Transcript Gi-LAN Use Cases

Network Based Services in Mobile Networks
Context, Typical Use Cases, Problem Area, Requirements
IETF 87 Berlin, 29 July 2013
BoF Meeting on Network Service Chaining (NSC)
[email protected]
[email protected]
IETF 87 - 29 July 2013
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Context: Mobile Networks and Service Platforms
Major Building Blocks of a LTE Service Platform
LTE Control Plane
Home Subscriber System
HSS
LTE Data Plane
Policy
& Charging
Rules
Function
PDN: Packet Data Network
Mobility Management Entity
MME
eNB
eNodeB
Cell
Aggregation
Network
Backhaul
Network
PCRF
S-GW
P-GW
Serving
Gateway
Packet
Gateway
Operator
Based
Services
SGi
Network
Services
(SGi-LAN)
Internet




SG-interface is the 3GPP reference point between P-GW and Packet Data Network.
SGi protocol structure, data content, scope not specified (equal for Gi in 3G networks).
Operator based services like, VoLTE, Mail, Web, RCS-e/Joyn, SMS, MMS not in scope.
Scope here: network services like firewalls, DPI, performance enhancement proxies
for videos, TCP optimization & header enrichment, NAT, load balancers, caching, etc.
 This class of services takes care of managing network traffic and network policing.
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Context: Principle of Typical Hard-Wired SGi-LAN Services
Current Common Approach – Logical View on Typical Use Cases
Web Service for Smartphone User
APN
Web
Proxy
LB
FW
NAT
@
Fixed-Mobile-Converged Enterprise Service
APN
Mobile
Access
Router
ACL
P-GW
MPLS VPN
Operator’s IMS offer
APN
Operator’s
IMS (VoLTE)
SBC
Video Service
APN: Access Point Name
LB: Load Balancer
FW: Firewall
ACL: Access Control List
SBC: Session Boarder Controller
IMS: IP Multimedia Subsystem
OTT: Over The Top
APN
Video
Optimizer
FW
OTT
Video Service
Service related IP interface, VLAN
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Problem: Hard-Wired SGi-LAN Services
Current Common Approach – More Physical View on Typical SGi-LAN
to Internet
GW
Router
PE
Router
IP BB
to IMS
PE
Router
TCP
Optimizer
SGi
P-GW
Router
Internet
FW/NAT
DPI
LB/NAT
Performance Enhancement
Proxy (PEP)
Video
Optimizer
Roaming
FW
HTTP
Optimizer
Caches
HTTP
Proxies
 With deployment of additional value-added services increasing number of functions required
in SGi-LAN. Some functions in dedicated devices, sometimes multiple functions in one box.
 Due to fast service introduction cycles service chains emerge, growth & change evolutionary.
 Very often static IP links, policy routing, VRFs etc. used to enforce required service sequence.
 Results in steadily increasing, handcrafted complexity and decreased visibility of functional
dependencies between service chains and underlying LAN topology. Means expensive OAM.
 Practically impossible to implement automated service provisioning and delivery platform.
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Requirement: Simplicity, Flexibility, Speed, Expandability
Vision: Service Chain Abstraction and Network Compilation
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4
2
graphs uni- or
bidirectional
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•
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3
Create Service Function Topology
Define Branch Conditions
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Compiler not yet invented creates
Configuration for Service Chains
Mediation Device
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Abstract service
Abstract link
S1
(virtual) service engine
(virtual) forwarding device
S1
S2
S3
S4
S5
S6
•
•
•
Physical Layer
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Preference for Telco Cloud
Forwarding Topologies for
multiple service chains
Branching rules in services
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Requirement: High Degree of Freedom in Chain Creation
Network provides us with sufficient Metadata to differentiate
Some metadata in P-GW state
UE:
terminal type (HTC one)
IMSI (country, carrier, user)
GTP Tunnel:
eNB-ID
time
PCRF:
user
APN (service)
QoS
policy
PCRF
Gx
Load
Probe
GTP Tunnel
P-GW
SGi
PEP
User Equipment (UE)
Probes may deliver cell load,
link loads, session loads etc.
for real time network policing
BGP-TE/LS
 We may connect all relevant service functions with all relevant sources for metadata or
 We may piggyback metadata information with the IP packets traversing a service chain.
 Piggybacking metadata seems to be more straightforward than picking them out with DPI.
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Summary:
 Market dynamics accelerate need and demand for more services at an even faster rate.
 With current approaches network service LANs and their service chains become more and
more complex, error-prone, hard to manage and hard to extend. It’s a dead end street.
 Vision is to decouple creation of service topologies and their internal branching conditions
from the creation of the associated underlying packet forwarding (overlay) network.
 Operators think in terms of an ordered sequences of network services (more precisely graphs)
selected out of a service pool and define forking conditions in the service graphs based on
metadata sets including user data, related service classes, type of user equipment in use,
network conditions etc.
 (Conditional) forwarding decisions done in a network service node may allow for more real
time flexibility than more static service topology paths in an underlying network.
 We would appreciate if IETF agrees to start a WG on Network Service Chaining analyzing
requirements and specifying solutions also supporting virtualized service environments.
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