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Cisco Bug: CSCtb77620 - GGSN mixes sessions

Last Modified

Feb 22, 2014

Products (1)

  • Cisco 7600 Gateway GPRS Support Node

Known Affected Releases

12.4(1.1)T

Description (partial)

Symptom:

GGSN may mix 2 PDP sessions into 1.

Conditions:

3GPP 23.060 v6.14.0 p. 11.1.1 Interactions between GTPv0 and GTPv1

"When a GTP v0 tunnel was established between the old SGSN and the GGSN, 
and both old and new SGSNs support GTPv1 the respective uplink Flow 
Label signalling shall be inserted in the two lower octets of the Uplink 
TEID Control Plane field of the SGSN Context Response message; the upper 
two octets shall be set to all zeros."

When in the above scenario the update PDP context request comes in from SGSN in GTPv1 with TEID = 0x0000yyyy, the GGSN cannot know - and this is due to missing requirement in the 3GPP specifications :

A. whether it is an Update PDP context request for a session with TEID 0x0000yyyy assigned in GTPv1 communication between GGSN and SGSN, in the handover scenario GTPv1 between source SGSN and GGSN & GTPv1 in between SGSN's & GTPv1 between target SGSN and GGSN

or

B. whether it is an Update PDP context request for a session which was assigned in GTPv0 communication between GGSN and SGSN the flow label 0xyyyy and for which a handover was made to GTPv1 between target SGSN and GGSN while both source and target SGSN talked with each other GTPv1

However the mix doesn't concern a PDP swap between 2  sessions as indicated in the above A and B cases where GGSN cannot know which PDP session it is, due to lack of 3GPP specifications.
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