faster

FTTC Fast Path (Interleaving) removal with Plusnet

by

A quick and free boost for my broadband connection this week. I’d been monitoring my DSL service and was noticing some errors on the downstream and with some quick research Interleaving was a common cause of this. Interleaving in short splits your packets down and reassembles at the far end, it’s great for stability but does increase latency. It’s not great if you use VOIP and if you’re a gamer it can increase that all important response time which you need as low as possible.

A quick webchat with Plusnet support and I’d asked for my service to be put on “fast track” or in other words, having interleaving removed. A 24 hour wait and to my surprise my connection has improved!

Before;

After;

 

The only issue with this is if Interleaving was helping the connection there is a possibility it will wobble and DLM will re-apply it but the service in general is very stable so I am hopeful that the change will last.

Back to a CHR?

by

Friday 13th was an exciting one in my household! Not only did I kill the internet for everyone for a good 3 hour period whilst I swapped from an Ikea Lack table to a “real” 6U cabinet causing huge disruption when my planned single patch panel turned into 3! I also fired up old faithful and stuck on a fresh copy of the latest (6.42.6) CHR into my VM box.

Now I have my spare ESXi box housed in the attic in a real rack it means I don’t need it screaming away in the cave so I can finally move back to a CHR build and keep it. My rough maths says the CHR unit will have around 4-5 times the performance of the RB3011 which will now get moved to the cave as a dedicated VLAN breakout switch (or maybe sold) but ultimately I can employ some far more complex queues without worrying that I’m running the CPU up too far.

My long term plan is to SFQ my LAN traffic but then pick out particular traffic types from that and SFQ them against each other whilst doing some PFIFO pulling them all together. I’ll try to document as much as I can but in short it will be a huge amount of packet marking so CPU grunt is needed. I’m even now tempted to look at upgrading the CPU so it’s more than a dual core!

Fun times ahead.

MikroTik Fast Track Learning Experience

by

Free performance enhancement? Must be a catch….

I’ve recently had to investigate making some lower powered MikroTik devices route at decent speeds, there is a much longer story which I won’t be going in to but in short I had a task of making a CRS112 (low powered 400Mhz single core CPU) able to route 100Mb services.

A little background is the CRS112 is primarily a switch, using hardware offload you can easily switch at line rate (Gigabit) however they don’t really do too well in routing or anything CPU oriented. For example viewing Winbox uses 20% CPU resources as does running FTP, Telnet and WWW services!

For basic NAT masquerade and a simple 12 line firewall rule my initial testing was only yielding speed test results in the 30-40Mb region. The first 2 lines of my firewall were as follows to try and be as efficient as I could be;

/ip firewall filter

add action=accept chain=forward comment="ACCEPT ESTABLISHED & RELATED" connection-state=established,related in-interface=pppoe_client1

add action=accept chain=input comment="ACCEPT ESTABLISHED & RELATED" connection-state=established,related in-interface=pppoe_client1

The goal was to route at least 50Mb through the CRS so I picked up something I left alone a long time ago as then there was no need to use CPU limited products and the cons outweighed the gains.

Fasttrack is a powerful little tool you can use to vastly improve throughputs on CPU limited devices, the plus sides of it are that my CRS112 that was only previously capable of routing 30Mb was now being limited by my PPP account at 150Mb and it still had gas in the tank! The device suddenly becomes a much more viable router however the draw back to this is that fast track effectively allows the packet “through the gates” and then takes no further part in it’s journey. Connection tracking is disabled meaning any further mangling of packets and queues simply do not know about the packets we have just expedited.

In most situations fasttrack is probably going to break more things than you’d like whilst trying to squeeze the last bit out of your router however on heavily CPU limited tasks where you only need a basic router it will certainly help.

The final firewall configuration only needed 2 lines adding (yes I tried without the accept rules and it won’t work);

/ip firewall filter

add action=fasttrack-connection chain=forward comment="ACCEPT ESTABLISHED & RELATED" connection-state=established,related in-interface=pppoe_client1

add action=fasttrack-connection chain=input comment="ACCEPT ESTABLISHED & RELATED" connection-state=established,related in-interface=pppoe_client1

add action=accept chain=forward comment="ACCEPT ESTABLISHED & RELATED" connection-state=established,related in-interface=pppoe_client1

add action=accept chain=input comment="ACCEPT ESTABLISHED & RELATED" connection-state=established,related in-interface=pppoe_client1

So to summarise, fasttrack is the devil unless you have a low powered device. Connection tracking is probably more valuable than making your under specced kit last an extra couple of weeks but a very good learning experience.