April 2005
Compiled by Charles Spurgeon
ITS Networking Services
Contents:
- Introduction
- Internet Traffic
- Active IP and MAC Addresses
- Assigned IP Addresses
- Domain Name Service Queries
- Active IP Subnets
- Core and Backbone Switching System
i. Introduction
UTnet, the campus computer network, supports teaching, research, and the administration and operation of The University of Texas at Austin with high-performance networking that is also designed to provide high reliability and manageability.
This UTnet status report provides a brief look at some statistics for UTnet, and documents the traffic rates, the current size of the network and the host population, and provides some data on the growth of the system.
a. Scope of UTnet
UTnet serves the University of Texas at Austin, which has an enrollment of approximately 50,000 students, as well as 2,721 faculty and 19,184 staff. The University has a $1.3 billion annual budget, with annual research funding that exceeds $400 million.
There are eight colleges and seven schools at UT Austin, as well as seven museums and 17 libraries. The main campus and JJ Pickle Research Campus (PRC) campus include 188 buildings, with a UTnet presence in the vast majority of them. UTnet also serves a number of external sites located around the city of Austin. All told, UTnet serves a combined total of roughly 200 buildings and sites.
b. UTnet Device Population
The UTnet network management system is actively managing over 3,134 network devices. This set of devices provides over 78,280 Ethernet interfaces, also called ports. Adding in another 4,268 ports in use at two large sites that are not in the UTnet management tools gives us a total of roughly 82,548 ports.
We estimate that there may be approximately 10% more switches and ports connected to UTnet that are not being managed in the UTnet Netmanage system, resulting in a total of roughly 3,450 devices supporting approximately 90,000 interfaces or ports.
c. Network Servers
There are approximately 70 network server computers used to provide critically important network services (DNS, DHCP, etc.), as well as network management and monitoring functions.
d. Telesys
There is a total capability of 1,944 Telesys dialup lines supported in three Telesys servers.
I. Internet Traffic
The traffic rates shown in this section are in megabits per second (Mbps) and are derived from long-term averages that include approximately one month of data. The actual peak hourly bit rates are significantly higher than these numbers reflect, and the five-minute and one-second peak bit rates can be much higher.
The long term average rates shown include the sum of all Internet traffic (Commodity Internet, the Internet2 research network, the TACCNET network, and peering connections with broadband providers Apogee and Bestline) sent and received by the UTnet border router over roughly equivalent periods of time in 2004 and 2005.
The result for 2005 is a traffic rate increase of between 5% (input) and 37% (output) over 2004 rates. Some of the difference in rates may be explained by changing traffic patterns over the last year, in which PRC traffic is now using the main campus Network Operations Center (NOC) router as a path to TACCNET, the Texas Advanced Computing Center network.
The provision levels for UTnet commodity Internet traffic are negotiated with the provider, the UT System Office of Telecommunications Services (OTS). We have projected the need for 10% additional bandwidth in fiscal year (FY) 2005-06 to cover peak commodity IP traffic needs.
|
Average
Input Rate |
Increase Over Prior Year |
Average
Output Rate |
Increase Over Prior Year |
March 20-April 20, 2005 |
172.02 |
5.4% |
143.39 |
37.4% |
April 2004 |
163.20 |
24.7% |
104.36 |
22.9% |
April 2003 |
130.87 |
|
84.90 |
|
A. UTnet Dual Fiber-Optic Core Traffic
The UTnet main campus core network is composed of a fiber-optic star cabling system that connects each building router to two high-performance Cisco Catalyst routers located in the NOC. There are other routers in the main campus NOC which support buildings that have only a single connection to the NOC.
The dual fiber-optic core statistics shown here account only for traffic seen by the two NOC routers. This does not account for any traffic that was sent between network segments located entirely within buildings, or located in the buildings supported by any of the core routers other than the two fiber-optic star routers.
In other words, this is only traffic that had to transit the dual fiber-optic star system to reach its destination. This traffic includes all traffic to and from the external Internet and Internet2 research networks.
The two fiber-optic core routers recorded the following traffic counts over a period of 13 weeks, 1 day and 6 hours (since they were last reloaded).
Time Period |
Number of Bytes |
Number of Bits |
|---|---|---|
| 13 weeks, 1 day, 6 hours |
444,974,294,752,751 Bytes |
3,559,794,358,022,008 bits |
Switched Bytes Long-term Average Rates:
3.35 billion bytes per minute
55,828,352 bytes per second
446,626,813.96 bits per second, or 446.62 Mbps
Compared with a long-term average of 2,477,439,230.88 bytes per minute in 2004, this represents a 35 percent increase.
Time Period |
Number of Packets |
|---|---|
| 13 weeks, 1 day, 6 hours |
930,237,593,192 |
Switched Packet Long-term Average Rate:
7,002,691.90 packets per minute
116,711.53 packets per second continual average rate
This is a 68.99% increase in average packets per second over 2004.
II. Active IP and MAC Addresses
An Internet Protocol (IP) address is required for communication over the network. The IP address is either statically assigned to a device and manually configured into it, or dynamically acquired by the device via the Dynamic Host Configuration Protocol (DHCP).
There is a separate medium access controller (MAC) address, also known as a "hardware address," that is configured into each Ethernet and wireless interface by the manufacturer. The MAC address is considered to be permanently assigned to the interface.
Various management servers in the UTnet management system track the IP and MAC addresses seen in use on UTnet. The combination of IP and MAC address information, for example, allows the UTnet management system to track computers by their address usage, and to locate the switch port to which a given computer may be connected.
This data represents a snapshot of the number of active computers seen on UTnet.
A. IP and MAC Address Statistics Excluding the Public Networks (Wired/Wireless)
The following sample represents the number of IP and MAC addresses recorded in the UTnet database over the last 90 days prior to April 10, 2005; these numbers exclude addresses from the wired and wireless Public Network Authentication (PNA) system.
| Year | Time Period | Ending Date |
Distinct IP Addresses |
Distinct MAC Addresses |
|---|---|---|---|---|
| 2005 | 90 days | April 10, 2005 |
58,760 |
50,266 |
| 2004 | 180 days | May 14, 2004 |
58,804 |
54,693 |
Analysis of a separate monitoring system based on Cisco Netflow data found 58,824 unique IP addresses. The Netflow addresses were seen in traffic crossing the UTnet core routing system over the last several weeks leading up to April 14, 2005. These include both wired and wireless/public ports.
B. IP and MAC Statistics for the Public Networks (Wired/Wireless)
The wired Ethernet ports and wireless access points (WAPs) that make up the Public Network on UTnet are connected through a set of Public Network Authentication (PNA) routers that keep their own statistics.
In the 90 days prior to April 10, 2005, the PNA system recorded the following data:
Year |
Time Period |
Ending Date |
Unique IP Addresses |
Unique MAC Addresses |
|---|---|---|---|---|
| 2005 |
90 days |
April 10, 2005 |
10,202 |
25,893 |
| 2004 |
90 days |
May 14, 2004 |
6,981 |
17,249 |
The PNA system also recorded the following information about users:
Year |
Time Period |
Ending Date |
Number of Unique Users - Wired |
Number of Unique Users - Wireless |
Total Number of Unique Users |
|---|---|---|---|---|---|
| 2005 |
90 days |
April 10, 2005 |
7,184 |
25,577 |
27,332 |
| 2004 |
90 days |
May 14, 2004 |
5,855 |
15,176 |
17,150 |
Note: The number of unique IP addresses varies from the number of MAC addresses since a given machine with a MAC address may acquire multiple different IP addresses over time. On the PNA system the set of IP addresses are all assigned dynamically, with short IP address lease times leading to a high rate of IP address reuse by the total set of machines being served.
Further note: Tracking and counting these numbers through a large, dynamic network system is not an exact science and the various elements being measured are never going to be in sync with one another. Therefore, the totals do not add up "correctly" or align neatly.
Yet another note: Firewalls that use network address translation to hide machine addresses from the global Internet also hide those addresses from the UTnet management system. At a rough guess there are well over 5,000 computers currently hidden behind NAT firewalls on UTnet.
The bottom line is that there was a host population of roughly 58-60,000 computers using UTnet during the Spring 2005 semester. This number could presumably range up to several thousand larger given the population of machines behind NAT routers.
III. Assigned IP Addresses
The count of assigned IP addresses for UTnet comes from the UTnet domain name server files. This count:
- includes addresses assigned in the private IP address range of 172.16/12 (172.16.0.0-172.31.255.255). These addresses are not globally routable, and are limited to use on campus only.
- includes addresses assigned in the globally routable space on the UTnet assigned networks (128.62.0.0/16, 128.83.0.0/16, 129.116.0.0/16, 146.6.0.0/16).
- includes dynamic addresses used for Resnet, the campus residence hall network.
- does not include a number of addresses assigned on private name servers located at various sites on campus.
- does not include the devices located behind firewalls in non-routable address space.
There are currently 23,274 private IP addresses assigned in the central name server, of which 19,273 are used to support virtual private network (VPN) and wireless operations.
A. Total Number of Assigned IP Addresses
There are a total of approximately 86,361 IP addresses assigned and available for use on UTnet, including:
- 4,000 private IP addresses
- 72,860 globally routable addresses (including DHCP and WAP addresses)
- 9,500 Resnet dynamic addresses
Date |
Number of IP Addresses |
Rate of Increase |
|---|---|---|
April 2005 |
86,361 |
11.1% increase over May 2004 (~11 months) |
May 2004 |
77,677 |
7.3% increase over March 2003 (~14 months) |
March 2003 |
72,347 |
36.8% increase over April 2002 (~11 months) |
April 2002 |
52,872 |
10.9% increase over April 2001 (~12 months) |
April 25, 2001 |
47,655 |
11.2% increase over Sept 2000 (~7 months) |
September 5, 2000 |
42,842 |
18.7% increase over May 1999 (~16 months) |
May 14, 1999 |
36,074 |
4.6% increase over Nov 1998 (~6 months) |
November 23, 1998 |
34,501 |
2.5% increase over May 1998 (~7 months) |
May 1, 1998 |
33,653 |
7.2% increase over Nov 1997 (~6 months) |
November 4, 1997 |
31,367 |
38.6% increase over Sept 1996 (~13 months) |
September 26, 1996 |
22,629 |
38% increase over Nov 1995 (~10 months) |
November 10, 1995 |
16,300 |
|
October 6, 1993 |
7,244 |
|
June 13, 1990 |
711 |
|
B. DHCP Addresses
Included in the count of IP addresses assigned in the globally routable space are entries with "dhcp" in the name, indicating that the address is used for dynamic host configuration outside of Resnet.
Date |
Number of DHCP Addresses |
Rate of Increase |
|---|---|---|
April 2005 |
26,559 |
15.7% increase over May 2004 (~11 months) |
May 2004 |
22,950 |
2.6% increase over March 2003 (~14 months) |
March 2003 |
22,356 |
25.7% increase over April 2002 (~11 months) |
April 2002 |
17,772 |
42.4% increase over April 2001 (~12 months) |
April 25, 2001 |
11,993 |
42.4% increase over Sept 2000 (~7 months) |
September 5, 2000 |
8,422 |
103.5% increase over May 1999 (~16 months) |
May 14, 1999 |
4,138 |
29.7% increase over Nov 1998 (~6 months) |
November 23, 1998 |
3,190 |
24.1% increase over May 1998 (~7 months) |
May 1, 1998 |
2,569 |
45.3% increase over Nov 1997 (~6 months) |
November 4, 1997 |
1,768 |
|
C. Wireless Addresses
Also included in the count of IP addresses are entries with "wap" in the name, indicating that the address is used for wireless access on campus. Each wireless access point (WAP) has a unique IP address; each user is dynamically assigned an address when they connect to a WAP.
Wireless networking has been growing explosively, as the growth numbers for the last year indicate.
Date |
Number of WAPs |
Rate of Increase |
|---|---|---|
April 2005 |
980 |
100% increase over May 2004 |
May 2004 |
490 |
55% increase over March 2003 |
April 2003 |
316 |
|
Date |
Number of Unique Wireless Users |
|---|---|
April 2005 |
25,577 |
May 2004 |
15,176 |
April 2003 |
3,000 (approximate) |
Date |
Number of Simultaneous Wireless Users |
|---|---|
April 2005 |
2,100 |
May 2004 |
1,500 |
April 2003 |
700 |
IV. Domain Name Service Queries
One of the most critically important services on UTnet is the domain name service (DNS). This is the service that translates names (for example, www.utexas.edu) into the IP addresses that computers use to send packets over the campus network and the worldwide Internet.
When you type a domain name or Web URL, a DNS query is sent to the UTnet name servers. In response, the DNS provides your computer with the IP address needed to initiate packet communications with the destination that you have entered.
ITS Networking operates multiple domain name servers in a resilient configuration designed to make the campus DNS service as highly available as possible.
A. DNS Traffic Statistics
The following statistics are for all name servers combined.
Morning busy period: 473 queries/sec
Afternoon busy period: 651 queries/sec
Total number of queries on an average day: 15,750,944
(182.30 queries per second, daily average)
V. Active IP Subnets
Each network segment on UTnet supports a block of IP addresses. These network segments, also known as IP subnets, are used to direct the flows of traffic over the UTnet system. New subnets are added to support new buildings and organizations and to provide new capacity for existing buildings and organizations.
The numbers provided here include subnets currently being used to deliver packets, therefore these are subnets that are active in the campus routing tables.
The number of subnets has increased by 16.2% over 2004.
Date |
Number of Subnets |
Rate of Increase |
|---|---|---|
April 2005 |
1,856 |
16.2% increase over 2004 |
May 2004 |
1,597 |
14.6% increase over 2003 |
March 2003 |
1,393 |
20.8% increase over 2002 |
April 2002 |
1,153 |
35.9% increase over 2001 |
April 25, 2001 |
848 |
14.2% increase over 2000 |
September 5, 2000 |
742 |
|
May 14, 1999 |
630 |
|
November 23, 1998 |
598 |
|
May 1, 1998 |
566 |
|
November 4, 1997 |
550 |
|
September 26, 1996 |
375 |
|
November 10, 1995 |
304 |
|
July 21, 1995 |
266 |
|
September 9, 1994 |
214 |
|
June 15, 1990 |
77 |
|
VI. Core and Backbone Switching System
The core routers and the backbone routers and switches move packets between IP subnets and provide inter-building IP packet switching. These routers and switches direct the flow of traffic through the UTnet system, based on the IP address and the subnet to which the address belongs.
Equipment |
Device |
|---|---|
Core Routers |
9 |
Equipment |
Device |
|---|---|
Backbone Routers |
53 |
Backbone Switches |
20 |
Equipment |
Device |
|---|---|
PoP Routers |
16 |
PoP Switches |
70 |
Grand total of core, backbone and PoP routers and switches: 168. (Note that there are a number of backbone locations that have both a switch and a router.)
A. Connected Buildings and Sites
The total number of buildings and sites with a UTnet point of presence is currently 137.
There are approximately 188 buildings in the campus list of buildings for the main campus and PRC campus, and most of them have some sort of network presence.
The number of UTnet points of presence is not that same as the number of buildings, however, since the 188 building names include a number of residence hall lounges that are part of residential buildings, storage buildings, etc.
Also, several building complexes that include multiple buildings are equipped with a single network point of presence device. While there may be many building switches in each building, there is only one point of presence device connecting the complex to the NOC.
B. Number of Connections and Speeds
The connection between the main campus and the PRC campus was upgraded to 10-Gigabit Ethernet in 2005. This connection travels over the fiber-optic Greater Austin Area Telecommunications Network (GAATN).
The majority of the backbone and PoP connections on the main and PRC campuses are based on 1-Gigabit Ethernet, although there are several sites on the main campus which have a 10-Gigabit Ethernet connection to the NOC over the dual fiber-optic backbone system.
Speed |
Quantity |
10 Gigabit Ethernet |
7 |
1 Gigabit Ethernet |
120 |
100 Megabit Ethernet |
52 |
1.5 Megabit Serial |
10 |
Total |
185 |
(Note that this is a count of total connections to sites and excludes connections used to link the core equipment to each other and to the UTnet border router.)
