[OSPF])

Strona startowa Ludzie pragną czasami się rozstawać, żeby móc tęsknić, czekać i cieszyć się z powrotem. 4Analiza dokumentów XML za pomocą PHP oraz Expat...niegdyś w lekkoatletyce przebiegnięcie mili w czasie czterech minut...I- Potrafię ją zamknąć - oznajmił Haman - tak, że nie będzie można jej otworzyć bez Talizmanu Wzrostu...przez kawiarnię, żeby spojrzeć na listę tytułów i wykonawców umieszczoną na szafie grającej...Wojtasiewicz h...Wenn dann die Mäuse sich quer und häufig durcheinander paaren heiĂźt es: Der Mensch ist schlieĂźlich kein Tier, das sich dermaĂźen verhält...do suszenia stuknęły o ściany domu – i znowu wszystko ucichło...requirements of the U... 
 

Ludzie pragną czasami się rozstawać, żeby móc tęsknić, czekać i cieszyć się z powrotem.

This allows you to have multiple routers at the central site for load balancing or
redundancy. Whichever router receives the call from the remote site will have the route installed dynamically. At the remote site, the routing protocol (RIP or ODR) must be denied from the dialer list.
For meshed topologies, you can minimize routing table updates by using a distance-vector
protocol, such as RIP or IGRP, in combination with Cisco’s snapshot routing feature. Snapshot
routing prevents regular routing updates from bringing up the ISDN connection. The changes in
routing tables are sent either when the link is opened by end-user traffic or at a regular configurable interval. Snapshot routing supports not only IP routing updates, but also Novell’s IPX routing and SAP updates.
Many NetBIOS implementations use a session keepalive (in addition to a data-link control
keepalive) to maintain sessions, so DDR may not work with NetBIOS. (The session level keepalive
will keep the dial line up.)
Local Switching
Local switching (available in Cisco IOS Release 11.1 and later) allows a single router to provide media conversion between SDLC and Token Ring and between QLLC and LAN. This is useful in
environments that need simplified SNA network design and improved availability. For example, by
converting SDLC to Token Ring, fewer FEP expansion frames are required; moves, adds, and
changes are easier; and recovery from a FEP or Token Ring interface coupler (TIC) failure can be
automatic (by using duplicate TIC addresses). Local switching can be used to connect SDLC devices directly to a Cisco router with a CIP card. Local switching can also be used over a WAN in which
the remote branch has SNA devices on LANs, but the central site FEP still requires serial
Designing DLSw+ Internetworks 7-27
Summary
connectivity (for example, when the FEP is a Cisco 3725 router). To use local switching, omit dlsw remote-peer commands. In the dlsw local-peer command, the peer ID is unnecessary. A sample network and its configuration are shown in Figure 7-18.
Figure 7-18
Local switching configuration in a mixed PU 2.0 and PU 2.1 environment.
C1
PU 2.1
MSD
Token
C2
Ring
Router A
PU 2.0
Peer A Router A
dlsw local-peer
interface serial 0
…
sdlc role primary
sdlc vmac 4000.3174.0000
sdlc address c1 xid-poll
sdlc partner 4000.3745.0001 c1
sdlc address c2
sdlc xid c2 01767890
sdlc partner 4000.3745.0001 c2
sdlc dlsw c1 c2
Summary
This chapter provided an introduction to DLSw+, including a description of DLSw+ and
configuration examples to enable you to quickly design and configure simple DLSw+ networks. It
reviewed the key components of the data-link switching (DLSw+) features and described the
extensions to the standard that are included in DLSw+. Finally, advanced features of DLSw+, the
benefits they provide, and a brief description of when and how to use them were discussed.
7-28
Cisco CCIE Fundamentals: Network Design
C H A P T E R
8
Designing ATM Internetworks
This chapter describes current Asynchronous Transfer Mode (ATM) technologies that network
designers can use in their networks today. It also makes recommendations for designing non-ATM
networks so that those networks can take advantage of ATM in the future without sacrificing current investments in cable.
This chapter focuses on the following topics:
• ATM overview
• Cisco’s ATM WAN solutions
ATM Defined
ATM is an evolving technology designed for the high-speed transfer of voice, video, and data
through public and private networks in a cost-effective manner. ATM is based on the efforts of Study Group XVIII of the International Telecommunication Union Telecommunication Standardization
Sector (ITU-T, formerly the Consultative Committee for International Telegraph and Telephone
[CCITT]) and the American National Standards Institute (ANSI) to apply very large-scale
integration (VLSI) technology to the transfer of data within public networks. Officially, the ATM
layer of the Broadband Integrated Services Digital Network (BISDN) model is defined by
CCITT I.361.
Current efforts to bring ATM technology to private networks and to guarantee interoperability
between private and public networks is being done by the ATM Forum, which was jointly founded
by Cisco Systems, NET/ADAPTIVE, Northern Telecom, and Sprint in 1991.
Role of ATM in Internetworks
Today, 90 percent of computing power resides on desktops, and that power is growing
exponentially. Distributed applications are increasingly bandwidth-hungry, and the emergence of
the Internet is driving most LAN architectures to the limit. Voice communications have increased
significantly with increasing reliance on centralized voice mail systems for verbal communications.
The internetwork is the critical tool for information flow. Internetworks are being pressured to cost less yet support the emerging applications and higher number of users with increased performance.
To date, local and wide-area communications have remained logically separate. In the LAN,
bandwidth is free and connectivity is limited only by hardware and implementation cost. The LAN
has carried data only. In the WAN, bandwidth has been the overriding cost, and such delay-sensitive traffic as voice has remained separate from data. New applications and the economics of supporting them, however, are forcing these conventions to change.
Designing ATM Internetworks 8-1
Role of ATM in Internetworks