headroom for dual or triple WAN plus LTE backup, or need local SSD logging at sites with intermittent connectivity to central management. Choose the SRX340 for standard medium branches up to roughly 150 users with one or two WAN circuits and centralised logging — you get the same Junos feature set and SD-WAN capability at a lower capital cost.

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