All University
networked equipment (printers,
servers, PCs and Macs) are able to communicate.
The
path the information needs to travel between
units will depend upon the location of the source and
target unit. These may be in the same building, on the
same area of the campus, or at
opposite ends of St Andrews. Campus Backbone
In
general terms Nodes link the computers within
the same building or
wing. Workgroup switches
will link buildings close
together (or bits of a very large building), an “Exchange”
links several workgroup sites, and the backbone connects between exchanges.The University, which
is widely dispersed throughout St Andrews, has invested heavily in its
networking infrastructure over the years. A privately owned network of fibre
links buildings, using mainly Fast, and some Gigabit,
Ethernet, to the campus backbone (see Ethernet Technology). There is category 5 UTP
cable, currently supporting up to 100Mbps to the desktop using (Layer 2) 3Com Fast Ethernet switches, within buildings. The
backbone is based on three (Layer
3) Cisco Catalyst 8540s switches (located
in North Haugh, Old Union, Westburn Lane Exchanges), which are fully meshed
using Gigabit Ethernet
technology (see LAN Switching).
Residential Networking Services
Residential Network
Services are provided to private residences using a Cisco AS5200 remote access
server, supporting 24 integrated 56kbps digital modems, and a RADIUS server,
which has nearly 900 registered users; and to the student residences via the
Residences Network, using Cisco Network Registrar 's integrated dynamic
DHCP/DNS software installed on NT servers. Further details about St Andrews Remote Access (SARA) service can be found under St Andrews Remote Access
(SARA) service and SARA Operations Manual. The Residences Network (RESNET) is a switched 100Mbps
Ethernet network connecting all University Residences, which is separated from
the campus by a Cisco PIX firewall, and currently has around 850 registered
users. The data communications infrastructure, and associated authorisation and
authentication procedures, is currently under active development in order to
cater for the expected rate of growth. Students can register for this service using Student Residence Network
Registration Form 2000. Further information about the Residences Network can be found under Network Connections in
Residence Study-Bedrooms
FaTMAN
A Cisco 7507 router and
Fore A1000 ATM switch links the university directly to Fife and Tayside
Metropolitan Area Network (FaTMAN) (see FaTMAN - Fife and Tayside Metropolitan Area
Network),
which is based on a fibre ring connecting, at speeds of 155Mbps using fully
meshed ATM permanent virtual links, the Universities of Dundee, Abertay, and
Northern College Dundee. Member institutes manage FaTMAN in a collaborative
fashion, where the University of St Andrews is the lead development site, and
University of Dundee is the lead operational site, for the MAN. Two resilient
155Mbps ATM links, between the Universities of St Andrews and Edinburgh, and
Universities of Dundee and Glasgow, connect FaTMAN to the Scottish MANs' core
(connecting Universities of Edinburgh, Strathclyde and Glasgow in a ring). This
ring runs at speeds of 622Mbps using ATM, linking all the Scottish MANs
(FaTMAN, EaStMAN, Clydenet and AbMAN) together, and onwards to Joint Academic Network (JANET) (see
JANET and UKERNA)
and the Internet
. The Scottish
MANs fibre infrastructure was supplied by THUS.
Videoconferencing
Services
The Scottish MANs
support high quality ATM based multipoint video conferencing, using Codecs and
MCUs provided by K-NET. The JANET Videoconferencing Management Centre, located
at the University of Edinburgh, enables multipoint booking of ATM, ISDN and IP
standards based videoconferencing and gateway facilities used throughout JANET
and beyond. Further details can be found under Videoconferencing at the University of
St.Andrews.
SuperJANET4
UKERNA has announced
their intentions to proceed with MCI WorldCom as their preferred
supplier for the SuperJANET4 backbone (see SuperJANET4 - Connecting Education). This development
includes 2.5Gb core network initially, moving to a 20Gb core network by 2002
based on wave-division multiplexing (WDM) technology; a highly reliable core
and links to regional networks; a topology of eight C-PoPs on telco premises;
and a test-bed network on which to develop SuperJANET itself and the potential
for other research activities. The contracts for the four Scottish MANs and the
Scottish MANs' Core are due for renewal in 2001/2. Investigation into an
alternative high quality video conferencing solution is required to ensure its
future compatibility with the network within Scotland. Also, Further Education
Institutes (FEI) are due to be shortly integrated into this predominantly
Higher Education Institutes (HEI) based regional network and the rest of JANET.
Internetworking
University hosts (printers, servers, PCs
and Macs) communicate via the campus data network using Transmission Control
Protocol/Internet Protocol (TCP/IP) (see Introduction to
Internetworking and Internet
Protocol). The IP addressing
scheme is integral to the process of routing IP datagrams
through an internetwork. Applications forms to request an IP Address for a host can be
found under Staff Network
Registration Form. The following IP parameters will be provided to enable the Network Interface Card (NIC) of the host to be configured for TCP/IP: Hostname, IP Address,
Subnet Mask, Gateway and Primary/Secondary DNS servers.
IP addresses have specific
components
and follow a basic format. These IP addresses can be subdivided and used to
create addresses for Subnetworks (subnets). Each system/host on a TCP/IP is assigned a unique
32-bit logical address that is divided into Network number and Host number. The 32-bit IP address
is grouped eight
bits at a time, separated by dots, and represented in decimal format (known as
dotted decimal notation). The minimum and maximum values for an octet is 0 and 255 respectively. The network number
used within
the University is 138.251.0.0 (all 0s in the host portion of
the address specifies the entire network), which has been subdivided into subnets using a Subnet Mask of 255.255.255.0 (eg. 138.251.33.0). The final octet indicates the host number (and possibly the data socket
number to which the host connects).
The IP datagrams are routed
between
hosts through
the campus backbone. All physical campus network segments connecting to this infrastructure support at least one subnet (see Departmental Segment
Subnets). Movement of a machine between interfaces on the
router without
a change the
appropriate change in address will cause communications to fail.
·Backbone – The
backbone is based upon a fibre optic high-speed cable
that carries data packets for both the voice
and the data network. This University private cabling is combined for
voice and data (multiple fibre optic cables in a single sheath), and is
carried in shared trenches around St Andrews between the three Exchanges. For the data network, the backbone links to
Routers or Gateways at each exchange which
further distribute the data packets. Data
traffic is two-way around the ring, and voice traffic is one-way (check).
·Gateways
or Routers (High
speed, Cisco manufactured boxes), act as data “Exchanges”. Each Router is also a switch (level 3
technology), and data is directed from the Router out to one or several
“Workgroup” switch. The routers the
University have, are each a Cisco 8540 Switch, and are located at:-
·Westburn
Lane Exchange (by Bute),
·The
Old Union Exchange, and the
·North
Haugh Exchange (Beside Purdie buliding)
·NB:
For voice network, there are several more “voice” exchanges (but on the same
backbone ring)
·A Workgroup Switch
(normally allocated per building) may connect to one or several nodes. The workgroup switch is Ethernet technology
at either gigabit or 100Mbps speed.
·Each Node houses
a Patch Panel and
one or several logical sub-nets.
·A sub-net (a
logical sub-network often mapping
directly to a physical Layer 2 technology switch housed within the node rack)
·There
is only one patch panel per Node, but depending upon the number of connections
required there may be several sub-nets. (Data sockets per sub-net/switch=256?). Each sub-net/Switch
links to the Patch
Panel (often housed physically in the same rack) which
has numbered sockets, each leading either directly to networked equipment (such
as servers) or more normally to a data socket located nearby. Note the University no longer uses hubs (which
provide shared band with)
and now always use switches)
·Each Data socket can
be connected to a PC/Mac/Printer or Server.
The data socket will normally have a reference number of the format
xxx/yyy. By convention xxx is a
reference to the nearest node, and yyy is the number of the socket in the Patch
panel for that node. But beware, not
all sockets have been named with this convention.
Still need to
understand DNS server, DHCP, Host file, etc.
What is the sequence of events for a user sign-on? General users and classroom users?
For a
list of exchanges, buildings and AppleTalk zones see http://www.st-and.ac.uk/~meg/ITS/backbone.txt