the benefit of vlan
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Apricot2001 Effectiveness of VLAN Chan Wai Kok ([email protected]) Faculty of Information Technology Salim Beg ([email protected]) Faculty of Engineering Multimedia University. The benefit of VLAN. Simplify the process of add, moves and changes - PowerPoint PPT PresentationTRANSCRIPT
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Apricot2001
Effectiveness of VLAN
Chan Wai Kok ([email protected])
Faculty of Information Technology
Salim Beg ([email protected]) Faculty of EngineeringMultimedia University
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The benefit of VLAN
• Simplify the process of add, moves and changes• Provide broadcast, multicast traffic isolation by
grouping similar traffic types to a VLAN.• Provide some form of security
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Goals of this presentation
• To find out the broadcast traffic trend• To study the effectiveness of VLAN in broadcast
isolation
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Why Broadcast isolation is important ?
• On a 1 Gbps capacity backbone network• If 1% traffic is (broadcast + multicast + unknown
unicast), all end stations with 10Mbps link may be congested (but backbone have more capacity!!!)
• Broadcast frames will take up CPU resources. E.g On Pentium 120Mhz, – 1000 broadcast pps :- 15 % CPU resource– 3000 broadcast pps :- 28 % CPU resource
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Related Work(Will E. Leland & Daniel V Wilson Bellcore 1989 - 1990)
• collected LAN traffic data for long time scale and analyzed the trend
• Their showed that there is a great disparity in the values of peak to mean ratio for packet arrival rate. (73 to 861 for 5 sec to 5 milisec respectively)
• LAN traffic is Bursty • Focus on behavior of total Ethernet traffic
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LAN Traffic (hourly)
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LAN Traffic (busiest hour)
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LAN Traffic (by minutes)
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LAN Traffic (Peak to mean ratio)
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Analysis Method
• Collect network traffic from few different IP Subnet and check the broadcast plus multicast traffic quantity.
• Run an IP Multicast application• See how it’s effect the broadcast plus multicast
traffic in the IP subnet.• Make some conclusions on the result
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Network Setup
• A Pentium PC is used as a network analyzer• Traces are taken for a few days• Network consists of WinNT servers and Win95 PCs.• Each IP subnet consists of 60, 85 and 45 hosts
respectively. 3 different labs.• Two Labs are is fully used during office hour. • Students accessing WinNT server to work• No Novell Server (future is IP)
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Type of Packets Detected
• ARP request• Spanning Tree Frame (hello frame)• Netbios• SAP• IP Multicast Solicitation
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Traffic statistic
• Average bandwidth (extremely low)– 1413, 1761, 1381 bps (office hour)– 809, 789, 406 bps (non office hour)
• Maximum bandwidth (1 % of 10Mbps)– 31920, 125408, 130752 bps (office hour)– 29824, 70640, 38608 bps (non office hour)
• Majority of the traffic is background traffic• Generally, broadcast traffic is very low
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Traffic Statistic (no IP Multicast)
Broadcast traffic (no IP Multicast)
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
1 2247 4493 6739 8985 11231 13477 15723 17969 20215
Second
Bit
pe
r s
ec
on
d
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Traffic Statistic (no IP Multicast)
Broadcast traffic (no ip mcast)
0
500
1000
1500
2000
2500
3000
3500
4000
1 54
10
7
16
0
21
3
26
6
31
9
37
2
42
5
47
8
53
1
58
4
63
7
69
0
74
3
79
6
84
9
90
2
95
5
Second
Bit
pe
r s
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on
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Traffic Statistic (no IP Multicast)
Broadcast traffic (no IP Multicast)
0
500
1000
1500
2000
2500
1 7
13
19
25
31
37
43
49
55
61
67
73
79
85
91
97
Second
Bit
pe
r s
ec
on
d
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Traffic Statistic with IP Multicast application
• One IP Multicast Channel sending audio and text.• Average bandwidth :- 112 Kbps• Maximum Bandwidth :- 155 Kbps• Dramatic increased of (broadcast plus multicast)
bandwidth when IP Multicast is ran.• Traffic isolation will required IP Multicast VLAN
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Traffic Statistic with IP Multicast application
Traffic Statistic with IP Multicast Application
0
20000
40000
60000
80000
100000
120000
140000
160000
1800001
14
27
40
53
66
79
92
10
5
11
8
13
1
14
4
15
7
17
0
18
3
19
6
20
9
22
2
Second
Bit
pe
r s
ec
on
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IP Multicast VLAN
• Router will duplicate IP Multicast packet to all IP Subnet that joined in IP Multicast group
• Some switch ports have multiple IP Subnet VLAN memberships. Therefore, may receive in duplicated IP Multicast packet
• IP Multicast VLAN is patented by 3com US Patent No: 5,818,838
• Term as IGMP spoofing• Dynamic filtering of IP Multicast group at switch port
level.
• Available in many commercial switches.
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IP Multicast Application
• Who is running IP Multicast at the 1st place ? • A 4.5 year studies on MBone traffic shows• 90% of users joined multicast group less than 74
times• top 1% joined MBone group > 350 times• 20% IP addresses - at least 1 hour per connection• 70% IP addresses :- average 1 min per connection
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IP Multicast Application
• Over 4.5 year• 20% of users joined MBone more than 1 day• 5% of users joined > 300 hours• A total of 33,545 unique IP is seen in 4.5 year• Jan 1998 :- 10,600 unique IP seen• ( > 20,000 IP didn’t joined any multicast session for
more than 1 year)• Jan 1999 :- 5,000 unique IP seen
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Conclusion
• When no IP Multicast application• Total Broadcast and multicast traffic is very low• problem of broadcast isolation does not arise at the
first place• VLAN is of little use
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Conclusion
• When IP Multicast is deployed• Dramatic increase in mean bandwidth• VLAN is useful only when IP Multicast application is
deployed• Make sure that current/future switch support IP
Multicast VLAN• However, IP Multicast application is still not popular
yet.• Studies have shown MBone is growing slowly and it
uses is not widespread.
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References
• http://imj.ucsb.edu/publications.html– BGPK. Almeroth, "A Long-Term Analysis of Growth and Usage
Patterns in the Multicast Backbone (MBone)", IEEE INFOCOM '00, Tel Aviv, ISRAEL, March 2000
• http://www.patents.ibm.com• http://www.argreenhouse.com/papers/wel/
– Will E. Leland, Daniel V. Wilson, “High Time-resolution Measurement and Analysis of LAN Traffic: Implications for LAN Interconnection,” Proceedings IEEE Infocom 1991, Bal Harbour, Florida, April 1991, pp.1360-1366. building and forwarding