Chapter 8 Management Network Connectivity

TCP/IP and OSI Networking

the packet appropriately. The IS also might provide a redirect (RD) message back to the source to tell it that a more direct route is available. If the destination address is an ES on another subnetwork in the same area, the IS knows the correct route and forwards the packet appropriately. If the destination address is an ES in another area, the Level 1 IS sends the packet to the nearest Level 2 IS. Forwarding through Level 2 ISs continues until the packet reaches a Level 2 IS in the destination area. Within the destination area, the ISs forward the packet along the best path until the destination ES is reached.

Link-state update messages help ISs learn about the network topology. Each IS generates an update specifying the ESs and ISs to which it is connected, as well as the associated metrics. The update is then sent to all neighboring ISs, which forward (flood) it to their neighbors, and so on. (Sequence numbers terminate the flood and distinguish old updates from new ones.) Using these updates, each IS can build a complete topology of the network. When the topology changes, new updates are sent.

IS-IS uses a single required default metric with a maximum path value of 1024. The metric is arbitrary and typically is assigned by a network administrator. Any single link can have a maximum value of 64, and path links are calculated by summing link values. Maximum metric values were set at these levels to provide the granularity to support various link types while at the same time ensuring that the shortest-path algorithm used for route computation is reasonably efficient. Three optional IS-IS metrics (costs)—delay, expense, and error—are not supported by the ONS 15310-MA SDH. IS-IS maintains a mapping of the metrics to the quality of service (QoS) option in the CLNP packet header. IS-IS uses the mappings to compute routes through the internetwork.

8.6.5 TARP

TARP is used when TL1 target identifiers (TIDs) must be translated to NSAP addresses. The TID-to-NSAP translation occurs by mapping TIDs to the NETs, then deriving NSAPs from the NETs by using the NSAP selector values (see Table 8-8 on page 8-25).

TARP uses a selective PDU propagation methodology in conjunction with a distributed database (that resides within the NEs) of TID-to-NET mappings. TARP allows NEs to translate between TID and NET by automatically exchanging mapping information with other NEs. The TARP PDU is carried by the standard CLNP Data PDU. TARP PDU fields are shown in Table 8-9.

 

 

Table 8-9

TARP PDU Fields

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Field

 

Abbreviation

 

Size (bytes)

Description

 

 

 

 

 

 

 

 

 

 

 

 

TARP Lifetime

 

tar-lif

 

2

The TARP time-to-live in hops.

 

 

 

 

 

 

 

 

 

 

 

TARP Sequence

tar-seq

 

2

The TARP sequence number used for loop detection.

 

 

 

Number

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Protocol

 

tar-pro

 

1

Used to identify the type of protocol address that the

 

 

 

Address Type

 

 

 

 

TID must be mapped to. The value FE is used to

 

 

 

 

 

 

 

 

identify the CLNP address type.

 

 

 

 

 

 

 

 

 

 

 

 

TARP Type

 

tar-tcd

 

1

The TARP Type Code identifies the TARP type of

 

 

 

Code

 

 

 

 

PDU. Five TARP types, shown in Table 8-10, are

 

 

 

 

 

 

 

 

defined.

 

 

 

 

 

 

 

 

 

 

 

 

TID Target

 

tar-tln

 

1

The number of octets that are in the tar-ttg field.

 

 

 

Length

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TID Originator

 

tar-oln

 

1

The number of octets that are in the tar-tor field.

 

 

 

Length

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Protocol

 

tar-pln

 

1

The number of octets that are in the tar-por field.

 

 

 

Address Length

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Cisco ONS 15310-MA SDH Reference Manual, Release 9.1 and Release 9.2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

78-19417-01

 

 

 

 

 

 

 

8-29

 

 

 

 

 

 

 

 

 

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Cisco Systems 15310-MA manual Tarp, Field, Size bytes Description
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15310-MA specifications

Cisco Systems has established itself as a leader in the networking domain, offering a wide array of solutions to meet the needs of modern businesses. Among its impressive product lineup are the Cisco 15310-CL and 15310-MA routers, designed to provide advanced network performance and reliability.

The Cisco 15310-CL is a versatile platform that primarily serves as a carrier-class router aimed at supporting high-speed data and voice services. It is built to handle the demands of large enterprises and service providers, offering a robust design that ensures maximum uptime and performance. One of its standout features is its modular architecture, which enables users to customize their configurations based on specific application needs. This scalability allows for future expansion without the need for a complete hardware overhaul.

Key technologies integrated into the Cisco 15310-CL include high-density Ethernet interfaces and a comprehensive suite of Layer 2 and Layer 3 protocol support. The device is capable of supporting multiple types of connections, including TDM, ATM, and Ethernet. This flexibility makes it an ideal choice for organizations that require seamless migration between various service types. Moreover, with features such as MPLS (Multiprotocol Label Switching) support and advanced Quality of Service (QoS) mechanisms, the router ensures that critical applications receive the necessary bandwidth and low latency required for optimal performance.

In contrast, the Cisco 15310-MA focuses on access solutions, providing a cost-effective entry point for businesses looking to enhance their network capabilities. It is well-suited for smaller offices or branch locations that need reliable connectivity without the expense and complexity associated with larger systems. The device supports a range of access methods and provides essential features like firewall capabilities, VPN support, and comprehensive security measures to protect sensitive data.

Both models benefit from Cisco's commitment to security and manageability, offering features like enhanced encryption protocols and user authentication mechanisms that help safeguard networks against threats. Additionally, they can be managed through Cisco’s intuitive software tools, simplifying configuration and monitoring tasks for IT administrators.

The Cisco 15310-CL and 15310-MA are ideal solutions for businesses seeking to enhance their network infrastructure, ensuring firms can keep pace with evolving technology demands while maintaining a focus on security and performance. Their combination of advanced features, modular capabilities, and robust support makes them valuable assets in the networking landscape.
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