WRT1900ACS vs WRT3200ACM

Hardware Questions and Recommendations
1

Hi all, soon to be OpenWRT newbie here. I've been meaning to get a *WRT compatible router for years now but it's never worked out timing-wise until now. So I'm looking at the Linksys WRT series and it looks like my choices are the WRT1900ACS and the WRT3200ACM. From what I can see the headline differences are the 1900 has 128MB flash and 1300MHz bandwidth @ 5GHz while the 3200 has 256MB and 2600MHz bandwidth @ 5GHz... does that pretty much summarize the main spec differences?

Does the extra flash make any significant difference in capability (i.e. in terms of the number of typical packages loaded into flash etc... do people find the 1900 limiting in that respect?) Also, in reading through a bunch of forum posts and bug reports, it seems like the 1900 has reached a higher relative level of stability vs the 3200 when it comes to wifi... is that a fair statement? (One of the issues I've seen reported which is a concern is Android device compatibility... is that still an issue? If so, is it specific to the 3200 or does the 1900 also have it?)

Should it help re: recommendations/feedback, here's my hardware situation and use case:

  • I'm primarily looking for high switch performance with low CPU utilization[1] on the router as I'll usually have 2-3 1000mbps wired devices and the balance 100mbps wired devices plugged in and all fairly active.
  • I've also got wide variety of wifi devices (usually only 2-3 are active) but mostly older (I think I might have one ac device, the rest are n (2.4 and 5) or even g) and I tend to run 1-2 generations behind the state of the art on this front and run the devices until they die. So I need a high degree of compatibility with devices but don't need a large number of simultaneous devices or tremendous bandwidth. (worst case usage scenario will be needing to do large file copies to/from a laptop when all wired ports are in use)
  • I don't have a need for terribly high Internet bandwidth (I'm at 25mbps now and can't see going above 100 during the life of the router)
  • Probably 90% of my traffic is LAN-based and some of the things I'm looking at using the router for are: probing/monitoring traffic, firewall and routing customization, serving files via a disk on the USB port (anyone running a linux mirror on their router? Interested is seeing any posts related to this), sniffing traffic via wireshark, running some simple web services, and occasional VPN use. So a bit of variety, but nothing too radical.

Any of the things I've listed a concern re: the 1900 or the 3200 or that would cause you to want to look at something else entirely?

[1] I normally wouldn't even mention this but one of the things I'm really fuzzy about in general with OpenWRT is what hardware features are unavailable due to lack of driver support pushing work on to the CPU. This is a concern both from the standpoint of relative power consumption of the device (vs stock firmware) as well as CPU headroom for other tasks.

Thanks in advance,
Phil

2

In terms of switch performance, all devices that have an actual switch should be close to identical - the switching happens in the (programmable) switch fabric and never hits the router's CPU (which would be the typical bottleneck). So unless you have special needs in term of routing and/ or filtering between local VLANs, basically any router will cope with that at (almost) line speed. The CPU utilization between wired stations connected to the switch ports of the same LAN segment would be zero for your depicted situation.

In terms of contemporary 802.11ac wlan support, your options are mostly ath9k (802.11n, often still used for the 2.4 GHz wlan card), ath10k(-ct), mwlwifi or mt76 (there's also brmcfmac available, but you really need to look into the details about the support state for your preferred device), all of them should basically work sufficiently, but all of them also have their own quirks and warts. You basically have to pick your poison here and hope for the best in terms of interoperability with your existing devices (ath10k and mwlwifi handle pretty much all of the connection handling in firmware, so you do depend on the quality of that - mt76 does a lot more in software, but at least at the moment there are still some weaknesses, especially in the 2.4 GHz band). ath10k(-ct) probably is still a bit ahead in the game of wireless performance and interoperability, with mwlwifi coming second.

For the WAN side, unless going with old or low-spec devices, 25 MBit/s aren't really anything to talk about either. Most of the 'better' contemporary devices should do around 100-150 MBit/s easily, SQM or VPN throughput would be limiting factor here, but 25 MBit/s aren't a problem on that side either.

As long as LAN traffic only happens between LAN station, meaning that it can pass through the switch fabric without CPU involvement (no probing or monitoring on the LAN side), this is -as previously mentioned- simple and not taxing to the router. While providing NAS like functionality is a big point in the vendor's buzzword bingo, it's not the best task from a security point of view - and at least in the recent past couldn't compete with even low-end NAS devices at all (USB 2.0 is taxing the CPU and while USB 3.x and eSATA are better in this regard, it's still quite CPU intensive); ipq40xx/ ipq806x and mvebu shouldn't be too bad in this regard. In general you wouldn't run wireshark on the router, but rather tcpdump (of course you can import its traces into wireshark on your client), as long as the router isn't supposed to listen to inter-device traffic on your LAN (allowing the switch to keep the traffic within the switch fabric), this wouldn't be much of a problem for any semi-capable device either. While traffic shaping via SQM is taxing the router, the up to ~100-150 MBit/s range is easily accomplished by all of the better contemporary devices. VPN might be a bit different, given that OpenVPN is very CPU intensive (and single threaded), while IPsec (strongswan) or wireshark are much easier on the CPU - 25 MBit/s however should be easily accomplished, towards 100 MBit/s you're looking at the higher end devices (ipq806x or mvebu).

In terms of headroom (samba4 needs at the very least 16 MB flash), you would be looking at >=32 MB flash and >= 256 MB RAM, coupled with at least a dual-core CPU - this can be met by the higher options on the market.

Given your specified use-case and taking a <=100 MBit/s WAN throughput into account, you can basically choose freely between ipq40xx, ipq806x or mvebu devices matching the afforementioned flash/ RAM requirements, you don't really need to aim for the higher end there; mt7621 might be a little on the weak end in terms of USB througput (NAS functionality) and SQM+VPN uses. Among these ipq40xx (e.g. AVM Fritz!Box or ZyXEL NBG6617) would be the cheapest option, with the Linksys WRT1200AC coming next - above that you'd see the ipq806x (very fast CPU, good for up to ~350-400 MBit/s WAN throughput) with the very similar Netgear r7800 or ZyXEL NBG6817 devices, followed by mid- and top end mvebu devices Linksys WRT1900AC/ WRT1900ACS or Linksys WRT3200ACM/ WRT32x (very fast CPU and very fast routing up to close to 1 GBit/s line speed). Given your specifications, any of these devices should meet your needs easily, it's only above 150-200 MBit/s when you need to aim for the higher end, respectively above 350-400 MBit/s to be left with top-end mvebu (or x86) as your only option. In terms of the afforementioned features I'm only referring to actually achievable features you can get with OpenWRT (>=18.06.x) today, not potential improvements only available to the vendor firmware (e.g. ipq806x could be on par with top-end mvebu, if their NSS/ NPU cores were used under OpenWrt, which might happen in the future, but currently isn't available yet).

Considering the wlan situation (and your limited needs in terms of routing performance/ WAN speed) I'd rather look at ipq40xx/ ipq806x than mvebu, probably either of the two listed ipq40xx would serve you well already (for half- to two thirds of the price for the faster options). If you limit your attention to mvebu alone, in quantities of 1, I see less sense in WRT1900AC/ WRT1900ACS than WRT3200ACM/ WRT32x, given the very low price delta between them; the WRT1200AC is priced significantly lower than those. Both Marvell 88W8864 (WRT1200AC/ WRT1900AC/ WRT1900ACS) and 88W8964 (WRT3200ACM/ WRT32x) should have rather similar levels of driver support and stability by now, but vendor attention (in terms of bugfixing) is more on the current crop of chipsets (which would be 88W8997 at this point) than the older ones.

4 Likes
3

I'd say that ath10k and mwlwifi as far as performance goes is pretty much on par and one might be slightly better over another depending on the clients but there's no advantage/disadvantage going either.

What you should have in mind however is that the mvebu platform is much more mature in terms of software (platform) and driver support which may be worth taking into account. In practice that means you're likely to see less quirks than with IPQ4/8 especially if you're looking at USB/eSATA (eSATA is highly recommended if you want to attach some kind of storage). There has also been some reports of poor ethernet performance on IPQ8 but that might be device specific.

As far as raw processing power goes the IPQ8 platform does have a slight advantage however it's very minor so it wont matter in the end. If you want some kind of NAS-ish capatibility I'd recommend the WRT3200ACM/WRT32X (same unit, different case) as they're usually priced very closely to each other and USB and eSATA is known to be very reliable.

Don't bother with MT7621 devices, they're slow and more or less deprecated by now as the majority of vendors are moving to ARM instead of MIPS.

4

One more vote for the wrt3200acm here. I know some one that runs a 4 drive rade setup from the E SATA port on there wrt3200acm.

5

slh,

Thanks for the detailed reply, it gives me a much better feel for the landscape. I figured the 1900 would probably be overkill (though I didn't realize it would be that much so) and depending on the state of 3200 support (I'm less worried about that now, thanks) and price delta (seems to fluctuate between $30-50) saw that the relatively low premium might make it the better option. Surprisingly, most of the less expensive models don't appear to be cheaper here in the U.S. (I checked them on Amazon and newegg) as all but one of them were ~$200... i.e. in the same range as the 3200 and more expensive than the 1900. I find those sort of price markups aren't unusual for things that are end-of-life or otherwise hard to find.

About the only thing about the WRT line that bugs me is the lack of cpufreq support (the latest info I could find was here: https://forum.openwrt.org/t/cpu-frequency-scaling-driver-for-mvebu-wrt3200acm-etc/) I know it probably wouldn't make more than a 1-2watt difference in overall power consumption but it will definitely shorten the life of the chip having it running flat-out 24x7 due to the increased heat. (I got a feel from that having gone through about 5 consumer grade routers in 10 years which all ran hot and each died within 3 years... then I got my latest router which sips power and has been running flawlessly for 7 years and only recently started developing 'issues'...) Oh well, as you said... pick your poison...

6

dizzy,

I'm definitely placing a value on the maturity of whatever platform I go with. I don't want to have deal with the teething problems like I've read about when the WRT was new-ish a couple of years ago... been there, done that with other tech.

7

It should also be mentinoned that the WRT3200ACM/32X does have bluetooth and an additional 2.4G wifi radio which people seems to use for "troublesome" devices. :slight_smile:

8

Please tell me more... everything I've read indicated that the 3200 only had dual radios like the 1900...

9

https://wikidevi.com/wiki/Linksys_WRT3200ACM --> Marvell 88W8887

10

Hmm... I was under the impression that it was only there for DFS channel monitoring. To what degree can that be used by OpenWRT? Is it locked to whatever channel the main (I assume) 5ghz band is using? A fully functional independent wifi monitor/sniffer? A complete wifi tx/rx radio?

11

Technically it's a fully independent wlan card, which -at least under OpenWrt- is not used otherwise (as e.g. for DFS scanning), however as it is SDIO connected, it's not that fast. The biggest problem about it (remembering old discussions, as I don't own the device in question myself) is that it seems to be locked to US as regulatory domain (while the other vary according to the target market), which isn't ideal in a linux system that intersects the limits of all internal (OTP), external (IEEE 802.11d) and user configured settings; a common advice is therefore to remove its driver to avoid it from being seen/ used by the router (although using it as a third radio for IoT stuff has some advantages as well).

12

That makes sense, given its intended purpose. The only thing I could find on a quick search of '88W8887 wrt3200acm openwrt' that seemed relevant was https://forum.archive.openwrt.org/viewtopic.php?id=64949&p=77 If you think of any other discussions re: doing useful/interesting things with that radio, links would be appreciated.

13

third radio

1 Like
14

that's very helpful, thank you!