How much RAM is enough in a router?

[L&LD]

Do need to clarify a point here - as I don't want to confuse folks...

For a given arch - more or less RAM will not make things faster, that's a capacity thing.

That being said - faster memory, more efficient memory controllers, wider paths to memory - this is all about performance.

Most consumer gear is engineered to a price point - and that is that - less than 500Mbps on the WAN side, and less that 50 connected clients - you're probably ok... wouldn't notice the difference until one puts things under the knife... once you get above those items, then things get interesting...

And with IoT coming on with capacity concerns - more RAM is better... add faster pipes, then the mem speed/width comes into play...

Thanks again. That is exactly what I was told too (I just couldn't state it as well).

I would probably change that to less than 100Mbps on the WAN side (only up or down, but not both consecutively, ime), with the other features enabled. That 50 connected clients is almost spot on to my experience though.

 

[L&LD]

And of course, 50 connected clients is far, far short of the /24 subnet allowance of 253 connected clients the router 'should' handle.

 

[sfx2000]

Funny thing is that both QCA and Broadcom could probably support about 200 WiFi associations on the WiFi chips - it would be a horrible experience perhaps, but supposedly they can do it (I recall reading about this, I'll try to dig up a link that is public).

Putting 254 clients on a router - enterprise class routers can definitely do this and much more than that - but that hypothetical Router/AP, about 2.5GB of RAM would do the job, but with perhaps a Gigabit of bandwidth across the internal switch fabric, it wouldn't be a very good experience

10 Gigabit would be ok, however... and those discussions have been had on other threads - but I'm expecting to see a Consumer Grade Router/AP with some level of 10G support probably by the end of 2016, or 1st half of 2017 at the latest - prices there are coming down, slowly, but they are coming down...

 

[RMerlin]

And if you have 512MB of RAM, and using less than 256MB, that's a pretty poor design - seems like AsusWRT might have some limits that someone has overlooked - a Linux system is properly balanced when all RAM is in use, and we're not hitting swap in an embedded platform.

Sorry, but that does not make sense. A Linux computer uses more RAM because you have local storage that gets accessed randomly as you launch applications or you access files, which will in turn populate buffers. A closed system like a router tends to have a far more "static" memory usage than a workstation. What do you expect the router to put in that extra RAM? There's no large file to cache. The apps are KB-sized themselves (Samba is the only multi-megabytes executable in the OS, and it's compiled as a multicall binary, shared between smbd and nmbd), with typical buffers used by the code being around 2-4 KB for the large ones.

To use RAM, you need to have SOMETHING to put in it. And it needs a reason to be put in there (such as recurring accesses). A home router simply does not have anything to put in there, unless you use it as a NAS. Transient data traffic only needs a few KBs at most for socket buffering. Anything too large, and you get gamers complaining about "bufferbloat"...

Once you have the rc init/monolithic super daemon mapped in RAM, you don't have much more to load dynamically. Events are sent to the rc daemon over signaling, so there's no sub-process spawned.

You will need to back up this claim with facts to convince me otherwise.

 

[sfx2000]

Sorry, but that does not make sense. A Linux computer uses more RAM because you have local storage that gets accessed randomly as you launch applications or you access files, which will in turn populate buffers. A closed system like a router tends to have a far more "static" memory usage than a workstation. What do you expect the router to put in that extra RAM? There's no large file to cache. The apps are KB-sized themselves (Samba is the only multi-megabytes executable in the OS, and it's compiled as a multicall binary, shared between smbd and nmbd), with typical buffers used by the code being around 2-4 KB for the large ones.

If one has 512MB of RAM, and only using <256MB, there's a problem - wasted memory, and yes, that can be used for state tables, applications, etc..

With most embedded systems, we define the amount of memory in the boot config (whether it's CFE, uBoot, etc), and if it's not defined properly, that extra memory will not be used, as the MMU in the system on chip will not be aware of memory outside of the scope of what it's told.

 

[RMerlin]

If one has 512MB of RAM, and only using <256MB, there's a problem - wasted memory, and yes, that can be used for state tables, applications, etc..

Unless, as I've been saying all along in this thread, 512 is simply more than the router needs.

The fact that I have 16 GB of RAM in my desktop PC and my memory usage caps at 12 GB in general (when running my usual VMs) does not indicate that there is a problem - it indicates that I have more resources than I need.

With most embedded systems, we define the amount of memory in the boot config (whether it's CFE, uBoot, etc), and if it's not defined properly, that extra memory will not be used, as the MMU in the system on chip will not be aware of memory outside of the scope of what it's told.

This has absolutely nothing to do with these routers. The memory is there, and it's available, and does get used if you start filling up /tmp, move a file over SMB, or tinker with Snort.

 

[RMerlin]

This discussion has been running in circles for those 5 pages, seriously.

 

[sfx2000]

Unless, as I've been saying all along in this thread, 512 is simply more than the router needs.

The fact that I have 16 GB of RAM in my desktop PC and my memory usage caps at 12 GB in general (when running my usual VMs) does not indicate that there is a problem - it indicates that I have more resources than I need.

Again - you're comparing Windows to Linux - and that's ok... and your perspective of 512MB being more than a router needs - I'll take issue with that.

It is my position and belief that 512MB is probably the sweet spot - right now - but it won't be very soon... and 256MB in an AC5300 class consumer router is simply insufficient.

 

[sfx2000]

This discussion has been running in circles for those 5 pages, seriously.

Let it run

Nice to have a discussion outside of the normal stuff...

 

[System Error Message]

Some humour for you. Theres no reason for a router not to have a few TB of ram, some just like to have big numbers but you may see more than 99% of your ram free even at the worst of times, still if you do decide to store the entire routing tables of the internet at least you're covered many times over.

 

[Vexira]

and here you were just talking about the router not being powerful enough to use all the ram . How can the manufacturer offer 2 different ram sizes when that would cost more without having a SoDIMM slot? Do we need to do a hack where we desolder the ram chip and solder a bigger one on?

Would that actually even work?
Wouldn't the firmware need to be modified just to recognize the new capacity and be optimized for it?

 

[coxhaus]

Some humour for you. Theres no reason for a router not to have a few TB of ram, some just like to have big numbers but you may see more than 99% of your ram free even at the worst of times, still if you do decide to store the entire routing tables of the internet at least you're covered many times over.

None of these routers they are talking about on this forum run BGP. There are a lot rules for running BGP. BGP is for network people not home and small businesses.

 

[Vexira]

None of these routers they are talking about on this forum run BGP. There are a lot rules for running BGP. BGP is for network people not home and small businesses.

I was about to say it would be nice to have alot of ram in the router means I could strap a massive hdd to it for download master or put my music library to it fro streaming any where in the house, since I re ber Merlin saying some about the the router ram and file caching on the hdd.

 

[System Error Message]

Would that actually even work?
Wouldn't the firmware need to be modified just to recognize the new capacity and be optimized for it?

for many routers yes, as they automatically detect the ram as they're very much like desktop PCs. I remember people have done this for GPUs and even PS3s as well.

 

[Kevin_Ham]

Guys did 1Gb RAM is enough for the router?

 

[Vexira]

Guys did 1Gb RAM is enough for the router?

It depends on the features I guess, should be enough, but I'd be qurious about the benifits of more in regards to torrents and attached HDDs also QoS.

 

[System Error Message]

It depends on the features I guess, should be enough, but I'd be qurious about the benifits of more in regards to torrents and attached HDDs also QoS.

you can end up using BGP at home, it really just depends on the ISP such as if you have multiple links and need to know which one is faster or which paths are faster.

You can also use ram as cache as well in the manner you mentioned, for data.