Dear Forum,

I experience some packet loss across my RB2011iL running RouterOS 6.5, and would like to locate the reason.

I am a beginner, struggeling with the the configuration of my network. The purpose of this post is twofold:
1. I want to solve the packet-loss problem
2. I would love to understand better what is going on in my home network

So while I am happy to receive specific comments, I am also happy to see references to background information and further readings (including older posts and mikrotik docs, althouth the mikrotik documentation is not easy to handle (for me).

My (simplified) physical configuration looks like this:
PROVIDER -(dsl)- FRITZBOX7312 -(ethernet)- RB2011 -(ethernet)- FRITZBOX7240 - TELEPHONE
The telephone is an old analoge one (for testing purposes), connected directly (wired) to the FB7240.
The network is a family's home network, typically with low load.

I experience big problems when I make a phone call. Large parts of the conversation gets lost, in both directions (for both partners of the calls).
It sounds like packet loss (but might also be long delays having similar effects).
If I connect the phone to the FB7312, I have no problems, so it seems that "something" is happening between the two Fritzboxes.

• How can I check if the router drops packets?
• What else could go wrong?
• How should I approach the problem?

Thanks a lot for any help.

Walt

I've had similar issues, and I've solved them by unconditionally setting outgoing packets' TTL to 64 (though you may also try 128, just in case).

You can do so using

ros code

/ip firewall mangle add chain=prerouting out-interface=!local action=change-ttl new-ttl=set:64 passthrough=yes

(assuming your local interface - the one facing your phone - is called "local")

Why is that happening?

For some reason, the TTL of outgoing packets ends up being such that they can barely reach their destination.

There's no definitive standard as to how much should each device lower a packet's TTL before passing it on (There's just the "lower it by at least 1" rule), plus, each packet might be routed differently before it reaches its destination... As such, there's no way to reliably diagnose whether a packet's TTL is enough. Unconditionally setting it to a value - 64 or other - at least gives you an anchor point - If you can establish a stable connection between the router and the end point using that TTL, then inner devices must be capable of doing the same, as long as they have enough TTL to reach your router (which they certainly do if some packets get through).

Hi boen_robot,

thanks for the quick reply. I made a router reset to its default config, and voip works again as expected.
As so often, the problem was (is) in front of the keyboard

I will be more careful when I rebuild my configuration - and probably use this forum intensively

Walt

This sounds a lot like the issue I have.
I have a simple setup;
DSL (Statis IP) - Router - Everything else
Everything else is my PC, VOIP ATA, TV, Android Box and two iPhone4

The issue is that most of the day, the internet slows to a crawl. I can't game, ping is all over the map with significant packet loss. VOIP calls are unreliable. Constant buffering when streaming video. Cant work from home because my Citrix session is laggy as hell. Then randomly, it all starts to work and I am no closer to a fix.

I've been troubleshooting and initially blamed my ISP. But, connecting my PC directly to the DSL modem gives me rock solid connection and gaming is smooth with good pings with none to minimal packet loss. Obviously, every other device is then off the network. As soon as I introduce the Router into the mix, I am back to the unreliable internet. Go back to my PC connecting directly to the modem and it all works again.

This TTL solution sounds like something I should try but I am not sure how to pass that command to the router via the Webfig or Winbox. Can you please comment on that.

well.. thanks
i have the same question too

To write that line you have many ways:

Winbox or Web Interface: Go the the option "New Teminal" and a new windows of CLI will open.
Telnet the router: in CMD (or a terminal if it linux) write "telnet" and the Routerboard IP (in my case: telnet 10.0.0.1)
SSH the router: Using some Hyperterminal program (in linux Directly SSH on the terminal like the Telnet) connect to the unit
Console: Conected with a console cord to the router, and using an hyperterminal program (Speed: 105200)

[quote="boen_robot"]I've had similar issues, and I've solved them by unconditionally setting outgoing packets' TTL to 64 (though you may also try 128, just in case).

You can do so using

ros code

/ip firewall mangle add chain=prerouting out-interface=!local action=change-ttl new-ttl=set:64 passthrough=yes

(assuming your local interface - the one facing your phone - is called "local")

Why is that happening?

Hi!

I get "failure: outgoing interface matching not possible in input and prerouting chains" whenever I try to set this command.

Am I missing something?

finally i am able to solve own interface ping loss problem by removing queue for Master BW.

boen_robot

This is a great solution i got by your post .

Thank you So much boen_robot
Wish your good luck