Title: Case for TaskDriven NetworkWide Abstraction approach to Enterprise Design
1 Case for Task-Driven Network-Wide
Abstraction approach to Enterprise Design
- Yu-Wei (Eric) Sung
- Internet Systems Lab
- Dept of ECE, Purdue University
- (with Prashant Garimella, Sunil Krothapalli, and
Sanjay Rao)
LISA 2007 Configuration WorkshopNov 12, 2007,
Dallas, TX
2Motivation Task-driven Network-wide Abstractions
- Tremendous interest in simplifying enterprise
design and configuration using abstractions - Many prior efforts
- Template-driven (eg Presto), BGP Policy
specification (eg RSPL), Vendor-neutral config
specification (eg SNMP MIBS) - Our proposal Task-driven Network-wide
abstraction approach to network design - Task-driven capture intended requirements, eg
performance, security, manageability - Network-wide consider requirement of the network
as a whole - Focus on enterprise campus networks ? not well
understood
3Methodology
- Three-pronged research framework
- First step White-Box approach to study
enterprise networks - Static analysis of topology and router/switch
configurations - Gain deeper understandings through interaction
with operators - White-box studies are rare
- Significant effort to bootstrap relationships
with operators - Sensitive nature of data access non-trivial
Bottom-Up, White-Box study
Top-DownNetwork Design
Abstraction
4Case Study VLAN
- Why study VLAN?
- Widely prevalent in enterprise/campus networks,
little understanding in research community - VLAN Configuration time-consuming, error-prone
- Critical area for abstraction
- Prevalent _at_ Purdue University
- 200 routers, 1300 switches, hundreds of VLANs
- First empirical study of VLAN usage (SIGCOMM INM
Workshop 2007)
5What is VLAN?
- A VLAN groups hosts attached to different
switches as if they are on the same wire - Each VLAN belongs to a stand-alone subnet
- Simplifies address assignment, e.g. writing ACLs
- VLAN spans at Purdue University
- 80 1-2 buildings some entire campus (e.g.
classrooms)
.
.
.
.
R1
S
R2
Trunk
S3
S2
S1
VLAN 3
.
Access
.
.
.
H2
H3
H4
H1
VLAN 2
VLAN 1
VLAN 2
VLAN 1
63 key components of VLAN Configuration
interface Vlan1 description subnet
192.168.1.0/24 ip address 192.168.1.1
255.255.255.0
interface FastEthernet0/1 switchport mode trunk
switchport trunk allowed vlan 1,2
R1
S
interface FastEthernet0/1 switchport mode
access switchport access vlan 1
Fa0/2
Fa0/1
Fa0/2
S1
Fa0/1
- Access port
- Trunk port
- Subnet Config
H1
H2
VLAN 1
VLAN 2
7Design Issues
- Communication between hosts from different VLANs
must go through a router - Performance Inefficiencies Longer delay, harder
to debug since data may flow through other
buildings - Placement of designated router Where to best
place the router for hosts in a given VLAN?
? Building1
Data
R2
R1
S
Trunk
S3
S2
VLAN 3
S1
.
Access
.
.
.
Physical
H2
H3
H4
H1
VLAN 2
VLAN 2
VLAN 1
VLAN 1
8Results
- Performance Inefficiencies
- Inefficiency hops in data flow path/ hops
in physical path - Inefficiencies as large as 14, gt 4 for about 12
host pairs - Placement of designated router
- Sub-optimal placement a router not placed in the
same building as where the majority of hosts in
that VLAN are - More pronounced for wider-spread VLANs 11, 33,
and 58 for VLANs that span 1, 2, and gt2
buildings - Typical cause evolution of network
- See INM07 paper for complete results and
discussions of other issues
9Example Task-driven VLAN Abstraction and
Top-down Network Design
- Abstraction Complete network topology consists
of routers/switches/hosts, a set of hosts in VLAN
X - Suggest a router for VLAN X
- Task 1 Minimize inefficiencies communicating
with all other VLANs - Task 2 Task 1 Host H in VLAN X is a major
network storage server for the entire network
10Summary Future Work
- Goal Task-driven, Network-wide abstraction to
enterprise network design - Three-pronged research framework
- First step White-box approach to studying
networks, providing critical insights for
abstraction design - VLAN as a case study
- Issues inefficiencies, sub-optimal router
placement - First study of VLAN usage in a real network
(INM07) - Going Forward
- Formulate VLAN abstractions and demonstrate their
applications - Generalizing other campus/enterprise networks
11Thank you
- We are looking for data!
- Please let me know if you have router/switch
configurations of an entire enterprise/campus. We
will provide useful tools in return. ? - Email sungy_at_purdue.edu
- Visit http//www.ece.purdue.edu/isl for more
info about our research - Questions?