The throughput Cisco publishes for the ISR 1100-4G is an SD-WAN IPsec figure: 477 Mbps on 1400-byte packets, 411 Mbps on an IMIX mix, across up to 250 SD-WAN overlay tunnels. Behind that number sits a fanless chassis that Cisco documents as a desk or shelf install rather than a rack install. Entitlement, not hardware, is what a second-hand unit turns on. The hardware itself is 4 GB of DDR4 ECC DRAM, dual 16 MB serial flash and 8 GB of eMMC bulk flash.
What the 477 Mbps figure on an ISR 1100-4G actually measures
Cisco's published throughput for the ISR 1100-4G is an SD-WAN IPsec figure: 477 Mbps on 1400-byte packets, 411 Mbps on an IMIX traffic mix, across up to 250 SD-WAN overlay tunnels. Every part of that sentence is load-bearing. The packet size is stated because encrypted throughput moves with it, the IMIX figure is the mixed-size profile that sits closer to real branch traffic, and the tunnel count is the scaling limit that decides how many sites a hub can terminate.
An SD-WAN figure describes the router doing SD-WAN. That distinction matters more here than on the platforms beside it, because Cisco documents this router for IOS XE SD-WAN in controller mode only, and names 20.9 as the last supported Viptela release. On the Catalyst 8300 and 8200 there is a second published mode to compare against; on this platform the headline throughput number and the licensing question are one question wearing two names.
So size a circuit against the measurement rather than against the number. A branch running an encrypted overlay is described by these figures. A branch doing something else is not described by them at all, and the honest answer in that case is that Cisco has not published the figure you would need.
Where this router physically goes: a desk, a shelf, or a rack tray
Cisco's installation guide puts the ISR 1100-4G on a desk or a shelf, horizontal, on four rubber feet that are part of the cooling design and are not to be removed. It asks for one inch of clearance above the chassis and half an inch at the sides, and it says plainly: do not stack routers. A 19-inch rack tray exists as a separate order line, part ACS-1100-RM1-19, and the router can face either way in it.
That is worth pausing on, because every other router in this catalogue is a rack device and this one is not. The chassis measures 10.2 by 7 by 1.1 inches and weighs 2.67 lb, it is fanless, and Cisco's own documentation treats a flat surface as the default rather than the exception. For a small site with no cabinet - a counter, a back office, a store room with a shelf - that removes a whole line of the installation. For a site that does have a cabinet, the tray is an order line to remember rather than an accessory that arrives in the box.
Two things this page will not tell you. Cisco scopes wall-mounting to routers it describes as designed for wall-mounting and does not describe this one that way, so we make no wall-mount claim. And Cisco publishes no rack-unit class name for this chassis at all; its own form-factor field holds the dimensions instead, which is why the dimensions row is the answer to that question here.
How many Ethernet ports Cisco says this router has, and why that is two answers
Cisco's own documents do not agree on this, and rather than pick a side we will show you both. The ISR 1100 data sheet's Table 9 lists four WAN and four LAN copper Gigabit ports. The architectural-highlights prose in the same data sheet describes up to four built-in 10/100/1000 Ethernet ports for WAN or LAN. The ordering guide carries no port table that would settle it.
A third Cisco surface adds detail without resolving it. The Hardware Installation Guide's comparison-of-models table shows GE SFP ports as zero for this router, and its chassis specifications list GE WAN ports as four with no LAN row at all - the token LAN does not appear in that chapter. The same guide's chassis table for the ISR1100-4GLTE lists both Ethernet RJ45 ports as four and GE WAN ports as four, which shows that Cisco does express an eight-port split when it means one.
We are not going to reconcile that for you, because doing so would mean publishing a number Cisco has not published in a single consistent place. If the port count is load-bearing for your design, ask us to confirm it against the specific unit before you commit to a quote, and we will check the chassis in front of us rather than the document.
Controller mode, and what it means for a second-hand unit
Cisco's data sheet states that this platform runs IOS XE SD-WAN in controller mode only, and names 20.9 as the last supported Viptela release. That is the disclosure, stated as Cisco states it.
What it means commercially is that the software position has to be settled before the hardware is bought, not after. A second-hand chassis arrives as hardware; entitlements belong to the account that purchased them and do not travel with the box. On a platform whose documented software mode is a controller-managed one, that makes the entitlement question the first question rather than an afterthought at the end of a build. Tell us what the deployment is being managed by and we will tell you what the chassis alone does and does not bring with it.
Memory, flash and what each one holds
Three storage figures sit on this router and each one does a different job. There is 4 GB of DDR4 ECC DRAM, which is working memory for the operating system and the processes running on it, with error correction so that a single-bit fault is corrected rather than propagated. There is dual 16 MB serial flash, which is small and deliberately so: it holds the boot code, and having two of them means a failed or interrupted upgrade of one has a second to fall back on.
Then there is 8 GB of eMMC pSLC bulk flash, of which 5.8 GB is usable. The gap between those two numbers is normal and worth explaining rather than hiding: pSLC operation and the space the controller reserves for wear levelling and spare blocks both come out of the raw figure before anything is written. The usable number is the one to size images and logs against. Cisco does not publish a memory expansion option for this platform in the material we have verified, so treat all three figures as fixed for the life of the unit.
| Specification | Cisco ISR 1100-4G |
|---|---|
| Mounting | Desk or shelf, horizontal; fanless; four rubber feet that must stay fitted; not stackable. Optional 19-inch rack tray ACS-1100-RM1-19 |
| Dimensions, W x D x H | 10.2 x 7 x 1.1 in, 259 x 178 x 28 mm |
| Weight | 2.67 lb, 1.21 kg |
| CPU | Intel 2.2 GHz, 4 cores |
| DRAM | 4 GB DDR4 ECC |
| Serial flash | Dual 16 MB |
| Bulk flash | 8 GB eMMC pSLC, 5.8 GB usable |
| SD-WAN IPsec throughput | 477 Mbps at 1400 bytes |
| SD-WAN IPsec at IMIX | 411 Mbps |
| SD-WAN overlay tunnels | 250 |
| Console | 1 x RJ-45, 115,200 baud |
| USB | 1 x Type A, USB 3.0, 4.5 W maximum |
| Cooling and operating temperature | Fanless, 0 to 40 C, 32 to 104 F, at sea level |
| Altitude | Maximum 3000 m, 10,000 ft |
| Humidity | 10 to 85% RH, non-condensing |
| MTBF | 1.6 million hours at 25 C ambient |
| Power supply | External adapter, 30 W, PID 341-100891-01; 100-240 VAC, 50-60 Hz, +12 VDC |
| Physical security | Kensington lock slot |
How the ISR 1100-4G compares with a Cisco ISR 4321
These two branch routers are separated by what their published throughput figures measure, and reading one number against the other without that context produces a false comparison. The row that matters most in this table is the one that names the measurement.
| Specification | ISR 1100-4G | ISR 4321 |
|---|---|---|
| Published throughput | 477 Mbps at 1400 bytes, 411 Mbps at IMIX | 50 Mbps by default, 100 Mbps with the performance licence, 1.6 Gbps at IMIX with Boost |
| What that figure measures | SD-WAN IPsec, an encrypted overlay | IPv4 forwarding, plain routed traffic |
| DRAM | 4 GB DDR4 ECC | 4 GB combined |
| Flash | Dual 16 MB serial, plus 8 GB eMMC bulk with 5.8 GB usable | 4 GB onboard |
Because the two numbers describe different things, no speed comparison between these two columns survives being written down. What the table does show is that one platform is sold and measured as an encrypted overlay device and the other is sold and measured as a routed-traffic device whose rate is tied to a licence, and that is the decision to make first. For the platforms above both of them see the Cisco Catalyst C8200-1N-4T and the Cisco Catalyst C8300-1N1S-4T2X, the full detail on this comparison sits on the Cisco ISR 4321 page, and the range as a whole is on our Cisco routers pages.
Condition, testing and warranty
The part number and the hardware are what Cisco built; the unit is refurbished rather than new. Each one runs the same sequence: inbound test on receipt, disassembly, cleaning, inventory, pick, assembly, configuration and an outbound test before it is packed. Whole systems carry a 2-year Enterasource warranty and ship free by FedEx Ground to the lower 48 states. No Cisco warranty transfers with second-hand hardware and we make no claim that it does.
The external power adapter, the rack tray and any cabling are separate line items unless a listing includes them, and on a router this small it is worth confirming the adapter explicitly rather than assuming it. Software entitlements are a separate purchase and stay with the account that made it. The rest of our refurbished Cisco switches and routers is catalogued alongside this one.
Frequently Asked Questions
How is a Cisco ISR 1100-4G mounted, and is it a rack router?
Cisco's installation guide mounts it on a desk or a shelf, sitting horizontally on four rubber feet that are part of the cooling design and are meant to stay fitted. It is fanless, it asks for an inch of clearance above and half an inch at the sides, and the guide says explicitly that routers should not be stacked on one another. If it does need to go into a cabinet, a 19-inch rack tray is available as part ACS-1100-RM1-19, ordered as its own line, and the router can sit either way round in it.
How many Ethernet ports does a Cisco ISR 1100-4G have?
Cisco publishes two answers and we will give you both rather than choose. Table 9 of the ISR 1100 data sheet lists four WAN and four LAN copper Gigabit ports. The architectural-highlights prose in the same data sheet describes up to four built-in 10/100/1000 Ethernet ports usable for WAN or LAN. The Hardware Installation Guide's chassis table for this model lists four GE WAN ports with no LAN row, while the equivalent table for the ISR1100-4GLTE lists both figures. If the count is load-bearing for your design, ask us to confirm it against the specific unit before quoting.
Is the 477 Mbps figure a general routing number?
No. It is an SD-WAN IPsec measurement taken on 1400-byte packets, with a companion figure of 411 Mbps on an IMIX mix and a scaling limit of up to 250 SD-WAN overlay tunnels. In other words it describes the router running an encrypted overlay, which is the workload Cisco documents this platform for. Applying it to plain routed traffic, or comparing it against a plain forwarding figure published for another platform, compares two different measurements and produces an answer that neither vendor figure supports.
What does "controller mode only" mean for a used ISR 1100-4G?
It is Cisco's own phrase from the data sheet: this platform runs IOS XE SD-WAN in controller mode only, and Cisco names 20.9 as the last supported Viptela release. Practically, it tells you that the software position on this router is a controller-managed one and needs to be settled as part of the purchase rather than after it. A second-hand chassis arrives as hardware, and entitlements belong to the account that bought them rather than to the box, so the management question comes first.
What transfers with a used ISR 1100-4G and what does not?
The hardware transfers: the chassis, the part number, the memory and flash fitted to it, and the external power adapter where one is included on the order. Software entitlements do not. A subscription or licence bought by the original owner sits in that owner's account, and buying their hardware does not move it. On a platform documented for controller-managed operation that is a particularly important distinction, because the entitlement is where the operating decisions live. Tell us how the site will be managed and we will set out what the chassis alone carries.
How is a used ISR 1100-4G checked before it ships?
It is tested when it arrives with us, then stripped down, cleaned, inventoried, picked against your order, reassembled, configured to the specification agreed and tested again on the way out. The part number and the hardware are what Cisco built. Whole systems carry an Enterasource warranty, stated in full on the listing, and go free by FedEx Ground to the lower 48 states. We publish no burn-in duration, no pass rate and no certification name, because those are claims we would not be able to evidence.
