Unifi UniFi PPPoE Dialer MTU affects IP assignment. Why?
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 Feb 25 2017, 02:09 AM, updated 6y ago
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#1
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All Stars
11,458 posts Joined: Oct 2007 From: KL  
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I have a friend subscribing to UniFiBiz 5 Static IPs.
If I configure the PPPoE dialer with MTU and MRU as 1492, she gets her correct /29 static IPs. If I configure the PPPoE dialer with no MTU nor MRU set, she gets a dynamic IP. The MTU eventually ends up as 1480 Anyone know why that is? This post has been edited by soonwai: Feb 25 2017, 02:50 AM |
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Feb 27 2017, 08:20 AM
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#2
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11,458 posts Joined: Oct 2007 From: KL
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QUOTE(NyOx @ Feb 27 2017, 07:33 AM) i think as long as below 1500 should be fine. MTU just a frame size. as far i know TM MTU max 1500. I know right. So wierd. Why does TM's pppoe server react differently just because the pppoe client is dialing with a different MTU and MRU size?i already play around MTU for my unifi and max MTU size can be configure 1492.  |
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Feb 27 2017, 08:50 PM
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#3
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11,458 posts Joined: Oct 2007 From: KL
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QUOTE(Alpha_Tay @ Feb 27 2017, 07:19 PM) it seem tplink router default at mtu 1480 since beginning? Mikrotik default is also 1480. Some Dlinks are at 1492. 1492 is the max you can go for PPP due to the 8 byte overhead of PPP and PPPoE but having some extra space is always safer. |
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Apr 10 2020, 11:23 PM
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#4
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11,458 posts Joined: Oct 2007 From: KL
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QUOTE(latiffesa @ Apr 10 2020, 10:52 PM) HI the reason for this MTU issue is very simple. Thanks, your first line is very clear. Which of your following lines did the first refer to?MTU means the largest size of data transmission via a network path The MTU size id dynamic means that it can be several variable below a ciling size This variable is auto detected by the ICMP protocol The entire ICMP protocol family is blocked by TM Unifi. IF TM unifi can identify which or their devices blocked the ICMP protocol than this issue wont arise anylonger The ICMP protocol is responsible to auto detect the MTU than make use of the dynimaic setting to make the VPN work right away About the VPN ...VPN protocl tends to load more header than the common way of cimmunication thus this is waht causing what you are experinceing right now so: 1. Either TM allow ICMP protocol or 2. All TM Customers entire malaysia need to manualy adjust this MTU niakulah liked this post
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