RT-N66U - Less performance than expected on high speed fibre connection

[SoCalReviews]

About 45-ish bytes per 1500 bytes packet (I don't recall the exact numbers, I only got the 1454 bytes per packet figure in my mind). Maybe that included other overhead caused by ATM, it's been years since I've looked into this I'm afraid.

From my experience with DSL 3-5% experienced loss would make sense. I actually thought that the real experienced loss in throughput could have been up to 10% or more depending on the equipment and how the WAN to LAN routing is set up. There is definitely a noticeable impact because I have had DSL with and without PPPoE and there is a difference. I can't imagine it being much less than 3% nor have I heard of it being an insignificant percentage of the total but who knows? If it wasn't a factor then its amazing that everyone in the DSL and cable forums that rate the ISPs have talked about it for more than a decade as being a factor. Maybe it is much less...more around .5% as rotor noted but that doesn't explain why it's so noticeable of a hit.

They didn't used to do this but with all the competition now from cable it seems that many of the ISPs who are providing DSL with PPPoE now days might actually be capping their speed tiers a notch above their advertised throughput to compensate for those various losses... You can usually read long threads in the DSL and cable forums that rate ISP services about these issues regarding packet loss and the degradation in throughput for DSL services with PPPoE. I wonder if the majority of the throughput losses that people have experienced in the past have always been partially due to the extra processing required.

Edit: Here we go. I just found this.

http://www.dslreports.com/forum/r22705962-PPPoE-DSL-Overhead-Questions

From the above thread link about PPPoE DSL Overhead Questions...."We know that PPPoE overhead takes about 15% off of the speed profile that a customer is on a customer with a 5 Meg plan will see around 4.25 Meg/s during a speed test."... and what Merlin said about ATM is mentioned... "BTW its 9.4% of ATM, 1.65% of TCP, 1.3% of IP, and .53% of PPPoE of overhead giving a total of 12.9%"

 

[rotor]

From my experience with DSL 3-5% experienced loss would make sense. I actually thought that the real experienced loss in throughput could have been up to 10% or more depending on the equipment and how the WAN to LAN routing is set up. There is definitely a noticeable impact because I have had DSL with and without PPPoE and there is a difference. I can't imagine it being much less than 3% nor have I heard of it being an insignificant percentage of the total but who knows? If it wasn't a factor then its amazing that everyone in the DSL and cable forums that rate the ISPs have talked about it for more than a decade as being a factor. Maybe it is much less...more around .5% as rotor noted but that doesn't explain why it's so noticeable of a hit.

They didn't used to do this but with all the competition now from cable it seems that many of the ISPs who are providing DSL with PPPoE now days might actually be capping their speed tiers a notch above their advertised throughput to compensate for those various losses... You can usually read long threads in the DSL and cable forums that rate ISP services about these issues regarding packet loss and the degradation in throughput for DSL services with PPPoE. I wonder if the majority of the throughput losses that people have experienced in the past have always been partially due to the extra processing required.

Edit: Here we go. I just found this.

http://www.dslreports.com/forum/r22705962-PPPoE-DSL-Overhead-Questions

From the above thread link about PPPoE DSL Overhead Questions...."We know that PPPoE overhead takes about 15% off of the speed profile that a customer is on a customer with a 5 Meg plan will see around 4.25 Meg/s during a speed test."... and what Merlin said about ATM is mentioned... "BTW its 9.4% of ATM, 1.65% of TCP, 1.3% of IP, and .53% of PPPoE of overhead giving a total of 12.9%"

That discussion thread is full of inaccuracies and incorrect terminology and comparing apples with oranges (the opening sentence of the original post "we know that PPPoE overhead..." is completely wrong at multiple levels).

For example, the overhead of AAL5 (which sits on top of ATM), varies between 8 bytes and 55 bytes per IP packet transmitted, and the size of an IP packet is variable, so right there you see a slight problem with working out a percentage overhead, when both the overhead and the payload sizes vary as the payload has to be fit into 48-byte ATM frames.

Strictly speaking, the discussion was about the overheads of PPP, and PPPoA imposes a 2 byte overhead per IP packet, that is a fact. 2 / 1500 = 0.13%. PPPoE imposes an additional 6 bytes, giving a total of 8 bytes as per my original response. I understand why there is so much conjecture; it is a very complex topic with many layers and protocols all interacting in various ways with each other.

Here is an excellent paper that I think does a superb job of explaining this whole topic:

http://www.frsf.utn.edu.ar/matero/visitante/bajar_apunte.php?id_catedra=300&id_apunte=4206

Thanks for the discussion, I am learning a lot!

 

[SoCalReviews]

That discussion thread is full of inaccuracies and incorrect terminology and comparing apples with oranges (the opening sentence of the original post "we know that PPPoE overhead..." is completely wrong at multiple levels).

For example, the overhead of AAL5 (which sits on top of ATM), varies between 8 bytes and 55 bytes per IP packet transmitted, and the size of an IP packet is variable, so right there you see a slight problem with working out a percentage overhead, when both the overhead and the payload sizes vary as the payload has to be fit into 48-byte ATM frames.

Strictly speaking, the discussion was about the overheads of PPP, and PPPoA imposes a 2 byte overhead per IP packet, that is a fact. 2 / 1500 = 0.13%. PPPoE imposes an additional 6 bytes, giving a total of 8 bytes as per my original response. I understand why there is so much conjecture; it is a very complex topic with many layers and protocols all interacting in various ways with each other.

Here is an excellent paper that I think does a superb job of explaining this whole topic:

http://www.frsf.utn.edu.ar/matero/visitante/bajar_apunte.php?id_catedra=300&id_apunte=4206

Thanks for the discussion, I am learning a lot!

Yes, Thanks for providing an additional link with more information. It's a very interesting topic that we are all learning from and I also appreciate the information that is coming out of this discussion. These kinds of router and connection issues are the kind that many people will have to deal with from ISPs especially as internet bandwidth increases and usage caps are implemented. I wasn't scientifically verifying the actual percentage loss of using PPPoE with DSL that was discussed in those posts. The reason I provided that link is that it represents the kind of posts and threads I have been reading for more than a decade in the forums that discuss this same topic about losses in throughput.

This has never been a hidden secret. The ISPs have known about it and the techs talk about it. I don't claim to be an expert on PPPoE nor do I want to imply that I know much more about it than someone else in this forum or any other forum who seems to have more knowledge about it. However, it is something I have asked former DSL ISP sales reps and techs on the phone about in the past in regards to their internet service and they have admitted that losses exist. The precise reasons for the losses, lost packets, when using PPPoE can be analyzed in detail but there definitely are significant verifiable losses that most users experience on DSL lines using it. You said you measured 300Mbps down from your service so it could be that your fiber ISP is compensating for losses with additional bandwidth or maybe there is another factor with how your provider is implementing it so you don't notice the impact of using PPPoE with their equipment.

 

[cryogenic666]

Would the new EdgeRouter Lite from Ubiquiti be an option for you here? It appears that it does support PPPoE, though it doesn't appear to have the most user-friendly configuration... But if you're comfortable with Mikrotik's RouterOS, I'd imagine you could plow through their implementation of Vyatta with minimal hassle. Plus it's only $99 USD.

 

[srinivasvaradaraj]

pfsense + barebone.

Personally, I would pitch in for an atom barebone from newegg, throw in pfsense for firewall/routing (or build Openbsd based unit for fun), use the N66U strictly as a switch & AP behind it. You get enterprise class throughput, shaping and routing with pf stack.

 

[Shikami]

I believe that the RT-N56U's hardware NAT processor can offload PPPoE. Also, I am curious if the modem is properly bridged, and the router is handling the packet properly?

It seems as if there is fragmentation or a path MTU leading to fragmentatio, and this is causing the punitive slow down. I could very well be wrong, but I would do just a little more investigating before the final decision.

 

[rotor]

Would the new EdgeRouter Lite from Ubiquiti be an option for you here?

It's possible, but they are very new and only just starting to trickle into the marketplace, so will have to wait and see what the reports are. And from experience, marketing and CPU speed don't correlate to PPPoE performance. Also, even though they are "just $99", here in the UK they are going for around £115 (almost $180).

 

[rotor]

Personally, I would pitch in for an atom barebone from newegg

That's pretty much what I'm planning to do.

 

[rotor]

I believe that the RT-N56U's hardware NAT processor can offload PPPoE. Also, I am curious if the modem is properly bridged, and the router is handling the packet properly?

It seems as if there is fragmentation or a path MTU leading to fragmentatio, and this is causing the punitive slow down. I could very well be wrong, but I would do just a little more investigating before the final decision.

Unfortunately, I have been unsuccessful in unearthing any evidence to support your belief.

 

[Shikami]

Unfortunately, I have been unsuccessful in unearthing any evidence to support your belief.

With no real technical information of your network, I can say that it would be the case for us too. But to note, that most issues with networking are simple 101 problems. Never really going beyond that much. Personally, from my DSL PPPoE days, I never experienced low throughput and bandwidth issues; and this was with less capable networking hardware of the day.

So, the curious question is, is your modem bridged, and only bridged? Therefore passing on the packets to the network (router). Is the N66u handling the PPPoE, and only it? I do recall a website that when testing the N66U the PPPoE bandwidth was higher than 500Mbp/s. I cannot find it at the moment, but that router should be more than capable of handling that. Not all the packet processing is handled by the processor with this router; it does have some offloading abilities too. Not to the extent of the N56U.

 

[unchiu]

Just solved the problem with my N66U having the exact problem as you.
Download this old firmware (Asuswrt-Merlin build 3.0.0.4.354.29 BETA 1) from here: http://www51.zippyshare.com/v/45006032/file.html and flash it like a normal firmware from Asus website.

That's it !

 

[RMerlin]

Just solved the problem with my N66U having the exact problem as you.
Download this old firmware (Asuswrt-Merlin build 3.0.0.4.354.29 BETA 1) from here: http://www51.zippyshare.com/v/45006032/file.html and flash it like a normal firmware from Asus website.

That's it !

No need to download it from a third party site, the file is still available on the official download site.

 

[unchiu]

I only know of http://www.mediafire.com/asuswrt-merlin/ and it is not working

 

[RMerlin]

I only know of http://www.mediafire.com/asuswrt-merlin/ and it is not working

See the sticky thread in the Asuswrt-Merlin sub-forum. The download URL has changed as Mediafire have discontinued support for custom URLs.

 

[wayner]

Sorry to necropoost but I am seeing the same issue as the OP but I don't use PPPoE as I have cable internet that is capable of more but which maxes out at 230Mbps when using my Asus RT-N66U.

@Merlin - any recommendation on what version to use with WAN speeds above 200Mbps?

 

[L&LD]

wayner, if you stick to your original thread you will find you get help or at least answers faster than spamming the forums with the same questions.

 

[dduttonnc]

i just upgraded from a 66x6 to a 350x20... and sometimes i can get 350 but only if no other device is using the internet.. STEAM for somereason CAPS out at 25MegaBYTES/sec (150/sec)

I have a Asus RT AC68U.. but when I try to access the internet while steam is at 25MB/sec , I can only get 5-7Mbits of CRAPPY speed.. im missing 150Mbits.. TWC has spent a MONTH trying to find the issue.... and i FINALLY DID... it's the DAMN ASUS ROUTER...

When I run a speedtest from one MACHINE CPU 1 is at 100% and CPU 2 is at 50%....

that's just ONE FILE to test the speed

when STEAM downloads, it DLs about 3-5 FILES AT ONCE.... the REASON it caps at 25Mbits/sec or 150Mbits is BOTH ROUTER CPUS are at 100% and 95%... THERES NO CPU LEFT except to handle 507 CRAPPY Mbits/sec...

Basiclly ANYTHING BUT a new ASUS CAN NOT handle this connection.... with ONE connection and ONE ONLY it can do 350Mbit BARELY... but the more connections you have the less and less it can handle... it REALITY the RT-AC68U can ONLY handle 150Mbits. when doing about 3 heavy downloads... if it's just ONE download connection.. and nothing else is really using the internet.. then it can do 300-350Mbps IF the source will let you DL that fast... Sony, Apple, nintendo, etc all cap your downloads.... even the xbox one... most are CAPPED at 50Mbits to prevent overloading of THEIR services... so for those places you are LIMITED to 50Mbits per IP address, since TWC using IPv6 now as well as the ps4 and xbox one... there's NO NAT NO private network with IP6 EACH system gets it's OWN public IP.. you can still have your router firewall it for safety.. BUT ip6 will let EACH computer DL from itunes at 50mbps... vs with ip4 they limit 50mbps to the IP address...

ANYWAY.. so I bought a new ASUS a while back ago for a 3rd access point... it's MUCH newer than my AC68U.. and FYI.. I JUST discovered the asus cpu limitation 5mins before i wrote this! Downstairs I have a ASUS RT-AC87U running as a SIMPLE AP for wifi and connected to a port switching up downstairs.. everything in my house is WIRED using cat 7 and i have about 4 8 port switching hubs in my house... ONLY portable devices use my wifi.. EVERYTHING is on a 1Gbps wired network with the capability of 10Gbps someday as the wires support that speed... Anyway

AC-68U (aka AC1900) CPU specs: 2 cores , BCM4708A0, @ 800Mhz.. some places claim u can OC them to 1000Mhz, I tried and the router crashes.. factory reset needed. 2 8000Mhz CPUs are just TOO SLOW to handle connections over 150Mbps with multiple devices accessing it at once... if you have this one or older.. you are WASTING your internet speed.. plus unless your devices are WIRED or they use 802.11AC, you will never get 300Mbps speed over Wifi.... if u really want 300-1000Mbps.... WIRE YOUR HOUSE....

AC-87U CPU specs: 2 core, BCM4709A0, CORES @ 1000Mhz for non wifi use, and another 2 core QT3840BC @ 500Mhz dedicated for Wifi use.. plus the main cpus in the 87u are a newer model and fast Mhz

So..... ASA..... DAMN P... I'mgoing to SWITCH them!!!

The 87U should handle the speeds and connections with NO ISSUE becuase it has 2 CPUs that are newer and 200Mhz faster for everything NON WIFI.. then 2 CPUS dedicated for using WIFI....


NO WONDER , me and TWC have pulled out hairs out... they have swapped my modem... refunded me $$$$.... I'm DEFINITELY not telling them it's the asus!!

so the 68U must use both 800Mhz CPUs for EVERYTHING..... if you go over a 100Mbps connection... maybe 150mbps, it cant handle it... 300Mbps with a 68 u or lesser/older model is USELESS.. it sort of works for me, but i only get full speed if its ONE connection from ONE device.. that's BS...

for those of u who have the 66u..... sorry people... only ONE CPU CORE AT 600Mhz... if you have a 300mbit connection with this router you probably will cap out at 200mbps with even ONE connection... and with multiple connections... ACK!! not sure it can even handle 100mbps (like 5 devices trying to DL at 20mbps each at once).. if u have a 66u and a 150-1000mbps connection, GET THE NEWEST ASUS ROUTER! (or at LEAST a used 87u!)... even the 87 u prob wont do much over 500Mbps....

 

[dduttonnc]

Sorry to necropoost but I am seeing the same issue as the OP but I don't use PPPoE as I have cable internet that is capable of more but which maxes out at 230Mbps when using my Asus RT-N66U.

@Merlin - any recommendation on what version to use with WAN speeds above 200Mbps?

NO ammount of software can help you.. that router is PHYSICALLY not capable of routing data that fast using a NAT based connection.. .if you were PURE IP6, then it would take some load off of it....

if you can't buy a new one.. turn ANY FANCY features OFF.. NO FIREWALL NO DDOS PROTECTION... NO LOGGING OF ANY KIND....even try to put a dchp/dns server on your PC.... take EVERY bit of CPU power OFF that thing.. and MAYBE.. just MAYBE you can get 300mbps in ONE FILE download from ONE machine.. but with a single core... if you try to lets say DL a game on STEAM... it will probably cap out on that router at about 50Mbps.... and then anything else in your house will have CRAP for internet because there's no cpu resources... so buy a used 87u or a NEW one and make SURE the new asus has the following

AT LEAST 2 CORE CPUS at 1000Mhz or faster that do ALL NON WIFI Work

2 core CPUS @ 500-800Mhz that JUST handle wifi...

that's the 87u and it will do 350mbps just fine... but no more... you'd need the NEWEST and BEST asus to get a true 1gbps internet speeds

 

[dduttonnc]

Now to get sleep.. it's5:50am here.. and I've been up all night...and MANY nights for a MONTH trying to solve my speed issues after upgrading from a 66x6 to a 300x20 (twc actually gives u more.. i get 350x25)... and I could get those speeds but ONLY on a speed test.. steam would DL at 25Mbytes/sec (150Mbits/s).. and then I'd have no bandwidth when I should have 150more.... it's NOT a bandwidth issue.. see my LONG post above.. it's a ROUTER CPU BOTTLE NECK

 

[wouterv]

What is the question?
Promissed Internet speed shall match with the modem, the internal infrastructure, the router, the client capabilities, if wireless: the client wireless specifications shall match the router wireless specifications. Last but not least for wireless your environment shall be wireless friendly (ideally open field without wireless neighbor devices, and optimal distance).
Many wireless adapters in client devices are by far not able to get the maximum out of a fancy wireless router.
Many routers are by far not able to serve multiple clients at high speed, wired or wireless, due to CPU or memory limitations.
Client operating system setup can be limiting as well, e.g. due to malware scanning or background tasks.