Hi,

I think that this problem is that OpenFlow Switch buffers packets.
Therefore, I think that the controller can not receive all Packet-In 
packets.


For the work around, please try configuring OpenFlow Switch not to 
buffer packets.
You can set the miss_send_len by using OFPSetConfig.
For details, please refer to the following.
 
http://ryu.readthedocs.io/en/latest/ofproto_v1_3_ref.html#ryu.ofproto.ofproto_v1_3_parser.OFPSetConfig

Please send Packet-In after running OFPSetConfig.


A similar problem has been discussed at the following e-mail.
 
https://www.mail-archive.com/[email protected]/msg12839.html

FYI, I am making some patches for another problem of dhcp.py.


Regards, Muraoka


On 2016年12月23日 01:06, Jacob Cox wrote:
> Hi Muraoka,
>
> My solution is based on necessity more than RFC due to the limited number of 
> bytes that I receive from the controller. I don't think I ever receive more 
> than 128 bytes. Of which, only 81 bytes are ever sent to dhcy.py. So, I'm 
> basically capturing what I can, since I figured it is better to be able to 
> inspect most of the DHCP header fields rather than none at all. In hindsight, 
> it may be better to throw out the sname as well (for inspections only). The 
> field is still 64 bytes, but I'm only able to catch 40 bytes of it. Unless 
> the useful information is contained in the first 40 bytes, then this solution 
> is not so useful. But, I tried to capture as much information as possible 
> given the buffer length I was receiving. I'm using an Open vSwitch on Mininet 
> for my experiments. I'm not sure how many other SDN switches limit their 
> packet headers to this extent, but I suspect many do.
>
> That Mininet code is available at  https://github.com/Ryuretic/RyureticLabs/ 
> as well under mininet/examples/Ryuretic/DHCP_Topo.py.
>
> Thanks,
> Jacob
> https://www.linkedin.com/in/jacobcox74
>
>
>
>
>
>
>
> -----Original Message-----
> From: Shinpei Muraoka [mailto:[email protected]]
> Sent: Thursday, December 22, 2016 12:15 AM
> To: [email protected]
> Cc: [email protected]
> Subject: Re: [Ryu-devel] Trouble parsing DHCP packets
>
> Hi,
>
> I am thinking of creating a patch using your source code.
>
> I have a question for your source code.
>
> The size of "sname" and "file" are defined by RFC 2131.
> ("sname" size is 64 bytes, "file" size is 128 bytes)
>
> In your source code there are cases where "sname" is 40 bytes and "file"
> does not exist.
> Did you create this code based on what?
> Also, Where is that case listed in RFC?
>
>
> Regards, Muraoka
>
> On 2016年12月22日 06:42, Jacob Cox wrote:
>> To make this work, I had to modify Ryu’s dhcp.py file. I just placed
>> my solution on stackoverflow, and I’m placing the complete file on
>> https://github.com/Ryuretic/RyureticLabs/tree/master/ryu/ryu/app/Ryure
>> tic/Support_Files shortly. Folks should be able to save their current
>> dhcp.py file as a backup and save my file to the packets folder.
>>
>>
>>
>> http://stackoverflow.com/questions/41244431/cant-parse-dhcp-packets-wi
>> th-ryus-get-protocoldhcp-dhcp/41272226#41272226
>>
>>
>>
>>
>>
>> Respectfully,
>>
>>
>>
>> Jacob Cox
>>
>>
>>
>>
>>
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