Cabletron Systems DMS-100 manual Transmission control protocol, User datagram protocol

Chapter 2: EIU messaging protocols 53

The MAPCI supports asynchronous output to both the scroll area and a “full screen” area. The input, however, is buffered in a line-by-line mode. This combination of features requires that the telnet client perform echoing of input characters.

The telnet server translates MAP display updates into VT100 character strings and sends them to the telnet client at the remote end. Telnet clients must directly connect to the CM using the CM address.

Transmission control protocol

TCP is a reliable transport layer protocol that provides communications services to various applications like telnet, FTP, and so on. TCP can reside on all the nodes capable of running Internet software. SuperNode TCP implementation is able to interoperate with most of the industry-standard TCP implementations.

User datagram protocol

UDP protocol provides connectionless transport protocol services unlike TCP, which provides connection-oriented transport services. The original SuperNode application for UDP is routing information protocol (RIP) on an EIU. The IP route path display tool is also using UDP for intra-SuperNode messaging between processes on different nodes. The UDP is designed such that it can use IP fragmentation and reassembly functions to support UDP datagram size of up to 4 kbyte.

Address resolution protocol

The address resolution protocol (ARP) protocol implements the address resolution protocol, which provides dynamic binding between IP address and a physical hardware address. ARP resolves IP address-to-Ethernet or MAC address translation through ARP protocol running on an EIU. The IP address to frame transport address (FTA) translation is done in ARP through simple static table lookup.

Internet control message protocol

The ICMP software provides the IP status and error-reporting mechanism, which is very closely coupled to IP. The ICMP messages handling in SuperNode is limited to a few specific messages. The ICMP echo and response messages are handled to provide ping capability. The ICMP redirect is handled to provide routing table updates to SuperNode hosts from the dynamic routing information on the EIU. TCP is notified of ICMP source quench messages.

Routing information protocol

The industry standard RIP is implemented for an EIU to enable it to participate in the exchange of dynamic routing information with other IP routers on the Ethernet LAN. The dynamic routing information is required on the SuperNode to be able to route datagrams to hosts on distant LANs.

DMS-100 Family EIU User Guide TELECOM12