Cisco GGSN Release 4.0 Configuration Guide, Cisco IOS Software Release 12.3(2)XB1 - Configuring Network Access to the GGSN [Cisco IOS Software Releases 12.3 Special and Early Deployments]

Table Of Contents

Configuring Network Access to the GGSN

Configuring an Interface to the SGSN

Verifying the Interface Configuration to the SGSN

Configuring a Route to the SGSN

Configuring a Static Route to the SGSN

Configuring OSPF

Verifying the Route to the SGSN

Configuring Access Points on the GGSN

Overview of Access Points

Description of Access Points in a GPRS/UMTS Network

Access Point Implementation on the Cisco GGSN

Basic Access Point Configuration Task List

Configuring the GPRS Access Point List on the GGSN

Creating an Access Point and Specifying its Type on the GGSN

Configuring Real Access Points on the GGSN

PDN Access Configuration Task List

VPN Access Using VRF Configuration Task Lists

Configuring Other Access Point Options

Verifying the Access Point Configuration

Verifying the GGSN Configuration

Verifying Reachability of the Network Through the Access Point

Configuring Access to External Support Servers

Configuring Virtual APN Access on the GGSN

Overview of the Virtual APN Feature

Virtual APN Configuration Task List

Configuring Virtual Access Points on the GGSN

Verifying the Virtual APN Configuration

Configuring Network-Initiated PDP Context Support on the GGSN

Overview of Network-Initiated PDP Context Support

Restrictions

Network-Initiated PDP Context Configuration Task List

Configuring Network-Initiated PDP Context Support at an APN

Specifying the GSN for GTP-MAP Protocol Conversion

Configuring the Static IP Address Mapping to IMSI

Configuring Other Network-Initiated PDP Options

Verifying the Network-Initiated PDP Context Configuration

Verifying the GGSN Configuration

Verifying Reachability of the MS Using Network-Initiated PDP Request

Blocking Access to the GGSN by Foreign Mobile Stations

Overview of Blocking Foreign Mobile Stations

Blocking Foreign Mobile Stations Configuration Task List

Configuring the MCC and MNC Values

Enabling Blocking of Foreign Mobile Stations on the GGSN

Verifying the Blocking of Foreign Mobile Stations Configuration

Controlling Access to the GGSN by MSs with Duplicate IP Addresses

Configuration Examples

Static Route to SGSN Example

Access Point List Configuration Example

VRF Tunnel Configuration Example

Virtual APN Configuration Example

Network-Initiated PDP Request Configuration Example

Blocking Access by Foreign Mobile Stations Configuration Example

Duplicate IP Address Protection Configuration Example

Configuring Network Access to the GGSN

This chapter describes how to configure access from the GGSN to a SGSN, PDN, and optionally to a virtual private network (VPN). It also includes information about configuring access points on the GGSN.

For a complete description of the GGSN commands in this chapter, refer to the Cisco IOS Mobile Wireless Command Reference. To locate documentation of other commands that appear in this chapter, use the command reference master index or search online.

This chapter includes the following sections:

•Configuring an Interface to the SGSN (Required)

•Configuring a Route to the SGSN (Required)

•Configuring Access Points on the GGSN (Required)

•Configuring Virtual APN Access on the GGSN (Optional)

•Configuring Network-Initiated PDP Context Support on the GGSN (Optional)

•Blocking Access to the GGSN by Foreign Mobile Stations (Optional)

•Controlling Access to the GGSN by MSs with Duplicate IP Addresses (Optional)

•Configuration Examples

Configuring an Interface to the SGSN

To establish access to an SGSN, you must configure an interface to the SGSN. In GPRS/UMTS, the interface between the GGSN and the SGSN is referred to as the Gn interface. GGSN Release 4.0 supports both a 2.5G and 3G Gn interface.

On the Cisco 7200 series router platform, this interface is a physical one. On the Catalyst 6500 series switch / Cisco 7600 series Internet router platform, this interface is logical one (on which IEEE 802.1Q-encapsulation has been configured) to the Layer-3 routed Gn VLAN configured on the Supervisor/MSFC2.

For more information about the Gn VLAN on the Supervisor/MSFC2, see Catalyst 6500 / Cisco 7600 Series Platform Prerequisites, page 2-2.

For more information about configuring interfaces, see the Cisco IOS Interface Configuration Guide and the Cisco IOS Interface Command Reference.

Configuring Physical Interfaces

The type of physical interface that you configure on the GGSN depends on whether you are supporting an SGSN that is collocated with a GGSN, or an enterprise GGSN that is connected to the SGSN through a WAN interface.

When a GGSN is collocated with the SGSN, the physical interface is frequently configured for Fast Ethernet. The supported WAN interfaces for a remote SGSN include T1/E1, T3/E3, and Frame Relay. For information on configuring WAN interfaces, see the Cisco IOS Interface Configuration Guide and the Cisco IOS Interface Command Reference.

To configure a physical Gn interface to the SGSN that supports Fast Ethernet on a Cisco 7200 series router, use the following commands beginning in global configuration mode:

Command

Purpose

Step 1

Router(config)# interface type slot/port

Defines a physical interface on the GGSN, where type is fastethernet, and slot/port is the hardware slot and port on the interface.

Step 2

Router(config-if)# ip address ip-address mask [secondary]

Specifies an IP address for the interface, where:

•ip-address—Specifies the IP address of the interface in dotted decimal format.

•mask—Specifies a subnet mask in dotted decimal format.

•secondary—Specifies that the configured address is a secondary IP address. If this keyword is omitted, the configured address is the primary IP address.

Configuring 802.1Q-Encapsulated Subinterfaces

To configure a subinterface that supports IEEE 802-1q encapsulation to the Gn VLAN, use the following commands beginning in global configuration mode:

Command

Purpose

Step 1

Router(config)# interface gigabitethernet slot/port.subinterface-number

Specifies the subinterface on which IEEE 802.1Q will be used.

Step 2

Router(config-if)# encapsulation dot1q vlanid

Defines the encapsulation format as IEEE 802.1Q (dot1q), and specifies the VLAN identifier.

Step 3

Router(config-if)# ip address ip-address mask

Sets a primary IP address for an interface.

Verifying the Interface Configuration to the SGSN

Cisco 7200 Platform

To verify the interface to the SGSN you can first verify your GGSN configuration and then verify that the interface is available.

Step 1 To verify that you have properly configured a Gn interface on the GGSN, use the show running-config command. The following example is a portion of the output from the command showing the FastEthernet0/0 physical interface configuration as the Gn interface to the SGSN:
GGSN# show running-config
Building configuration...
Current configuration : 2875 bytes
!
version 12.2
. . .
!
interface FastEthernet0/0
 description Gn interface to SGSN
 ip address 10.10.1.3 255.255.255.0
 no ip mroute-cache
 duplex full
. . .
Step 2 To verify that a physical interface is available, use the show ip interface brief command. The following example shows that the FastEthernet0/0 interface to the SGSN is in "up" status and the protocol is also "up":
GGSN# show ip interface brief 
Interface                  IP-Address      OK? Method Status                Protocol
FastEthernet0/0            10.10.1.3       YES NVRAM  up                    up 
FastEthernet1/0            10.29.0.2       YES NVRAM  up                    up      
FastEthernet1/1            10.13.0.2       YES NVRAM  up                    up      
FastEthernet2/0            unassigned      YES NVRAM  administratively down down    
Ethernet6/0                10.99.0.12      YES NVRAM  up                    up      
Ethernet6/1                unassigned      YES NVRAM  administratively down down    
Ethernet6/2                unassigned      YES NVRAM  administratively down down    
Ethernet6/3                unassigned      YES NVRAM  administratively down down    
Ethernet6/4                unassigned      YES NVRAM  administratively down down    
Ethernet6/5                unassigned      YES NVRAM  administratively down down    
Ethernet6/6                unassigned      YES NVRAM  administratively down down    
Ethernet6/7                10.35.35.2      YES NVRAM  up                    up      
Virtual-Access1            10.44.44.1      YES TFTP   up                    up      
Virtual-Template1          10.44.44.1      YES manual down                  down 
Catalyst 6500 / Cisco 7600 Platform

Step 1 To verify that you have properly configured a Gn interface on the Supervisor/MSFC2, use the show running-config command. The following example is a portion of the output from the command showing the FastEthernet8/22 physical interface configuration as the Gn interface to the SGSN:
Sup# show running-config
Building configuration...
Current configuration :12672 bytes
!
version 12.2
...
interface FastEthernet8/22
 no ip address
 switchport
 switchport access vlan 302
!
interface Vlan101
 description Vlan to GGSN for GA/GN
 ip address 10.1.1.1 255.255.255.0
!
interface Vlan302
 ip address 40.0.2.1 255.255.255.0
Step 2 To verify the physical interface and the Gn VLAN are available, use the show interface command on the Supervisor/MSFC2. The following example shows that the FastEthernet8/22 physical interface to the charging gateway is up as well as the Gn VLAN, VLAN 101.
Sup# show ip interface brief FastEthernet8/22
Interface                  IP-Address      OK? Method Status                Protocol
FastEthernet8/22           unassigned      YES unset  up                    up 
Sup# show ip interface brief Vlan302
Interface                  IP-Address      OK? Method Status                Protocol
Vlan302                    40.0.2.1        YES TFTP   up                    up      
Sup#
Step 3 To verify the Gn VLAN configuration and availability, use the show vlan name command on the Supervisor/MSFC2. The following example shows the Gn VLAN Gn_1
Sup# show vlan name Gn_1
VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
302  Gn_1                             active    Gi4/1, Gi4/2, Gi4/3, Gi7/1
                                                Gi7/2, Gi7/3, Fa8/22, Fa8/26
VLAN Type  SAID       MTU   Parent RingNo BridgeNo Stp  BrdgMode Trans1 Trans2
---- ----- ---------- ----- ------ ------ -------- ---- -------- ------ ------
302  enet  100302     1500  -      -      -        -    -        0      0   
Remote SPAN VLAN
----------------
Disabled
Primary Secondary Type              Ports
------- --------- ----------------- ------------------------------------------ 
Step 4 On the GGSN, to verify that you have properly configured a Gn subinterface to the Gn VLAN, use the show running-config command. The following example is a portion of the output from the command showing a FastEthernet5/1 physical interface configuration as the Gn interface to the charging gateway:
GGSN# show running-config
Building configuration...
Current configuration :7390 bytes
!
! Last configuration change at 16:56:05 UTC Wed Jun 25 2003
! NVRAM config last updated at 23:40:27 UTC Fri Jun 13 2003
!
version 12.3
.....
interface GigabitEthernet0/0.2
 description Ga/Gn Interface
 encapsulation dot1Q 101
 ip address 10.1.1.72 255.255.255.0
 no cdp enable
!
.....
ip route 40.1.2.1 255.255.255.255 10.1.1.1
Step 5 To verify that the subinterface is available, use the show ip interface brief command. The following example shows that the GigabitEthernet0/0.2 subinterface to the Gn VLAN is in "up" status and the protocol is also "up":
GGSN# show ip interface brief GigabitEthernet0/0.2
Interface                  IP-Address      OK? Method Status                Protocol
GigabitEthernet0/0.2       10.1.1.72       YES NVRAM  up                    up 
Configuring a Route to the SGSN

To communicate with the SGSN, you can use static routes or a routing protocol, such as Open Shortest Path First (OSPF).

Note For the SGSN to communicate successfully with the GGSN, the SGSN must also configure a static route, or be able to dynamically route to the IP address of the GGSN virtual template, not the IP address of a GGSN interface.

The following sections provide some basic commands that you can use to configure a static route or enable OSPF routing on the GGSN. For more information about configuring IP routes, see the Cisco IOS IP Configuration Guide and Cisco IOS IP Command References.

The following topics are included in this section:

•Configuring a Static Route to the SGSN

•Configuring OSPF

•Verifying the Route to the SGSN

Configuring a Static Route to the SGSN

A static route establishes a fixed route to the SGSN that is stored in the routing table. If you are not implementing a routing protocol, such as OSPF, then you can configure a static route to the SGSN, to establish the path between network devices.

To configure a static route from an interface to the SGSN, use the following commands beginning in global configuration mode:

Command

Purpose

Router(config)# ip route prefix mask {ip-address | interface-type interface-number} [distance] [tag tag] [permanent]

Configures a static IP route, where:

•prefix—Specifies the IP route prefix for the destination. (This is the IP address of the SGSN.)

•mask—Specifies the prefix mask for the destination. (This is the subnet mask of the SGSN network.)

•ip-address—Specifies the IP address of the next hop that can be used to reach the destination network.

•interface-type interface-number—Specifies the network interface type and interface number that can be used to reach the destination network. (This is an interface on the GGSN for the Gn interface.)

•distance—Specifies an administrative distance for the route.

•tag tag—Specifies a tag value that can be used as a "match" value for controlling redistribution via route maps.

•permanent—Specifies that the route will not be removed, even if the interface shuts down.

Configuring OSPF

As with other routing protocols, enabling OSPF requires that you create an OSPF routing process, specify the range of IP addresses to be associated with the routing process, and assign area IDs to be associated with that range of IP addresses.

Note On the Catalyst 6500 / Cisco 7600 platform, the OSPF routing process is configured on the Supervisor/MSFC2 to advertise only the GTP SLB virtual server and the GGSN virtual template addresses.

To configure OSPF, use the following commands beginning in global configuration mode:

Command

Purpose

Step 1

Router(config)# router ospf process-id

Enables OSPF routing, and enters router configuration mode, where process-id specifies an internally used identification parameter for an OSPF routing process.

The process-id is locally assigned and can be any positive integer. A unique value is assigned for each OSPF routing process.

Step 2

Router(config-router)# network ip-address wildcard-mask area area-id

Defines an interface on which OSPF runs and defines the area ID for that interface, where:

•ip-address—Specifies the IP address to be associated with the OSPF network area.

•wildcard-mask—Specifies the IP address mask that includes "don't care" bits for the OSPF network area.

•area-id—Specifies the area that is to be associated with the OSPF address range. It can be specified as either a decimal value or as an IP address. If you intend to associate areas with IP subnets, you can specify a subnet address as the area-id.

Verifying the Route to the SGSN

To verify the route to the SGSN you can first verify your GGSN configuration and then verify that a route has been established.

Cisco 7200 Platform

Step 1 To verify the GGSN configuration, use the show running-config command and verify the static route that you configured to the SGSN, or your OSPF configuration. The following example shows a partial configuration of an OSPF configuration for the 10.10.0.0 network using the FastEthernet0/0 interface to the SGSN:
GGSN# show running-config
Building configuration...
Current configuration : 2875 bytes
!
version 12.2
. . .
!
interface FastEthernet0/0
 description Gn interface to SGSN
 ip address 10.10.1.3 255.255.255.0
 no ip mroute-cache
 duplex full
!
interface FastEthernet6/0
 ip address 172.16.43.243 255.255.255.240
 no ip mroute-cache
 duplex half
!
!
interface loopback 1
 ip address 10.11.11.1 255.255.255.0
!
interface Virtual-Template1
 ip unnumber loopback 1
 encapsulation gtp
!
router ospf 1
 log-adjacency-changes
 network 10.10.0.0 0.0.255.255 area 0
!
ip default-gateway 172.16.43.241
ip classless
ip route 10.22.22.1 255.255.255.255 FastEthernet2/0
ip route 192.64.0.0 255.0.0.0 172.16.43.241
ip route 172.16.0.0 255.255.0.0 172.16.43.241
no ip http server
no ip pim bidir-enable
. . .
Step 2 To verify that the GGSN has established a route to the SGSN, you can use the show ip route command as shown in bold in the following example:
GGSN# show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP 
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area 
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 
       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP 
       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area 
       * - candidate default, U - per-user static route, o - ODR 
       P - periodic downloaded static route 
Gateway of last resort is not set 
     10.11.11.0/24 is subnetted, 1 subnets 
C       10.11.11.0 is directly connected, Virtual-Access1 
     172.16.0.0/16 is variably subnetted, 1 subnets, 2 masks 
S       172.16.0.0/16 [1/0] via 172.16.43.241 
C       172.16.43.243/28 is directly connected, FastEthernet6/0 
     10.0.0.0/24 is subnetted, 1 subnets 
O       10.10.1.0 [110/2] via 10.10.1.3, 00:00:10, FastEthernet0/0 
C       10.10.1.0 is directly connected, FastEthernet0/0 
Catalyst 6500 / Cisco 7600 Platform

Step 1 To verify the Supervisor/MSFC2 configuration, use the show running-config command and verify the route that you configured to the SGSN. The following example shows a partial configuration of a configuration to the SGSN:
Sup# show running-config
Building configuration...
Current configuration :3642 bytes
!
version 12.3
...
ip slb vserver V0-GGSN
 virtual 10.10.10.10 udp 3386 service gtp
!
vlan 101
 name Internal_Gn/Ga
!
vlan 302
 name Gn_1
!
vlan 303
 name Ga_1
!
interface FastEthernet8/22
 no ip address
 switchport
 switchport access vlan 302
!
interface FastEthernet8/23
 no ip address
 switchport
 switchport access vlan 302
!
interface FastEthernet8/24
 no ip address
 switchport
 switchport access vlan 303
!
interface Vlan101
 description Vlan to GGSN for GA/GN
 ip address 10.1.1.1 255.255.255.0
!
interface Vlan302
 ip address 40.0.2.1 255.255.255.0
!
interface Vlan303
 ip address 40.0.3.1 255.255.255.0
!
router ospf 300
 log-adjacency-changes
 summary-address 9.9.9.0 255.255.255.0
 redistribute static subnets route-map GGSN-routes
 network 40.0.2.0 0.0.0.255 area 300
 network 40.0.3.0 0.0.0.255 area 300
!
ip route 9.9.9.42 255.255.255.255 10.1.1.42
ip route 9.9.9.43 255.255.255.255 10.1.1.43
ip route 9.9.9.44 255.255.255.255 10.1.1.44
ip route 9.9.9.45 255.255.255.255 10.1.1.45
ip route 9.9.9.46 255.255.255.255 10.1.1.46
ip route 9.9.9.72 255.255.255.255 10.1.1.72
ip route 9.9.9.73 255.255.255.255 10.1.1.73
ip route 9.9.9.74 255.255.255.255 10.1.1.74
ip route 9.9.9.75 255.255.255.255 10.1.1.75
ip route 9.9.9.76 255.255.255.255 10.1.1.76
!
access-list 1 permit 9.9.9.0 0.0.0.255
!
route-map GGSN-routes permit 10
 match ip address 1
Step 2 To verify the GGSN configuration, use the show running-config command. The following example shows a partial configuration of a configuration to the SGSN:
Sup# show running-config
Building configuration...
Current configuration :3642 bytes
!
version 12.3
!
...
interface GigabitEthernet0/0
 no ip address
!
interface GigabitEthernet0/0.2
 description Ga/Gn Interface
 encapsulation dot1Q 101
 ip address 10.1.1.72 255.255.255.0
 no cdp enable
!
ip route 40.1.2.1 255.255.255.255 10.1.1.1
ip route 40.2.2.1 255.255.255.255 10.1.1.1
ip route 40.1.3.10 255.255.255.255 10.1.1.1
ip route 40.2.3.10 255.255.255.255 10.1.1.1
Step 3 To verify that the Supervisor/MSFC2 has established a route to the SGSN, you can use the show ip route command as shown in bold in the following examples:
Sup# show ip route ospf 300
9.0.0.0/8 is variably subnetted, 12 subnets, 2 masks
O       9.9.9.0/24 is a summary, 1w1d, Null0
!
Sup# show ip route 9.9.9.72
Routing entry for 9.9.9.72/32
  Known via "static", distance 1, metric 0
  Redistributing via ospf 300
  Routing Descriptor Blocks:
  * 10.1.1.72
      Route metric is 0, traffic share count is 1
!
Configuring Access Points on the GGSN

Successful configuration of access points on the GGSN requires careful consideration and planning to establish the appropriate access for mobile sessions to external PDNs and private networks.

The following topics are included in this section:

•Overview of Access Points

•Basic Access Point Configuration Task List

•Configuring Real Access Points on the GGSN

•Configuring Virtual APN Access on the GGSN

•Verifying the Access Point Configuration

Configuration of access points on the GGSN also requires properly establishing communication with any supporting DHCP and RADIUS servers that you might be using to provide dynamic IP addressing and user authentication functions at the access point.

Details about configuring other services such as DHCP and RADIUS for an access point are discussed in the "Configuring Dynamic Addressing on the GGSN" and "Configuring Security on the GGSN" chapters.

Overview of Access Points

This section includes the following topics:

•Description of Access Points in a GPRS/UMTS Network

•Access Point Implementation on the Cisco GGSN

Description of Access Points in a GPRS/UMTS Network

The GPRS and UMTS standards define a network identity called an access point name (APN). An APN identifies the part of the network where a user session is established, and in the GPRS/UMTS backbone, it serves as a reference to a GGSN. An APN is configured on and accessible from a GGSN in a GPRS/UMTS network.

An APN can provide access to a public data network (PDN), or a private or corporate network. An APN also can be associated with certain types of services such as Internet access or a Wireless Application Protocol (WAP) service.

The APN is provided by either the mobile station (MS) or by the SGSN to the GGSN in a create PDP context request message when a user requests a session to be established.

To identify an APN, a logical name is defined that consists of two parts:

•Network ID—A mandatory part of the APN that identifies the external network to which a GGSN is connected. The network ID can be a maximum of 63 bytes and must contain at least one label. A network ID of more than one label is interpreted as an Internet domain name. An example of a network ID might be "corporate.com."

•Operator ID—An optional part of the APN that identifies the PLMN in which a GGSN is located. The operator ID contains three decimal-separated labels, where the last label must be "gprs." An example of an operator ID might be "mnc10.mcc200.gprs."

When the operator ID exists, it is placed after the network id, and corresponds to the DNS name of a GGSN. The maximum length of an APN is 100 bytes. When the operator ID does not exist, a default operator ID is derived from the mobile network code (MNC) and mobile country code (MCC) information contained in the international mobile subscriber identity (IMSI).

Access Point Implementation on the Cisco GGSN

Configuring access points is one of the central configuration tasks on the Cisco GGSN. Proper configuration of access points is essential to successful implementation of the GGSN in the GPRS/UMTS network.

To configure APNs, the Cisco GGSN software uses the following configuration elements:

•Access point list—Logical interface that is associated with the virtual template of the Cisco GGSN. The access point list contains one or more access points.

•Access point—Defines an APN and its associated access characteristics, including security and method of dynamic addressing. An access point on the Cisco GGSN can be a virtual or real access point.

•Access point index number—Integer assigned to an APN that identifies the APN within the GGSN configuration. Several of the GGSN configuration commands use the index number to reference an APN.

•Access group—An additional level of security on the router that is configured at an access point to control access to and from a PDN. When an MS is permitted access to the GGSN as defined by a traditional IP access list, the IP access group further defines whether access is permitted to the PDN (at the access point). The IP access group configuration can also define whether access from a PDN to an MS is permitted.

Access Point Types on the GGSN

Cisco IOS GGSN Release 3.0 and later supports the following access point types:

•Real—Use real access point types to configure the GGSN for direct access to a particular target network through an interface. The GGSN always uses real access points to reach an external network.

•Virtual—Use virtual access point types to consolidate access to multiple target networks through a virtual APN access point at the GGSN. The GGSN always uses real access points to reach an external network, so virtual access points should be used in combination with real access points on the GGSN.

Cisco IOS GGSN Release 1.4 and earlier only supports real access points.

GGSN Release 3.0 and later supports virtual access point types to address provisioning issues in the PLMN. For more information about configuring virtual access point access to the GGSN from the PLMN, see the "Configuring Virtual APN Access on the GGSN" section.

Basic Access Point Configuration Task List

This section describes the basic tasks that are required to configure an access point on the GGSN. Detailed information about configuring access points for specialized functions such as network-initiated PDP context support (Cisco 7200 series platform only), or for virtual APN access are described in separate sections of this chapter.

To configure an access point on the GGSN, perform the following basic tasks:

•Configuring the GPRS Access Point List on the GGSN (Required)

•Creating an Access Point and Specifying its Type on the GGSN (Required)

Configuring the GPRS Access Point List on the GGSN

The GGSN software requires that you configure an entity called an access point list. You configure the GPRS access point list to define a collection of virtual and real access points on the GGSN.

When you configure the access point list in global configuration mode, the GGSN software automatically associates the access point list with the virtual template interface of the GGSN. Therefore, the GGSN supports only a single access point list.

Note Be careful to observe that the GPRS access point list and an IP access list are different entities in the Cisco IOS software. A GPRS access point list defines access points and their associated characteristics, and an IP access list controls the allowable access on the router by IP address. You can define permissions to an access point by configuring both an IP access list in global configuration, and configuring the ip-access-group command in your access point configuration.

To configure the GPRS access point list and configure access points within it, use the following commands beginning in global configuration mode:

Command

Purpose

Router(config)# gprs access-point-list list-name

Specifies a name for a new access point list, or references the name of the existing access point list and enters access-point list configuration mode.

Creating an Access Point and Specifying its Type on the GGSN

You need to define access points within an access point list on the GGSN. Therefore, before you can create an access point, you must define a new access point list, or specify the existing access point list on the GGSN to enter access-point list configuration mode.

When you create an access point you must assign an index number to the access point, specify the domain name (network ID) of the access point, and specify the type of access point (virtual or real). Other options that you can configure for an access point are summarized in the "Configuring Other Access Point Options" section.

To create an access point and specify its type, use the following commands beginning in global configuration mode:

Command

Purpose

Step 1

Router(config)# gprs access-point-list list-name

Specifies a name for a new access point list, or references the name of the existing access point list and enters access-point list configuration mode.

Step 2

Router(config-ap-list)# access-point access-point-index

Specifies an index number for a new access point definition, or references an existing access point definition, and enters access point configuration mode.

Step 3

Router(config-access-point)# access-point-name apn-name

Specifies the network (or domain) name for a PDN that users can access from the GGSN at a defined access point.

Note The apn-name must match the APN that has been provisioned at the MS, HLR, and DNS server.

Step 4

Router (config-access-point)# access-type {virtual | real}

(Optional) Specifies the type of access point. The available options are:

•virtual—APN type that is not associated with any specific physical target network on the GGSN.

•real—APN type that corresponds to an interface to an external network on the GGSN. This is the default value.

Configuring Real Access Points on the GGSN

The GGSN uses real access points to communicate to PDNs or private networks that are available over a Gi interface on the GGSN. Use real access point types to configure the GGSN for direct access to a particular target network through an interface.

If you have configured a virtual access point, you must also configure real access points to reach the target networks.

The GGSN supports configuration of access points to public data networks and to private networks. The following sections describe how to configure different types of real access points:

•PDN Access Configuration Task List

•VPN Access Using VRF Configuration Task Lists

PDN Access Configuration Task List

Configuring a connection to a public PDN includes the following tasks:

•Configuring an Interface to a PDN (Gi interface) (Required)

•Configuring an Access Point for a PDN (Required)

Configuring an Interface to a PDN

To establish access to a PDN in the GPRS/UMTS network, you must configure a interface on the GGSN to connect to the PDN. In interface is referred to as the Gi interface.

On the Cisco 7200 series router platform, this interface is a physical one. On the Catalyst 6500 series switch / Cisco 7600 series Internet router platform, this interface is logical one (on which IEEE 802.1Q-encapsulation has been configured) to a Layer-3 routed Gi VLAN configured on the Supervisor/MSFC2.

For more information about the Gi VLAN on the Supervisor/MSFC2, see Catalyst 6500 / Cisco 7600 Series Platform Prerequisites, page 2-2.

For more information about configuring interfaces, see the Cisco IOS Interface Configuration Guide and the Cisco IOS Interface Command Reference.

Configuring Physical Interfaces

To configure a physical interface to the PDN using Fast Ethernet over the Gi interface (Cisco 7200 series router platform), use the following commands beginning in global configuration mode:

Command

Purpose

Step 1

Router(config)# interface type slot/port

Defines a physical interface on the GGSN, where type is fastethernet, and slot/port is the hardware slot and port on the interface.

Step 2

Router(config-if)# ip address ip-address mask [secondary]

Specifies an IP address for the interface, where:

•ip-address—Specifies the IP address of the interface in dotted decimal format.

•mask—Specifies a subnet mask in dotted decimal format.

•secondary—Specifies that the configured address is a secondary IP address. If this keyword is omitted, the configured address is the primary IP address.

Note If you are using VRF for VPN access, you must enable CEF switching on the GGSN. If you enable CEF switching at the global configuration level, then it is automatically enabled for each interface unless it has been specifically disabled at the interface.

Configuring 802.1Q-Encapsulated Subinterfaces

To configure a subinterface that supports IEEE 802-1q encapsulation to the Gi VLAN, use the following commands beginning in global configuration mode:

Command

Purpose

Step 1

Router(config)# interface gigabitethernet slot/port.subinterface-number

Specifies the subinterface on which IEEE 802.1Q will be used.

Step 2

Router(config-if)# encapsulation dot1q vlanid

Defines the encapsulation format as IEEE 802.1Q (dot1q), and specifies the VLAN identifier.

Step 3

Router(config-if)# ip address ip-address mask

Sets a primary IP address for an interface.

Configuring an Access Point for a PDN

To configure an access point for a PDN, you must define a real access point in the GPRS access point list.

To configure a real access point on the GGSN, use the following commands beginning in global configuration mode:

Command

Purpose

Step 1

Router(config)# gprs access-point-list list-name

Specifies a name for a new access-point list, or references the name of an existing access-point list and enters access-point list configuration mode.

Step 2

Router(config-ap-list)# access-point access-point-index

Specifies an index number for a new access point definition, or references an existing access point definition, and enters access point configuration mode.

Step 3

Router(config-access-point)# access-point-name apn-name

Specifies the network (or domain) name for a PDN that users can access from the GGSN at a defined access point.

Note The apn-name must match the APN that has been provisioned at the MS, HLR, and DNS server.

Step 4

Router(config-access-point)# access-type real

Specifies an APN type that corresponds to an interface to an external network on the GGSN. This is the default value.

For an example of a GPRS access point configuration, see the "Access Point List Configuration Example" section.

VPN Access Using VRF Configuration Task Lists

The Cisco IOS GGSN software supports connectivity to a virtual private network (VPN) using virtual routing and forwarding (VRF).

The GGSN software provides a couple of ways that you can configure access to a VPN, depending on your platform, network configuration over the Gi interface between the GGSN and your PDNs, and the VPN that you want to access.

Note VRF is not supported on the Catalyst 6500 / Cisco 7600 Supervisor/MSFC2, therefore, you must tunnel encapsulated VRF traffic through the Supervisor/MSFC2 via a GRE tunnel from the GGSN to the PDN. For more information on configuring a tunnel, see "Configuring Access to a VPN With a Tunnel" section.

To configure VPN access using VRF on the GGSN, perform the following tasks:

•Enabling CEF Switching (Required)

•Configuring a VRF Routing Table on the GGSN (Required)

•Configuring a Route to the VPN Using VRF (Required)

•Configuring an Interface to a PDN Using VRF (Required)

•Configuring Access to a VPN (Required)

For sample configurations, see the "VRF Tunnel Configuration Example" section.

Enabling CEF Switching

When you enable CEF switching globally on the GGSN, all interfaces on the GGSN are automatically enabled for CEF switching.

Note To ensure CEF switching functions properly, wait a short period of time before enabling CEF switching after it has been disabled using the no ip cef command.

To enable CEF switching for all interfaces on the GGSN, use the following commands beginning in global configuration mode:

Command

Purpose

Step 1

Router(config)# ip cef

Enables CEF on the route processor card.

Step 2

Router(config)# gprs gtp ip udp ignore checksum

Disables verification of the UDP checksum to support CEF switching on the GGSN.

Configuring a VRF Routing Table on the GGSN

To configure a VRF routing table on the GGSN, use the following command beginning in global configuration mode:

Command

Purpose

Step 1

Router(config)# ip vrf vrf-name

Configures a VRF routing table, and enters VRF configuration mode.

Step 2

Router(config-vrf)# rd route-distinguisher

Creates routing and forwarding tables for a VRF and specifies the default route distinguisher for a VPN.

Configuring a Route to the VPN Using VRF

Be sure that a route exists between the GGSN and the private network that you want to access. You can verify connectivity by using the ping command from the GGSN to the private network address. To configure a route, you can use a static route or a routing protocol.

Configuring a Static Route Using VRF

To configure a static route using VRF, use the following command beginning in global configuration mode:

Command

Purpose

Router(config)# ip route vrf vrf-name prefix mask [next-hop-address] [interface {interface-number}] [global] [distance] [permanent] [tag tag]

Configures a static IP route, where:

•vrf-name—Specifies the name of the VPN routing/forwarding instance (VRF) for the static route.

•prefix—Specifies the IP route prefix for the destination.

•mask—Specifies the prefix mask for the destination.

•next-hop-address—Specifies the IP address of the next hop that can be used to reach the destination network.

•interface interface-number—Specifies the network interface type and interface number that can be used to reach the destination network.

•global—Specifies that the given next hop address is in the non-VRF routing table.

•distance—Specifies an administrative distance for the route.

•tag tag—Specifies a tag value that can be used as a "match" value for controlling redistribution via route maps.

•permanent—Specifies that the route will not be removed, even if the interface shuts down.

Verifying a Static Route Using VRF

To verify that the GGSN has established the static VRF route that you configured, use the show ip route vrf privileged EXEC command as shown in the following example:
GGSN# show ip route vrf vpn1 static
     172.16.0.0/32 is subnetted, 1 subnets
U       172.16.0.1 [1/0] via 0.0.0.0, Virtual-Access2
     10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
S       10.100.0.3/32 [1/0] via 10.110.0.13
Configuring an OSPF Route Using VRF

To configure an OSPF route using VRF, use the following command beginning in global configuration mode:

Command

Purpose

Router(config)# router ospf process-id [vrf vrf-name]

Enables OSPF routing, and enters router configuration mode, where,

•process-id—Specifies an internally used identification parameter for an OSPF routing process. The process-id is locally assigned and can be any positive integer. A unique value is assigned for each OSPF routing process.

•vrf vrf-name—Specifies the name of the VPN routing/forwarding instance.

Configuring an Interface to a PDN Using VRF

To establish access to a PDN, an interface on the GGSN to connect to the PDN. This interface is referred to as the Gi interface.

On the Cisco 7200 series router platform, this interface is physical. On the Catalyst 6500 series switch / Cisco 7600 series Internet router platform, this interface is a logical one (on which IEEE 802.1Q-encapsulation has been configured) to a Layer-3 routed Gi VLAN configured on the Supervisor/MSFC2.

For more information about the Gi VLAN on the Supervisor/MSFC2, see Catalyst 6500 / Cisco 7600 Series Platform Prerequisites, page 2-2.

For more information about configuring interfaces, see the Cisco IOS Interface Configuration Guide and the Cisco IOS Interface Command Reference.

Configuring Physical Interfaces

To configure a physical interface to the PDN using Fast Ethernet over the Gi interface, use the following commands beginning in global configuration mode:

Command

Purpose

Step 1

Router(config)# interface type slot/port

Defines a physical interface on the GGSN, where type is fastethernet, and slot/port is the hardware slot and port on the interface.

Step 2

Router(config-if)# ip vrf forwarding vrf-name

Associates a VRF with an interface or subinterface.

Note The vrf-name argument should match the name of the VRF that you configured using the ip vrf command.

Step 3

Router(config-if)# ip address ip-address mask [secondary]

Specifies an IP address for the interface, where:

•ip-address—Specifies the IP address of the interface in dotted decimal format.

•mask—Specifies a subnet mask in dotted decimal format.

•secondary—Specifies that the configured address is a secondary IP address. If this keyword is omitted, the configured address is the primary IP address.

Note If you are using VRF for VPN access, you must enable CEF switching on the GGSN. If you enable CEF switching at the global configuration level, then it is automatically enabled for each interface unless it has been specifically disabled at the interface.

Configuring 802.1Q-Encapsulated Subinterfaces

To configure a subinterface that supports IEEE 802-1q encapsulation to the Gi VLAN, use the following commands beginning in global configuration mode:

Command

Purpose

Step 1

Router(config)# interface gigabitethernet slot/port.subinterface-number

Specifies the subinterface on which IEEE 802.1Q will be used.

Step 2

Router(config-if)# encapsulation dot1q vlanid

Defines the encapsulation format as IEEE 802.1Q (dot1q), and specifies the VLAN identifier.

Step 3

Router(config-if)# ip address ip-address mask

Sets a primary IP address for an interface.

Configuring Access to a VPN

After you have completed the prerequisite configuration tasks, on the Cisco 7200 platform, you can configure access to a VPN with a tunnel or without a tunnel.

On the Catalyst 6500 / Cisco 7600 platform, VRF is not supported on the Supervisor/MSFC2. To successfully configure access to a PDN via VRF, you must tunnel encapsulated VRF traffic through the Supervisor/MSFC2 via a GRE tunnel between the GGSN and PDN.

Figure 5-1 is a logical view of a GRE tunnel configured between the VRF-aware GGSN and PDN, tunneling the encapsulated VRF information through the "VRF-unaware" Supervisor/MSFC2.

Figure 5-1 Tunnel Configuration from the GGSN to PDN through the Catalyst 6500 / Cisco 7600 Supervisor/MSFC2

The following sections describe the different methods you can configure to access a VPN:

•Configuring Access to a VPN Without a Tunnel

•Configuring Access to a VPN With a Tunnel

Configuring Access to a VPN Without a Tunnel

On the Cisco 7200 platform, if you configure more than one Gi interface to different PDNs, and need to access a VPN off one of those PDNs, then you can configure access to that VPN without configuring an IP tunnel. To configure access to the VPN in this case, you need to configure the vrf access point configuration command.

Note The Catalyst 6500 / Cisco 7600 Supervisor/MSFC2 does not support VRF, therefore, you must tunnel VRF traffic through the Supervisor via a GRE tunnel as described in "Configuring Access to a VPN With a Tunnel" section.

To configure access to a VPN in the GPRS access point list, use the following commands beginning in global configuration mode:

Command

Purpose

Step 1

Router(config)# gprs access-point-list list-name

Specifies a name for a new access point list, or references the name of the existing access point list and enters access-point list configuration mode.

Step 2

Router(config-ap-list)# access-point access-point-index

Specifies an index number for a new access point definition, or references an existing access point definition, and enters access point configuration mode.

Step 3

Router(config-access-point)# access-point-name apn-name

Specifies the network (or domain) name for a PDN that users can access from the GGSN at a defined access point.

Note The apn-name must match the APN that has been provisioned at the MS, HLR, and DNS server.

Step 4

Router(config-access-point)# access-type real

Specifies an APN type that corresponds to an interface to an external network on the GGSN. This is the default value.

Step 5

Router(config-access-point)# vrf vrf-name

Configures VPN routing and forwarding at a GGSN access point and associates the access point with a particular VRF instance.

Step 6

Router(config-access-point)# exit

Exits access point configuration mode.

For information about the other access point configuration options, see the "Configuring Other Access Point Options" section.

Configuring Access to a VPN With a Tunnel

If you have only a single Gi interface to a PDN from which you need to access one or more VPNs, or you are configuring access to a VPN via VRF on the Catalyst 6500/Cisco 7600 platform, you can configure an IP tunnel to access those private networks. On the Catalyst 6500 / Cisco 7600 platform, you configure the tunnel to tunnel the VRF traffic through the Supervisor/MSFC2 which does not support VRF.

To configure access to the VPN using a tunnel, perform the following tasks:

•Configuring the VPN Access Point (Required)

•Configuring the IP Tunnel (Required)

Configuring the VPN Access Point

To configure access to a VPN in the GPRS access point list, use the following commands beginning in global configuration mode:

Command

Purpose

Step 1

Router(config)# gprs access-point-list list-name

Specifies a name for a new access point list, or references the name of the existing access point list and enters access-point list configuration mode.

Step 2

Router(config-ap-list)# access-point access-point-index

Specifies an index number for a new access point definition, or references an existing access point definition, and enters access point configuration mode.

Step 3

Router(config-access-point)# access-point name apn-name

Specifies the access point network ID, which is commonly an Internet domain name.

Note The apn-name must match the APN that has been provisioned at the MS, HLR, and DNS server.

Step 4

Router(config-access-point)# access-mode {transparent | non-transparent}

(Optional) Specifies whether the GGSN requests user authentication at the access point to a PDN. The available options are:

•transparent—No security authorization or authentication is requested by the GGSN for this access point. This is the default value.

•non-transparent—GGSN acts as a proxy for authenticating.

Step 5

Router(config-access-point)# access-type real

Specifies an APN type that corresponds to an interface to an external network on the GGSN. This is the default value.

Step 6

Router(config-access-point)# ip-address-pool {dhcp-proxy-client | radius-client | local pool-name | disable}

(Optional) Specifies a dynamic address allocation method using IP address pools for the current access point. The available options are:

•dhcp-proxy-client—DHCP server provides the IP address pool.

•radius-client—RADIUS server provides the IP address pool.

•local—Specifies that a local pool provides the IP address. This option requires that a local pool has been configured using the ip local pool global configuration command.

•disable—Turns off dynamic address allocation.

Note If you are using a dynamic address allocation method, then you must configure this command according to the appropriate IP address pool source.

Step 7

Router(config-access-point)# vrf vrf-name

Configures VPN routing and forwarding at a GGSN access point and associates the access point with a particular VRF instance.

Step 8

Router(config-access-point)# exit

Exits access point configuration mode.

For information about the other access point configuration options, see the "Configuring Other Access Point Options" section.

Configuring the IP Tunnel

When you configure a tunnel, you might consider using loopback interfaces as the tunnel endpoints rather than real interfaces because loopback interfaces are always up.

To configure an IP tunnel to a private network, use the following commands beginning in global configuration mode:

Command

Purpose

Step 1

Router(config)# interface tunnel number

Configures a logical tunnel interface number.

Step 2

Router(config-if)# ip vrf forwarding vrf-name

Associates a VRF instance with the interface.

Step 3

Router(config-if)# ip address ip-address mask [secondary]

Specifies an IP address for the tunnel interface.

Note This IP address is not used in any other part of the GGSN configuration.

Step 4

Router(config-if)# tunnel source {ip-address | type number}

Specifies the IP address (or interface type and port or card number) of the Gi interface to the PDN or a loopback interface.

Step 5

Router(config-if)# tunnel destination {hostname | ip-address}

Specifies IP address (or host name) of the private network that you can access from this tunnel.

Configuring Other Access Point Options

This section summarizes the configuration options that you can specify for a GGSN access point.

Some of these options are used in combination with other global router settings to configure the GGSN. Further details about configuring several of these options are discussed in other topics in this chapter and other chapters of this book.

Note Although the Cisco IOS software allows you to configure other access point options on a virtual access point, only the access-point-name and access-type commands are applicable to a virtual access point.

To configure options for a GGSN access point, use any of the following commands beginning in access- point list configuration mode:
Command

Purpose

Step 1

Router(config-ap-list)# access-point access-point-index

Specifies an index number for a new access point definition, or references an existing access point definition, and enters access point configuration mode.

Step 2

Router(config-access-point)# access-point-name apn-name

Specifies the network (or domain) name for a PDN that users can access from the GGSN at a defined access point.

Note The apn-name must match the APN that has been provisioned at the MS, HLR, and DNS server.

Step 3

Router(config-access-point)# aaa-accounting {enable | disable}

Enables or disables accounting for a particular access point on the GGSN.

Note If you have configured a transparent access APN and you want to provide accounting at that APN, you need to configure the aaa-accounting enable command at the APN.

Step 4

Router(config-access-point)# aaa-group {authentication | accounting} server-group

Specifies a default AAA server group and assigns the type of AAA services to be supported by the server group for a particular access point on the GGSN, where:

•authentication—Assigns the selected server group for authentication services on the APN.

•accounting—Assigns the selected server group for accounting services on the APN.

•server-group—Specifies the name of a AAA server group to be used for AAA services on the APN.

Note The name of the AAA server group that you specify must correspond to a server group that you configure using the aaa group server command.

Step 5

Router(config-access-point)# access-type {virtual | real}

(Optional) Specifies the type of access point. The available options are:

•virtual—APN type that is not associated with any specific physical target network.

•real—APN type that corresponds to an interface to an external network on the GGSN. This is the default value.

Step 6

Router(config-access-point)# access-mode {transparent | non-transparent}

(Optional) Specifies whether the GGSN requests user authentication at the access point to a PDN. The available options are:

•transparent—No security authorization or authentication is requested by the GGSN for this access point. This is the default value.

•non-transparent—GGSN acts as a proxy for authenticating.

Step 7

Router(config-access-point)# access-violation deactivate-pdp-context}

(Optional) Specifies that a user's session be ended and the user packets discarded when a user attempts unauthorized access to a PDN through an access point.

Step 8

Router(config-access-point)# aggregate {auto | ip-network-prefix{/mask-bit-length | ip-mask}}

(Optional) Configures the GGSN to create an aggregate route in its IP routing table when receiving PDP requests from MSs on the specified network through a particular access point on the GGSN.

Note The aggregate auto command will not aggregate routes when using local IP address pools.

Step 9

Router(config-access-point)# anonymous user username [password]

(Optional) Configures anonymous user access at an access point.

Step 10

Router(config-access-point)# block-foreign-ms

(Optional) Restricts GGSN access at a particular access point based on the mobile user's home PLMN.

Step 11

Router(config-access-point)# dhcp-gateway-address ip-address

(Optional) Specifies a DHCP gateway to handle DHCP requests for mobile station (MS) users entering a particular PDN access point.

Step 12

Router(config-access-point)# dhcp-server {ip-address} [ip-address] [vrf]

(Optional) Specifies a primary (and backup) DHCP server to allocate IP addresses to MS users entering a particular PDN access point.

Step 13

Router(config-access-point)# dns primary ip-address secondary ip-address

(Optional) Specifies a primary (and backup) DNS to be sent in create PDP responses at the access point.

For more information about configuring the DNS for an access point, see "Configuring the NBNS and DNS Address for an APN" section on page 10-15.

Step 14

Router(config-access-point)# gtp response-message wait-accounting

(Optional) Configures the GGSN to wait for a RADIUS accounting response before sending a create PDP context response to the SGSN.

Step 15

Router(config-access-point)# ip-access-group access-list-number {in | out}

(Optional) Specifies access permissions between an MS and a PDN through the GGSN at a particular access point, where access-list-number specifies the IP access list definition to be used at the access point. The available options are:

•in—Applies the IP access list definition from the PDN to the MS.

•out—Applies the IP access list definition from the MS to the PDN.

Note To disable the sending of ICMP messages, ensure that the no ip unreachable interface configuration command has been configured on the virtual template interface.

Step 16

Router(config-access-point)# ip-address-pool {dhcp-proxy-client | radius-client | local pool-name | disable}

(Optional) Specifies a dynamic address allocation method using IP address pools for the current access point. The available options are:

•dhcp-proxy-client—DHCP server provides the IP address pool.

•radius-client—RADIUS server provides the IP address pool.

•local—Specifies that a local pool provides the IP address. This option requires that a local pool has been configured using the ip local pool global configuration command.

•disable—Turns off dynamic address allocation.

Note If you are using a dynamic address allocation method, then you must configure this command according to the appropriate IP address pool source.

Step 17

Router(config-access-point)# msisdn suppression [value]

(Optional) Specifies that the GGSN overrides the MSISDN number with a pre-configured value in its authentication requests to a RADIUS server.

Step 18

Router(config-access-point)# nbns primary ip-address secondary ip-address

(Optional) Specifies a primary (and backup) NBNS to be sent in the create PDP responses to at the access-point.

For more information about configuring the NBNS for an access point, see "Configuring the NBNS and DNS Address for an APN" section on page 10-15.

Step 19

Router(config-access-point)# network-request-activation

(Optional) Enables an access point for network-initiated PDP requests through a VPN.

Note Supported on the Cisco 7200 series platform only.

Step 20

Router(config-access-point)# ppp-regeneration [max-session number] [setup-time seconds]

(Optional) Enables an access point to support PPP regeneration, where:

•max-session number—Specifies the maximum number of PPP regenerated sessions allowed at the access point. The default value is device dependent and is determined by the maximum number of IDBs that can be supported by the router.

•setup-time seconds—Specifies the maximum amount of time (between 1 and 65535 seconds) within which a PPP regenerated session must be established. The default value is 60 seconds.
Step 21
Router(config-access-point)# ppp-regeneration verify-domain
(Optional) Configures the GGSN to verify the domain sent in the PCO IE sent in a create PDP context request against the APN sent out by the user when PPP-regeneration is being used.

Note If a mismatch occurs, the create PDP context request is rejected with the cause code "Service not supported."
Step 22

Router(config-access-point)# radius attribute nas-id format

(Optional) Specifies that the GGSN sends the NAS-Identifier in access requests at the APN where format is a string sent in attribute 32 containing an IP address (%i), a hostname (%h), and a domain name (%d).

Step 23

Router(config-access-point)# radius attribute suppress imsi

(Optional) Specifies that the GGSN suppresses the 3GPP-IMSI number in its authentication and accounting requests to a RADIUS server.

Step 24

Router(config-access-point)# radius attribute suppress qos

(Optional) Specifies that the GGSN suppresses the 3GPP-GPRS-Qos Profile in its authentication and accounting requests to a RADIUS server.

Step 25

Router(config-access-point)# radius attribute suppress sgsn-address

(Optional) Specifies that the GGSN suppresses the 3GPP-GPRS-SGSN-Address in its authentication and accounting requests to a RADIUS server.

Step 26

Router(config-access-point) redirect intermobile ip ip address

(Optional) Specifies that mobile-to-mobile traffic be redirected.

Step 27

Router(config-access-point) security verify {source | destination}

Specifies that the GGSN verify the source or destination address in TPDUs received from a Gn interface.

Step 28

Router(config-access-point)# session idle-time number

(Optional) Specifies the time (between 1 and 168 hours) that the GGSN waits before purging idle mobile sessions for the current access point.

Step 29

Router(config-access-point)# subscription-required

(Optional) Specifies that the GGSN checks the value of the selection mode in a PDP context request to determine if a subscription is required to access a PDN through the access point.

Step 30

Router(config-access-point)# vrf vrf-name

(Optional) Configures VPN routing and forwarding at a GGSN access point and associates the access point with a particular VRF instance.
Verifying the Access Point Configuration

This section describes how to verify that you have successfully configured access points on the GGSN, and includes the following tasks:

•Verifying the GGSN Configuration

•Verifying Reachability of the Network Through the Access Point

Verifying the GGSN Configuration

To verify that you have properly configured access points on the GGSN, use the show running-config command and the show gprs access-point commands.

Note The gprs access-point-list command first appears in the output of the show running-config command under the virtual template interface, which indicates that the gprs access point list has been configured and is associated with the virtual template. To verify your configuration of specific access points within the gprs access point list, look further down in the show output where the gprs access-point-list command appears again followed by the individual access point configurations.

Step 1 From global configuration mode, use the show running-config command as shown in the following example taken from the Cisco 7200 series platform. Verify that the gprs access-point-list command appears under the virtual template interface, and verify the individual access point configurations within the gprs access-point-list section of the output as shown in bold:
GGSN# show running-config
Building configuration...
Current configuration : 3521 bytes
!
version 12.2
no service single-slot-reload-enable
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
service gprs ggsn
!
hostname ggsn
!
ip cef
!
no logging buffered
logging rate-limit console 10 except errors
!
aaa new-model
aaa group server radius foo
 server 172.18.43.7 auth-port 1645 acct-port 1646
aaa authentication ppp foo group foo
aaa authorization network foo group foo
aaa accounting network foo start-stop group foo
!
ip subnet-zero
!
!
ip cef
no ip dhcp-client network-discovery
!
!
interface Loopback1
 ip address 10.2.3.4 255.255.255.255
!
interface FastEthernet0/0
 ip address 172.18.43.174 255.255.255.240
 duplex half
!
interface Ethernet1/0
 description Gi interface to gprt.cisco.com
 ip address 10.8.8.6 255.255.255.0
 duplex half
!
interface Ethernet1/1
 description Gi interface to gprs.cisco.com
 ip address 10.9.9.4 255.255.255.0
 duplex half
!
interface Ethernet1/2
 ip address 10.15.15.10 255.255.255.0
 duplex half
!
interface loopback 1
 ip address 10.40.40.3 255.255.255.0
!
interface Virtual-Template1
 ip unnumber loopback 1
 encapsulation gtp
 gprs access-point-list gprs
!
ip default-gateway 172.18.43.161
ip kerberos source-interface any
ip classless
ip route 10.7.7.0 255.255.255.0 10.8.8.2
ip route 10.102.82.0 255.255.255.0 172.18.43.161
ip route 192.168.0.0 255.255.0.0 172.18.43.161
ip route 172.18.0.0 255.255.0.0 172.18.43.161
no ip http server
!
. . .
!
gprs access-point-list gprs
!
  access-point 1
   access-point-name gprs.cisco.com
   access-mode non-transparent
   aaa-group authentication foo
   network-request-activation
   exit
!
  access-point 2
   access-point-name gprt.cisco.com
   exit
!
  access-point 3
   access-point-name gpru.cisco.com
   ip-address-pool radius-client
   access-mode non-transparent
   aaa-group authentication foo
   exit
!
gprs maximum-pdp-context-allowed 90000
gprs gtp path-echo-interval 0
gprs default charging-gateway 10.15.15.1
!
gprs memory threshold 512
!
...
radius-server host 172.18.43.7 auth-port 1645 acct-port 1646 non-standard
radius-server retransmit 3
radius-server key 7 12150415
call rsvp-sync
!
no mgcp timer receive-rtcp
!
mgcp profile default
!
gatekeeper
 shutdown
end
Step 2 To view the configuration of a specific access point on the GGSN in further detail, use the show gprs access-point command and specify the index number of the access point, as shown in the following example:
GGSN# show gprs access-point 2
    apn_index 2          apn_name = gprt.cisco.com
    apn_mode: transparent
    apn-type: Real
    accounting: Disable
    wait_accounting: Disable
    dynamic_address_pool: not configured
    apn_dhcp_server: 0.0.0.0
    apn_dhcp_gateway_addr: 0.0.0.0
    apn_authentication_server_group: 
    apn_accounting_server_group: 
    apn_username: , apn_password:
    subscribe_required: No
    deactivate_pdp_context_on violation: No
    network_activation_allowed: No
    Block Foreign-MS Mode: Disable
    VPN: Disable 
    GPRS vaccess interface: Virtual-Access1
    number of ip_address_allocated 0
    Total number of PDP in this APN :1
    aggregate:
    In APN:    Disable
    In Global: Disable
Step 3 To view a summary of every access point that is configured on the GGSN, use the show gprs access-point all command as shown in the following example:
GGSN# show gprs access-point all
There are 3 Access-Points configured
Index   Mode            Access-type    AccessPointName      VRF Name
-----------------------------------------------------------------------
1       non-transparent    Real       gprs.cisco.com 
-----------------------------------------------------------------------
2       transparent        Real       gprt.cisco.com
-----------------------------------------------------------------------
3       non-transparent    Real       gpru.cisco.com
-----------------------------------------------------------------------
Verifying Reachability of the Network Through the Access Point

The following procedure provides a basic methodology for verifying reachability from the MS to the destination network.

Note There are many factors that can affect whether or not you can successfully reach the destination network. Although this procedure does not attempt to fully address those factors, it is important for you to be aware that your particular configuration of the APN, IP routing, and physical connectivity of the GGSN, can affect end-to-end connectivity between a host and an MS.

To verify that you can reach the network from the MS, perform the following steps:

Step 1 From the MS (for example, using a handset), create a PDP context with the GGSN by specifying the APN to which you want to connect. In this example, you specify the APN gprt.cisco.com.

Step 2 From global configuration mode on the GGSN, use the show gprs access-point command and verify the number of created network PDP contexts (in the Total number of PDP in this APN output field).

The following example shows one successful PDP context request:
GGSN# show gprs access-point 2
    apn_index 2          apn_name = gprt.cisco.com
    apn_mode: transparent
    apn-type: Real
    accounting: Disable
    wait_accounting: Disable
    dynamic_address_pool: not configured
    apn_dhcp_server: 0.0.0.0
    apn_dhcp_gateway_addr: 0.0.0.0
    apn_authentication_server_group: 
    apn_accounting_server_group: 
    apn_username: , apn_password:
    subscribe_required: No
    deactivate_pdp_context_on violation: Yes
    network_activation_allowed: No
    Block Foreign-MS Mode: Disable
    VPN: Disable 
    GPRS vaccess interface: Virtual-Access1
    number of ip_address_allocated 0
    Total number of PDP in this APN :1
    aggregate:
    In APN:    Disable
    In Global: Disable
Step 3 To test further, generate traffic to the network. To do this, use the ping command from a handset, or a laptop connected to the handset, to a host on the destination network, as shown in the following example:
ping 192.168.12.5
Note To avoid possible DNS configuration issues, try to use the IP address (rather than host name) of a host that you expect to be reachable within the destination network. For this test to work, the IP address of the host that you select must be able to be properly routed by the GGSN.

In addition, the APN configuration and physical connectivity to the destination network through a Gi interface must be established. For example, if the host to be reached is in a VPN, the APN must be properly configured to provide access to the VPN.

Step 4 After you have begun to generate traffic over the PDP context, use the show gprs gtp pdp-context tid command to see detailed statistics including send and receive byte and packet counts.

Tip To find the TID for a particular PDP context on an APN, use the show gprs gtp pdp-context access-point command.

The following example shows sample output for a PDP context for TID 81726354453647FA:
GGSN# show gprs gtp pdp-context tid 81726354453647FA
TID              MS Addr         Source  SGSN Addr       APN
81726354453647FA 10.2.2.1        Static  172.16.44.1     gprt.cisco.com
    current time :Dec 06 2001 13:15:34
    user_name (IMSI): 18273645546374     MS address: 10.2.2.1
    MS International PSTN/ISDN Number (MSISDN): 243926901
    sgsn_addr_signal: 172.16.44.1        ggsn_addr_signal: 10.30.30.1
    signal_sequence:  7                  seq_tpdu_up:      0
    seq_tpdu_down:    5380
    upstream_signal_flow:   371          upstream_data_flow:   372
    downstream_signal_flow: 1            downstream_data_flow: 1
    RAupdate_flow:          0
    pdp_create_time:   Dec 06 2001 09:54:43
    last_access_time:  Dec 06 2001 13:15:21
    mnrgflag:          0                tos mask map: 00
    gtp pdp idle time: 72
    gprs qos_req: 091101               canonical Qos class(req.): 01
    gprs qos_neg: 25131F               canonical Qos class(neg.): 01
    effective bandwidth: 0.0
    rcv_pkt_count:       10026         rcv_byte_count:    1824732       
    send_pkt_count:      5380          send_byte_count:   4207160       
    cef_up_pkt:          10026         cef_up_byte:       1824732
    cef_down_pkt:        5380          cef_down_byte:     4207160
    cef_drop:            0
    charging_id:         12321224
    pdp reference count: 2
    ntwk_init_pdp:       0
Configuring Access to External Support Servers

You can configure the GGSN to access external support servers to provide services for dynamic IP addressing of MSs using the Dynamic Host Configuration Protocol (DHCP) or using Remote Authentication Dial-In User Service (RADIUS). You can also configure RADIUS services on the GGSN to provide security, such as authentication of users accessing a network at an APN.

The GGSN allows you to configure access to DHCP and RADIUS servers globally for all access points, or to specific servers for a particular access point. For more information about configuring DHCP on the GGSN, see the "Configuring Dynamic Addressing on the GGSN" chapter. For more information about configuring RADIUS on the GGSN, see the "Configuring Security on the GGSN" chapter.

Configuring Virtual APN Access on the GGSN

This section includes the following topics:

•Overview of the Virtual APN Feature

•Virtual APN Configuration Task List

•Verifying the Virtual APN Configuration

For a sample configuration, see the "Virtual APN Configuration Example" section.

Overview of the Virtual APN Feature

GGSN Release 3.0 and later supports virtual APN access from the PLMN using the virtual access point type on the GGSN. The virtual APN feature on the GGSN allows multiple users to access different physical target networks through a shared APN access point on the GGSN.

In a GPRS/UMTS network, the user APN information must be configured at several of the GPRS/UMTS network entities, such as the HLR and DNS server. In the HLR, the user subscription data associates the IMSI (unique per user) with each APN that the IMSI is allowed to access. At the DNS server, APNs are correlated to the GGSN IP address. If DHCP or RADIUS servers are in use, the APN configuration can extend to those servers too.

The virtual APN feature reduces the amount of APN provisioning required by consolidating access to all real APNs through a single virtual APN at the GGSN. Therefore, only the virtual APN needs to be provisioned at the HLR and DNS server, instead of each of the real APNs to be reached. The GGSN also must be configured for the virtual APN.

Note On the Catalyst 6500 / Cisco 7600 platform, identical virtual APN configurations much exist on each GGSN load-balanced via a virtual server.

The Cisco GGSN software determines the ultimate target network for the session by receiving the create PDP context request at the virtual access point and extracting the domain name to direct the packet to the appropriate real APN. The real APN is the actual destination network.

Note The associated real APN name is used in G-CDRs and authentication requests sent to a virtual APN.

Figure 5-2 shows how the GGSN supports a create PDP context request from an MS processed through a virtual APN on the GGSN.

Figure 5-2 Virtual APN PDP Context Activation on the GGSN

1.

At the MS, the user connects to the network with a username in the form of login@domain, such as ciscouser@CorporateA.com. The SGSN sends a create PDP context request to the GGSN using the virtual APN of "corporate." The create PDP context also includes the username in login@domain format in the protocol configuration option (PCO) information element.

2.

The GGSN extracts the domain from the information in the PCO, which corresponds to the real target network on the GGSN. In this example, the GGSN finds CorporateA.com as the domain and directs the session to the appropriate real APN for the target network. In this case, the real APN is corporateA.com. The GGSN uses the complete username to do authentication.

3.

The local or corporate AAA server is selected based on the domain part of the username, which is CorporateA.com in this case.

Benefits of the Virtual APN Feature

The virtual APN feature provides the following benefits:

•Simplifies provisioning of APN information at the HLR and DNS servers.

•Improves scalability for support of large numbers of corporate networks, ISPs, and services.

•Increases flexibility of access point selection.

•Eases deployment of new APNs and services.

Restrictions of the Virtual APN Feature

The virtual APN feature has the following restriction:

•S-CDRs and G-CDRs do not include the domain information (G-CDRs include the real domain name).

Virtual APN Configuration Task List

To configure the GGSN to support virtual APN access, you must configure one or more virtual access points. You also need to configure the real access points that provide the information needed to connect to the physical networks of the external PDNs or VPNs.

In addition to the configuring the GGSN, you must also ensure proper provisioning of other GPRS/UMTS network entities as appropriate to successfully implement the virtual APN feature on the GPRS/UMTS network.

To configure virtual APN access on the GGSN, perform the following tasks:

•Configuring Virtual Access Points on the GGSN (Required)

•Configuring Real Access Points on the GGSN (Required)

–PDN Access Configuration Task List

–VPN Access Using VRF Configuration Task Lists

For a sample configuration, see the "Virtual APN Configuration Example" section.

Configuring Virtual Access Points on the GGSN

Use virtual access point types to consolidate access to multiple real target networks on the GGSN. The GGSN always uses real access points to reach an external network, so virtual access points are used in combination with real access points on the GGSN.

You can configure multiple virtual access points on the GGSN. Multiple virtual access points can be used to access the same real networks. One virtual access point can be used to access different real networks.

Note Be sure that you provision the HLR and configure the DNS server to properly correspond to the virtual APN domains that you have configured on the GGSN. For more information, see the "Configuring Other GPRS/UMTS Network Entities With the Virtual APN" section.

To configure a virtual access point on the GGSN, use the following commands beginning in global configuration mode:

Command

Purpose

Step 1

Router(config)# gprs access-point-list list-name

Specifies a name for a new access-point list, or references the name of the existing access-point list and enters access-point list configuration mode.

Step 2

Router(config-ap-list)# access-point access-point-index

Specifies an index number for a new access point definition, or references an existing access point definition, and enters access point configuration mode.

Step 3

Router(config-access-point)# access-point-name apn-name

Specifies the network (or domain) name for a PDN that users can access from the GGSN at a defined access point.

Note The apn-name must match the APN that has been provisioned at the MS, HLR, and DNS server.

Step 4

Router (config-access-point)# access-type virtual

Specifies an APN type that is not associated with any specific physical target network on the GGSN. The default access type is real.

Note Although the Cisco IOS software allows you to configure other access point options on a virtual access point, no other access point options are applicable if they are configured.

Configuring Other GPRS/UMTS Network Entities With the Virtual APN

When you configure the GGSN to support virtual APN access, be sure that you also meet any necessary requirements to properly configure other GPRS/UMTS network entities to support the virtual APN implementation.

The following GPRS/UMTS network entities might also require provisioning to properly implement virtual APN support:

•DHCP server—Requires configuration of the real APNs.

•DNS server—The DNS server that the SGSN uses to resolve the address of the GGSN must identify the virtual APN with the IP address of the GTP virtual template on the GGSN. If GTP SLB is implemented, then the virtual APN should be associated with the IP address of the GTP load balancing virtual server instance on the SLB router.

•HLR—Requires the name of the virtual APN in subscription data, as allowable for subscribed users.

•RADIUS server—Requires configuration of the real APNs.

•SGSN—Requires the name of the virtual APN as the default APN (as desired) when the APN is not provided in user subscription data.

Verifying the Virtual APN Configuration

This section describes how to verify that you have successfully configured virtual APN support on the GGSN, and includes the following tasks:

•Verifying the GGSN Configuration

•Verifying Reachability of the Network Through the Virtual Access Point

Verifying the GGSN Configuration

To verify that you have properly configured access points on the GGSN, use the show running-config command and the show gprs access-point commands.

Note The gprs access-point-list command first appears in the output of the show running-config command under the virtual template interface, which indicates that the gprs access point list has been configured and is associated with the virtual template. To verify your configuration of specific access points within the gprs access point list, look further down in the show output where the gprs access-point-list command appears again followed by the individual access point configurations.

Step 1 From privileged EXEC mode, use the show running-config command as shown in the following example from the Cisco 7200 platform. Verify the interface configuration and virtual and real access points as shown by the arrows:
GGSN# show running-config
Building configuration...
Current configuration : 3521 bytes
!
version 12.2
no service single-slot-reload-enable
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
! Enable the router for GGSN services
!
service gprs ggsn
!
hostname ggsn
!
ip cef
!
no logging buffered
logging rate-limit console 10 except errors
aaa new-model
aaa group server radius foo
 server 172.18.43.7 auth-port 1645 acct-port 1646
aaa authentication ppp foo group foo
aaa authorization network foo group foo 
aaa accounting network foo start-stop group foo
!
ip subnet-zero
!
!
no ip dhcp-client network-discovery
!
!
interface Loopback1
 ip address 10.2.3.4 255.255.255.255
!
interface FastEthernet0/0
 ip address 172.18.43.174 255.255.255.240
 duplex half
!
interface FastEthernet2/0
 description Gn interface
 ip address 192.168.10.56 255.255.255.0
!
! Define Gi physical interfaces to real networks
!
interface Ethernet1/0
 description Gi interface to corporatea.com
 ip address 10.8.8.6 255.255.255.0
 no ip mroute-cache
 duplex half
!
interface Ethernet1/1
 description Gi interface to corporateb.com
 ip address 10.9.9.4 255.255.255.0
 no ip mroute-cache
 duplex half
!
interface Ethernet1/2
 description Gi interface to corporatec.com
 ip address 10.15.15.10 255.255.255.0
 no ip mroute-cache
 duplex half
!
interface loopback 1
 ip address 10.40.40.3 255.255.255.0
!
interface Virtual-Template1
 ip unnumber loopback 1
 encapsulation gtp
 gprs access-point-list gprs
!
ip default-gateway 172.18.43.161
ip kerberos source-interface any
ip classless
ip route 10.7.7.0 255.255.255.0 10.8.8.2
ip route 10.102.82.0 255.255.255.0 172.18.43.161
ip route 192.168.1.1 255.255.255.255 FastEthernet2/0
ip route 172.18.0.0 255.255.0.0 172.18.43.161
no ip http server
!
gprs access-point-list gprs
!
! Configure a virtual access point called corporate
!
 access-point 1
   access-point-name corporate
   access-type virtual
   exit
!
! Configure three real access points called corporatea.com, 
! corporateb.com, and corporatec.com
!
 access-point 2
   access-point-name corporatea.com
   access-mode non-transparent
   aaa-group authentication foo
   exit
!
 access-point 3
   access-point-name corporateb.com
   exit
   !
 access-point 4
   access-point-name corporatec.com
   access-mode non-transparent
   aaa-group authentication foo
   exit
   !
 !
gprs maximum-pdp-context-allowed 90000
gprs gtp path-echo-interval 0
gprs default charging-gateway 10.15.15.1
!
gprs memory threshold 512
!
radius-server host 172.18.43.7 auth-port 1645 acct-port 1646 non-standard
radius-server retransmit 3
radius-server key 7 12150415
call rsvp-sync
!
no mgcp timer receive-rtcp
!
mgcp profile default
!
!
gatekeeper
 shutdown
!
end
Step 2 To view the configuration of a specific access point on the GGSN in further detail, use the show gprs access-point command and specify the index number of the access point, as shown in the following examples.

The following output shows information about a real access point:
GGSN# show gprs access-point 2
    apn_index 2          apn_name = corporatea.com
    apn_mode: non-transparent
    apn-type: Real
    accounting: Disable
    wait_accounting: Disable
    dynamic_address_pool: not configured
    apn_dhcp_server: 0.0.0.0
    apn_dhcp_gateway_addr: 0.0.0.0
    apn_authentication_server_group: foo
    apn_accounting_server_group: 
    apn_username: , apn_password:
    subscribe_required: No
    deactivate_pdp_context_on violation: No
    network_activation_allowed: No
    Block Foreign-MS Mode: Disable
    VPN: Disable 
    GPRS vaccess interface: Virtual-Access1
    number of ip_address_allocated 0
    Total number of PDP in this APN :1
    aggregate:
    In APN:    Disable
    In Global: Disable
The following output shows information about a virtual access point:
GGSN# show gprs access-point 1
    apn_index 1          apn_name = corporate
    apn_mode: transparent
    apn-type: Virtual
    accounting: Disable
    wait_accounting: Disable
    dynamic_address_pool: not configured
    apn_dhcp_server: 0.0.0.0
    apn_dhcp_gateway_addr: 0.0.0.0
    apn_authentication_server_group: 
    apn_accounting_server_group: 
    apn_username: , apn_password:
    subscribe_required: No
    deactivate_pdp_context_on violation: No
    network_activation_allowed: No
    Block Foreign-MS Mode: Disable
    VPN: Disable 
    GPRS vaccess interface: Virtual-Access2
    number of ip_address_allocated 0
    Total number of PDP in this APN :0
    aggregate:
    In APN:    Disable
    In Global: Disable
Step 3 To view a summary of every access point that is configured on the GGSN, use the show gprs access-point all command as shown in the following example:
GGSN# show gprs access-point all
There are 4 Access-Points configured
Index   Mode            Access-type    AccessPointName      VRF Name
-----------------------------------------------------------------------
1       transparent        Virtual    corporate 
-----------------------------------------------------------------------
2       non-transparent    Real       corporatea.com
-----------------------------------------------------------------------
3       transparent        Real       corporateb.com
-----------------------------------------------------------------------
4       non-transparent    Real       corporatec.com
-----------------------------------------------------------------------
Verifying Reachability of the Network Through the Virtual Access Point

To verify reachability of the real destination network through the virtual access point, you can use the same procedure described in the "Verifying Reachability of the Network Through the Access Point" section.

In addition, you should meet the following guidelines for virtual access point testing:

•When you initiate PDP context activation at the MS, be sure that the username that you specify (in the form of login@domain in the create PDP context request) corresponds to a real APN that you have configured on the GGSN.

•When you generate traffic to the network, be sure to select a host on one of the real destination networks that is configured for APN support on the GGSN.

Configuring Network-Initiated PDP Context Support on the GGSN

Note This feature is not supported on the Catalyst 6500 series switch / Cisco 7600 series internet router platform.

This section includes the following topics:

•Overview of Network-Initiated PDP Context Support

•Network-Initiated PDP Context Configuration Task List

•Verifying the Network-Initiated PDP Context Configuration

For a sample configuration, see the "Network-Initiated PDP Request Configuration Example" section.

Overview of Network-Initiated PDP Context Support

In GPRS Release 1.4 and earlier, the GGSN only supports creation of PDP contexts that are originated by an MS. GGSN Release 3.0 and later supports network-initiated PDP contexts for statically configured IP addresses. This means that the GGSN supports a process for creating PDP contexts initiated by an external IP network.

When the GGSN receives a PDU destined for an MS from the IP network, it verifies whether a PDP context is already established for that MS on the GGSN. If the MS does not have an existing PDP context on the GGSN, then the GGSN issues a Send Routing Information request to the home location register (HLR). The GGSN uses a GSN that provides the necessary GTP-to-Mobile Application Part (MAP) conversion to communicate with the HLR. If the HLR determines that the Send Routing Information request can be served, it sends the GGSN the address of the SGSN (through the protocol-converting GSN) that is currently serving that MS. The GGSN sends a PDU Notification Request to the SGSN serving the MS, and the SGSN requests that the MS establish the PDP context with the GGSN.

Restrictions

The GGSN supports creation of network-initiated PDP contexts with the following restrictions:

•IP addresses corresponding to the International Mobile Subscriber Identity (IMSI) of an MS must be statically configured on the GGSN using the gprs ni-pdp ip-imsi single command.

•If you are implementing VPN access through a VRF at the access point, you must configure the access point for VRF before you configure the IP to IMSI address mappings using the gprs ni-pdp ip-imsi single global configuration command. If you configure the gprs ni-pdp ip-imsi single command before you configure VRF at the access point, then the addresses that you specify become part of the global routing table and not the VRF routing table.

Network-Initiated PDP Context Configuration Task List

The GGSN supports network-initiated PDP contexts for both VPN and non-VPN networks. However, access through a VPN is preferable for greater flexibility in IP addressing and better control over security and other functions at the GGSN access point.

To configure network-initiated PDP context support on the GGSN through a VPN, perform the following tasks:

•Configuring Network-Initiated PDP Context Support at an APN (Required)

•Specifying the GSN for GTP-MAP Protocol Conversion (Required)

•Configuring the Static IP Address Mapping to IMSI (Required)

•Configuring Other Network-Initiated PDP Options (Optional)

To verify your configuration, see the "Verifying the Network-Initiated PDP Context Configuration" section.

For a sample configuration, see the "Network-Initiated PDP Request Configuration Example" section.

Configuring Network-Initiated PDP Context Support at an APN

To support network-initiated PDP context activation on the GGSN at a specific APN, you must enable network request activation at the access point.

The GGSN supports network-initiated PDP contexts at multiple VPNs. To do this, you must create an access point for each VPN that you want to support and you must configure VRF at the APN. In addition to configuring VRF at the APN, other tasks are required to complete the VRF configuration. For more information about configuring VRF support on the GGSN, see the "VPN Access Using VRF Configuration Task Lists" section.

To configure network-initiated PDP context support at an APN, use the following commands beginning in global configuration mode:

Command

Purpose

Step 1

Router(config)# gprs access-point-list list-name

Specifies a name for a new access point list, or references the name of the existing access point list and enters access-point list configuration mode.

Step 2

Router(config-ap-list)# access-point access-point-index

Specifies an index number for a new access point definition, or references an existing access point definition, and enters access point configuration mode.

Note The access-point-index that you specify in this command must correspond to the apn-index in the gprs ni-pdp ip-imsi single command.

Step 3

Router(config-access-point)# access-point-name apn-name

Specifies the network (or domain) name for a PDN that users can access from the GGSN at a defined access point.

Note The apn-name must match the APN that has been provisioned at the MS, HLR, and DNS server.

Step 4

Router(config-access-point)# network-request-activation

Enables an access point for network-initiated PDP requests.

Step 5

Router(config-access-point)# vrf vrf-name

(Optional) Configures VPN routing and forwarding at a GGSN access point and associates the access point with a particular VRF instance.

For information about other access point configuration options, see the "Configuring the GPRS Access Point List on the GGSN" section.

Specifying the GSN for GTP-MAP Protocol Conversion

To specify the address of the GSN for GTP-MAP protocol conversion, use the following command in global configuration mode:

Command

Purpose

Router(config)# gprs default map-converting-gsn {ip-address | hostname} [ip-address | hostname]

Specifies the IP address or host name of the primary (and backup) GSN to communicate with the HLR in sending and receiving MAP messages.

Configuring the Static IP Address Mapping to IMSI

The GGSN supports network-initiated PDP context requests from both a VPN or other intranet using statically configured address mappings only.

When you configure the static IP address mapping to IMSI, you must specify the proper APN number where you have enabled the network-request-activation command.

To configure the static IP address mapping to the IMSI of an MS, use the following command in global configuration mode:

Command

Purpose

Router(config)# gprs ni-pdp ip-imsi single apn-index ip-address imsi

Specifies a static IP address to IMSI mapping for a single MS for network-initiated PDP requests from a particular APN, with the following values:

•apn-index—Specifies the access-point where you have have enabled network-initiated PDP context support using the network-request-activation command.

•ip-address—Specifies the static IP address of that corresponds to the PDP address in the request coming from the APN.

•imsi—Specifies the international mobile subscriber identity of the MS that you want to map to the configured ip-address.

Reissue this command for each MS that you want to support, using a different IP address and IMSI value.

Configuring Other Network-Initiated PDP Options

To configure other network-initiated PDP context options on the GGSN, use the following commands beginning in global configuration mode:

Command

Purpose

Router(config)# gprs ni-pdp pdp-buffer number

(Optional) Specifies the maximum size of the GGSN buffer to be used for each network-initiated PDP request. The default value is 2000 bytes.

Router(config)# gprs ni-pdp percentage percentage-number

(Optional) Specifies the maximum percentage of PDP contexts on the GGSN that can be network-initiated. The default value is 10 percent.

Router(config)# gprs ni-pdp discard-period number

(Optional) Specifies the amount of time that the GGSN waits, after an unsuccessful network-initiated PDP delivery attempt, before discarding subsequent PDP PDUs received on the Gi interface. The default value is 300 seconds (5 minutes).

Router(config)# gprs ni-pdp cache-timeout number

(Optional) Specifies the maximum amount of time that an SGSN address is cached by the GGSN. The default value is 600 seconds (10 minutes).

Verifying the Network-Initiated PDP Context Configuration

This section describes how to verify that you have sucessfully configured the GGSN for network-initiated PDP context support, and includes the following tasks:

•Verifying the GGSN Configuration

•Verifying Reachability of the MS Using Network-Initiated PDP Request

Verifying the GGSN Configuration

To verify that you have properly configured the GGSN for network-initiated PDP context support, use the show running-config and show gprs access-point commands.

Step 1 From privileged EXEC mode, use the show running-config command as shown in the following example. Verify the access point and global configuration values as shown in bold:
GGSN# show running-config
Building configuration...
Current configuration : 3521 bytes
!
version 12.2
no service single-slot-reload-enable
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
service gprs ggsn
!
hostname ggsn
!
ip cef
!
no logging buffered
logging rate-limit console 10 except errors
aaa new-model
aaa group server radius foo
 server 172.18.43.7 auth-port 1645 acct-port 1646
aaa authentication ppp foo group foo
aaa authorization network foo group foo 
aaa accounting exec default start-stop group foo
aaa accounting network foo start-stop group foo
!
ip vrf vpn1
 rd 100:1
!
ip subnet-zero
!
ip cef
!
no ip dhcp-client network-discovery
!
!
interface Loopback1
 ip address 10.2.3.4 255.255.255.255
!
interface FastEthernet0/0
 ip address 172.18.43.174 255.255.255.240
 duplex half
!
interface Ethernet1/0
 description Gi interface to gprt.cisco.com
 ip address 10.8.8.6 255.255.255.0
 ip vrf forwarding vpn1
 no ip mroute-cache
 duplex half
!
interface Ethernet1/1
 description Gi interface to gprs.cisco.com
 ip address 10.9.9.4 255.255.255.0
 no ip mroute-cache
 duplex half
!
interface Ethernet1/2
 ip address 10.15.15.10 255.255.255.0
 duplex half
!
interface loopback 1
 ip address 10.40.40.3 255.255.255.0
!
interface Virtual-Template1
 ip unnumber loopback 1
 encapsulation gtp
 gprs access-point-list gprs
!
ip default-gateway 172.18.43.161
ip kerberos source-interface any
ip classless
ip route 10.7.7.0 255.255.255.0 10.8.8.2
ip route 10.102.82.0 255.255.255.0 172.18.43.161
ip route 192.168.0.0 255.255.0.0 172.18.43.161
ip route 172.18.0.0 255.255.0.0 172.18.43.161
no ip http server
!
. . .
!
For network-initiated PDP context support at a VPN, verify that you have enabled network-initiated PDP context support at the APN and have properly configured the APNs for VPN access as shown in bold:
!
. . .
gprs access-point-list gprs
!
  access-point 1
   access-point-name gprs.cisco.com
   access-mode non-transparent
   aaa-group authentication foo
   network-request-activation
   exit
!
  access-point 2
   access-point-name gprt.cisco.com
   network-request-activation
   vrf vpn1
   exit
   !
  access-point 3
   access-point-name gpru.cisco.com
   access-mode non-transparent
   aaa-group authentication foo
   exit
   !
gprs maximum-pdp-context-allowed 90000
gprs gtp path-echo-interval 0
gprs default charging-gateway 10.15.15.1
!
gprs memory threshold 512
!
gprs gtp ip udp ignore checksum
!
. . .
!
Verify that you have configured the protocol-converting SGSN and configured the IP address-to-IMSI mappings for each of the MSs that you want to support, as shown in bold:
!
. . .
gprs default map-converting-gsn 10.7.7.1
gprs ni-pdp ip-imsi single 1 10.100.1.1 11111111111111F1
gprs ni-pdp ip-imsi single 2 172.31.1.2 11111111111111F2
gprs ni-pdp ip-imsi single 2 172.31.1.3 11111111111111F3
!
!
radius-server host 172.18.43.7 auth-port 1645 acct-port 1646 non-standard
radius-server retransmit 3
radius-server key 7 12150415
call rsvp-sync
!
no mgcp timer receive-rtcp
!
mgcp profile default
!
!
gatekeeper
 shutdown
!
end
Step 2 From privileged EXEC mode, use the show gprs access-point command and verify that the network_activation_allowed output field contains the value Yes, as shown in the following example:
GGSN# show gprs access-point 1
    apn_index 1          apn_name = gprs.cisco.com
    apn_mode: non-transparent
    apn-type: Real
    accounting: Disable
    wait_accounting: Disable
    dynamic_address_pool: not configured
    apn_dhcp_server: 0.0.0.0
    apn_dhcp_gateway_addr: 0.0.0.0
    apn_authentication_server_group: foo
    apn_accounting_server_group: 
    apn_username: , apn_password:
    subscribe_required: No
    deactivate_pdp_context_on violation: No
    network_activation_allowed: Yes
    Block Foreign-MS Mode: Disable
    VPN: Disable 
    GPRS vaccess interface: Virtual-Access1
    number of ip_address_allocated 0
    Total number of PDP in this APN :0
    aggregate:
    In APN:    Disable
    In Global: Disable
Verifying Reachability of the MS Using Network-Initiated PDP Request

To verify that you can reach the MS from the PDN, perform the following steps:

Step 1 From the PDN side of the IP network, generate traffic to the MS. To do this, you can use the ping command with the IP address of the MS.

In the configuration example shown in Figure 5-4, you could issue ping 10.100.1.1, ping 172.31.1.2, or ping 172.31.1.3.

Step 2 From privileged EXEC mode on the GGSN, use the show gprs gtp statistics command and verify the number of rejected and created network PDP contexts (in the ntwk_init_pdp_act_rej and total ntwkInit created pdp output fields).

The following example shows 1 successful network-initiated PDP context:
GGSN# show gprs gtp statistics
GPRS GTP Statistics:       
  version_not_support    0              msg_too_short              0       
  unknown_msg            0              unexpected_sig_msg         1       
  unexpected_data_msg    0              mandatory_ie_missing       0       
  mandatory_ie_incorrect 0              optional_ie_invalid        0       
  ie_unknown             0              ie_out_of_order            0       
  ie_unexpected          0              ie_duplicated              0       
  optional_ie_incorrect  0              pdp_activation_rejected    0       
  path_failure           0              total_dropped              0       
  no_resource            0              get_pak_buffer_failure     0       
  rcv_signalling_msg     4              snd_signalling_msg         8       
  rcv_pdu_msg            0              snd_pdu_msg                1       
  rcv_pdu_bytes          0              snd_pdu_bytes              100           
  total created_pdp      1              total deleted_pdp          0           
  ntwk_init_pdp_act_rej  0              total ntwkInit created pdp 1
Step 3 Use the show gprs gtp pdp-context tid command and verify that the ntwk_init_pdp output field contains the value 1, as shown in the following example.

Note To find the TID of a PDP context for a particular MS, use the show gprs gtp pdp-context ms-address command.
GGSN# show gprs gtp pdp-context tid 81726354453647F2
TID              MS Addr         Source  SGSN Addr       APN
81726354453647F2 10.100.1.1      Static  10.7.7.1        gprs.cisco.com
    current time :Dec 06 2001 13:15:34
    user_name (IMSI): 182736455463742     MS address: 10.100.1.1
    MS International PSTN/ISDN Number (MSISDN): 21436587214365
    sgsn_addr_signal: 10.7.7.1           ggsn_addr_signal: 10.30.30.1
    signal_sequence:  7                  seq_tpdu_up:      0
    seq_tpdu_down:    5380
    upstream_signal_flow:   371          upstream_data_flow:   372
    downstream_signal_flow: 1            downstream_data_flow: 1
    RAupdate_flow:          0
    pdp_create_time:   Dec 06 2001 09:54:43
    last_access_time:  Dec 06 2001 13:15:21
    mnrgflag:          0                tos mask map: 00
    gtp pdp idle time: 72
    gprs qos_req: 091101               canonical Qos class(req.): 01
    gprs qos_neg: 25131F               canonical Qos class(neg.): 01
    effective bandwidth: 0.0
    rcv_pkt_count:       10026         rcv_byte_count:  1824732       
    send_pkt_count:      5380          send_byte_count: 4207160       
    cef_up_pkt:          10026         cef_up_byte:     1824732
    cef_down_pkt:        5380          cef_down_byte:   4207160
    cef_drop:            0
    charging_id:         12321224
    pdp reference count: 2
    ntwk_init_pdp:       1
Blocking Access to the GGSN by Foreign Mobile Stations

This section describes how to restrict access to the GGSN from mobile stations outside of their home PLMN. It includes the following topics:

•Overview of Blocking Foreign Mobile Stations

•Blocking Foreign Mobile Stations Configuration Task List

•Blocking Access by Foreign Mobile Stations Configuration Example

Overview of Blocking Foreign Mobile Stations

The GGSN allows you to block access by mobile stations who are outside of the PLMN. When you enable blocking of foreign mobile stations, the GGSN determines if an MS is inside or outside of the PLMN based on the mobile country code (MCC) and mobile network code (MNC). You must specify the MCC and MNC codes on the GGSN to properly configure the home public land mobile network (HPLMN) values.

When you enable the blocking foreign MS access feature on the access point, then when the GGSN receives a GTP create PDP context request message, the GGSN compares the MCC and MNC in the TID against the home operator codes that you configure on the GGSN. If the MS mobile operator code fails the matching criteria on the GGSN, then the GGSN rejects the create PDP context request message.

Blocking Foreign Mobile Stations Configuration Task List

To implement blocking of foreign mobile stations on the GGSN, you must enable the function and specify the supporting criteria for determining whether an MS is outside of its home PLMN.

To configure blocking of foreign mobile stations on the GGSN, perform the following tasks:

•Configuring the MCC and MNC Values (Required)

•Enabling Blocking of Foreign Mobile Stations on the GGSN (Required)

•Verifying the Blocking of Foreign Mobile Stations Configuration

Configuring the MCC and MNC Values

To configure the MCC and MNC values that the GGSN uses to determine if a request is from a roaming MS, use the following command in global configuration mode:

Command

Purpose

Router(config)# gprs mcc mcc-num mnc mnc-num

Configures the mobile country code and mobile network node that the GGSN uses to determine whether a create PDP context request is from a foreign MS.

Note The GGSN automatically specifies values of 000 for the MCC and MNC. However, you must configure non-zero values for both the MCC and MNC.

Enabling Blocking of Foreign Mobile Stations on the GGSN

To enable the GGSN to block foreign mobile stations from establishing PDP contexts, use the following command in access-point configuration mode:

Command

Purpose

Router(config-access-point)# block-foreign-ms

Restricts GGSN access at a particular access point based on the mobile user's HPLMN.

Note The MCC and MNC values used to determine whether a request is from a roaming MS must be configured before the GGSN can be enabled to block foreign mobile stations.

Verifying the Blocking of Foreign Mobile Stations Configuration

This section describes how you can verify the blocking of foreign mobile stations configuration on the GGSN. It includes the following topics:

•Verifying Blocking of Foreign Mobile Stations at an Access Point

•Verifying the MCC and MNC Configuration on the GGSN

Verifying Blocking of Foreign Mobile Stations at an Access Point

To verify whether the GGSN is configured to support blocking of foreign mobile stations at a particular access point, use the show gprs access-point command. Observe the value of the Block Foreign-MS Mode output field as shown in bold in the following example:
GGSN# show gprs access-point 1
    apn_index 1          apn_name = gprs.corporate.com
    apn_mode: transparent
    apn-type: Real
    accounting: Disable
    wait_accounting: Disable
    dynamic_address_pool: dhcp-proxy-client
    apn_dhcp_server: 10.99.100.5
    apn_dhcp_gateway_addr: 10.27.1.1
    apn_authentication_server_group: foo
    apn_accounting_server_group: foo1
    apn_username: , apn_password:
    subscribe_required: No
    deactivate_pdp_context_on violation: Yes
    network_activation_allowed: Yes
    Block Foreign-MS Mode: Enable
    VPN: Enable  (VRF Name : vpn1) 
    GPRS vaccess interface: Virtual-Access2
    number of ip_address_allocated 0
    Total number of PDP in this APN :0
    aggregate:
    In APN:    auto
    In Global: 30.30.0.0/16
               21.21.0.0/16
Verifying the MCC and MNC Configuration on the GGSN

To verify the configuration elements that the GGSN uses as matching criteria to determine whether a request is coming from a foreign mobile station, use the show gprs gtp parameters privileged EXEC command. Observe the values of the output fields shown in bold in the following example. The example shows that the GGSN is configured for the USA country code (310) and for the Bell South network code (15):
GGSN# show gprs gtp parameters
    GTP path echo interval                        = 60                
    GTP signal max wait time T3_response          = 1                
    GTP max retry N3_request                      = 5                
    GTP dynamic echo-timer minimum                = 5                
    GTP dynamic echo-timer smooth factor          = 2                
    GTP buffer size for receiving N3_buffer       = 8192                
    GTP max pdp context                           = 45000 
    GPRS MCC Code                                 = 310 
    GPRS MNC Code                                 = 15
Note For a reference table of some of the established MCC and MNC codes, refer to the Appendix of the Cisco IOS Mobile Wireless Command Reference.

Controlling Access to the GGSN by MSs with Duplicate IP Addresses

An MS can not have the same IP address as another GPRS/UMTS network entity. You can configure the GGSN to reserve certain IP address ranges for use by the GPRS/UMTS network, and to disallow them from use by an MS.

During a create PDP context request, the GGSN verifies whether the IP address of an MS falls within the specified excluded range. If there is an overlap of the MS IP address with an excluded range, then the PDP context request is rejected. This measure prevents duplicate IP addressing in the network.

You can configure up to 100 IP address ranges. A range can be one or more addresses. However, you can configure only one IP address range per command entry. To exclude a single IP address, you can repeat the IP address in the start-ip and end-ip arguments. IP addresses are 32-bit values.

Note On the Catalyst 6500 / Cisco 7600 platform, identical configurations much exist on each GGSN load-balanced via a virtual server.

To reserve IP address ranges for use by the GPRS/UMTS network and block their use by an MS, use the following command in global configuration mode:

Command

Purpose

Router(config)# gprs ms-address exclude-range start-ip end-ip

Specifies the IP address ranges used by the GPRS/UMTS network, and thereby excluded from the MS IP address range.

Configuration Examples

This section includes the following configuration examples for configuring different types of network access to the GGSN:

•Static Route to SGSN Example

•Access Point List Configuration Example

•VRF Tunnel Configuration Example

•Virtual APN Configuration Example

•Network-Initiated PDP Request Configuration Example

•Blocking Access by Foreign Mobile Stations Configuration Example

•Duplicate IP Address Protection Configuration Example

Static Route to SGSN Example

Cisco 7200 Platform

The following example shows how to configure a static route from a physical interface on the GGSN to the SGSN.

Notice the following areas in the GGSN configuration shown in this example:

•FastEthernet0/0 is the physical interface to the SGSN, which is known as the Gn interface.

•In this example, the SGSN is located at IP address 192.168.1.1. Using the ip route command, a static route is configured to the SGSN located at 192.168.1.1 from the FastEthernet0/0 interface on the GGSN.

GGSN Configuration
! Configure Gn interface on GGSN to communicate with SGSN
!
interface FastEthernet0/0
 ip address 10.0.0.2 255.0.0.0
 no ip directed-broadcast
 no ip mroute-cache
 no keepalive
!
ip route 192.168.1.1 255.255.255.255 FastEthernet0/0
Note For the SGSN to successfully communicate with the GGSN, the SGSN must configure a static route, or be able to dynamically route to the IP address used by the GGSN virtual template.

Catalyst 6500 / Cisco 7200 Platform

On the GGSN:
!
...
!
interface Loopback100
 description GPRS GTP V-TEMPLATE IP ADDRESS
 ip address 9.9.9.72 255.255.255.0
!
interface GigabitEthernet0/0.2
 description Ga/Gn Interface
 encapsulation dot1Q 101
 ip address 10.1.1.72 255.255.255.0
 no cdp enable
!
interface Virtual-Template1
 description GTP v-access
 ip unnumbered Loopback100
 encapsulation gtp
 gprs access-point-list gprs
!
ip route 40.1.2.1 255.255.255.255 10.1.1.1
ip route 40.1.3.10 255.255.255.255 10.1.1.1
ip route 40.2.2.1 255.255.255.255 10.1.1.1
ip route 40.2.3.10 255.255.255.255 10.1.1.1
!
...
!
Related configuration on the Supervisor/MSFC2:
!
...
!
interface FastEthernet8/22
 no ip address
 switchport
 switchport access vlan 302
!
interface FastEthernet9/41
 no ip address
 switchport
 switchport access vlan 303
!
interface Vlan101
 description Vlan to GGSN for GA/GN
 ip address 10.1.1.1 255.255.255.0
!
interface Vlan302
 ip address 40.0.2.1 255.255.255.0
!
interface Vlan303
 ip address 40.0.3.1 255.255.255.0
!
ip route 9.9.9.72 255.255.255.255 10.1.1.72
ip route 9.9.9.73 255.255.255.255 10.1.1.73
ip route 9.9.9.74 255.255.255.255 10.1.1.74
ip route 9.9.9.75 255.255.255.255 10.1.1.75
ip route 9.9.9.76 255.255.255.255 10.1.1.76
ip route 40.1.2.1 255.255.255.255 40.0.2.11
ip route 40.1.3.10 255.255.255.255 40.0.3.10
ip route 40.2.2.1 255.255.255.255 40.0.2.11
ip route 40.2.3.10 255.255.255.255 40.0.3.10
!
...
!
Access Point List Configuration Example

The following example (from the Cisco 7200 platform) shows a portion of the GGSN configuration for a GPRS access point list:
!
interface virtual-template 1
 ip unnumber loopback 1
 no ip directed-broadcast
 encapsulation gtp
 gprs access-point-list abc
!
! Defines a GPRS access point list named abc
! with 3 access points
!
gprs access-point-list abc
 access-point 1
  access-point-name gprs.pdn1.com
  ip-address-pool dhcp-proxy-client
  dhcp-server 10.102.100.3 
  dhcp-gateway-address 10.30.30.30
  exit
!
 access-point 2
  access-point-name gprs.pdn2.com
  ip-address-pool dhcp-proxy-client
  dhcp-server 10.60.0.1       
  dhcp-gateway-address 10.27.27.27 
  exit
!
 access-point 3
  access-point-name www.pdn3.com
  access-mode non-transparent
  dhcp-gateway-address 10.25.25.25
  aaa-group authentication foo
  exit
!
. . .

VRF Tunnel Configuration Example

Cisco 7200 Platform

The following example shows a partial configuration for a virtual private network named "vpn1" using VRF:
! Configure a VRF routing table
! and define an identifier
!
ip vrf vpn1
 rd 100:1
!
! Enable CEF switching
!
ip cef
!
interface Loopback101
 ip address 10.14.101.1 255.255.255.255
!
! Configure a tunnel interface
! to a private network using VRF
!
interface Tunnel1
 ip vrf forwarding vpn1
 ip address 10.1.101.1 255.255.255.0
 tunnel source 10.14.101.1
 tunnel destination 10.13.101.1
!
! Configure OSPF routing using VRF
!
router ospf 101 vrf vpn1
log-adjacency-changes
redistribute static subnets
network 10.1.101.0 0.0.0.255 area 0
!
! Configure VRF at the access point
!
gprs access-point-list gprs
 access-point 1
  access-point-name gprs.cisco.com
  vrf vpn1
  exit
Catalyst 6500 / Cisco 7600 Platform

The following examples show a partial configuraiton for two VPNs (vpn1 and vpn2) and their associated GRE tunnel configurations (Tunnel1 and Tunnel2).

On the GGSN:
service gprs ggsn
!
hostname 6500-7-2
!
ip cef
!
ip vrf vpn1
 description GRE Tunnel 1
 rd 100:1
!
ip vrf vpn2
 description GRE Tunnel 3
 rd 101:1
!
interface Loopback1
 ip address 150.1.1.72 255.255.0.0
!
interface Loopback100
 description GPRS GTP V-TEMPLATE IP ADDRESS
 ip address 9.9.9.72 255.255.255.0
!
interface Tunnel1
 description VRF-GRE to PDN 7500(13) Fa0/1
 ip vrf forwarding vpn1
 ip address 50.50.52.72 255.255.255.0
 tunnel source 150.1.1.72
 tunnel destination 165.2.1.13
!
interface Tunnel2
 description VRF-GRE to PDN PDN 7200(12) Fa3/0
 ip vrf forwarding vpn2
 ip address 80.80.82.72 255.255.255.0
 tunnel source 150.1.1.72
 tunnel destination 167.2.1.12
!
interface GigabitEthernet0/0.1
 description Gi 
 encapsulation dot1Q 100
 ip address 10.1.2.72 255.255.255.0
!
interface Virtual-Template1
 description GTP v-access
 ip unnumbered Loopback100
 encapsulation gtp
 gprs access-point-list gprs
!
ip local pool vpn1_pool 100.2.0.1 100.2.255.255 group vpn1
ip local pool vpn2_pool 100.2.0.1 100.2.255.255 group vpn2
ip route vrf vpn1 0.0.0.0 0.0.0.0 Tunnel1
ip route vrf vpn2 0.0.0.0 0.0.0.0 Tunnel2
gprs access-point-list gprs
  access-point 1
   access-point-name apn.vrf1.com
   access-mode non-transparent
   aaa-group authentication ipdbfms
   ip-address-pool local vpn1_pool
   vrf vpn1
   !
  access-point 2
   access-point-name apn.vrf2.com
   access-mode non-transparent
   aaa-group authentication ipdbfms
   ip-address-pool local vpn2_pool
   vrf vpn2
   !
Related configuration on the Supervisor / MSFC2:
interface FastEthernet9/5
 no ip address
 switchport
 switchport access vlan 167
 no cdp enable
!
interface FastEthernet9/10
 no ip address
 switchport
 switchport access vlan 165
 no cdp enable
!
interface Vlan165
 ip address 165.1.1.1 255.255.0.0
!
interface Vlan167
 ip address 167.1.1.1 255.255.0.0
!
! provides route to tunnel endpoints on GGSNs
!
ip route 150.1.1.72 255.255.255.255 10.1.2.72
!
! routes to tunnel endpoints on PDN
!
ip route 165.2.0.0 255.255.0.0 165.1.1.13
ip route 167.2.0.0 255.255.0.0 167.1.1.12
Virtual APN Configuration Example

The following example shows a GGSN that is configured for a virtual APN access point that serves as the focal connection for three different real corporate networks.

Notice the following areas in the GGSN configuration shown in this example:

•Three physical interfaces (Gi interfaces) are defined to establish access to the real corporate networks: Ethernet 1/0, Ethernet 1/1, and Ethernet 1/2.

•Four access points are configured:

–Access point 1 is configured as the virtual access point with an APN called corporate. No other configuration options are applicable at the virtual access point. The "corporate" virtual APN is the APN that is provisioned at the HLR and DNS server.

–Access points 2, 3, and 4 are configured to the real network domains: corporatea.com, corporateb.com, and corporatec.com. The real network domains are indicated in the PCO of the PDP context request.

Figure 5-3 Virtual APN Configuration Example

GGSN Configuration
!
version 12.2
no service single-slot-reload-enable
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
! Enable the router for GGSN services
!
service gprs ggsn
!
hostname ggsn
!
ip cef
!
no logging buffered
logging rate-limit console 10 except errors
aaa new-model
aaa group server radius foo
 server 172.18.43.7 auth-port 1645 acct-port 1646
aaa authentication ppp foo group foo
aaa accounting network foo start-stop group foo
!
ip subnet-zero
!
!
no ip dhcp-client network-discovery
!
!
interface Loopback1
 ip address 10.2.3.4 255.255.255.255
!
interface FastEthernet0/0
 ip address 172.18.43.174 255.255.255.240
 duplex half
!
interface FastEthernet2/0
 description Gn interface
 ip address 192.168.10.56 255.255.255.0
!
! Define Gi physical interfaces to real networks
!
interface Ethernet1/0
 description Gi interface to corporatea.com
 ip address 10.8.8.6 255.255.255.0
 no ip mroute-cache
 duplex half
!
interface Ethernet1/1
 description Gi interface to corporateb.com
 ip address 10.9.9.4 255.255.255.0
 no ip mroute-cache
 duplex half
!
interface Ethernet1/2
 description Gi interface to corporatec.com
 ip address 10.15.15.10 255.255.255.0
 no ip mroute-cache
 duplex half
!
interface loopback 1
 ip address 10.40.40.3 255.255.255.0
!
interface Virtual-Template1
 ip unnumber loopback 1
 encapsulation gtp
 gprs access-point-list gprs
!
ip default-gateway 172.18.43.161
ip kerberos source-interface any
ip classless
ip route 10.7.7.0 255.255.255.0 10.8.8.2
ip route 10.21.21.0 255.255.255.0 Ethernet1/1
ip route 10.102.82.0 255.255.255.0 172.18.43.161
ip route 192.168.1.1 255.255.255.255 FastEthernet2/0
ip route 172.18.0.0 255.255.0.0 172.18.43.161
no ip http server
!
gprs access-point-list gprs
!
! Configure a virtual access point called corporate
!
 access-point 1
   access-point-name corporate
   access-type virtual
   exit
!
! Configure three real access points called corporatea.com, 
! corporateb.com, and corporatec.com
!
 access-point 2
   access-point-name corporatea.com
   access-mode non-transparent
   aaa-group authentication foo
   exit
 access-point 3
   access-point-name corporateb.com
   access-mode transparent
   ip-address-pool dhcp-client
   dhcp-server 10.21.21.1
   exit
   !
 access-point 4
   access-point-name corporatec.com
   access-mode non-transparent
   aaa-group authentication foo
   exit
   !
 !
gprs maximum-pdp-context-allowed 90000
gprs gtp path-echo-interval 0
gprs default charging-gateway 10.15.15.1
!
gprs memory threshold 512
!
radius-server host 172.18.43.7 auth-port 1645 acct-port 1646 non-standard
radius-server retransmit 3
radius-server key 7 12150415
call rsvp-sync
!
no mgcp timer receive-rtcp
!
mgcp profile default
!
!
gatekeeper
 shutdown
!
end
Network-Initiated PDP Request Configuration Example

Note GGSNs implemented on the Catalyst 6500 series switch / Cisco 7600 series internet router platform do not support network-initiated PDP contexts.

The following example shows a GGSN that is configured to support network initiated PDP contexts at a VPN on access point 1 for statically configured IP addresses. This example also shows support of network-initiated PDP contexts for MSs with an IP address of 172.31.1.2 and 172.31.1.3, which have been statically configured on the GGSN through access point 2.

Figure 5-4 Network Initiated PDP Request Configuration Example

GGSN Configuration
!
version 12.2
no service single-slot-reload-enable
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
! Enable the router for GGSN services
!
service gprs ggsn
!
hostname ggsn
!
ip cef
!
no logging buffered
logging rate-limit console 10 except errors
!
aaa new-model
!
aaa group server radius foo
 server 172.18.43.7 auth-port 1645 acct-port 1646
aaa authentication ppp foo group foo
aaa accounting network foo start-stop group foo
!
! Configure a VRF routing table
! and define an identifier
!
ip vrf vpn1
 rd 100:1
!
ip subnet-zero
!
no ip dhcp-client network-discovery
!
!
! Enable CEF switching
!
ip cef
!
interface Loopback1
 ip address 10.2.3.4 255.255.255.255
!
interface FastEthernet0/0
 ip address 172.18.43.174 255.255.255.240
 duplex half
!
interface Ethernet1/0
 description Gi interface to gprt.cisco.com
 ip address 10.8.8.6 255.255.255.0
 no ip mroute-cache
 duplex half
!
! Configure VRF at the interface
!
interface Ethernet1/1
 description Gi interface to gprs.cisco.com
 ip address 10.9.9.4 255.255.255.0
 ip vrf forwarding vpn1
 no ip mroute-cache
 duplex half
!
interface Ethernet1/2
 ip address 10.15.15.10 255.255.255.0
 duplex half
!
interface loopback 1
 ip address 10.40.40.3 255.255.255.0
!
interface Virtual-Template1
 ip unnumber loopback 1
 encapsulation gtp
 gprs access-point-list gprs
!
ip default-gateway 172.18.43.161
ip kerberos source-interface any
ip classless
ip route 10.7.7.0 255.255.255.0 10.8.8.2
ip route 10.102.82.0 255.255.255.0 172.18.43.161
ip route 192.168.0.0 255.255.0.0 172.18.43.161
ip route 172.18.0.0 255.255.0.0 172.18.43.161
no ip http server
!
gprs access-point-list gprs
!
! Configure an access point for gprs.cisco.com
! and enable network initiated PDP context support
! for a VPN
!
 access-point 1
   access-point-name gprs.cisco.com
   aaa-group authentication foo
!
! Enable network initiated PDP context support
!
   network-request-activation
!
! Configure VRF at the access point
!
   vrf vpn1        
   exit
!
! Configure an access point for gprt.cisco.com
! and enable network-initiated PDP context support
!
 access-point 2
   access-point-name gprt.cisco.com
   network-request-activation
   exit
   !
 access-point 3
   access-point-name gpru.cisco.com
   access-mode non-transparent
   aaa-group authentication foo
   exit
   !
gprs maximum-pdp-context-allowed 90000
gprs gtp path-echo-interval 0
gprs default charging-gateway 10.15.15.1
!
gprs memory threshold 512
!
gprs gtp ip udp ignore checksum
!
! Configure the IP address of the SGSN to perform GTP-to-MAP and
! MAP-to-GTP conversion between the HLR and GGSN
!
gprs default map-converting-gsn 10.7.7.1
!
! Configure a static IP address to IMSI mapping for each MS
!
gprs ni-pdp ip-imsi single 1 10.100.1.1 11111111111111F1
gprs ni-pdp ip-imsi single 2 172.31.1.2 11111111111111F2
gprs ni-pdp ip-imsi single 2 172.31.1.3 11111111111111F3
!
!
radius-server host 172.18.43.7 auth-port 1645 acct-port 1646 non-standard
radius-server retransmit 3
radius-server key 7 12150415
call rsvp-sync
!
no mgcp timer receive-rtcp
!
mgcp profile default
!
!gatekeeper
 shutdown
!
end
!
Blocking Access by Foreign Mobile Stations Configuration Example

The following example shows a partial configuration where access point 100 blocks access by foreign mobile stations:
!
version 12.2
no service single-slot-reload-enable
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
! Enables the router for GGSN services
!
service gprs ggsn
!
hostname ggsn
!
ip cef
!
gprs access-point-list gprs
!
access-point 100
 access-point-name blocking
! 
! Enables blocking of MS to APN 100
! that are outside ! of the PLMN
!
 block-foreign-ms
exit
!
. . .
!
! Configures the MCC and MNC codes
!
gprs mcc 123 mnc 456
Duplicate IP Address Protection Configuration Example

The following example shows a partial configuration that specifies three different sets of IP address ranges used by the GPRS/UMTS network (which are thereby excluded from the MS IP address range):
gprs ms-address exclude-range 10.0.0.1 10.20.40.50
gprs ms-address exclude-range 172.16.150.200 172.30.200.255
gprs ms-address exclude-range 192.168.100.100 192.168.200.255