Juniper SRX firewalls protect networks of every size, from a single retail store to a large data center. Juniper calls them services gateways, because they combine routing, firewall and VPN functions in one device.
However, sizing is where most buyers go wrong. This guide explains how to size a firewall, compares the SRX300 and SRX4600, and explains what the SRX4600-AC hardware-only SKU means for licensing.
What Juniper SRX firewalls do
An SRX sits at the edge of a site or a data center and inspects the traffic that crosses it. It enforces security policy, builds VPN tunnels to other sites and routes traffic, all on Junos OS. As a result, teams that already run EX switches or MX routers can manage SRX firewalls with the same skills.
Overall, the range runs from desktop units for branch offices to rack-mount firewalls for data centers. The SRX300 sits at the small end, while the SRX4600 sits near the top.
How to size Juniper SRX firewalls
Start with real traffic, not the size of your internet circuit. Because throughput drops when you turn on VPN and security services, size for the features you will actually use. For example, the SRX300 handles up to 1 Gbps of firewall traffic but 300 Mbps of IPsec VPN.
Throughput and VPN
First of all, list each site's peak traffic and the share that crosses a VPN. Then leave headroom for growth, since a firewall usually stays in place for several years. If most of your traffic goes over IPsec, the VPN figure matters more than the firewall figure.
Ports and interfaces
After that, count the links. A branch might need one WAN link, a backup link and a few LAN ports, while a data center firewall needs 10G or 100G links to the core. So match port types and speeds to the switches and routers around the firewall.
High availability
For critical sites, plan for two firewalls in a cluster. The SRX4600 has dedicated SFP+ HA ports for this, so failover links do not use up data ports. In contrast, a small branch may accept a single SRX300 with a spare on the shelf.
Power and licensing
Also check the power feed and the software. The SRX4600 takes redundant AC or DC supplies, at 1600 W for AC and 1100 W for DC. Meanwhile, security features such as threat prevention often need separate licenses, which we cover below.
Juniper SRX firewalls compared: SRX300 vs SRX4600
These two models sit at opposite ends of the SRX range. So the choice between them usually comes down to site size, traffic and how much redundancy you need.
SRX300 for branches
The SRX300 is a desktop firewall for small branch and retail sites. It has 6 1GbE RJ-45 ports as well as 2 1GbE SFP ports. As a result, it delivers up to 1 Gbps of firewall throughput and 300 Mbps of IPsec VPN.
Because it is small, the SRX300 fits on a shelf or in a small rack. For a chain of stores, it also makes a good standard unit that you can prepare once and ship to each site.
SRX4600 for data centers
The SRX4600 is a 1U next-generation firewall for large enterprises and data centers. It has 4 QSFP28 ports, 8 10GbE SFP+ ports and dedicated SFP+ HA ports. In addition, it supports redundant AC or DC power supplies.
So the SRX4600 fits where traffic runs at 10G and 100G, such as a data center edge or a campus core. It also pairs well with MX routers or QFX switches in the same racks.
What the SRX4600-AC SKU means for licensing
The SRX4600-AC is the AC-powered SRX4600 chassis without a software bundle. By contrast, the SRX4600-SYS-JB-AC is the same hardware bundled with Junos base software. So the difference sits in the software, not the box.
This matters when you buy spare or used hardware. If you already hold the right licenses, then a hardware-only unit can make a cost-effective replacement. However, for a new deployment, plan your software and security licenses before you order, so the firewall arrives ready to run.
Juniper SRX firewalls part numbers we supply
Silverback supplies every model below in new or used condition. So send us the part number, and get pricing and lead time within one business day.
| Part number | Product | Notes |
|---|---|---|
| SRX300 | SRX300 branch firewall | Desktop, 6x 1GbE RJ-45, 2x 1GbE SFP, 1 Gbps firewall |
| SRX4600 | SRX4600 firewall | 1U, 4x QSFP28, 8x 10GbE SFP+, SFP+ HA ports |
| SRX4600-AC | SRX4600 firewall, AC power, hardware only | No software bundle; SRX4600-SYS-JB-AC adds Junos base |
New vs used Juniper SRX firewalls
Used firewalls make sense for spares, labs and sites with steady traffic. For example, a used SRX300 makes a low-cost cold spare for a branch rollout. Still, buy new when you need the latest features and a full support contract from day one.
Before you buy a spare, run show chassis hardware on the live unit. That way, the replacement matches its exact model and power type. Silverback supplies new and used SRX firewalls, tested before they ship. So ask for new or used condition, and read refurbished vs new enterprise hardware for more on the trade-offs.
Buyback and why buy Juniper SRX firewalls from Silverback
Firewalls hold configs, keys and logs, so retire them with care. Silverback buys back old firewalls and offers certified data destruction under R2v3, ISO 14001 and ISO 45001. As a result, sensitive settings do not walk out the door with the hardware.
Silverback is a trusted supplier of Juniper hardware and also a certified HPE Business Partner. See the full Juniper product range, or read our guides to MX edge routers and EX campus switches.
Of course, full specs live on juniper.net. Meanwhile, you can browse our inventory or request pricing for any model above.
Frequently Asked Questions
What is the difference between the SRX4600 and SRX4600-AC?
The SRX4600-AC is the AC-powered SRX4600 chassis without a software bundle. The SRX4600-SYS-JB-AC is the same hardware with Junos base software.
Is the SRX300 enough for a small office?
For many small branches, yes. It offers up to 1 Gbps of firewall throughput and 300 Mbps of IPsec VPN, with 6 RJ-45 ports and 2 SFP ports.
Does the SRX4600 support DC power?
Yes. It takes redundant AC power supplies at 1600 W or DC power supplies at 1100 W.
Do you sell used SRX firewalls?
Yes. Silverback supplies new and used SRX firewalls, tested before they ship. Ask for new or used condition when you request a quote.
Can you wipe our retired firewalls?
Yes. Silverback offers certified data destruction and buys back retired firewalls, so configs and keys leave your network safely.
Get a quote for Juniper SRX firewalls
Whether you need a batch of SRX300 units for branches or an SRX4600 pair for a data center, Silverback can help. Send us your part list, and we will reply with pricing and lead time within one business day.
Then call (888) 391-5211 or get a free quote online. Ask for new or used condition, and tell us your traffic so we can confirm the right size.
