Dugal Errata Download the errata Submit Errata. Candidates who are writing the examination in Japanese apart from English should report the same in Cisco or in Pearson VUE snza at least 15 days before the commencement of the exam. Singapore Telecommunications Business Setup. Routing and Switching Capabilities of the Security Appliance 3. Cisco Security Appliance Technology and Features 2. Labs can be run in any order, any number of times.
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SNA has reached a position of prominence in the computer industry based on its completeness and its continued support by IBM. Over the years, SNA has been expanded to accommodate evolution in computer networking. Originally an extremely hierarchical architecture designed especially for terminal-to-host communications, SNA has evolved to include support for peer-to-peer networks as well as certain standardized network media and protocols.
Knowledge of networking fundamentals is assumed. The two models are shown in Figure 1. Figure 1. The SNA transmission control layer provides a reliable end-to-end connection service, as well as encryption and decryption services. The SNA presentation services layer specifies data transformation algorithms that translate data from one format to another.
The presentation services layer also coordinates resource sharing and synchronizes transaction operations. Finally, the SNA transaction services layer provides application services in the form of programs that implement distributed processing or management services.
In addition to the seven layers just discussed, SNA terminology includes an additional phrase that further describes portions of its layered architecture. When these nodes are on different networks, the path control network attempts to ensure that the communicating entities believe they are talking to nodes on their own networks. Nodes are network components that contain host protocol implementations; links are transmission facilities that carry data between two SNA nodes.
The term "link" also assumes the ability for the two -connected nodes to operate a data link control procedure between them. Traditional SNA communication involves four separate physical entities: Hosts. Hosts control all or part of a network.
They provide computation, program execution, data base access, directory services, and network management. Front-end processors. Front-end processors now often called communication controllers manage the physical network, control communication links, and route data through a network. Cluster controllers. Cluster controllers now often called establishment controllers control input and output operations of devices attached to them. Terminals sometimes called workstations provide the user interface to the network.
SNA offers support for a variety of data link control techniques, including the following: Mainframe channels. ESCON uses optical fiber as the network medium.
However, although the two SNA nodes are considered to be adjacent to one another, they require certain data link control protocol capabilities which X. Token Ring Network. NAUs communicate with one another through sessions. LUs function as end-user access ports into the network, providing users with access to network resources and managing the transmission of information between end users. Nodes may have multiple LUs. Physical units PUs. PUs monitor and control attached network links and other network resources associated with a particular node.
Control points CPs. CPs manage nodes and their resources. They are differentiated from PUs in that they determine which actions must be taken, whereas PUs cause the actions to actually occur. SNA nodes are assigned to one of two categories: Subarea nodes. Subarea nodes provide all network services, including intermediate routing and address mapping between local and network-wide addresses.
Node types 4 T4 and 5 T5 are subarea nodes. Although there is no relationship between SNA node types and actual physical entities, T5 nodes are usually contained in hosts, and T4 nodes are usually contained in front-end processors.
VTAM is an example of a T5 node. VTAM controls the logical flow of data through a net-work, provides an interface between application subsystems and a network, and protects application subsystems from unauthorized access. NCP routes data and controls its flow between the front-end processor and other network resources.
Peripheral nodes. Peripheral nodes use only local addressing and communicate with other nodes through subarea nodes. Node types 1 T1 and 2 T2 are examples of peripheral nodes. T1 nodes now obsolete reside in unintelligent terminals; T2 nodes typically reside in intelligent terminals or establishment controllers. Traditional SNA components are typically organized as depicted in Figure 2.
Figure 2. A subarea, which is comprised of a subarea node and its attached peripherals, is an example of a logical network. A domain consists of a SSCP and the network resources that it can control. SSCPs in different domains can cooperate with one another to compensate for host processor failures. Figure 3 illustrates the concepts of subareas and domains.
Figure 3. A new type of network, the peer-to-peer network, emerged. IBM responded to the trend toward peer-to-peer networking with the introduction, over a period of years, of several new concepts allowing peer-to-peer networking in SNA environments. It supports communication between dissimilar as well as similar node types. For example, communication between a T5 and a T2. The PU 2. NNs contain a CP in their path control layer.
This allows intermediate routing and distributed name resolution within T2. Figure 4. Subarea addresses are global and must be unique within the entire network. Subarea addresses are assigned to NAUs when they are activated. Subarea addresses generally consist of two parts: a subarea and an element. The subarea portion identifies the subarea within the network, while the element portion identifies the element within the subarea.
All NAUs within a given subarea share the same subarea address but have different element addresses. Peripheral node addresses differ depending on whether the node is a T2 or a T2. T2 addresses refer to NAUs and are statically assigned. They are referred to as local form session identifiers.
When sessions traverse multiple address spaces, a session connector component is used to bridge the address spaces where they meet. SNI gateways act as the bridge between SNA networks, accepting data from one network and transmitting it to the appropriate destination in another network.
APPN intermediate routing functions. As with any network, directory services are used to map SNA network resources to locations. LUs in peripheral nodes can be located by the subarea address of the attached subarea. When a query reaches a node with the requested resource, it sends a positive response back to the node from which it received the request.
Crossed queries are interpreted as a negative reply by both nodes. End-node resources may be learned either through static assignment or through registration with the appropriate network node.
Traffic directed to a particular TG can traverse any of the physical links included in that TG, thereby providing extra reliability because link failures can be compensated for and bandwidth because any link in the group can be used for transmission. TG sequence numbers are used to resequence out-of-order messages at each hop. Four transmission priorities are supported at each transmission group: low, medium, high, and Network Services Traffic the highest priority. Multilink TGs are only supported between T4 nodes.
Routes between subareas may be explicit or virtual. Explicit routes are physical connections between two subarea nodes, and are defined as an ordered sequence of subareas and connecting TGs. Since explicit routes are unidirectional, two one in each direction are required to create a full duplex path.
Virtual routes are two-way logical connections between two subarea nodes. A given virtual route is said to flow over an explicit route and the reverse explicit route that follows the same physical path. Virtual routes do not cross network boundaries. When network interconnection is required, a SNA network interconnect session connector bridges the two virtual routes. Virtual routes also include values that define transmission priority and global flow control parameters. Global flow control is provided by pacing, a technique where a receiver with sufficient buffer space grants pacing windows to the sender.
Each pacing window allows the sender to transmit a certain amount of information before the sender must request the next pacing window. Components of SNA routing are illustrated in Figure 5. Figure 5. Each APPN intermediate node contains a session connector to bridge between the two path controls. The session connector uses a different local form session identifier on each TG it couples and, therefore, swaps the appropriate values into the transmission header at each hop.
Global flow control is produced by back pressure, where pacing window reductions by end nodes pro-voke intermediate nodes to reduce their window sizes, which eventually affects the transmission rate of the source end node. It is defined by characteristics such as response time, security, and availability, and is specified either automatically at logon or manually by the user when a session is initiated.
Each COS name is associated with a list of virtual routes that the network administrator has decided will meet the desired service level requirement. From that list, an available virtual route is chosen. In subarea routing, the user defines classes of service, the virtual routes they map to, and the TGs that the underlying explicit routes traverse.
CCSP SNAA Quick Reference
Get unlimited day access to over 30, books about UX design, leadership, project management, teams, agile development, analytics, core programming, and so much more. Designing Private Networks Over the I. Despite the large and rapidly expanding number of VPN products, all fall into three broad categories: Routing and Switching Capabilities of the Security Appliance 3. This examination will also help the candidates to enhance their skills in the Cisco ASA security appliance products. Table of Contents 1. Candidates who are writing the examination in Japanese apart from English should report the same in Cisco or in Pearson VUE centers at least 15 days before the commencement of the exam.
IBM SNA Networking
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