<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px"><div><span>Yes, the default MTU is 1500. AFAIK i don't think that i have made a mistake since the packets are fragmented according to this MTU. Furthermore, without ETX it works well. </span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-style: normal; background-color: transparent;"><span>My suspicion is that when hello packets are fragmented it is somehow affect the etx calculation. what do you think?</span></div> <div class="qtdSeparateBR"><br><br></div><div class="yahoo_quoted" style="display: block;"> <div style="font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-size: 16px;"> <div style="font-family: HelveticaNeue, 'Helvetica
Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-size: 16px;"> <div dir="ltr"> <font size="2" face="Arial"> On Saturday, October 25, 2014 10:45 AM, Henning Rogge <hrogge@gmail.com> wrote:<br> </font> </div> <br><br> <div class="y_msg_container">So you modified the code in olsrd to somehow keep the MTU smaller than<br clear="none">it really is? Maybe you forgot one place?<br clear="none"><br clear="none">Henning<br clear="none"><div class="yqt5619162374" id="yqtfd89601"><br clear="none">On Fri, Oct 24, 2014 at 4:17 PM, Scoobi Doo <<a shape="rect" ymailto="mailto:madroobalras@yahoo.com" href="mailto:madroobalras@yahoo.com">madroobalras@yahoo.com</a>> wrote:<br clear="none">> The MTU limit is on the olsr packet not on the whole IP packet. the total<br clear="none">> packet size is 128 + udp headers + IP headers. It's still a standard IPv4<br clear="none">> packet with just a small payload - olsr packet.<br
clear="none">><br clear="none">><br clear="none">> On Friday, October 24, 2014 2:54 PM, Henning Rogge <<a shape="rect" ymailto="mailto:hrogge@gmail.com" href="mailto:hrogge@gmail.com">hrogge@gmail.com</a>> wrote:<br clear="none">><br clear="none">><br clear="none">> On Fri, Oct 24, 2014 at 1:30 PM, Scoobi Doo <<a shape="rect" ymailto="mailto:madroobalras@yahoo.com" href="mailto:madroobalras@yahoo.com">madroobalras@yahoo.com</a>> wrote:<br clear="none">>> Hi,<br clear="none">>> Your answer regarding using ETX code brings me back to another problem. I<br clear="none">>> don't use ETX because i'm having simulations on narrowband nodes, which<br clear="none">>> force me to change the size of the MTU (from 1500 to 128).<br clear="none">><br clear="none">> Not sure an IP (especially IPv6) network with MTU 128 does work<br clear="none">> well... you might need to think about layer-2
fragmentation.<br clear="none">><br clear="none">>>When the network<br clear="none">>> gets larger and the olsrd starts to fragment the messages (serialize<br clear="none">>> functions) the routing table in ETX-mode is not correct in a simple<br clear="none">>> full-mesh topology. From tests that i ran i saw that no matter what is the<br clear="none">>> MTU size whenever the network becomes larger so messages get fragmented,<br clear="none">>> the<br clear="none">>> olsrd fails to build the right routing table. When i use non-ETX code i<br clear="none">>> don't see that problem.<br clear="none">>> I prefer using ETX. did you encounter in such a problem?<br clear="none">><br clear="none">> Most likely there is an "off by X" problem in the fragmentation<br clear="none">> code... it most likely doesn't trigger on IPv4 because messages stay<br clear="none">> small enough.<br
clear="none">><br clear="none">><br clear="none">> Henning Rogge<br clear="none">><br clear="none">><br clear="none"></div><br><br></div> </div> </div> </div> </div></body></html>