Cisco Cisco IOS Software Release 12.2(18)SXE

Delivers tunnel creation messages destined to the virtual GGSN IP address to one of the real 
GGSNs, using the weighted round robin load-balancing algorithm. See the 

 for more information about this algorithm.

Requires DFP in order to account for secondary PDP contexts in GTP v1.

GPRS load balancing with GTP cause code inspection enabled allows IOS SLB to monitor all 
PDP context signaling flows to and from GGSN server farms. This enables IOS SLB to monitor GTP 
failure cause codes, detecting system-level problems in both Cisco and non-Cisco GGSNs.

 lists the PDP create response cause codes and the corresponding actions taken by IOS SLB.

GPRS load balancing with GTP cause code inspection enabled has the following characteristics:

Must operate in directed server NAT mode.

Supports stateful backup. See the 

 for more information.

Tracks the number of open PDP contexts for each GGSN, which enables GGSN server farms to use 
the weighted least connections (leastconns) algorithm for GPRS load balancing. See the 

 for more information about this algorithm.

Enables IOS SLB to deny access to a virtual GGSN if the carrier code of the requesting International 
Mobile Subscriber ID (IMSI) does not match a specified value.

Enables IOS SLB to account for secondary PDP contexts even without DFP.

Request Accepted

Establish session

No Resource Available

Fail current real, reassign session, drop the response

All dynamic addresses are occupied

Fail current real, reassign session, drop the response

No memory is available

Fail current real, reassign session, drop the response

System Failure

Fail current real, reassign session, drop the response

Missing or Unknown APN

Forward the response

Unknown PDP Address or PDP type

Forward the response

User Authentication Failed

Forward the response

Semantic error in TFT operation

Forward the response

Syntactic error in TFT operation

Forward the response

Semantic error in packet filter

Forward the response

Syntactic error in packet filter

Forward the response

Mandatory IE incorrect

Forward the response

Mandatory IE missing

Forward the response

Optional IE incorrect

Forward the response

Invalid message format

Forward the response

Version not supported

Forward the response