Hey Priyaranjan
Actually if you have noticed there are 4 SPIs in total.
UE will have 2 SPI-C ,SPI-S and PCSCF also have 2 SPI-C ,SPI-S.
UDP case for which wireshark snippet is given:
UE(192.168.1.118) using SPI-C(301) and then PCSCF(192.168.1.116) using
SPI-C(201)
So in this flow 2 SPIs are used but each side using only one out of 2 both
have.
TCP case ,for same flow all 4 SPIs will be used .
Hope this will clarify .Otherwise capture one register trace in TCP ,UDP
and check it properly.
Thanks & regards
Ankur Bansal
On Tue, Jun 2, 2015 at 2:24 PM, Priyaranjan Nayak <[email protected]
> wrote:
> Hi Ankur,
>
> Thanks for your valuable information.
> I am seeing two SPI value are used in between two normal UDP socket
> communication.
> Below is the wireshark snippet
> [image: Inline image 2]
>
> Could you please clarify me why is it happening ?
> Do we have any scenario where UDP will use two SPI values ?
>
>
> On Mon, Jun 1, 2015 at 9:39 PM, ankur bansal <[email protected]> wrote:
>
>> Hi
>>
>> 1. Do we need two(server and client) spi values at the time of
>> communication over UDP or TCP ?
>> Yes two Spi values required mostly for tcp
>> UDP case : UE sending Register to PCSCF uses Spi-c(UE) and P-CSCF
>> sends response back using Spi-c(PCSCF)
>>
>> TCP case : UE sending Register to PCSCF uses Spi-c(UE) and P-CSCF
>> sends response back using Spi-s(PCSCF)
>> As Same socket will be used for sending responses
>> on which request came
>>
>> 2. At the time of communication how can we share the pre-shared key ?
>>
>> Keys to encrypt,decrypt is communicated to PCSCF during
>> Registration-401 flow where
>> S-CSCF will send IK,CK keys in 401 response towards P-CSCF which
>> P-CSCF
>> will remove before relaying 401 to UE .UE would generate these keys
>> from SIM .
>>
>> Thanks
>> Ankur Bansal
>>
>> On Mon, Jun 1, 2015 at 12:53 PM, Priyaranjan Nayak <
>> [email protected]> wrote:
>>
>>> Hi All,
>>>
>>> We have a SIP client (endpoint) and wanted to integrate IPSec to the SIP
>>> Client.
>>> The client will sent the Security-Client header to server and server will
>>> sent the Security-server header to the client. In these messages client
>>> and
>>> server are sending the spi-c and sip-s value to each other for further
>>> communication. Could you please clarify me below questions ?
>>>
>>> 1. Do we need two(server and client) spi values at the time of
>>> communication over UDP or TCP ?
>>> 2. At the time of communication how can we share the pre-shared key ?
>>>
>>> Thanks
>>> Priyaranjan
>>> _______________________________________________
>>> Sip-implementors mailing list
>>> [email protected]
>>> https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
>>>
>>
>>
>
>
> --
> Thanks
> Priyaranjan
>
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