Suspecting MTU problem with POP

RouterOS General
1

Hey guys,

I got a problem and I wanted to have your advices. I got a Mikrotik RB1000 and last night I enabled the PCC. I don’t know if it has any link to this but, in some distant offices and even some local hosted server (just to test), we can’t POP email. One interface seems ok and the other doesn’t. It depends on the office. We think that it could be a MTU related or problem, anyone got an idea on this. And by the way, we use Exchange Server 2003 as our email server.

Best Regards,
tehknox

2

So, this morning no more email were coming in so I disble 4 of my rules for the PCC and it started to work again. So here is a screenshot of my Mangle Rules in my Mikrotik. Is there anything that could be missing ? Because, everything else is working.

Best Regards,
tehknox

–Attachement Removed

3

Post the output of “/ip firewall export” and “/ip route export” and paste the text instead of screenshots.

4

I joined the two output files as there is a lot of rules.
route_export.txt (1.51 KB)
firewall_export.txt (10.5 KB)

5

Looks to me like with your current PCC rules that it has the potential to match several connections, and then causing you problems. Instead of leaving the denominator the same among all the rules and just modifying your remainder, it appears you have 2 different denominator(3 on some rules and 2 on others). This should be the same among all of the connection mark rules, and should be equal to the number of rules you have. Then just modify the remainder among all of them.

6

you do not mention how many connections are balanced, but should make sure that the classifier has enabled “both addresses and ports”. :smiley:

best regards

7

For your information, I got two WAN IN (Telus and Videotron). I understand the denominator/remainder thing but I don’t know why I should select the “both-addresses-and-ports” ?

Would my rules look like this ?

add action=mark-connection chain=prerouting comment="Per Connection Classifier (PCC) to Telus except local destination traffic" disabled=yes \
    dst-address-type=!local new-connection-mark=telus_in_conn passthrough=yes per-connection-classifier=both-addresses:4/0 src-address=192.168.110.0/24
add action=mark-connection chain=prerouting comment="" disabled=yes dst-address-type=!local in-interface=LAN100 new-connection-mark=telus_in_conn \
    passthrough=yes per-connection-classifier=both-addresses:4/1
add action=mark-connection chain=prerouting comment="Per Connection Classifier (PCC) to Videotron except local destination traffic" disabled=yes \
    dst-address-type=!local new-connection-mark=videotron_in_conn passthrough=yes per-connection-classifier=both-addresses:4/2 src-address=192.168.110.0/24
add action=mark-connection chain=prerouting comment="" disabled=yes dst-address-type=!local in-interface=LAN100 new-connection-mark=videotron_in_conn \
    passthrough=yes per-connection-classifier=both-addresses:4/3

Best Regards,
tehknox

8

Different classifiers balance differently.

I don’t think that has anything to do with your issue, I think Feklar is spot on.

http://wiki.mikrotik.com/wiki/How_PCC_works_(beginner)

9

Thanks a lot for this Wiki Link. It really helped me to understand what Felkar suggested. I’ll be trying this new configuration really soon.

Thanks again to you!

Best Regards,
tehknox