The ASN uses a highly-scalable architecture, which provides cost-effective, growth-oriented solutions for remote, regional and departmental office access (see Figure 1). Typical applications and configurations include:
The ASN's processor module is based on the Wellfleet Backbone Node's Fast Routing Engine (FRE) technology, using Motorola's 68040 microprocessor to maintain high forwarding and filtering rates across its network interfaces (see Figure 2). The aggregate forwarding performance is up to 50,000 packets/second per unit and up to 200,000 packets/second per 4-unit stack. Additionally, management inquiries are easily processed without affecting performance. The ASN's 8.0MB, 16MB or 32MB of DRAM is configurable to support customized partitioning between local and global memory. Router software, routing tables and management services, resides in local memory while global memory is dedicated to packet buffers. Through these reserved buffers, the ASN prevents traffic overflow which would result in network delays caused by large bursts of traffic (file transfer operations, for example).
The ASN supports a 4.0MB standard PCMCIA Flash memory card for nonvolatile storage of the ASN's system software, configuration file and event log. To provide redundancy, the 4.0MB Flash can be logically divided into two partitions of equal size. Each partition is a uniquely addressable and fully functional Flash file system volume. Copies of boot images and configuration files can be stored on each partition.
The ASN's optional 256KB Fast Packet Cache increases forwarding performance through hardware acceleration of frequently accessed packet information.
The ASN's processor module supports the interconnection of up to four
interface modules (net modules) for cost-effective network
connectivity. Additionally, the stackable design provides for easy
system expansion by enabling up to four ASNs to be interconnected
through the Stack Packet Exchange (SPEX
The ASN provides network connectivity via a selection of net modules and adapter modules (see Table 1). An ASN can support up to four net modules. Net modules are available that provide dual Ethernet, dual Token Ring, FDDI, dual Synchronous and ISDN BRI interfaces to meet a wide variety of connectivity requirements. The Stack Packet Exchange (SPEX) net module allows up to four ASNs to be interconnected in a stack configuration, for maximum expansion, connectivity and flexibility.
Maximum Number of Net Modules Modules per ASN Unit Dual Ethernet 4 Dual Token Ring 4 Single FDDI 2 (Multimode) Dual Synchronous 4 SPEX 1
Ethernet/802.3: The Ethernet/802.3 interface supports IEEE 802.3 and Version 1.0/2.0 Ethernet formats. Both a 10Base-T and an AUI connector are provided on Ethernet ASN models for a choice of Ethernet connectivity. A cable from the interface's 15-pin AUI connector provides optional connectors to a variety of media, including broadband, baseband, Starlan, fiber and shielded twisted-pair. This flexibility accommodates the media that best suits distance, cost and reliability criteria.
Token Ring/802.5: The Token Ring interface can operate at either 4.0Mb or 16Mb ring speeds (software configurable), providing the flexibility to migrate to higher speeds as performance requirements dictate. A 9-pin D-subminiature connector is provided on the Token Ring ASN models for Token Ring cable attachment.
The Token Ring interface also supports the IEEE 802.5 Media Access Control (MAC) token passing protocol, the 802.2 Type 1 (connectionless) protocol, the 802.2 Type 2 (connection-oriented) protocol and the 16Mbs Early Token Release (ETR) protocol. All Wellfleet Token Ring interfaces feature Madge Networks advanced Token Ring accelerator software, FastMAC Plus. It uses advanced buffering techniques to minimize per-frame overhead on the TI Token Ring chip set. These features enable the interface to send and receive data faster.
FDDI: The FDDI interface provides a standard 100Mbs dual attached, multi-mode FDDI interface. The multi-mode interface supports 62.5/125 or 50/125 micron fiber at distances up to 2 kilometers between stations. The FDDI interface is compatible with ANSI X3T9.5 Physical Medium Dependent (PMD), Physical Protocol (PHY), Media Access Control (MAC) and Station Management (SMT) standards.Synchronous: The Synchronous interface supports V.35, RS232, RS449/422 balanced and X.21. Each Synchronous interface operates from 1200bps to 2.048Mbs, full-duplex, allowing use of lines up to T1 and E1 rates. Dial Back-Up, dial on demand and bandwidth on demand using Raise DTR and V.25bis dial signaling are supported over V.35 and RS232 interfaces. Additionally, internal and external clocking, as well as the entire range of wide area networking protocols that are supported by Wellfleet routers are supported by the Synchronous interface.
Alternatively, the Synchronous interface can be configured to integrate IBM SDLC traffic across the internetwork by connecting local or remote IBM equipment directly to the Synchronous interface and using either Wellfleet DLSw for SDLC or Transparent Sync Pass-Thru.
PU Type 2.0 and 2.1 devices are supported to provide a highly flexible interconnection solution. The Synchronous interface supports connection to these devices using a V.24 (RS232), V.35 or X.21 physical interface. Additionally the Synchronous interface ensures optimum SDLC performance by supporting numerous SDLC parameters (see Table 2).
Parameter Function NRZ/NRZI Specifies Line Support: Non-Return to Zero or Non-Return to Zero Inverted Half/Full-Duplex Specifies how Server Communicates with Downstream PU Constant/Switched Specifies how Server Controls Carrier Request To Send Signal to a Modem Transmit Clocking Specifies Transmit Clocking Type: Internal or External
ISDN Basic Rate Interface (BRI) ISDN BRI for Wellfleet routers provides two 64Kbs B channels for data and one 16Kbs D channel for signaling. ISDN BRI is supported via an adapter module attached to the Synchronous net module. This eliminates the need for an external ISDN terminal adapter. A Synchronous module supports one ISDN BRI adapter module. Each ASN unit can support two ISDN BRI adapter modules. Wellfleet's ISDN BRI supports all major international signaling specifications (see Table 3).
Region / Country ISDN Standard Australia AUSTEL TS013 Europe Euro ISDN (NET3) France VN-3 Japan INS-64 North America National ISDN-1 AT&T 5E6 ISDN Northern Telecom DMS
The SPEX net module enables up to four ASNs to be integrated in a stack configuration. Using an external cabling scheme, the SPEX provides a 160Mbs processor interconnect based on the Parallel Packet Exchange (PPX (TM)) processor interconnect technology featured in the high-performance Wellfleet Backbone Node. This feature maximizes connectivity by supporting up to 24 network interfaces in a 4-router stack.
On-Line operational servicing (hot swap) is also supported to allow
individual ASNs to be removed or added without affecting other units
within the stack. Additionally, the entire stack is managed as a
single routing platform. Each router is managed as an individual slot
would be within a Wellfleet multiple-slot router/bridge. This
simplifies network management by eliminating the requirement of
managing each ASN as an autonomous device.
The ASN maximizes network connectivity in multi-vendor,
multi-protocol environments by supporting all major LAN and WAN
protocols. Industry-standard IBM transport is also supported via the
Wellfleet Data Link Switching (DLSw) support (RFC 1434) (see
Table 5). To maintain remote office availability,
ASNs also support dial-up services. This allows ASNs to provide fully
featured router functionality to meet a wide range of remote office
requirements. Software Suites: Four software suites are
available for the Access Stack Node - Basic, LAN, WAN and Corporate
(see Table 5). This allows the ASN to be
configured with software that fits a site's particular
requirements. The ASN features an innovative, highly efficient system software
architecture that distributes forwarding, filtering and management
functions across each unit in a stack configuration. In addition to
ensuring high network performance, the architecture enables Wellfleet routers to
offer exceptional fault isolation capabilities. All processing for each network interface is done by its
directly attached ASN processor module. Each processor module uses its
own copy of the routing/bridging code, forwarding/filtering tables
and network management code. Routing and management updates are
automatically included in the processor module's tables when they are
received, and then passed to all other ASN processor modules within
the stack configuration. Certain computation-intensive and memory-intensive routing update protocols,
such as OSPF, are activated on only one ASN processor module within a
stack configuration. This allows the processor intensive activities
required by OSPF's link-state routing protocol to be performed by a
single processor module that distributes the results to other
processor modules within the stack. In the unlikely event of an ASN
processor module failure, OSPF's "hot-standby soloist" is
automatically and quickly activated on another ASN processor module,
without the loss of current routing information. Less intensive
routing protocols, such as IPX RIP, VINES RTP and AppleTalk RTMP, can
be active on multiple ASN processor modules. Additionally, overhead
processes, such as network management tasks, are distributed among the
stacked ASNs (see Figure 3).
The ASN provides extensive internal fault management capabilities that
eliminate total system failure in the event of a hardware or software
component malfunction. These capabilities ensure continued node and
network availability by isolating malfunctions before they can affect
other components in the node and other connected networks. Network
management can be notified of fault conditions via the automatic
generation of an SNMP trap. Online Dynamic Reconfiguration: Dynamic
reconfiguration eliminates the
need to schedule network downtime to reconfigure any ASN.
Configuration parameters can be changed by issuing SNMP Set commands
while the node is operational. Any changes made with SNMP Set are
volatile and are lost when the ASN reboots. To preserve changes, the
ASN's active configuration must be saved permanently to a file on the
PCMCIA Flash memory. This file defines the ASN's new baseline
configuration and ensures that the node will be properly configured to
meet the current network requirements. The changes made may be saved
on the Flash memory card at any time. Hardware Fault Isolation: If a hardware
failure occurs, the
malfunctioning component is logically disabled and isolated from the
rest of the system. Hardware failures can be isolated to an individual
net module or network interface. Within multiple ASN stack
configurations, fault isolation can include individual ASN processor
module, Flash card or power supply hardware. Software Fault Isolation and Recovery: A
software process can also fail
independently without affecting the operation of other processes. The
operating system automatically isolates the failed software process
without disrupting other protocols executing on the ASN or other ASNs
within a stack configuration, and automatically restarts the failed
process. If the process cannot be recovered, it is terminated. Partial Boot: Bay Networks
partial boot capability enables the ASN to
be started with failed hardware components and/or configuration
errors. Power-up diagnostics determine the status of each processor
module and link module. Any failed processor module is not booted. The
software automatically configures around improperly configured
hardware. The ASN provides maximum system availability through online
operational servicing capabilities. Individual ASNs within a stack
configuration can be added or removed without affecting the operation
of the rest of the stack. This eliminates downtime for upgrades and
repairs of ASN stack configurations. The ASN automatically boots when
it is reconnected to the stack system and power is turned on.
Bay Networks provides comprehensive traffic management capabilities
for Wellfleet routers through Multi-line Circuits, Uniform Traffic
Filters, Traffic Prioritization and Data Compression, maximizing
remote office-to-central site security and bandwidth availability. Multiline Circuits provides two methods for transmitting traffic over
its data paths - address-based selection and random selection.
Address-based selection determines the path a packet takes based on
its source and destination addresses. Once a path has been established
for a given address pair, subsequent packets will follow the same
path. This ensures the sequentiality of packets and is a valuable
feature for protocols that cannot tolerate packets received out of
order. Random selection determines the path each packet takes based on
a randomly assigned number that corresponds to a particular data path
in the circuit. This provides for even distribution across the circuit
to avoid congestion and is intended for use with protocols that can
accept packets received out of sequence. The ability to select the
method of transmitting data across the circuit enables Multiline
Circuits to maximize the performance of a wide range of applications. Uniform Traffic Filters: Uniform Traffic
Filters enables inbound and
outbound traffic filters to be easily established for all supported
network protocol traffic. Uniform Traffic Filters provides an
efficient method for developing an effective and comprehensive network
security strategy. In addition, Uniform Traffic Filters preserves WAN
bandwidth and can increase performance by reducing network congestion. Inbound traffic filters can be configured to accept or drop incoming
packets from any Wellfleet router's local area or serial network
interface. Outbound traffic filters can be configured to drop outgoing
packets destined for any Wellfleet router's serial interface. Also,
Uniform Traffic Filters can be configured to execute a log action when
a datagram's fields match the values defined in the filter. Filters
can be created using predefined protocol-specific fields or
user-defined fields. Up to 31 inbound filters and 31 outbound filters
(including Traffic Prioritization filters) can be defined for each
protocol on every supported network interface. Filter precedence can be defined for multiple filters configured on an
interface, reducing filter definition complexity. All filters are
configured via Site Manager, the node management application for
Wellfleet routers. Traffic Prioritization: Traffic
Prioritization filters can assign a
high priority to time-sensitive and/or mission-critical traffic,
thereby reducing the occurrence of session timeouts and improving
application response times. Priority filters can be configured to
place packets into one of three priority queues - high, normal or low
- for transmission through a Wellfleet node's outbound serial
interface. Priority filters can be applied to the complete family of
Wellfleet routing and bridging protocols. Priorities can be assigned
to packets based on their protocol, source network, destination
network and packet type, as well as other fields that are
identifiable by an offset in a packet. The number of priority filters
defined for a protocol on an interface depends on the number of
outbound Uniform Traffic Filters assigned to the protocol on the
interface. For example, if there are no outbound Uniform Traffic
Filters defined for a protocol, then 31 priority filters can be
assigned. However, if, for example, sixteen outbound Uniform Traffic
Filters are defined for a protocol, then fifteen priority filters can be
assigned. Traffic Prioritization can be configured to use either a strict
dequeuing algorithm or a bandwidth allocation dequeuing algorithm to
transmit packets across a serial line. The router's strict dequeuing
algorithm transmits all packets from the high-priority queue before
transmitting packets from the normal and low-priority queues. The
bandwidth allocation dequeuing algorithm allows packets from the
normal and low-priority queues to be transmitted when the
high-priority queue still contains packets, based on user-assigned
bandwidth allocation percentages for each queue. This ensures that
packets assigned lower priorities are transmitted in environments with
large amounts of high-priority traffic. Each serial line attached to a
Wellfleet router can use the strict or bandwidth allocation dequeuing
algorithm and can be reconfigured at any time in response to changes
in configuration and/or performance requirements. Data Compression: The Wellfleet router
software-based Data Compression feature maximizes internetwork performance by
reducing the amount of bandwidth required to transport LAN protocols
over WAN links. Based on the Lempel-Ziv algorithm, the payload
compression mechanism provides a compression ratio of 2:1 and is
optimized for Fractional T1/E1 links. Payload compression compresses
only the data portion of network protocol packets, leaving packet
headers intact. Because packet headers are not compressed, packet
switched services, such as X.25 and Frame Relay, can still be used. EZ-Install and EZ-Update simplify ASN installation and make router
reconfiguration and software updates from a central site quick and
easy. EZ-Install: EZ-Install eliminates the
time and expense of sending a technical resource to install and
configure an ASN. All that is required at the remote site is
connecting the ASN's LAN and serial interfaces and turning on the
power. With EZ-Install, the ASN obtains its software image from Flash
memory and its configuration file through the network. Using
EZ-Install, an ASN automatically obtains its IP address from an
upstream Wellfleet router and its configuration file from a
central-site server using the BOOTP protocol (see
Figure 4). After an ASN's configuration file has
been successfully downloaded to DRAM via EZ-Install, the unit's
configuration file can be saved to Flash memory for nonvolatile local
storage.
Multi-Protocol Routing and Bridging
Distributed Software Architecture
Fault Management
Online Operational Servicing (Hot-Swap)
Traffic Management
Remote Installation and Management
EZ-Update: EZ-Update facilitates the automatic downloading of software updates and configuration files, minimizing the time and expense associated with software maintenance. The existing ASN configuration file and software image are stored in the ASN's nonvolatile Flash memory for use as backup in case any problems are encountered while downloading new software. To use EZ-Update, the ASN is dynamically configured to boot its configuration file and software image from the central site. The ASN can then be rebooted or power-cycled and a new configuration file and/or software image will be downloaded to the ASN's DRAM from a central-site server. Once it has been determined that the new configuration file or software update is acceptable, it can be saved to the ASN's Flash memory, replacing the previous configuration file and/or software image.
Bay Networks provides comprehensive node configuration, monitoring and control by combining a management support foundation with two SNMP-based tools: Optivity/Internetwork and the Technician Interface (TI). ASN's in a stack configuration are easily managed as a single routing platform. This simplifies node management by eliminating the need for the autonomous management of multiple routers. EZ-Configure, Online Dynamic Reconfiguration and Dynamic Software Builder and Loader features minimize memory requirements and enable remote sites to be configured quickly and easily.
Security is ensured with a 2-level password mechanism (read vs. read/write). The ASN supports a TFTP client/server agent and an SNMP agent that enables configuration, monitoring and control of each of the ASN's network interfaces. The SNMP agent can respond to Get/Set requests independently. All MIB variables (MIB II and Wellfleet's extensive, enterprise-specific MIB) are also provided.
Site Manager: Optivity/Internetwork integrates Site Manager, Bay Networks node management application for Wellfleet routers with RouterMan, an intuitive router monitoring application and PathMan, a graphical network diagnostic tool to simplify and improve management of complex router internetworks.
RouterMan offers real-time router performance and status reporting. The application's intuitive graphical user interface provides at-a-glance overall router status. Fault and performance statistics, history and analysis are provided for the overall router, by protocol or by interface. A simple color-coded interface and fault history log provides proactive detection and indication of potential router problems.
PathMan dynamically determines the complete data path between any two network end stations, assisting network managers in troubleshooting large complex networks. All network components on the selected path appear automatically in a system-generated display of the route, showing exactly how devices are connected within the network. Color-coded icons display each device's status, enabling rapid problem identification.
Site Manager is a platform-independent, SNMP-based application developed expressly for simplifying the configuration and management of Wellfleet routers. It provides an intuitive point-and-click user interface that streamlines the configuration process and eliminates cryptic commands. Site Manager offers central configuration management that simplifies network setup and expansion, real-time operations and monitoring and real-time event and fault monitoring for efficient problem identification and isolation. Site Manager is available for MS Windows, SPARC, HP/9000 and IBM RS/6000 platforms.
Optivity/Internetwork operates independently or with the leading SNMP Platforms - HP OpenView, IBM NetView for AIX and SunNet Manager for additional capabilities.
EZ-Configure: Site Manager's EZ-Configure feature enables configuration file templates to be copied or modified for use at sites with similar configurations. This saves the time associated with building a completely new configuration file when a new site is brought online. EZ-Configure is useful for networks with many ASNs that have similar configuration requirements, such as branch banks.
Dynamic Software Builder and Loader: Site Manager's Software Builder works with the ASN's Dynamic Loader to preserve the ASN's Flash memory and DRAM space. The Software Builder allows ASN software images to be customized. Only required software functionality is maintained in the ASN's software image. For example, if a site only requires IP and IPX support, other network protocols can be deleted from the software image to preserve Flash memory space.
The ASN's Dynamic Loader feature preserves DRAM space by only loading to DRAM the routing functionality that is required by a particular ASN configuration. Using the previous example, if a particular office does not require IPX support, then Dynamic Loader would load only IP to DRAM, rather than the ASN's complete software image.
Technician Interface (TI): This terminal-based (TTY-compatible) tool enables basic configuration and maintenance locally or through Telnet. The Technician Interface is based on a simple command line interpreter that supports SNMP-based access to the MIB, displays the event log, and supports file system management and other administrative commands. The TI also supports out-of-band access to the ASN through a modem connection.
Measuring only 4.33 inches by 17.50 inches by 17.00 inches (10.99 cm by 44.45 cm by 43.18 cm), the ASN requires minimal space. Quiet and compact, the ASN can operate in either a wiring closet or desktop environment and is rack-mountable. LEDs indicate module status for easy troubleshooting assistance (see Table 4 and Figure 5). Each net module has a LED labeled FAIL, which when lighted indicates that the module is either not configured or malfunctioning.
LED Status Indicator DCD1 Data Carrier Detect Present on Synchronous Net Module COM1 Port DCD2 Data Carrier Detect Present on Synchronous Net Module COM2 Port XMT and RCV P1 Transmitting and Receiving Data on Ethernet Net Module AUI1 or 10BT1 Port XMT and RCV P1 Transmitting and Receiving Data on Ethernet Net Module AUI2 or 10BT2 Port WFAIL Detection of a Wire Fault in Either the Receive or Transmit Line (Token Ring) NSRT Port has Inserted into the Token Ring LAN RCVR Receiving Data from the Token Ring LAN SD Incoming Signal Detected by FDDI Interface TX Transmitting Data Across FDDI Interface Sand P Router is Present on the FDDI Ring FR Transmitting a Frame from SPEX Net Module FC SPEX Net Module is Using Flow Control
Basic LAN WAN Corporate Feature Suite Suite Suite Suite
Network Protocols IP x x x x OSI x x DECnet Phase IV x x Novell IPX x x Banyan VINES x x AppleTalk Phase 2 x x Xerox XNS x x
IBM Integration Source Route Bridge x x x x LAN Network Manager Agent x x x x Data Link Switching for Ethernet and Token Ring x x x x Data Link Switching for SDLC x x Transparent Sync Pass-Thru x x x x
Bridging Transparent (Ethernet and FDDI) x x x x Translation Bridge Ethernet-Token Ring x x x x Ethernet-FDDI x x x x Token Ring-FDDI x x x x Native Mode LAN (NML) x x x x
Wide Area Networking Wellfleet HDLC Encapsulation x x x x Point-to-Point Protocol (PPP) x x x x Frame Relay x x SMDS x x X.25 x x ATM DXI x x x Dial Back-Up x x x x Bandwidth on Demand Q3,1995 Q3,1995 Q3,1995 Q3,1995 Dial on Demand x x x x
Traffic Management Multiline Circuits x x x x Uniform Traffic Filters x x x x Traffic Prioritization x x x x Data Compression x x x x
Node Management EZ-Install / EZ-Update x x x x Dynamic Loader x x x x