www.RuggedCom.com
3
RuggedSwitch
TM
RS401
RuggedServer™ RS401
4-Port Serial Device Server with Integrated 4-Port Managed Ethernet Switch
Serial IP Encapsulation
Many 'legacy' devices (RTU, PLC, IED, etc.) only
support serial communications via RS232 or RS485.
ROS encapsulates the serial data within a TCP
connection allowing these devices to be reached via
an IP network. A wide range of baud rates, frame
packetization options, and diagnostics allows any serial
protocol to function. The RS401 has specific support for
the following serial protocols:
.
Raw Socket serial encapsulation
.
Modbus TCP (client and server)
.
DNP 3
.
WIN and TIN
.
Microlok
MODBUS TCP
The Modbus protocol is ubiquitous in the industrial
control and automation world. ROS converts Modbus
RTU master/slave serial data packets to Modbus TCP
client/server packets for transmission over an IP network.
This allows communications to Modbus RTU slaves via
Ethernet and allows multiple masters to poll the same
slave device.
Remote Dial-Up Access
A v.90 modem coupled with the PPP (Point to Point
Protocol) allows ROS to provide dial-up access via
POTS (plain old telephone system) providing connectivity
to serial devices and Ethernet LAN. PAP/CHAP
authentication provide security against
unauthorized access.
Rapid Spanning Tree Protocol (IEEE 802.1w)
RSTP allows the creation of fault-tolerant ring and mesh
Ethernet networks that incorporate redundant links that
are 'pruned' to prevent loops. The ROS optimized version
of RSTP yields worst-case failovers of 5ms times the
'bridge diameter' and allows rings of up to 80 switches.
For example, a ring of ten switches will have failover
times under 50ms. ROS implements both STP and RSTP
to ensure interoperability with commercial switches
unlike other proprietary 'ring' based solutions.
Quality of Service (IEEE 802.1p)
Some networking applications such as real-time control
or VoIP (voice over IP) require predictable arrival times for
Ethernet frames. Switches can introduce latency in times
of heavy network traffic due to the internal queues that
buffer frames and than transmit on a first come first serve
basis. ROS supports 'Class of Service' in accordance
with IEEE 802.1p that allows time critical traffic
to jump ahead to the front of the queue thus
minimizing latency and reducing jitter to allow such
demanding applications to operate correctly. ROS allows
priority classification by port, tags, MAC address, and IP
type of service (TOS). A configurable "weighted fair
queuing" algorithm controls how frames are emptied from
the queues.
VLAN (IEEE 802.1q)
Virtual local area networks (VLAN) allow the segregation
of a physical network into separate logical networks with
independent broadcast domains. A measure of security is
provided since hosts can only access other hosts on the
same VLAN and traffic storms are isolated. ROS supports
802.1q tagged Ethernet frames and VLAN trunks. Port
based classification allows legacy devices to be assigned
to the correct VLAN.
IGMP Snooping
ROS uses IGMP snooping (Internet Group Management
Protocol v1&v2) to intelligently forward or filter multicast
traffic streams (e.g. MPEG video) to or from hosts on the
network. This reduces the load on network trunks and
prevents packets from being received on hosts that are
not involved. ROS has a very powerful implementation
of IGMP snooping that:
.
Can be enabled on a per VLAN basis
.
Detects and filters all multicast streams regardless of
whether subscribers exist
.
Supports "router-less" operation by supporting an
"active" mode
.
Restores traffic streams immediately after an RSTP
topology change
Ethernet Port Mirroring
ROS can be configured to duplicate all traffic on one
port to a designated mirror port. When combined with
a network analyzer, this can be a powerful
troubleshooting tool.
Ethernet Port Configuration and Status
ROS allows individual ports to be 'hard' configured for
speed, duplex, auto-negotiation, flow control and more.
This allows proper connection with devices that do
not negotiate or have unusual settings. Detailed status
of ports with alarm and SNMP trap on link problems
aid greatly in system troubleshooting.
Ethernet Switch Management Features
