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Overhead and Performance Study of the General
Internet Signaling Transport (GIST) Protocol
Xiaoming Fu (Uni Goettingen)
Henning Schulzrinne (Columbia Uni)
Hannes Tschofenig (Siemens)
Christian Dickmann, Dieter Hogrefe (Uni Goettingen)
Telematics group
University of Göttingen, Germany
Telematics group
University of Göttingen, Germany
Overview
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•
•
•
Background
Terminology
Operation Overview
Evaluation
–
–
–
–
Overhead
E2e performance
Scalability
Security
• Conclusions
Xiaoming Fu ([email protected])
2
Telematics group
University of Göttingen, Germany
Background
• Middlebox: interposed entity doing more than IP
forwarding (NAT, firewall, cache, …)
– Can also be QoS and other boxes – PHB, profile meters,
AQM etc…
Firewall
B
Host A NAT
10.1.1.4
QoS
C New traffic class
Host D
• Not in harmony with the Internet architecture
Xiaoming Fu ([email protected])
3
Telematics group
University of Göttingen, Germany
Background
• Perhaps need sort of common control plane functions for
end-to-end communications
– QoS is just an example of control functions
– NAT, firewalls and other functions are also in consideration
– One needs to perform certain configuration of such control
functions before (and during) an end-to-end communication
• Actually, this is somewhat re-inventing "circuit-switching"
concept in ATM or telephony networks!
• If we want to allow its use the Internet, a general
signaling function for IP is necessary
– Signaling: to install, maintain, remove states in network nodes
– It needs to traverse heterogeneous IP-based nodes
– It needs to cater for accommodating various controlling purposes
Xiaoming Fu ([email protected])
4
Telematics group
University of Göttingen, Germany
Network Control Signaling Protocol Examples
• Path-decoupled (Client/Server)
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COPS
MEGACO
DIAMETER
MIDCOM
• Path-coupled
– Resource Reservation Protocol (RSVP) IETF
proposed standard for QoS signaling (03/97)
– IETF NSIS (Next Steps in Signaling) with QoS
signaling as first application
Xiaoming Fu ([email protected])
5
Telematics group
University of Göttingen, Germany
RSVP review
• RFC 2205
• Integrated Service QoS models: GS, CLS
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–
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Per-flow reservation
Multicast flow
Limited extensibility (objects and semantics)
Refreshes: packet losses due to congestion, route changes
Not adapted to today’s needs
• RFC 2961: added hop-by-hop reliability and
summary refreshes
• Other extensions: aggregated reservation,
reservation over different networks (MPLS, 802.x)
Xiaoming Fu ([email protected])
6
Telematics group
University of Göttingen, Germany
Selected issues with RSVP
• Insufficient modularity
– Designed specifically for (IntServ) QoS
– Difficult to accommodate new signaling applications:
firewall/NATs, network diagnostics, etc.
• No/difficult support for mobility
– Node mobility has been an immense reality
• Weak security framework and AAA support
– No operator today will choose to deploy a solution
without sufficient security for global Internet use
Xiaoming Fu ([email protected])
7
Telematics group
University of Göttingen, Germany
NSIS Framework (RFC 3726)
• Flexible/extendable message transport
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Reliability/order provisioning
Keepalive and multiplexing
Some security services
Common transport functions
• Flexible/extendable multiple signalling application
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Per flow QoS (IntServ)
Flow aggregate QoS (DiffServ)
Firewall and Network Address Translator (NAT)
Traffic meter configuration
And others
• A two-layer split
– Transport layer (NTLP or GIST): message transport
– Signalling layer (NSLP): QoS NSLP, NATFW NSLP, etc.
• Contains the application intelligence
Xiaoming Fu ([email protected])
8
Telematics group
University of Göttingen, Germany
NSIS Two-Layer Split
Resource
specific layer
NSIS Signalling Layer (NSLP)
NSIS Transport Layer (NTLP)
Signalling
Appl. Protocol
Common
Signalling
?
?
IP forwarding
Two names for transport layer:
• NTLP (the basic concept)
• GIST (the protocol implementation
• General Internet Signalling Transport
Xiaoming Fu ([email protected])
9
Telematics group
University of Göttingen, Germany
GIST: NSIS Transport Layer (NTLP)
• GIST responsible for
– Transport signalling message through network
– Finding necessary network elements
• Abstraction of transport to NSLPs
NSLP
level
– NSLP do not care about transport at all
S ignalling
A pplication -Q oS
S ignalling
S ignalling
A pplication - A N O
A pplication - m idcom
G IS T S tate M aintenance
NTLP level
G IS T M essage E ncapsulation
UDP
DCCP
S C TP
IP
S ecurity
P rotocols
(TLS , IP sec)
TC P
G IS T
Focus of specification
is this
...w hich includes m anagem ent of all of this
IP
Xiaoming Fu ([email protected])
10
Telematics group
University of Göttingen, Germany
View on NSIS’ Layers
Need QoS!
NSLP
View
NSLP
Stack
Need QoS!
NSLP
Stack
Here it is!
Need QoS
NSLP
Stack
Here it is!
Here it is!
Are you my
next node?
(discovery)
Abstraction
NTLP
View
Network
View
NTLP
Stack
UDP
transport
NTLP
Stack
NSIS router
Router
NSIS
without
Host A
NSIS
Xiaoming Fu ([email protected])
TCP connection
Router
without
NSIS
NSLP
Stack
NTLP
Stack
NTLP
Stack
NSIS router
NSIS
Host B
11
Telematics group
University of Göttingen, Germany
GIST Session Setup
Xiaoming Fu ([email protected])
12
Telematics group
University of Göttingen, Germany
Evaluation
• Scalability
– Can it be scalable for large number of sessions and nodes?
• Extensibility and mobility
– Can it be easily extended to build most signaling applications?
– Can mobility be intrinsically supported?
• Security
– Can it be well protected without much performance penalty?
• Overhead
– Will the overhead added by NSIS be too large?
Xiaoming Fu ([email protected])
13
Telematics group
University of Göttingen, Germany
Extensibility and mobility
• NSIS allows
– GIST use of any types of discovery mechanism
– Definition of any new NSLPs
– node mobility: thru the use of independent NSIS session identifiers
• Support a large variety of transport protocols
– SCTP and PR-SCTP
– TCP and its variants (both loss and delay based)
– UDP (and even DCCP)
• In the implementation level:
– The GIST daemon and GIST-API are developed with sufficient
modularity/independency on underlying platforms and NSLPs
– Currently we support xBSD, Linux and MacOS: fairly easy to port
Xiaoming Fu ([email protected])
14
Telematics group
University of Göttingen, Germany
Performance testing: testbed
Background
Traffic generator
Background
Traffic generator
S1
D1
100Mbps
100mbps
S2
100mbps
R1
100Mbps
R2
1GMbps
R2
100Mbps
D2
100mbps
100Mbps
D3
S3
H1
Xiaoming Fu ([email protected])
S3
15
Telematics group
University of Göttingen, Germany
Performance/scalability: 3 hops
RSVP
GIST (C-mode)
Number of sessions
60000
55000
50000
45000
40000
35000
30000
25000
20000
15000
10000
5000
0
60000
55000
50000
45000
40000
35000
30000
25000
20000
15000
10000
5000
1000
RSVP
160
140
120
100
80
60
40
20
0
1000
Memory consumption (MB)
GIST (D-mode)
80
70
60
50
40
30
20
10
0
0
Num ber of sessions
7
Avg. RTT (seconds)
6
5
4
3
2
1
Number of sessions
60000
55000
50000
45000
40000
35000
30000
25000
20000
15000
10000
Xiaoming Fu ([email protected])
5000
1000
0
0
CPU consumption (%)
GIST (C-mode)
16
Telematics group
University of Göttingen, Germany
Overhead
Xiaoming Fu ([email protected])
17
Telematics group
University of Göttingen, Germany
Security
• Two-layer security
– Interconnected!
• Transport layer (NTLP)
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–
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Securing signaling transport
Using TCP/SCTP with TLS
Certificates
Discovery phase: use of cookies
• Signaling layer
– Authentication and authorization
– Policy decisions (e.g., user allowed to load filter rule?)
Xiaoming Fu ([email protected])
18
Telematics group
University of Göttingen, Germany
Conclusions
• Extensible IP signaling framework (NSIS) tries to address
the mobility, complexity, transport, and security issues in
RSVP
– Not only QoS signaling, but also generic signaling for any type
of middlebox configuration
– Fundamental building block: GIST protocol
• GIST overhead is higher than RSVP but the complexity
worth the added extensibility, modularity.
• GIST performance is comparable with RSVP, with good
scalability
• GIST/NSIS implementation: http://user.cs.unigoettingen.de/~nsis
Xiaoming Fu ([email protected])
19
Telematics group
University of Göttingen, Germany
Thank you!
Xiaoming Fu ([email protected])
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