The SecGW is a
high-density IP Security (IPSec) gateway for mobile wireless carrier networks.
It is typically used to secure backhaul traffic between the Radio Access
Network (RAN) and the operator core network.
IPSec is an open
standards set that provides confidentiality, integrity, and authentication for
data between IP layer peers. The SecGW uses IPSec-protected tunnels to connect
outside endpoints. SecGW implements the parts of IKE/IPSec required for its
role in mobile networks.
The SecGW is enabled
as a Wireless Security Gateway (WSG) service in a StarOS instance running in a
virtual machine on a Virtualized Services Module (VSM) in an ASR 9000.
The following types
of LTE traffic may be carried over encrypted IPSec tunnels in the Un-trusted
S1-C and S1-U: Control and User
Traffic between eNodeB and EPC
X2-C and X2-U:
Control and User Traffic between eNodeBs during Handoff
carry only Control Traffic, however there exists a case for carrying
non-Internet User traffic over secured tunnels
The ASR 9000
services architecture encompasses how the platform interfaces with the services
independent of where the service is actually instantiated. It provides a common
control plane, management plane and data plane infrastructure such that a
consistent end user experience is provided whether the service is running on a
service blade, on the RSP, on an attached appliance or server, or even running
inline in the router.
The ASR 9000
platform supports the following functions:
management via CLI and XML for:
service package including licenses
instantiation with associated parameters
termination, re-start and upgrades
configuration of the WSG service from the service creation infrastructure
Provides a set of
templates for service parameters
the hypervisor (Virtual Machine Manager client) to setup the StarOS WSG service
on multiple virtual machines (VMs)
The figure below
shows the relationship between IOS-XR running on the ASR 9000 and StarOS
running on the VSM.
Figure 3. IOS-XR and VSM
The 10GE interfaces
on the SecGW virtual machines are visible as 10GbE interfaces on the ASR 9000.
The ASR 9000 line card forwards IP traffic to VSM 10GbE ports.
VSM Resource Mapping
to VPC-VSM VMs
There are four CPU
sockets on the VSM. Each CPU supports multiple cores. A VPC-VSM
instance uses multiple virtual CPUs (vCPUs) consisting of available cores
for its virtual machine.
Each CPU socket is
associated with a Crypto engine. PCI Ports are also assigned to
accept traffic from the ASR 9000 line cards.
The table below shows
how resources are assigned among the four CPUs on the VSM.
Table 1 Resource Assignments
for VSM CPUs
20 (20-29, 60-69)
20 (30-39, 70-79)
Only twelve PCI ports
can be mapped to ASR 9000 line card traffic. The table below shows
how the interfaces are distributed.
Table 2 PCI Port Mapping
For all VMs except
VM1, the NICs are allocated from the corresponding socket. But in
VM1, the third NIC (42:0.0) is picked from a different socket. To
achieve maximum throughput, that NIC is used as the management port
and the other two are used for the service.
To make the interface-to-port
mapping symmetric across all the VMs, the third NIC is always used
as the management port.
Virtualized Packet Core
for VSM (VPC-VSM) consists of the set virtualized mobility functions
that implement mobility specific services and applications within the
core of the network. VPC-VSM is essentially StarOS running within
a Virtual Machine (VM).
VPC-VSM only interacts
with supported hypervisors. It has little or no knowledge of physical
Each VPC-VSM VM takes
on the roles of an entire StarOS system. The only interfaces exposed
outside the VM are those for external management and service traffic.
Each VM is managed independently.
Each VPC-VSM VM performs
the following StarOS functions:
for CLI and Logging
Local context (management)
NPU simulation via fastpath
Non-local context (subscriber
Crypto processing (IPSec)
For a complete description
of VPC-VSM functionality, refer to the VPC-VSM System Administration
Up to four instances
of VPC-VSM can run on an ASR 9000 VSM. Each VSM CPU supports only
one VPC-VSM instance. VSM resources are allocated to each SecGW
VM; no other application VM is supported on any VSM CPU. vNICs must
be passed to the SecGW VMs from RSP.
The StarOS-based Security
Gateway (SecGW) application is a solution for Remote-Access (RAS)
and Site-to-Site (S2S) mobile network environments. It is implemented
via StarOS as a WSG (Wireless Security Gateway) service that leverages
the IPSec features supported by StarOS.
SecGW delivers the
S2S IP Encryption capabilities required in UMTS/HSPA and
LTE 3GPP LTE/SAE network architectures.
For complete descriptions
of supported IPSec features, see the IPSec Reference.
The SecGW is a licensed
StarOS feature. A separate license is required for each VPC-VSM instance
and SecGW. Contact your Cisco account representative for detailed
information on specific licensing requirements.
The following are
key features of the SecGW product:
Functions in a virtualized
environment on one or more VSM blades in an ASR9000
Supports DES, 3DES, AES and NULL
Encryption algorithms, and MD5, SHA1/2, HMAC-SHA2 and AES-XCBC Hash algorithms.
mechanisms for High Availability both within and outside of the ASR 9000
encompasses Inner-Outer pairs – v6-v6, v6-v4, v4-v6, v4-v4
provisioning of IPSec configuration for a new WSG service in the existing SecGW
Each of the four
SecGWs on a VSM must be configured separately.
Load balancing has
not been implemented for the SecGWs; incoming calls will not be automatically
distributed across the four SecGWs on a VSM. A workaround is to use VLANs for
load balancing. The public side interface of each SecGW can be configured for a
separate VLAN. Calls from multiple peers are routed to the same IP address via
a different VLAN to distribute the traffic load.
The following IPSec
features are supported by StarOS for implementation in an SecGW application:
Multiple Child SA
Management Protocol (CMPv2)
Recovery/Interchassis Session Recovery for both RAS and S2S
Support for IKE
PSK support with
up to 255 octets
Certificate Status Protocol (OCSP)
Lookup for Peer IP in show Commands
Blacklist/Whitelist by IDi
CRL fetching with
Admission Control (CAC)
PSK Support for
up to 1000 Remote Secrets
as IKE Initiator
Support to provide DNS server address to the Peer
Reverse Route Injection
SecGW also supports
Reverse Route Injection (RRI). RRI injects routes in the reverse
direction onto the ASR 9000 VSM so that clear traffic can be routed
to the correct interface on the target VPC-VSM. For additional information,
see the Reverse Route Injection chapter.
Each SecGW instance
is configured individually via its Management port. However, the
Cisco Prime network management tool can be used to configure and
manage individual SecGW instances.
A common or default
configurations can be captured as "templates" in
Cisco Prime which are then applied to each SecGW instance or all
SecGW instances in the network.
For additional information
on the Cisco Prime Mobility suite, contact your Cisco account representative.
Alternatively an operator
can create a StarOS configuration file on the first gateway. The resulting
configuration file can then be copied and edited offline with different
parameters. The edited configuration file is then copied to the
flash drive of the second SecGW. The process is repeated until all
four SecGWs have been initially configured.
made to the configuration of each SecGW must be saved to the local configuration
file. For security and recovery the individual configuration files
should then be saved off the VMS to a target network destination.
For additional information,
see the VPC-VSM System
Each SecGW creates
a oneP session with the ASR 9000 for route insertions, policy creation and
flow creation. For additional information, refer to the oneP Communication chapter.
ASR 9000 VSM IPSec
This section briefly
describes the IPSec High Availability (HA) capabilities for VSM service cards
within an ASR 9000.
For this release the
ASR 9000 supports the following levels of High Availability
The process recovery
feature stores backup Security Association (SA) data in an AAA manager task.
This manager runs on the SecGW where the recoverable tasks are located.
Figure 4. Process Recovery Diagram
VSM-to-VSM ICSR 1:1
In this redundancy
scenario, Interchassis Session Recovery ICSR utilizes the Service Redundancy
Protocol (SRP) implemented between VMs in a VSM running separate instances of
VPC-VSM/SecGW in the same ASR 9000 chassis.
VSM card status data
is exchanged between VPN managers on active and standby VSMs via SRP. SA data
is also exchanged via SRP.
Administration Guide fully describes ICSR configuration procedures.
SecGW HA supports
hot standby redundancy between VMs in a VSM in different ASR 9000 chassis. The
Standby VSM is ready to become active once a switchover is triggered. SA
re-negotiation is not required and traffic loss is minimal.
information, see the
Injection (RRI) chapter.
HA involves configuration of both SRP and ConnectedApps (CA) for RRI
ConnectedApps (CA) communication between the client running on the wsg-service
VM and IOS-XR running on the ASR 9000.
commands configure the CA client parameters, including those associated with HA
mode. For additional information, refer to the
SecGW supports the
following network deployment scenarios:
In a RAS scenario, a
remote host negotiates a child SA with the SecGW and sends traffic inside the
child SA that belongs to a single IP address inside the remote host. This is
the inner IP address of the child SA. The outer IP address is the public IP
address of the remote host. The addresses on the trusted network behind the
SecGW to which the host talks could be a single IP or a network.
Figure 5. RAS
In an S2S scenario,
the remote peer sets up a child SA to the SecGW. The source of the traffic
inside the child SA can be from multiple IP addresses on the remote peer's
side. As in the remote access scenario, the addresses on the trusted network
behind the SecGW can be a single IP or a network.
In this scenario
also, the remote peer can setup multiple child SAs to the SecGW.
For S2S tunnels
established using the WSG service, the TSi and TSr contain protocol as well as
source and destination IP ranges.
Figure 6. S2S Tunnel
The figures below
indicate traffic packet flows to and from the SecGW.