[Serusers] Problem with MTU size in SER with MIPv6.

[Andrei Pelinescu-Onciul]

On Nov 23, 2006 at 10:11, Jose Angel Calvo <jacc15dkz at yahoo.es> wrote:
> Thank you for your help and sorry for my english.
> I have a problem with mipv6 and a server SIP, SER (SIP Express Router).
> The mipv6 path is  "mipv6-2.0.2"  in  kernel  2.6.16.24-Ubuntu.
> 
> The problem occurs when a packet is too big (it must be fragmented), and go to the node what makes function of P-CSCF (Proxy in SIP) and Correspondent Node. If the P-CSCF is not a CN, all is OK. But if the node is CN, then i have the problem. The SER logs are:
> 

[...]

> The problem is in the MTU size, because if the packet is not fragmented, there is not a problem. But the INVITE packet
>  needs to fragment, what it means, i always have the same problem.
> 
> My questions are:
> 
> - Have anybody the same o similar problem?
Nobody that  I know of :-)


> - The MTU size is a problem in SER?
No, there shouldn't be (there is no place where we look at the MTU).


> - Have anybody sent fragmented packets with SER?

Yes, and it works.

Could you give more details?
- what version of ser are you running (ser -V)?
- is it vanilla ser or a modified version?
- the packet is sent over TCP? UDP?
- a coredump backtrace? (for this you'll have to start ser with
 -w directory_where_core_can_be_written, e.g.  ser -f ser.cfg -w /tmp/)
After the crash, run gdb path_to_ser/ser /tmp/core, type bt
 and send me the output. Note: the core file might have another name
  (e.g. core.3456). Just look for core.* .


Andrei