Companies and organizations increasingly rely on the rapid and
efficient flow of information as a key strategic asset. They view their
internetworks as the conduits of this information that enhance productivity and
provide competitive advantages in the global marketplace.
Ultimately, it is the order of magnitude improvement in organizational
productivity that is the compelling benefit of robust internetworks. Yet
beneath this wide-ranging umbrella, MIS managers must focus on several issues
that have tremendous influence on determining the effectiveness of their
internetworks. Two of these issues—the availability of user applications and
the total cost of ownership of a network—are inextricably linked to every
company’s information systems strategy.
No company in the world can match Cisco Systems when it comes to
maximizing the applications availability and minimizing the total cost of
internetwork ownership. Over the last decade, our proven technology and
complete range of scalable solutions have enabled us to set the pace in the
networking industry. More than anything else, Cisco owes its leadership
position to its unique and robust
Internetwork Operating System (Cisco
IOS®)—the value-added software that resides at the
heart of all Cisco internetworking solutions.
Cisco IOS software is the key differentiator that separates Cisco’s
internetworking solutions from other alternatives in the industry. For Systems
Network Architecture (SNA) mission-critical application users, Cisco IOS
software provides the industry’s most flexible migration paths to client/server
and peer-to-peer applications of the future. Cisco IOS software’s value-added
intelligence supports users and applications throughout the entire enterprise.
It provides security and data integrity for the internetwork. It
cost-effectively manages resources through the control and unification of
complex, distributed network intelligence. Finally, it functions as a flexible
vehicle to add new services, features, and applications to the
Two critical issues drive the evolution of today’s information systems:
total cost of ownership and applications availability. In IBM environments,
companies can reduce their costs of ownership dramatically with the
consolidation of multiple SNA and non-SNA networks into one multiprotocol
internetwork. This consolidation eliminates redundant and expensive wide-area
communications links and reduces personnel costs because it simplifies
multiprotocol environments management. In addition, it provides an
infrastructure that allows access to any application from any point in the
A consolidated internetwork must support common applications
availability across any media or platform to ensure success. It must also
provide high availability for mission-critical applications and predictable
response time for end users. This requires a range of features that optimize
link utilization, reroute around link failures, and prioritize mission-critical
Enterprise Networks Today
The enterprise of today and tomorrow has requirements that
span all four internetworking sectors: Workgroup, IBM Internetworking, Core,
Many challenges confront network managers as they consider SNA
integration. Perhaps most important is the need to cost-effectively consolidate
SNA and LAN internetworks while SNA end-user response time and availability is
Many enterprises also require a scalable solution that can handle
networks of over 100,000 SNA devices. In addition, with the proliferation of
new technologies in the local-area network (LAN) and wide-area network (WAN)
arenas, the solution must offer flexible WAN and LAN choices to protect current
and future investments. As enterprises become more dependent on their
internetworks to be competitive, it becomes increasingly important that the
internetwork be adaptable to new technologies. Finally, today’s multiprotocol
internetworks require comprehensive network management tools that simplify
management and allow centralized control, automation, and proactive resource
Mission-critical applications must be available twenty-four hours a
day, seven days a week. To successfully integrate mission-critical traffic with
LAN traffic, network administrators must be able to ensure applications
availability. To do so requires a reliable transport mechanism that can reroute
around failed links or load balance across multiple links.
To ensure high performance, internetworks must fully utilize all
available bandwidth and offer methods to handle periodic congestion. To fully
utilize bandwidth requires high-powered platforms that can balance traffic
across all available links and automatically dial backup links to handle peak
traffic. As internetworks carry increased traffic, the likelihood of periodic
traffic congestion increases. Techniques must be available that allow network
designers to prioritize mission-critical traffic ahead of less important
traffic, like electronic mail or noncritical file transfers. In addition,
features that allow network designers to allocate bandwidth percentages to
specific protocols will ensure that SNA users maintain predictable
An integrated multiprotocol solution must be scalable to connect
arbitrarily large numbers of LANs or end stations. Features are required that
can control source-route bridging (SRB) and NetBIOS broadcasts, to thereby
avoid traffic flooding on Token Ring (TR) LANs. High-density, high-performance
solutions can minimize space requirements, reduce costs, improve performance,
and simplify network design.
To protect current and planned investment and improve application
access, internetworking platforms must offer flexible media support.
Consolidation of Synchronous Data Link Control (SDLC) networks and LAN networks
can greatly reduce costs while it protects customers’ investment in SDLC
devices. In addition, end users need to access SNA applications regardless of
how they are connected to the network, whether it is through SDLC, Token Ring,
Ethernet, Fiber Distributed Data Interface (FDDI), or Asynchronous Transfer
Because WAN costs are a recurring expense, flexibility in the choice of
WAN options is critical. Multiple options—from dedicated links, to
circuit-switched, to packet-switched—allow customers to select the service that
provides the best performance and availability at the least cost.
The final consideration is one of the most important. Comprehensive
network management tools must allow network administrators to provide users
with maximum network uptime and a high degree of applications availability. In
addition, integrated management must simplify personnel training and
administrative procedures. The ability to automate router installations and to
centralize other router management activities means that skilled staff need not
be present at each remote site.
SNA Integration Challenge
Cisco IOS software addresses the integration challenge with
solutions that maximize availability, scalability, performance, flexibility,
Cisco is the industry leader in the integration of IBM SNA networks
within the framework of today’s expanding multiprotocol global internetworks.
In 1993, Cisco held over 67 percent of the SNA router market, according to an
IDC study. Since initiating its five-phase SNA integration strategy in 1990,
Cisco has introduced many industry firsts: the creation of the virtual ring
concept, the first route caching mechanism, the highest-performing Token Ring
card, and the first fully integrated SDLC conversion capability. The company is
currently developing direct attachment to mainframe channels for
Worldwide SNA Router Market 1993
Cisco leads the SNA router market of over $400 million, which
represents 23.5 percent of the overall router market in 1993.
IBM internetworking is unlike any other internetworking market segment.
The challenges are unique, and the solutions are complex. To succeed in this
market requires a serious commitment of resources and people. Cisco has made
this commitment, building an infrastructure of dedicated resources with years
of experience in IBM internetworking. As part of this infrastructure, Cisco
offers IBM-specific network consultants to help you install your
Through its five-phase strategy for IBM integration, Cisco has
delivered cost-effective, feature-rich, high-performance products. Cisco
continues to enhance these offerings and is now delivering its fifth phase:
full support of SNA peer-to-peer internetworking via Advance Peer-to-Peer
Networking (APPN) Network Node (NN) technology, and the integration of
mainframes and LAN internetworks via direct channel attachment.
Cisco IOS Software Extended Five-Phase IBM Integration
Enhanced VR, Scalability, Dynamic Spanning Tree
IGS TR/Cisco 3000
SDLC TWS, SDLC Broadcast
SDLLC Local Termination
LAN Network Manager
QLLC Conversion, DLSw Standard
IBM Chipset 4-Port TR
SNA PU Type 4 Properties
Custom Queuing, 270 kpps SRB
TCP Offload, Channel APPN
Two key concerns of MIS managers are network availability and the
maintenance of consistent end-user service levels. Cisco has developed several
techniques that ensure a high level of reliability when SNA traffic is
transmitted across a multiprotocol internetwork.
SNA, when transported across a Token Ring backbone, has two primary
limitations: an inability to nondisruptively reroute around network failures,
and a low tolerance for network delays. Both problems cause sessions to be
dropped, which forces users to restart and subsequently lose valuable data and
Cisco overcomes the rerouting limitation through IP encapsulation.
Through the encapsulation of the SNA traffic in IP packets, Cisco
internetworking platforms can nondisruptively reroute SNA traffic around link
failures. To avoid session loss, new routes must be found in less than 10
seconds. Cisco’s Enhanced Interior Gateway Routing Protocol (Enhanced IGRP) and
Open Shortest Path First (OSPF) routing protocols can generally reroute around
failed links in less than two seconds, making the link outage and recovery
transparent to end users.
When SNA traffic shares links with other LAN traffic, link congestion
can sometimes cause network delays. If round-trip delays exceed a few seconds,
SNA devices will begin error recovery, and in some cases, SNA sessions will be
dropped. In addition, SNA sends frequent control messages to ensure that
session connections are active. These messages can waste expensive WAN
Cisco offers two features that help to overcome this limitation: IP
routing and local acknowledgment. IP routing reroutes based on congestion or
adapts to changes in traffic patterns. With local acknowledgment, Cisco
products locally terminate link connections (both SDLC and LLC2), which
prevents SNA session timeouts and minimizes control messages on the
Cisco’s Local Sessions Termination Feature
Cisco’s Local Session Termination feature enhances session
availability and performance.
Cisco internetworks offer tremendous scalability through several key
features that provide support for very large Token Ring environments. With
Cisco IOS software, several scalability limitations are removed, and you are
allowed to do these thing:
Increase the number of Token Ring LANs that can be bridged together
across an enterprise.
Increase the number of end systems that you can support without an
increase in line speeds.
Attach more LANs to a single device and improve overall throughput
within a building or campus.
The source-route bridging protocol—commonly used to bridge Token Ring
LANs—is not well suited to handle large Token Ring environments, because it
limits the data path to less than seven bridges and eight rings. Many
enterprises use one backbone LAN to connect one or more LANs on each floor of a
building and another backbone LAN to connect multiple buildings on a campus.
When one campus connects to another campus, it is quite easy to have LANs that
cannot be bridged together because of the SRB limitation.
Cisco IOS software allows multiple internetworking platforms connected
over arbitrary media to be configured as a single virtual
ring, which removes the limitations of SRB and allows arbitrarily
large Token Ring LANs. The virtual ring simplifies network topology and helps
you to build large-scale networks, because it hides multiple hops. It provides
intelligent path selection, because routing within the virtual ring can occur.
And it reduces explorer traffic—which is used to find routes in a SRB
network—because explorer frames within a virtual ring are not exponentially
Virtual Ring Architecture
Cisco’s virtual ring architecture allows integration to scale
to the largest, most complex networks.
Cisco IOS software can significantly improve WAN utilization via the
minimization of broadcast traffic on the WAN. Two key types of broadcast
traffic are source-route explorer frames and NetBIOS Name Queries.
In an SRB network, end stations broadcast explorer packets to find
session partners. Because each explorer packet is duplicated over each possible
path, explorers can generate an inordinate amount of traffic in a large meshed
Token Ring environment. To minimize these broadcasts, Cisco uses
proxy explorers. With proxy explorers, when the Cisco IOS
software learns the route to a given end system, it caches this information.
Subsequent explorer frames to the same address are not broadcast across the
bridged LAN. This can significantly reduce traffic in SNA networks, which saves
expensive WAN resources.
Both the IBM LAN server and Microsoft LAN Manager operating systems use
the NetBIOS protocol. When NetBIOS clients access servers, they first broadcast
a name query across the entire bridged LAN. The query is sent several times to
ensure that it reaches its destination, which creates a large amount of traffic
that can consume lower-speed lines. To reduce this extra traffic, Cisco
developed NetBIOS name caching. With name caching, only
the first query is broadcast across a WAN, and the response is cached.
Subsequent queries to the same name are not broadcast across the bridged LAN.
Cisco also supports access lists, so a network administrator can control which
servers can be accessed from a given location. This avoids any unnecessary
waste of WAN resources, because all name queries for these resources are
blocked at the Cisco router.
In campus or building networks, Cisco offers a high-density Token Ring
solution on its
7000 high-end platform. The Cisco 7000 supports up to twenty Token Rings
via the use of Cisco’s four-port Token Ring card, which is based on the IBM
“Spyglass” chipset and offers the highest-available Token Ring performance in
an internetworking platform. Combined with silicon packet switching, the Cisco
7000 delivers a total aggregate throughput of over 270,000 packets per second
Legacy SNA generally has predictable, low bandwidth requirements, while
client/server protocols tend to have bursty, higher bandwidth requirements.
When legacy SNA traffic shares bandwidth with client/server protocols, it is
critical that a technique be available to prioritize mission-critical traffic,
which ensures that end-user response time is not impacted. Cisco has developed
many features that ensure that high-priority messages are delivered quickly and
reliably, regardless of congestion on a link.
Without a priority mechanism, mission-critical traffic may get delayed
behind large file transfers, which impacts customer service or delays important
financial transactions. Network delays can sometimes be avoided with an
increase in line speeds, but that is not always possible. To ensure that
mission-critical traffic always takes precedence over less important network
traffic, Cisco offers priority output queuing.
Priority output queuing enables network
administrators to prioritize traffic, which provides the granularity that is
required to ensure that mission-critical data can be isolated above all other
traffic. Cisco offers four options by which traffic can be prioritized:
By protocol—This allows specified protocols to be prioritized ahead
of all other traffic. For example, if SNA traffic is mission-critical, SNA
messages can be given highest priority, followed by TCP/IP, then NetBIOS and
By message size (small messages first)—This provides a simple means
to prioritize interactive traffic ahead of batch file
By physical port—With the prioritization of an SDLC line ahead of a
LAN or even the prioritization of one SDLC line ahead of another, network
administrators can prioritize traffic from one department over another. For
example, sales-related traffic flow can be prioritized ahead of administration
By SNA device—Prioritization by Logical Unit (LU) address allows
specified devices (such as customer service terminals) to be prioritized ahead
of others (for example, printers or administrative
With Cisco’s custom queuing, network managers can guarantee that,
during periods of congestion, mission-critical traffic receives a guaranteed
minimum amount of bandwidth. If mission-critical traffic is not using its
entire allotment of bandwidth, that bandwidth can be used by other traffic. For
example, bandwidth could be reserved such that SNA traffic receives 40 percent
of the bandwidth, TCP/IP traffic gets 25 percent, IPX gets 20 percent, and
NetBIOS gets 15 percent, which ensures that SNA always has a large portion of
the communication link available to it. If SNA traffic was light and only using
20 percent of the link, the remaining 20 percent allocated to SNA could be used
by either TCP/IP or IPX traffic, which ensures maximum bandwidth
Custom queuing offers the same granular definition that is available
with priority output queuing. Custom queuing is designed for environments that
want to ensure a minimal level of service for all protocols.
Prioritization and Bandwidth Management
Cisco’s custom queueing capability provides predictable
response times for mission-critical applications.
With Cisco’s wide selection of supported media and WAN services,
network administrators can select media and services that offers the best
price-to-performance ratio without concern for loss of connectivity. Cisco
offers SDLC transport or conversion to LAN protocols, to protect customers’
investments in SDLC. Cisco supports key LAN media (Token Ring, Ethernet, and
FDDI) as well as conversion between LAN protocols. Finally, Cisco offers
support for a wide selection of WAN services and has led the industry in the
support of emerging new technologies, including Switched Multi-megabit Data
Service (SMDS), Frame Relay, ATM, and High-Speed Serial Interface
For companies that want to integrate SDLC environments with
multiprotocol LANs, Cisco offers two options: convert SDLC to Token Ring or
Ethernet, or transport SDLC without conversion.
SDLC conversion can be used to convert remote SDLC-attached devices to
Token Ring, which facilitates migration to a LAN environment. Through the use
of this option, remote SDLC devices appear to a front-end processor (FEP) as
Token Ring-attached, which enhances performance, simplifies configuration, and
reduces line requirements on the FEP. In addition, smaller FEPs can be used to
support SNA traffic.
In many SNA environments, Ethernet is becoming an increasingly popular
option, due to the low cost of Ethernet adapters and the enhanced manageability
with hubs. Presently, IBM 3745 FEPs do not support SNA over Ethernet. Cisco
products allow remote Ethernet-attached devices to access mainframes via a 3745
FEP through the conversion of Ethernet to either SDLC or Token Ring.
Cisco platforms can also be used to convert traffic from remote
SDLC-attached devices to Ethernet, which allows mainframe access via less
costly 3172 establishment controllers.
Some environments need the ability to transport SDLC without conversion
(for example, environments without Token Ring cards on their FEPs). Cisco’s
SDLC transport allows network consolidation of multiprotocol LANs and SNA/SDLC
environments without media conversion. SDLC transport can be used to carry
FEP-to-FEP traffic in addition to FEP-to-controller traffic.
When SDLC transport is used to connect controllers to a FEP, Cisco
offers an option called virtual multidrop, which makes
multiple remote SDLC lines appear to the FEP as part of one virtual multidrop
line. This option reduces costs, because it lowers the number of FEP lines
required and simplifies configuration requirements for moves and
Cisco offers high-performance transport of any protocol across Token
Ring, Ethernet, and FDDI. With Cisco IOS software, SNA traffic can traverse any
LAN media; for example, SNA can traverse FDDI or Ethernet backbone LANs. In
addition, media conversion is possible between any pair of the supported LAN
Because WAN services are a recurring cost, flexibility in the choice of
WAN services is key. Cisco internetworking platforms allow users to select the
service that provides the best performance and availability at the least cost.
These include dedicated point-to-point links at speeds that range from 1.2 kbps
to 155 Mbps; circuit-switched services for low call-volume applications;
packet-switched services, including X.25, Frame Relay, and SMDS; and
cell-switching services, such as ATM. Cisco’s Frame Relay support allows
separate virtual circuits for SNA and non-SNA traffic, which provides a means
to ensure the service level of SNA while SNA is consolidated on a single
physical link with other protocols.
With dedicated circuits, the network allocates a fixed amount of
bandwidth to exclusively serve the two end points on a given link.
Circuit-switched services, on the other hand, offer advantages in low
call-volume applications because they provide flexible, dynamic WAN connections
that are more cost-effective than dedicated circuits. Cisco supports all of
today’s array of analog and digital circuit-switched networks, including the
Integrated Services Digital Network (ISDN) physical interface.
A Cisco circuit-switched innovation known as dial-on-demand routing
(DDR) allows connections to be dynamically created when there is traffic to be
sent and automatically disconnected when no longer required. Cisco’s unique
dial backup and load-sharing capabilities automatically dial backup lines when
the primary link either fails or reaches a predefined level of
Cisco internetworking platforms support all of the key packet-switched
services, including X.25, Frame Relay, SMDS, and emerging ATM networks. Cisco
products not only support attachment to X.25, they can provide an X.25
backbone, which allows router networks to transport data from devices that only
support X.25 interfaces. Cisco also supports Qualified Logical Link Control
(QLLC), the protocol widely used by SNA devices that connect over an X.25
network. Because it provides conversion of X.25 QLLC traffic to LAN or SDLC
traffic, this feature lets users improve performance on their X.25 backbones
and consolidate traditional SNA networks with newer LAN
Cisco’s WAN Support
Cisco’s comprehensive WAN support provides organizations with
flexibility, scalability, and lower total cost of ownership.
As internetworks become increasingly strategic assets, many
organizations face the challenging task of how to build a well-managed and
productive internetwork that maximizes end-to-end applications availability
while it minimizes total cost of ownership. As internetworks expand—often to
remote locations—management resources are often limited.
Cisco’s strategy to handle these challenges is threefold:
centralization, automation, and integration. This strategy is accomplished with
a comprehensive package of management applications based on industry-standard
platforms and protocols. CiscoWorks offers these services:
Configuration services lower the cost to
install, upgrade, and reconfigure routers. Further, Cisco’s AutoInstall feature
virtually eliminates the time and cost to install remote platforms. With
AutoInstall’s plug-and-play features, a remote site simply plugs the router
into the network; the central operations center handles the tasks to configure
it and bring it online. CiscoWorks also allows you to group routers and apply
common configuration changes to all routers at the same scheduled
Comprehensive monitoring services provide
network managers with operational and diagnostic data used to ensure maximum
network uptime and applications availability. Through the use of extensive
Network Management Protocol (SNMP) Management Information Base (MIB)
attributes, network managers can use CiscoWorks show
commands to view traffic and error statistics at each interface and for each
protocol. Further, debug commands enable fast
Diagnostic services help administrators minimize
network downtime; for example, there are tools that test router connectivity,
trace packet routes, and debug router internal
CiscoWorks runs on NetView/6000 (also known as NetView for AIX), HP
OpenView, and SunNet Manager. CiscoWorks also supports a service point
interface to NetView to provide central visibility and control. The service
point interface ensures that important events can be viewed from a central
NetView console and allows applications to be automatically started from
NetView, if certain conditions occur. CiscoWorks comes with a set of NetView
programs to assist with the management of a Cisco network from NetView.
Cisco platforms also support two-way communication with IBM’s LAN
Network Manager. This feature allows network administrators to seamlessly
manage their Token Ring LANs from a central site LAN Network Manager, which
protects the customer’s investment in training and management
Cisco offers comprehensive management functions that support
SNMP, NetView, and IBM’s LAN Network Manager.
Cisco supports an extensive list of Open System Interconnection (OSI),
Consultative Committee for International Telegraph and Telephone (CCITT), and
Internet Engineering Task Force (IETF) open standards.
Where standards do not exist or lack functionality, Cisco has provided the
functionality to address key customer requirements.
Cisco has supported SNA transport over IP backbones since 1990. A
subset of the features that Cisco has offered to support SNA transport are now
collectively referred to as Data Link Switching (DLSw).
DLSw is also an emerging SNA-over-IP routing specification designed to
facilitate the integration of SNA and LAN internetworks, via the encapsulation
of nonroutable SNA and NetBIOS protocols within routable IP protocols. The
primary goal of DLSw is to provide an open standard that router vendors can use
to achieve base-level interoperability among their products. Finally, the DLSw
standard includes key recent enhancements over solutions that already exist,
including standardized flow control and enhanced management.
Cisco plans to support the DLSw standard in Q1, 1995. Cisco’s DLSw will
not only support the standard, it will include additional features, such as
extensive media and transport flexibility, and it will add scalability
enhancements to allow even larger, integrated networks to support any-to-any
connectivity. At the same time as Cisco adds new functionality to the DLSw
standard, it will continue to maintain full interoperability and backward
compatibility with existing solutions—which will deliver the most robust DLSw
implementation in the industry.
Cisco has developed a comprehensive strategy to migrate branch offices
from legacy and SNA networks to integrated client/server and peer-to-peer
internetworks. These solutions meet all of the access requirements for remote
branch offices: LAN to LAN connectivity, legacy media and protocol support,
public network access, and SNA host access.
For LAN media, Cisco offers support for SNA and NetBIOS—on both Token
Ring and Ethernet, across all platforms—through SRB/RSRB and Transparent
Bridging solutions. In addition, Cisco’s translational bridging addresses
Ethernet-to-Token Ring connectivity for these nonroutable protocols. Cisco’s
DLSw implementation extends features like local acknowledgment and route
caching to Ethernet-based SNA networks, and it enhances the robustness of Token
In branch offices with legacy protocols, Cisco provides a variety of
capabilities, including Serial Tunneling of asynchronous, bisynchronous, and
SDLC traffic, as well as integrated SDLC-to-LAN conversion. These capabilities
consolidate the diverse types of traffic that exist in branch environments. As
an example, a typical bank branch can consolidate bisynchronous automatic
teller machines, SDLC teller platforms, LAN-based office automation, and
asynchronous alarm systems onto a single communication facility.
Cisco’s IBM Access Strategy
SNA Host Architecture
Frame Relay - Layer 3
X.25 - Layer 3
Frame Relay - Layer 2 (RFC 1490)
Cisco’s IBM access strategy provides comprehensive support
for client/server, SNA, and legacy protocol access through a variety of
packet-switching facilities that support various SNA host access options for
mission-critical, mainframe-based SNA applications.
Cisco offers many flexible options for connection to public networks.
In the Frame Relay domain, Cisco supports two transport options—layer 2 or
layer 3. Cisco’s layer 2 choice conforms to
allows SNA and NetBIOS to be transported directly over Frame Relay. Customers
can also choose to transport at layer 3—which encapsulates SNA and NetBIOS in
IP and sends it over Frame Relay—to reap the benefits of IP’s dynamic routing
capabilities, such as nondisruptive session reroute. In addition, Cisco
provides a cost-effective platform for customers that are migrating from
dedicated SDLC networks to Frame Relay, in the form of a Cisco Frame Relay
Access Device (CFRAD). The Cisco FRAD can be upgraded to full routing
capabilities as LANs are deployed. Cisco’s IBM access strategy supports a
variety of SNA host access methods. For SNA users on TCP/IP networks, Cisco has
provided TN3270 client services in its access server products. With Cisco’s
direct channel attachment to TCP/IP mainframes, TN3270 users benefit from
greater levels of performance and scalability. For SNA users on APPN networks,
Cisco will offer APPN’s Dependent Logical Unit Requester (DLUR) for 3270 access
from legacy controllers and gateways, to avoid costly upgrades to these legacy
Finally, Cisco’s Native Client Interface Architecture (NCIA) provides
customers with a new option for SNA applications access that combines the full
functionality of native SNA interfaces at both the host and client with the
flexibility to leverage their TCP/IP backbones. NCIA encapsulates SNA traffic
within a client PC or workstation, to provide direct TCP/IP access while the
native SNA interface at the end-user level is preserved. This can obviate the
need for a standalone gateway and provide flexible TCP/IP routing over the
backbone with a native SNA interface to the host. Cisco is also offering a
Downstream Physical Unit (DSPU) Concentration function that concentrates
multiple SNA Physical Units (PUs)—such as clients and cluster controllers—and
provides a single PU image to the host. This simplifies host configuration and
minimizes WAN overhead.
Cisco’s Native Client Interface Architecture
SNA clients with NCIA provide full-function native SNA
interfaces to users and provide flexible TCP/IP access to enterprise backbones
over any IP media without the requirement of a standalone gateway. Cisco’s
platform provides efficient native SNA interface to
A router is an excellent vehicle to use to integrate the mainframe,
because mainframe customers already use routers in conjunction with LAN channel
controllers. The advantage of a direct attachment to a mainframe channel is
greater performance and better integration with fewer points of failure. With
the use of the Cisco 7000 platform, Cisco’s strategy is to combine the power of
the media-speed mainframe interface with media-speed LAN, WAN, and ATM
interfaces and Cisco’s 270 kpps silicon switching engine, to offer the
industry’s most powerful mainframe and LAN integration solution.
Cisco’s Channel Interface Processor (CIP) supports both Enterprise
Systems Connection (ESCON)—IBM’s high-speed channel architecture, first
introduced in 1990—and Bus and Tag connections—IBM’s older channel
architecture, widely used in the current installed base of mainframes.
The Cisco 7000 CIP includes a powerful onboard protocol processing
engine to ensure that no bottlenecks are created. In addition, the Cisco 7000
offers dual power supplies and hot-plugable interface cards to ensure high
availability. Across all of Cisco’s platforms, Cisco IOS software offers
dynamic reconfiguration of any configuration option, which further improve
availability because it minimizes the need for scheduled downtime. With the
7000’s high-density LAN and WAN cards, FDDI, and ATM interface modules, it is
the premier mainframe channel integration platform.
Cisco’s direct channel attachment allows users to tightly
integrate mainframes, both with today’s networks and those of the
Cisco is committed to supporting IBM’s advanced peer-to-peer
networking. Cisco will provide native APPN Network Node support in its
internetworking platforms and has licensed IBM source code to ensure 100
percent network node compatibility. Cisco products, with their extensive
support of LAN and WAN media, provide an ideal, high-performance platform to
support IBM’s APPN NN. Cisco products with NN functionality can be used in a
pure APPN network with a mix of other vendors’ APPN platforms. Alternatively,
Cisco’s APPN platform can be used in integrated multiprotocol internetworks,
with Cisco’s prioritization techniques providing a means to control bandwidth
allocation. Cisco will also provide a cost-effective method to allow 3270
legacy traffic to take advantage of APPN: the DLUR function. With the use of
this capability, multiple controllers or SNA gateways that support legacy SNA
can attach to a Cisco platform, and legacy traffic can be transported across a
native APPN backbone without the need for upgrades to APPN.
Cisco will also support APPN’s High Performance Routing (HPR) protocol,
which will enable native SNA to nondisruptively recover from link failures and
which will improve APPN performance.
Cisco products allow customers to integrate legacy SNA networks today
and choose from a variety of options for future migration: TCP/IP based,
APPN-based, or mixed TCP/IP and APPN.
Cisco’s APPN Solution
Cisco’s APPN implementation supports both today’s legacy
applications and future peer-to-peer applications while it guarantees 100
percent compatibility with APPN end solutions.
Cisco and IBM are collaborating on many fronts to enhance product
capability, customer service, and manageability and to protect customers’
investments in computing and networking facilities. The two companies
cooperated to develop the four-port Token Ring card with the IBM “Spyglass”
chipset, which offers the highest performance in the market. Cisco has also
licensed ESCON and Bus and Tag technologies from IBM for incorporation into the
Cisco 7000 CIP. Additionally, Cisco uses IBM test facilities to ensure
compatibility between the Cisco channel interface and IBM mainframes.
Cisco and IBM also work closely together as part of the APPN
Implementors’ Workshop (AIW), which is an IBM body developed to define APPN
protocols. Cisco licenses the APPN source code from IBM. The two companies also
cooperatively established the Data Link Switching Working Group within the AIW,
to help promote the development of the DLSw standard.
For service, IBM’s field service organization performs on-site
maintenance, stocks and delivers spare parts, and provides installation
services for Cisco customers. Cisco is also actively collaborating with IBM to
enable interoperability with LAN Network Manager agents on IBM’s Token Ring
network management platform. In addition, Cisco is a member of the NetView/6000
Association, which incorporates the Cisco MIB into NetView/6000 and certifies
compatibility. Finally, Cisco is providing CiscoWorks applications for
NetView/6000, as well as compatibility certification.
Working with IBM
Cisco has many cooperative relationships with IBM, to enhance
product compatibility, customer service, and manageability.
As customers implement Cisco technology and integrate their SNA
environments into multiprotocol internetworks, new options become available.
Whatever direction the customer chooses—whether to evolve from SNA to APPN,
from SNA to client/server, or to maintain a pure SNA environment—Cisco will
provide the most flexible migration paths to future networks.
At the heart of Cisco’s efforts is its industry-leading Internetwork
Operating System that integrates all environments: IBM-oriented access, core
backbone, mainframe integration, and workgroup technologies. Cisco’s years of
experience with internetworking all major protocols and environments across
every type of WAN service, combined with the company’s dedication to the IBM
environment, make Cisco the premier internetworking vendor for IBM SNA and
mainframe integration both today and tomorrow.
Integrated Internetworking with IOS
Cisco’s comprehensive IBM internetworking strategy provides
the most flexible migration options in all areas of future internetworks;
Access, Workgroup, Backbone, and Data Center.