W-uw 3“me
`
`Application Note:
`LAN lnternet Helps
`Prudential Securities
`Compete
`
`To stay competitive, companies oi all types and sizes
`are finding it necessary to integrate diverse operations
`to achieve targeted levels of efficiency and economy.
`
`By Nathan J. Muller
`
`0 stay competitive, companies of all
`types and sizes are finding it necessary
`to integrate diverse operations to achieve
`targeted levels of efficiency and economy.
`More important than dollars saved on equipment
`is the increased productivity of employees, which
`can improve customer service. However, such
`integration projects are not easy to implement
`because of the mix of products that must be tied
`into the enterprise network.
`This was the situation recently encountered by
`Prudential Securities, 3 fully owned subsidiary
`of the Prudential Insurance Company, which
`provides brokerage services from offices world-
`wide. The company devised a plan to upgrade
`its network that included the move from SNA-
`
`More important than dollars saved on
`equipment is the increased
`productivity of employees, which can
`improve customer service.
`
`to achieve greater
`to LAN-based networks
`efficiencies and economies in service delivery.
`The resulting network would have to serve
`multiple departments, including real estate, tax,
`ordering, unit trust, information systems develop-
`ment, futures trading, personal financial manage—
`ment, investment banking, and retail sales.
`
`Nathan Muller is an independent consultant in Oxford, Con-
`necticut. He specializes m advanced technology marketing and
`education.
`
`Until recently, Prudential Securities relied upon
`the traditional SNA architecture. This entailed
`
`The Move trom SNA
`
`a».
`
`lNTERNATlONAL JOURNAL OF NETWORK MANAGEMENT 95
`
`Page 1 of 8
`
`FIS Exhibit 1028
`
`

`

`.) Wfi‘hm..uigw;hMWWl—“§¢i
`
`
`
`the use of low-speed analogue lines/modems
`in a polled multi—drop arrangement. Non-SNA
`communications protocols required the use of
`separate networks, while the multiplicity of
`communications protocols and facilities compli-
`cated network management and drove up
`operating costs.
`One byproduct of network consolidation
`activity is the diversity of protocols that can
`be accommodated on the enterprise network.
`Moving from SNA-
`to LAN-based networks
`would allow Prudential Securities to integrate
`a variety of PCs and accommodate different
`protocols, such as Novell’s lPX, IBM's SNA/3270,
`Digital Equipment Corp.'s DECnet and LAT,
`and TCP/Il", among others. The integration of
`different computers and protocols would also give
`Prudential Securities the networking flexibility
`needed to meet
`the current and emerging
`demands of customers.
`
`increasingly differentiating
`With customers
`brokers on the basis of the speed and accuracy
`of transaction processing, it was deemed impera-
`tive by Prudential Securities that its network be
`up to date and optimized for efficiency and cost
`savings. To achieve this level of integration,
`Prudential evaluated the products of many inter-
`networking vendors, including those of IBM. At
`the time, Prudential found that IBM’s source-
`
`nel, but rather offloads them so they can focus
`on strategic considerations instead of being mired
`down in the details of the protocols, such as
`addressing and routing. Once plugged in, about
`all the ILANs need is some fine tuning.
`
`The Resultlng Network
`
`Over
`
`three hundred offices worldwide are
`
`connected through modems to the distributed
`network at the Prudential Securities headquarters
`location in Manhattan. There, a star network
`
`links five home-office buildings (Figure 1). Each
`building has its own LANs, which are intercon-
`nected via lLANs over different media at a
`minimum T-l
`rate of 1.544 Mb/s. There are
`microwave links between the Cold Street and
`
`Seaport hubs, which operate at the Ethernet rate
`of 10 Mb/s and the T-3 rate of 45 Mb/s.
`
`The T—3 facilities support dual 16 Mb/s Token-
`Ring LANs and other data like 3270 terminal
`traffic and voice between the Gold Street and
`
`Seaport hubs. Gateways are used for protocol
`translation of Novell's lPX and IBM’s NetBlOS,
`among others, between the Token Rings and the
`SNA host.
`
`routing bridges were unable to support non-
`lBM protocols and that they presented potential
`security problems. Since the IBM bridges used a
`PS/2 platform, the presence of a keyboard invited
`tampering. Even with the keyboard removed and
`a plug on the bare connector, it is a relatively
`simple matter for an intruder to remove the plug
`and reinstall a keyboard to gain access. Prudential
`also considered the bridge/routers offered by
`other vendors, but
`found that
`they did not
`support SNA in the company’s multiprotocol
`environment.
`
`Novell's lntemet Packet Exchange (lPX) com-
`munications protocol enables NetWare users to
`route messages from one node to another. Any
`application program that manages its own client-
`server or peer-to-peer communications on a
`Novell network can access IPX, but lPX does not
`guarantee delivery of messages. Introduced by
`IBM, NetBlOS is a commonly used transport
`protocol for PC local area networks, which is
`also implemented in Microsoft’s MS-Net and
`LAN Manager. Applications use NetBlOS for
`dient-server or peer-to-peer communications. In
`the datagram mode, the fastest method of message
`transfer, NetBlOS does not guarantee message
`(Marlboro, MA)
`CrossComm Corporation’s
`delivery; in the session mode, a connection is
`[LAN bridge was selected precisely because it
`established until broken and message delivery
`overcame these problems and for its ease of
`is guaranteed.
`installation, which
`is
`exemplified
`by
`the
`Prudential also had the need to pass infor-
`mation between Token Ring and Ethernet LANs.
`catchphrase
`’plug-and-play’. Specifically,
`the
`lLAN unit learns all device addressses upon
`This is effectively handled by the ILANs, since
`they are designed to facilitate interconnection of
`attachment to the LAN and automatically sets
`up the routes between LANs, irrespective of the
`the two LAN types by forwarding and converting
`communications protocols being used. This does
`frames at the media access control (MAC) layer
`(see the Appendix). This is no small task because
`not alleviate the need for skilled network person—
`
` "' ‘aua'
`
`m.>-W¢....._..z a.
`— ....r _
`
`96
`
`IUNE 1993
`
`Page 2 of 8
`
`

`

`"s.
`
`'
`
`--: th4xz4f‘2m9m
` .m-wvmmM W
`
`Seaport
`4 Mbps Token Hlng
`
`Financial Square
`4 Mbps Token Ring
`
`
`
`T1
`
`T1
`
`Separate Otftoo
`
`ILAN Bfidges
`
`
`
`130 John Street
`4 Mbps Token Fling
`
`Have 1. Prudential Securities corporate backbane network
`
`127 John Street
`4 Mbps Token Ring
`
`there are over 1000 connections on Token Ring
`and Ethernet LANs at Prudential Securities.
`
`their protocol
`have been used primarily for
`conversion capabilities was not justified.
`Although some routers also offer this capability,
`Although the [LAN provides the option of
`connecting older SNA equipment to the Token
`they do so at a premium price (Table 1). Since
`Ring by means of an SDLC pass-through capa-
`Prudential did not need the routing capability“
`bility, Prudential had already upgraded this
`spending up to $75,000 for devices that would
`35-: a; ”-mmv Nada _-m-.4 x9.
`4—!va
`:wmrmywa in” .m J 3::
`... Mm»...
`'m.1~< x w. ~mfi: _,.~- :3.
`
`INTERNATIONAL IOURNAL OF NETWORK MANAGEMENT 97
`
`Page 3 of 8
`
`

`

`
`
`
`
`
`
`Router applications
`Bridge applications
`
`(Cost: 36000—30900] (Cost: up to $75,000]
`
`
`
`
`
`
`
`
`
`Accommodate several data
`
`
`
`
`
`
`
`links and can exploit complex
`
`
`
`
`
`mesh topologies in cases of
`
`
`
`
`link failure and congestion.
`
`
`
`Support multiple network and
`
`
`
`
`
`router layer protocols at the
`some time.
`
`
`Offer advanced
`
`
`administration and control
`
`
`
`services based on network
`
`
`
`
`and subnetwork addresses.
`
`
`
`
`
`
`
`
`
`
`
`Best for point-to-point, simple
`
`
`
`
`mesh or star topologies.
`
`
`
`Easier to install and maintain
`
`
`
`
`than routers.
`
`
`
`
`
`
`
`Operate independently of
`
`
`higher-level protocols.
`
`
`
`
`
`Offer a flexible method for
`
`
`
`
`
`
`
`
`
`filtering traffic according to
`source-destination addresses.
`
`
`
`
`protocol type, and
`
`application.
`
`
`
`
`
`
`
`Table 1. Bridge and router applications
`
`
`
`
`
`
`
`
`
`
`
`
`tems. The [MS resides on a single PC. From the
`
`
`
`
`
`
`
`IMS screen, any ILAN can be remotely configured,
`
`
`
`
`
`network performance statistics {Figure 2) and
`
`
`
`
`
`real-time alarms gathered, and topology map
`
`
`
`
`
`
`
`displayed. Table 2 gives descriptions of the fields
`
`
`
`
`
`
`shown in Figure 2. Moreover,
`the enterprise
`
`
`
`
`
`network can be troubleshooted quickly using
`
`
`
`
`CrossCornrn's Exper’I‘est, a valuable diagnostic
`
`
`
`
`
`tool which allows a segment-by-segment con-
`
`
`
`
`
`
`
`
`nectivity test for determining if a problem is in
`
`
`
`
`
`the network or applications software.
`
`
`
`
`
`
`
`For example, a remote ILAN can be instructed
`
`
`
`
`
`
`to test
`the connection integrity between itself
`
`
`
`
`
`
`
`and a questionable server. Then the [LAN can
`the connection between the IMS and the
`test
`
`
`
`
`
`
`
`
`
`
`
`
`
`remote ILAN, completing the network test. With
`
`
`
`
`
`
`
`ExperTest, any segment of the network can be
`
`
`
`
`
`
`tested without
`the need for extra equipment
`
`
`
`
`
`and without dispatching technicians to remote
`locations.
`
`IMS allows Prudential Securities to achieve its
`
`
`
`
`
`
`
`
`
`
`
`goals of greater network uptime, configuration
`
`
`
`
`
`flexibility and economies in equipment and
`
`
`
`
`personnel. Specifically, Prudential can accommo-
`
`
`
`
`date incremental growth, mitigate congestion
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`equipment for LAN interconnection. If the com-
`
`
`
`
`
`
`pany chooses to implement this technology in
`
`
`
`
`
`
`the future, additional cost savings will result
`from the choice of CrossCornm as the LAN
`
`
`
`
`
`
`
`interconnect vendor.
`
`
`
`
`
`
`
`Disaster recovery is implemented in association
`
`
`
`
`
`
`
`with CornDisco. Every night, all data from Pru-
`dential’s home-office locations is sent to 3 Com-
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Disco backup facility in New Jersey via a 56 kbl’s
`
`
`
`
`
`
`
`link from its Financial Square location (refer
`
`
`
`
`
`
`
`
`
`again to Figure 1}. Within 10 minutes of a
`
`
`
`
`
`
`
`
`computer failure on the internet,
`lost data can
`
`
`
`
`
`
`be retrieved from the backup site.
`
`
`
`
`Network Management
`
`
`
`
`
`
`
`With CrossComm’s network management sys—
`
`
`
`
`
`
`tem, the Internetwork Management System (IMS),
`
`
`
`
`
`
`
`Prudential Securities has the ability to isolate
`
`
`
`
`
`across
`the distributed computing
`problems
`environment. Prudential finds that the IMS does
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`job of
`troubleshooting in such an
`a better
`
`
`
`
`environment than host-based management sys-
`
`98
`
`
`iUNE I993
`
`
`
`
`Page 4 of 8
`
`Page 4 of 8
`
`

`

`also eased Prudential’s migration from depart-
`ment level, to facility, to enterprise networking.
`Other solutions such as traditional
`routers
`
`are not only more expensive, but offer no
`performance advantages in the star architecture
`employed by Prudential Securities. In the final
`analysis, Prudential found that the ILANs pro-
`vided the better price—performance ratio and
`offered the best hedge against disaster.
`
`convert frames between Ethernet and
`
`Using the MAC layer to forward and
`Token Ring LANs is one of the latest
`capabilities to be added to bridges,
`including CrossComm’s ILAN.
`
`Appendix: More About MAC-
`Iayer Frame Conversion
`
`Using the MAC layer to forward and convert
`frames between Ethernet and Token Ring LANs
`is one of the latest capabilities to be added to
`bridges, including CrossComm’s ILAN. This type
`of bridge performs two tasks that distinguish
`them from other bridges. They perform the
`routine functions of filtering and forwarding
`packets: determining whether
`a packet
`is
`addressed to a point inside the LAN and retaining
`it, or passing it through the bridge to an external
`LAN.
`
`In addition, Ethemet-to-Token Ring bridges
`convert packets between the two formats,
`a
`process known as
`frame conversion. These
`bridges perform frame conversion while main-
`taining destination information. In other words,
`the destination information must be readable in
`
`Ethernet for Token Ring packets, and vice versa.
`This process is aided by IEEE standards, which
`ensure that the frames used in both LANs contain
`
`essentially the same information despite the
`differences in frame formats.
`
`An Ethernet frame contains a preamble and a
`start frame delimiter (Figure 3). Next comes the
`destination address,
`followed by the source
`address. This is followed by the length field and
`the user’s data, which cannot exceed 1500 bytes.
`
`INTERNATIONAL JOURNAL OF NETWORK MANAGEMENT 99
`
`Network Statistics (2i on "Finance“
`
`0 days, 0:25:48
`421
`511
`378
`381
`
`3)
`
`Age of Statistics
`Rcvd Packets
`thd Packets
`Multicast Packets
`Forwarded Packets
`Xmit Congest (no mom)
`Src Routea Packets
`Pkts Filtered (normal)
`Kept Ott Fitter
`Kept On Filter
`Wrong Packet Type
`Src Route Packets Frlered
`All Route Brddst Packets
`Singe Route Brunt Packets
`Unknown Destinations
`RIF Error
`Hop Court Exceeded
`Age at Sp. Tree State
`Sp. Tree State Changes
`
`OOOOOOOOOOO‘OO
`
`IMS network performance statistics When Network
`Figure 2.
`Statistics is selected from the network menu the statistics
`window shown above is opened. While this window is
`opened, the operator can log network statistics to a file
`that can be imported to a spreadsheet or graphics
`program for further manipulation and/or display. There are
`four network menus, one for each possible network
`connection. (Source: CrossComm Corp.)
`
`
`
`IMS allows Prudential Securities
`to achieve its goals of greater
`network uptime, configuration flexibility
`and economies in equipment and
`personnel.
`
`
`on the network, and protect against potential
`disasters.
`
`The Bottom Line
`
`The migration from SNA-based network to
`LANs permits multiple protocols to be handled
`on the same facility, allowing devices
`from
`different manufacturers to be networked. Not
`
`only have CrossComm’s ILANs provided a rela-
`tively inexpensive protocol-independent way of
`interconnecting LANs at high speed, they have
`
`Page 5 of 8
`
`
`
`

`

`_.m._.- w .: "v5.9 mass..-
`
`v
`
`.
`
`..
`
`_
`
`_-_-» _._..-- «9‘ was»?
`
`..M5;.\x<s.s--
`
`-\
`
`-.r_-
`
`Am‘m
`
`
`Field
`
`
`
`Description
`
`
`
`
`Age of Statistics
`
`Rcvd Packets
`
`
`thd Packets
`
`
`Multicast Packets
`
`
`
`Forwarded Packets
`
`
`
`
`
`
`Xmit Congest [no mem]
`
`
`
`Src Routed Packets
`
`
`
`
`
`
`
`Pkts Filtered [normal]
`
`
`
`
`Kept Off Filter
`
`
`
`
`Kept On Filter
`
`
`
`
`Wrong Packet Type
`
`Src Route Packets Filtered
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Elapsed time since traffic and error
`statistics were cleared for the
`
`
`
`
`
`selected network.
`
`
`
`
`
`
`
`Total number of packets received.
`
`
`
`
`
`Total number of packets transmitted.
`
`
`
`
`
`Total number of multicast (including
`
`
`
`broadcast] packets received.
`
`
`
`
`Total number of packets fonvarded
`to another network.
`
`
`
`
`
`
`
`
`
`Number of packets dropped by [all
`
`
`
`
`
`
`lines on} this network because the
`
`
`
`
`network capacity was inadequate to
`handle the traffic.
`
`
`
`
`
`
`
`
`Number of source routing packets
`received on this network. This number
`
`
`
`
`
`
`
`
`
`
`
`does not inciude packets sent while
`
`
`
`
`
`the bridge is operating in transparent
`mode; therefore. if
`it does not
`
`
`
`
`
`
`
`
`
`
`change when the operator expects
`
`
`
`
`to see source-routing traffic,
`
`
`
`transparent bridging must be
`checked.
`
`
`
`
`
`
`
`Of the Recvd Packets [above]. the
`total number that were filtered
`
`
`
`
`
`
`normally.
`
`
`
`
`
`
`Of the Recvd Packets [above], the
`
`
`
`
`
`
`
`total number filtered by a Kept Off
`Filter.
`
`
`
`
`
`
`
`Of the Recvd Packets [above], the
`
`
`
`
`
`
`
`total number filtered by a Kept On
`Filter.
`
`
`
`
`
`
`Total number of packets received by
`the ILAN node. but not forwarded
`
`
`
`
`
`
`
`
`
`
`because the necessary bridging
`
`
`
`
`
`option was disabled. This will
`
`
`
`
`
`
`
`happen, for example. if one type of
`
`
`
`
`
`driver [e.g. Ethemet] receives a
`
`
`
`
`
`packet formatted for another type
`
`
`
`
`
`
`[e.g. Token Ring], so cannot forward
`it.
`
`
`
`
`
`Number of discovery packets
`
`
`
`
`blocked because the general
`
`
`
`bridging parameters requested
`
`
`
`blocking of source-routed packets.
`Table 2.
`
`
`
`
`
`
`
`
`
`. w..s°w.-=n ::.
`
`.- ..._-
`
`-. -. -.
`
`'
`
`-
`
`:.J~s¢ szamF mnmjrmwwmfigu. mum?mumwe
`
`
`
`1'00
`
`
`IUNE 1993
`
`
`
`Page 6 of 8
`
`Page 6 of 8
`
`

`

`Number of ‘all route“ broadcast
`
`
`
`
`
`
`
`
`
`
`
`packets. {These packets are useful for
`
`
`
`
`
`
`discovering the fastest route to a
`
`target.)
`
`
`
`
`Number of packets blocked because
`
`
`
`
`the generai bridging parameters
`
`
`
`
`
`requested biocking packets for which
`the address is unknown, and Node 0
`
`
`
`
`
`
`
`
`
`
`
`
`
`was not available for routing these
`
`packets.
`
`
`
`Applicable for source-routing
`
`
`
`
`
`packets. Number of packets received
`
`
`
`
`
`
`
`with an error in the routing information
`
`
`
`
`
`
`
`[9.9. for a loop in the path].
`
`
`
`Applicable for source-routing
`
`
`
`
`discovery packets. Number of
`
`
`
`
`
`packets received for which the count
`
`
`
`
`
`of Route Designator [RD] fields
`
`
`
`
`
`exceeded [or equalled] the Hop
`Count Limit for this network.
`
`
`
`
`
`
`
`
`
`
`Elapsed time the network has been
`
`
`
`
`
`
`at the current spanning tree state.
`
`
`
`
`
`
`Number of times the spanning tree
`
`
`
`
`
`
`state has changed for this network.
`
`
`§_-_---.\_’:,§$.v.$<;::_o_ -ww.4 We
`
`
`
`
`
`
`
`
`
`All Route Brdcst Packets
`
`
`
`
`
`Unknown Destinations
`
`
`
`RIF Error
`
`
`
`
`
`
`Hop Count Exceeded
`
`
`
`
`
`
`Age at Sp. Tree State
`
`
`
`
`Sp. Tree State Changes
`
`
`
`
`
`
`
`
`
`
`Table 2. Continued [Source: Cross Comm Corp.)
`
`
`
`
`
`
`
`
`
`
`If
`the data unit is smaller than the protecol
`
`
`
`
`
`
`
`
`
`
`
`requires it to be, the data field is 'padded' by a
`
`
`
`
`
`
`
`
`number of extra bytes that are inserted to
`
`
`
`
`
`
`
`
`maintain the integrity of the frame. Finally, there
`
`
`
`
`
`is a frame check sequence.
`
`
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`frame
`The Token Ring format has a start
`delimiter, then a frame with access control and
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`frame control information in the header. This is
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`followed by the destination address and source
`address. Next comes the user data, which is
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`followed by a frame check sequence. Then there
`is an end frame delimiter and frame status
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`information.
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`When an Ethernet LAN is linked to a Token
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`Ring LAN, the information in the frame is altered
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`and the Ethernet frame’s frame check sequence
`(FCS), which acts as a check sum, must be
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`recalculated. An added camplication is that Ether—
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`net and Token Ring LANs use different frame
`sizes. The maximum frame size is about 1500
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`bytes for 10 bes Ethernet, 4K bytes for the 4
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`Mb/s Token Ring and as much as 17.8K bytes
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`for the 16 Mbr‘s Token Ring. Therefore, when a
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`Token Ring packet is sent to an Ethernet LAN,
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`the Token Ring packet must be broken into a
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`number of smaller packets that can fit on an
`Ethernet LAN.
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`There are several ways in which vendors avoid
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`this problem. One technique is that of frame
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`size negotiation, which is used on the Token
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`Ring side of a bridge. Whenever the bridge
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`determines that a packet must pass from the
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`Token Ring side to the Ethernet side it sends a
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`packet back to the sending Token Ring device,
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`requesting it to modify the frame size in conform-
`ance with the Ethernet standard.
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`Upon completion of packet fragmentation there
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`is the problem of maintaining destination address
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`information across the bridge. This is because
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`there are separate standards for bridging proto-
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`cols. Specifically,
`there is the Spanning Tree
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`Protocol on the Ethernet side and source routing
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`on the Token Ring side.
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`Going from Token Ring to Ethernet can be
`new;
`x“é'-r£"'
`uw‘.;ssc2='¢:;5::,¢x,:;:.
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`iNTERNATIONAL JOURNAL OF NETWORK MANAGEMENT 101
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`Page 7 of 8
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`Page 7 of 8
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`

`

`
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`mm:wdmmmMrm-m M—rgmwmmiwr-wamumwmmw - n “new mewmr raw.
`
`Header
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`Addressing
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`Data Field
`
`Frame Check
`Sequence
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`
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`IEEE 802.3 Elhemet Frame
`
`”a Data
`
`lEEE 802.5 Token Ring Frame
`
`Legend
`
`DA = Destination Address
`SA = Source Address
`FC = Frame Control
`CRC = Cyclic Redundancy Check
`ED = Ending Delimiter
`FS = Frame Status
`SD = Starting Delimiter
`AC = Access Control
`
`nged A comparison or Erherner and Token Ring frame structures.
`
`handled by setting up a pseudo-ring number for
`the Ethernet side of the bridge. This allows the
`Token Ring side of the bridge to talk to the
`Ethernet side. When the packet crosses
`the
`bridge, the source routing information is stripped
`off and replaced with standard transparent bridge
`information.
`
`Going from the Ethernet side of a bridge to
`the Token Ring side is more difficult. This is
`because the Ethernet side of the bridge has to
`maintain a table of addresses. To build this table,
`
`the bridge sends out exploratory packets to learn
`the location of devices on the network. With
`
`source routing on Token Ring networks, the end
`
`stations only need to learn a route, since the
`bridge does not maintain a database of addresses.
`But in converting an Ethernet packet to a Token
`Ring packet, the Token Ring side must maintain
`an address database and learn all the addresses
`on the network.
`I
`
`If you wish to order reprints for this or any
`other articles in the International journal of
`Network Management, please see the Special
`
`Reprint instructions inside the front cover.
`
`1055—7148/93/02m95-0850900
`© 1993 by John Wiley 8: Sons, Ltd
`
`M-
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`.
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`.
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`.
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`the-‘ e
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`,<.
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`.
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`.amm-¢-
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`,
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`w.-- ,
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`e
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`,. 7 ,
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`.g~1«v.,~mm=mr.m/mu&.< ~14
`
`102
`
`IUNE 1993
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`Page 8 of 8
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