Cisco Systems 10000 manual - page 6

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Figure 4
L2TP Tunneled Architecture
TheCisco 10000 Series operates as a highly scalable LAC with a comprehensive set of PPP, AAA/RADIUS, and L2TP
attributes.In many cases, an ISP will contract the service provider to dictate the service rate for the subscriber. This
is usually implemented by ATM traffic shaping capabilities on the Cisco 10000 Series. A single LAC can support
subscriber sessions for many remote ISPs, and it is common to provision a unique L2TP tunnel per destination ISP.
Remote Access to MPLS
RemoteAccess to MPLS (RA-MPLS) offers service providers an alternative to L2TP for the provisioning of wholesale
services. Instead of building unique L2TP tunnels per ISP, a unique VPN per ISP is provisioned over an MPLS core
(Figure 5). Layer 2 access protocols are terminated at the service provider’s edge and placed into the appropriate
VPN. Subscriber traffic is routed through the VPN to the destination ISP’s network, and then onto the Internet.
Figure 5
RA-MPLS
TheCisco 10000 Series operates as a highly flexible provider edge MPLS device, supporting the widest range of Layer
2 encapsulations. It offers an array of per-VPN services, including Hot Standby Router Protocol (HSRP), AAA/
RADIUS, and DHCP.
Subscriber DSLAM
IP/PPP
L2TP
IP
PPPoA or PPPoEoA
ATM
Cisco
10000
Series
LAC
ATM
RADIUS/AAA
IP Network
LNS
RADIUS/AAA
Subscriber DSLAM
IP
P
P
P
P
MPLS VPN
IP
RFC 1483/RBE or PPPoX
ATM
Cisco
10000
Series
PE
ATM
RADIUS/AAA
IP Network
PE
RADIUS/AAA