11 List of system variables
3GPP48.016Base Station System (BSS) - Serving GPRS Support Node (SGSN) interfaceGeneral Packet Radio Service (GPRS)Network serviceRelease 17TS
Table 11.1: System timers
|
Timer name |
Timer value |
Notes |
Relation to other timers |
|---|---|---|---|
|
Tns-block |
1s to 120s |
Guards the blocking and unblocking procedures |
none |
|
Tns-reset |
1s to 120s |
Guards the reset procedure |
none |
|
Tns-test |
1s to 60s |
Periodicity of the NS-VC test procedure |
none |
|
Tns-alive |
3s |
Guards the NS-VC test procedure |
none |
|
Tsns-prov |
1s-10s |
Guards the SNS procedures |
none |
Table 11.2: System counters
|
Counter name |
Value |
Notes |
|---|---|---|
|
NS-BLOCK-RETRIES |
3 |
recommended value |
|
NS-UNBLOCK-RETRIES |
3 |
recommended value |
|
NS-ALIVE-RETRIES |
10 |
recommended value |
|
SNS-ADD-RETRIES |
3 |
recommended value |
|
SNS-CONFIG-RETRIES |
3 |
recommended value |
|
SNS-CHANGEWEIGHT-RETRIES |
3 |
recommended value |
|
SNS-DELETE-RETRIES |
3 |
recommended value |
|
SNS-SIZE-RETRIES |
3 |
recommended value |
Annex A (informative):
Recommended usage of BVCI and NSEI
This annex recommends a way to use BVCIs and NSEIs, avoiding huge and unflexible configuration data at the SGSN. This annex uses concepts defined in 3GPP TS 48.018.
The key points are:
– A BVCI needs not to be unique within an SGSN, a BVCI is unique within an NS Entity. BVCI together with NSEI uniquely identify a BVC within an SGSN (the global identifier within an SGSN is BVCI+NSEI).
– BVCIs corresponding to PTP functional entities need not to be statically configured at the SGSN side: no fixed, permanent relationship is required in the SGSN between PTP BVCIs and NS-VCs.
With the NSEI, the SGSN needs not to be updated when a new cell (BVCI) is added to a BSS (NSEI). The pre‑configuration of a cell in the SGSN and the constraint in the number of BVCs in an SGSN are not needed:
– The SGSN keeps detailed MM information about an MS while the MS is in the READY state, i.e. the SGSN knows the BVCI and NSEI which can be used to contact the MS for downlink transmission. The BVCI and NSEI are passed from NS to BSSGP and from BSSGP to the upper layers as a primitive parameter in every uplink packet received by the SGSN. Subsequent downlink LLC frames to this MS shall be transmitted by the SGSN over the BVC identified by this BVCI+NSEI.
– An SGSN in STANDBY state will page an MS before sending downlink traffic. The MS will respond with an LLC packet that will put the MM context in READY state and will deliver the BVCI and NSEI to the user of BSSGP.
For paging purposes, the SGSN only needs to know the correspondence between each Routeing Area and one or more NSEI(s) where to send the corresponding paging messages. Paging messages for a mobile in STANDBY state shall always be sent over BVCI=0 of an NSEI and for a mobile in READY state the circuit page is sent over the PTP BVC identified by the BVCI+NSEI. There may be NSEI(s) where BVCI=0 is not used.
Annex B (informative):
Recommended usage of Resource Distribution for IP
This annex recommends a way to support resource distribution over the Gb in an IP sub-network. Resource distribution provides a means to control the IP endpoint at which the NS user traffic for a mobile is received.
Some examples of resource distribution over the Gb:
Example 1: Both NS entities trigger resource distribution (refer to figure B.1).
The BSS receives an uplink LLC PDU from the mobile and creates a mobile context. Now the BSS selects the source IP/UDP1 endpoint (internal implementation dependent) and a destination IP/UDP3 endpoint (IP load sharing dependent) on which to send NS SDUs associated with the mobile.
The BSS sends the uplink NS-UNITDATA (with R-bit set and the LSP corresponding to the IP endpoints selected) to the SGSN from IP/UDP1 to IP/UDP3. On receipt of uplink NS-UNITDATA for the mobile the SGSN may also choose to change the IP endpoint at which it wishes to receive uplink NS-UNITDATA for the mobile to IP/UDP4. The SGSN responds by sending a downlink NS-UNITDATA with R-bit and C-bit set to 1 from the IP/UDP4 at to IP/UDP1.
Subsequent uplink and downlink NS-UNITDATA for the mobile shall follow the dotted path (IP/UDP1 and IP/UDP4) through the IP sub-network.
Figure B.1: Example 1 of both NS entities requesting change flow
Example 2: Only one NS entity triggers resource distribution (refer to figure B.2).
The BSS sends an uplink NS-UNITDATA with R-bit set from IP/UDP1 to IP/UDP3 at the SGSN. The SGSN may choose not to trigger resource distribution, but the SGSN confirms receipt of the "request change flow" by sending the in the next downlink NS-UNITDATA with C-bit set to IP/UDP1.
Subsequent uplink data transfer for the mobile will follow the dotted paths from IP/UDP1 to IP/UDP3 and downlink data transfer from IP/UDP4 to IP/UDP1.
Figure B.2: Example 2 of only one NS entity requesting change flow
Example 3: NS entity triggering resource distribution without data (refer to figure B.3).
The SGSN may wish to receive uplink data for a mobile at IP/UDP4 and not IP/UDP3. The SGSN may not have downlink data, in which case the SGSN may send a downlink NS-UNITDATA (with R-bit set) containing a BSSGP DL‑UNITDATA with an LLC PDU of length 0.
Subsequent uplink data transfer for the mobile will follow the dotted path from IP/UDP1 to IP/UDP4 through the IP sub‑network.
Figure B.3: Example 3 of NS entity requesting change flow without data
Example 4: NS entities without any resource distribution function (refer to figure B.4).
The BSS and SGSN may not care which IP endpoint data arrives at as long as the requirements for the load sharing function are met.
In this case the paths taken by the uplink and downlink data are independent.
Figure B.4: Example 4 of NS entity not requesting change flow
Annex C (informative):
Change History
|
Meeting / Date |
Doc |
CR |
Rev |
Subject/Comment |
New version |
|
January 2016 |
– |
– |
– |
Creation of Rel-13 version based on version 12.0.0 |
13.0.0 |
|
Change history |
|||||||
|
Date |
Meeting |
TDoc |
CR |
Rev |
Cat |
Subject/Comment |
New version |
|
2017-03 |
RP-75 |
– |
– |
– |
– |
Version for Release 14 (frozen at TSG-75) |
14.0.0 |
|
2018-06 |
RP-80 |
– |
– |
– |
– |
Update to Rel-15 version (MCC) |
15.0.0 |
|
2020-07 |
RP-88e |
– |
– |
– |
– |
Upgrade to Rel-16 version without technical change |
16.0.0 |
|
2022-03 |
RP-95e |
– |
– |
– |
– |
Upgrade to Rel-17 version without technical change |
17.0.0 |