[SIPForum-discussion] Flooding in SIP.

Seshagiri Kondaveti seshagiri.kondaveti at aricent.com
Thu Jun 24 13:14:43 UTC 2010

I think in this scenario, UAS responds with 486 Busy with Retry-After header.

Pl correct me if I am wrong.

486 Busy Here

   The callee's end system was contacted successfully, but the callee is

   currently not willing or able to take additional calls at this end

   system.  The response MAY indicate a better time to call in the

   Retry-After<http://rfc-ref.org/RFC-TEXTS/3261/kw-retry-after.html> header field<http://rfc-ref.org/RFC-TEXTS/3261/kw-header_field.html>.  The user could also be available

   elsewhere, such as through a voice mail service<http://rfc-ref.org/RFC-TEXTS/3261/kw-voice_mail_service.html>.  Status 600 (Busy

   Everywhere) SHOULD be used if the client<http://rfc-ref.org/RFC-TEXTS/3261/kw-client.html> knows that no other end

   system will be able to accept this call.


From: discussion-bounces at sipforum.org [mailto:discussion-bounces at sipforum.org] On Behalf Of ayyanar.kalimuthu at wipro.com
Sent: Wednesday, June 23, 2010 8:22 AM
To: intesab at hotmail.com; discussion at sipforum.org
Subject: Re: [SIPForum-discussion] Flooding in SIP.

The T1*64 is nothing but Timer B which is INVITE transaction timeout timer. On expiry of this timer, the UAC receives a
408 Request timeout response from the UAS since it is unable to process the request within T1*64 (500 ms * 64 = 32 seconds).

From: discussion-bounces at sipforum.org [mailto:discussion-bounces at sipforum.org] On Behalf Of intesab hussain
Sent: Tuesday, June 22, 2010 5:07 PM
To: discussion at sipforum.org
Subject: [SIPForum-discussion] Flooding in SIP.

   Hi everyone,

      I have 2 Questions regarding to flooding attack.

      1.  When INVITE is forwarded to proxy upto what time it must be get connected ?    As I know it is 64*TI, whereas TI=500ms and in one article I read 3 minutes. Please someone clarify the correct timing.

      2. How UAC can receive multiple request at a time? At a time only single person can talk and other may be in waiting. How Flooding effects on UAC in case of multiple request at a time, As it is not possible to talk with many persons at a time.

    Thanks in advance.


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