Cisco Systems BC-281 manual Local Acknowledgment, BC-284

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Configuring Data-Link Switching Plus

Technology Overview

•UDP unicast support

•Load balancing

•Support for LLC1 circuits

•Support for multiple bridge groups

•Support for RIF Passthrough

•SNA type of service feature support

•Local acknowledgment for Ethernet-attached devices and media conversion for SNA PU 2.1 and PU 2.0 devices

•Conversion between LLC2 to SDLC between PU 4 devices

•Local or remote media conversion between LANs and either SDLC Protocol or QLLC

•SNA View, Blue Maps, and Internetwork Status Monitor (ISM) support

MIB enhancements that allow DLSw+ features to be managed by the CiscoWorks Blue products, SNA Maps, and SNA View. Also, new traps alert network management stations of peer or circuit failures. For more information, refer to the current Cisco IOS release note for the location of the Cisco MIB website.

Local Acknowledgment

When you have LANs separated by wide geographic distances, and you want to avoid sending data multiple times, and the loss of user sessions that can occur with time delays, encapsulate the source-route bridged traffic inside IP datagrams passed over a TCP connection between two routers with local acknowledgment enabled.

Logical Link Control, type 2 (LLC2) is an ISO standard data-link level protocol used in Token Ring networks. LLC2 was designed to provide reliable sending of data across LAN media and to cause minimal or at least predictable time delays. However, DLSw+ and WAN backbones created LANs that are separated by wide, geographic distances-spanning countries and continents. As a result, LANs have time delays that are longer than LLC2 allows for bidirectional communication between hosts. Local acknowledgment addresses the problem of unpredictable time delays, multiple sendings, and loss of user sessions.

In a typical LLC2 session, when one host sends a frame to another host, the sending host expects the receiving host to respond positively or negatively in a predefined period of time commonly called the T1 time. If the sending host does not receive an acknowledgment of the frame it sent within the T1 time, it retries a few times (normally 8 to 10). If there is still no response, the sending host drops the session.

Figure 127 illustrates an LLC2 session in which a 37x5 on a LAN segment communicates with a 3x74 on a different LAN segment separated via a wide-area backbone network. Frames are transported between Router A and Router B by means of DLSw+. However, the LLC2 session between the 37x5 and the 3x74 is still end-to-end; that is, every frame generated by the 37x5 traverses the backbone network to the 3x74, and the 3x74, on receipt of the frame, acknowledges it.

 

Cisco IOS Bridging and IBM Networking Configuration Guide

BC-284

78-11737-02

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Contents Configuring Data-Link Switching Plus BC-281DLSw Standard DLSw Version 2 StandardIP Multicast BC-282DLSw+ Features Enhanced Peer-on-Demand Routing FeatureUDP Unicast Expedited TCP ConnectionLocal Acknowledgment BC-284BC-285 LLC2 Session without Local AcknowledgmentBC-286 DLSw+ Support for Other SNA Features BC-287Command Purpose Defining a DLSw+ Local Peer for the RouterDefines the DLSw+ local peer Following is a sample dlsw local peer statementTCP Encapsulation Defining a DLSw+ Remote PeerBC-289 TCP/IP with RIF Passthrough Encapsulation FST EncapsulationDefines a remote peer with FST encapsulation BC-290Direct Encapsulation DLSw Lite EncapsulationDefines a remote peer with direct encapsulation Defines a remote peer with DLSw Lite encapsulationToken Ring Mapping DLSw+ to a Local Data-Link ControlBC-292 Ethernet BC-293Associated with this serial interface Enables DLSw+ on an Sdlc interfaceBC-294 Configuring Advanced Features BC-295Peer Groups and Border Peers ScalabilityBC-296 BC-297 Enables peer groups and border peers BC-298Local, remote, and group caches Configures peer-on-demand defaultsBC-299 Displays content of group, local and remote caches NetBIOS Dial-on-Demand RoutingFollowing command enables NetBIOS DDR Explorer FirewallsFollowing command configures the SNA DDR feature UDP Unicast FeatureSNA Dial-on-Demand Routing BC-301Configures a dynamic peer Promiscuous Peer DefaultsLLC1 Circuits Dynamic PeersConfigures promiscuous peer defaults AvailabilityLoad Balancing BC-303Local router BC-304Configures transparent redundancy Backup PeersEthernet Redundancy Addresses on a transparent bridged are mappedModes of Operation Configures a backup peerBC-306 Access Control Network ManagementTraffic Bandwidth and Queueing Management BC-307DLSw+ Bridge Group List Defines a port listBC-308 Filter Lists in the Remote-Peer Command Static PathsStatic Resources Capabilities Exchange BC-309Configuring DLSw+ Timers BC-310BC-311 Following sections provide DLSw+ configuration examples BC-312Router B Router aBC-313 BC-314 DLSw+ with Peer Groups Specified ExampleRouter C BC-315BC-316 FEPRouter D BC-317DLSw+ with Sdlc Multidrop Support Configuration Examples Router EFollowing example, all devices are type PU BC-318Following example, all devices are type PU 2.1 Method BC-319BC-320 Hostname Router aBC-321 DLSw+ Translation Between Fddi and Token RingDLSw+ Translation Between Sdlc and Token Ring Media Example BC-322BC-323 Sdlc partner 1000.5aed.1f53 d2 sdlc dlsw d2Ring DLSw+ over Frame Relay Configuration ExampleBC-324 DLSw+ over Qllc Configuration Examples Following three examples describe Qllc support for DLSw+Example BC-325DLSw+ with RIF Passthrough Configuration Example BC-326DLSw+ with Enhanced Load Balancing Configuration Example BC-327DLSw+ Peer Cluster Feature Configuration Example BC-328DLSWRTR2 BC-329Shows a DLSw+ border peer network configured with DLSw+ Rsvp BC-330DLSw+ with Ethernet Redundancy Configuration Example BC-331DLSw+ with Ethernet Redundancy in a Switched Environment BC-332BC-333 BC-334
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