ISDN Connection Management

Termination Process

When the P840 has determined that there are no sessions active on an ISDN call, the P840 will attempt to close the call. If the partner P840 still has sessions assigned to that call, the call will be maintained until each side has determined that there are no active sessions using the call.

When the connection to the partner ISDN P840 is configured to use Auto-Call, the ISDN call will be suspended when there are no session in the table. The ISDN call will be re-established to the Auto-Call number the next time the P840 needs to send data to the partner ISDN P840.

If the operator of the P840 performs a link reset, the suspended call will be closed unilaterally.

IP Specifics

IP Address Connect

As stated previously, an IP Address Connect connection is an ISDN connection that is established to a specific destination P840 dependent upon the destination IP address contained within IP traffic received from the local LAN.

This means that the P840 continuously monitors IP traffic from the local LAN, as all IP routers do, and makes ISDN connections to partner P840s when IP traffic needs to be sent to remote LANs. Once the IP traffic is passed to the remote LAN and all sessions are closed, the local P840 will then disconnect the ISDN call and continue to monitor the local LAN for IP traffic.

The IP Address Connect table consists of IP addresses and associated ISDN numbers of remote partner P840 IP Routers. Either one or both of the ISDN calls may be used for IP Address Connect use. When one of the ISDN calls is defined for Auto-Call purposes, the remaining ISDN call may be used for IP Address Connect use.

The combination of Auto-Call and Address Connect allows part of the WAN environment to be established statically and still allow dynamic connections to other networks depending upon destination IP addresses.

Suspension of TCP/IP Sessions

When Connection Management is enabled, TCP sessions that are established across the ISDN calls are monitored and maintained in a table. The TCP session table may contain up to 256 entries. The P840 will filter all traffic for any TCP/IP session over the 256 limit of the table preventing any new TCP sessions from being established.

While an ISDN call is suspended, if the P840 observes that one of the devices in the session stops sending keepalive packets, the P840 will begin to generate keepalive packets and send them to the device in order to determine the status of the device. The length of time the P840 waits before beginning to generate keepalive packets is definable by the operator.

If the device does not respond to five consecutive keepalive packets sent from the P840, the P840 will determine that the device has gone away and the P840 will send a packet to each end of the TCP session to shut down the session. When the shut down packet is generated for the remote device, the P840 will re-activate the suspended ISDN call and transmit the shut down packet to the remote device. Once the remote P840 determines that the TCP session is no longer active, the remote P840 will stop generating and responding to the keepalive packets for that TCP session.

RIP—Routing Information Protocol

P840 ISDN routers incorporate a 3 second settling time for IP RIP updates. This means that a P840 will wait for three seconds after an initial change in the network is reported before transmitting that change on to the remaining P840 routers connected on the Wide Area Network.

21

Page 21
Image 21
Perle Systems P840 manual IP Specifics, Termination Process, IP Address Connect, Suspension of TCP/IP Sessions

P840 specifications

Perle Systems is renowned for its high-performance networking hardware, and the Perle P840 model exemplifies this reputation with its advanced features and technologies. Designed for small to medium-sized enterprises, the P840 serves as a versatile and reliable solution for connectivity needs.

One of the main features of the Perle P840 is its robust network performance, supporting both Ethernet and serial connectivity. With support for RS-232, RS-422, and RS-485 interfaces, the P840 enables seamless integration of legacy devices into modern network architectures, allowing businesses to leverage existing infrastructure without the need for extensive upgrades.

The P840 also boasts advanced security features to protect sensitive data during transmission. It supports SSL encryption and VPN capabilities, ensuring that data travels securely across the network. Additionally, it implements strong authentication protocols, providing organizations with peace of mind knowing that their communications are safeguarded against potential threats.

Another standout characteristic of the P840 is its flexibility in configuration. It offers multiple port configurations, allowing for customization based on specific user needs. With options for both managed and unmanaged modes, the device can easily adapt to various network environments. This flexibility makes it suitable for diverse applications, including industrial automation, process control, and telecommunications.

The Perle P840 is designed for durability and reliability, featuring a rugged enclosure that can withstand demanding environments. Its solid-state components reduce the risk of failure, contributing to increased uptime and lower maintenance costs. Furthermore, the compact design allows for easy installation in tight spaces, making it a practical choice for various deployment scenarios.

In terms of management and monitoring, the P840 includes an intuitive web-based interface, enabling administrators to configure settings and monitor network performance effortlessly. SNMP support further enhances management capabilities, allowing for integration into larger network management systems.

Overall, the Perle P840 stands out as a powerful solution for enterprises seeking seamless connectivity, robust security, and flexibility in configuration. Its combination of advanced features and durable design makes it an ideal choice for industries requiring reliable serial and network connectivity in challenging environments. With the P840, businesses can build a resilient networking infrastructure that supports their growing demands while safeguarding their critical data.