302 lines
5.8 KiB
HTML
302 lines
5.8 KiB
HTML
<HTML
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><HEAD
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><TITLE
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>Considerations when buying second-hand terminal
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servers</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
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REL="HOME"
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TITLE="Remote Serial Console HOWTO"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="Terminal server configuration"
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HREF="ts.html"><LINK
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REL="PREVIOUS"
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TITLE="Terminal server configuration"
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HREF="ts.html"><LINK
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REL="NEXT"
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TITLE="Cisco 2511"
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HREF="ts-cisco2511.html"></HEAD
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><BODY
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CLASS="SECTION"
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BGCOLOR="#FFFFFF"
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TEXT="#000000"
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LINK="#0000FF"
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VLINK="#840084"
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ALINK="#0000FF"
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><DIV
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CLASS="NAVHEADER"
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><TABLE
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SUMMARY="Header navigation table"
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WIDTH="100%"
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BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>Remote Serial Console HOWTO</TH
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></TR
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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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><A
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HREF="ts.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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><TD
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WIDTH="80%"
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ALIGN="center"
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VALIGN="bottom"
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>Appendix E. Terminal server configuration</TD
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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><A
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HREF="ts-cisco2511.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
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></TABLE
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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="SECTION"
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><H1
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CLASS="SECTION"
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><A
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NAME="TS-BUY"
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></A
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>E.1. Considerations when buying second-hand terminal
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servers</H1
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><P
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>Internet Service Providers have been large users of terminal
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servers in the past. Each modem would be connected to a terminal
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server port and incoming users would be permitted to send
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<SPAN
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CLASS="ACRONYM"
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>IP</SPAN
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> packets anywhere, not just to some predefined
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minicomputer. Manufacturers renamed the equipment to <SPAN
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CLASS="QUOTE"
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>"access
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servers"</SPAN
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> or <SPAN
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CLASS="QUOTE"
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>"modem servers"</SPAN
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> to reflect this new
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use.</P
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><P
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>These access servers have been superseded by a new generation
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which allows telephone trunks to be plugged directly into the
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<SPAN
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CLASS="ACRONYM"
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>ISP</SPAN
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>'s router. There are no discrete modems; the
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modem tones are decoded by digital signal processing chips within
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the router. As a result terminal servers are currently readily
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available on the second-hand market.</P
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><P
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>When purchasing a second-hand terminal server ensure that you
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are also buying the rights to the software. Some companies license
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their software and have contract terms which state that the license
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cannot be resold, but has to be repurchased from the company if the
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terminal server changes hands.</P
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><P
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>Many vendors require a current maintenance contract to obtain
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software updates. These maintenance agreements can be expensive, a
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common figure is 15% per annum of the manufacturer's retail price.
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You may be able to source a cheaper software updates from a
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third-party maintenance supplier.</P
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><P
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>Many older terminal servers are no longer sold or supported
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by their vendors. Search the vendor's web site for <SPAN
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CLASS="QUOTE"
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>"end of
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life"</SPAN
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>.</P
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><P
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>Vendor support can be a particular issue when the
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most-recently available software does not fit within the
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<SPAN
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CLASS="ACRONYM"
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>RAM</SPAN
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> or flash memory contraints of the terminal
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server you have purchased. You should check this before purchasing
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a seond-hand terminal server. Upgrading flash memory can be
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particularly difficult, as the <SPAN
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CLASS="ACRONYM"
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>ROM</SPAN
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> on the
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motherboard may also need to be replaced with one aware of the new
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flash memory's characteristics.<A
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NAME="AEN4030"
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HREF="#FTN.AEN4030"
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><SPAN
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CLASS="footnote"
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>[1]</SPAN
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></A
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></P
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><P
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>Third-party parts suppliers such as <A
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HREF="http://www.kingston.com/"
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TARGET="_top"
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>Kingston</A
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> or <A
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HREF="http://www.memoryx.net/"
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TARGET="_top"
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>MemoryX</A
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> can usually provide
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dynamic <SPAN
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CLASS="ACRONYM"
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>RAM</SPAN
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> and flash memory. They cannot
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usually supply <SPAN
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CLASS="ACRONYM"
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>ROM</SPAN
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>s or static
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<SPAN
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CLASS="ACRONYM"
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>RAM</SPAN
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>.</P
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><P
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>Most old terminal servers will not support
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<SPAN
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CLASS="APPLICATION"
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>Secure Shell</SPAN
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>. In this is the case
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accessing the terminal server by its ethernet port is a poor idea:
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when you login to the console you password will travel across the
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Internet in clear text. Either dial in to the terminal server or
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use a one-time password system such as the
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<SPAN
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CLASS="PRODUCTNAME"
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><SPAN
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CLASS="ACRONYM"
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>RADIUS</SPAN
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></SPAN
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> protocol with
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<SPAN
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CLASS="PRODUCTNAME"
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>S/KEY</SPAN
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> authentication.</P
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><P
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>An alternative to using a terminal server is to use a
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multiport serial card in another <SPAN
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CLASS="SYSTEMITEM"
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>Linux</SPAN
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> system.</P
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></DIV
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><H3
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CLASS="FOOTNOTES"
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>Notes</H3
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><TABLE
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BORDER="0"
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CLASS="FOOTNOTES"
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WIDTH="100%"
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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WIDTH="5%"
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><A
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NAME="FTN.AEN4030"
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HREF="ts-buy.html#AEN4030"
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><SPAN
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CLASS="footnote"
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>[1]</SPAN
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></A
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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WIDTH="95%"
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><P
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>This is a fault with the design of flash memory. It
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identifies itself with a model designator rather than with the
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timings required to read and write the memory. So to load
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software from flash memory the boot <SPAN
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CLASS="ACRONYM"
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>ROM</SPAN
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> must
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have a table of flash memory models and
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timings.</P
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></TD
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></TR
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></TABLE
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><DIV
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CLASS="NAVFOOTER"
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><HR
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ALIGN="LEFT"
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WIDTH="100%"><TABLE
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SUMMARY="Footer navigation table"
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WIDTH="100%"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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><A
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HREF="ts.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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><TD
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WIDTH="34%"
|
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ALIGN="center"
|
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VALIGN="top"
|
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><A
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HREF="index.html"
|
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ACCESSKEY="H"
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>Home</A
|
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></TD
|
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><TD
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WIDTH="33%"
|
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ALIGN="right"
|
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VALIGN="top"
|
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><A
|
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HREF="ts-cisco2511.html"
|
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ACCESSKEY="N"
|
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>Next</A
|
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></TD
|
|
></TR
|
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><TR
|
|
><TD
|
|
WIDTH="33%"
|
|
ALIGN="left"
|
|
VALIGN="top"
|
|
>Terminal server configuration</TD
|
|
><TD
|
|
WIDTH="34%"
|
|
ALIGN="center"
|
|
VALIGN="top"
|
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><A
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HREF="ts.html"
|
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ACCESSKEY="U"
|
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>Up</A
|
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></TD
|
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><TD
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WIDTH="33%"
|
|
ALIGN="right"
|
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VALIGN="top"
|
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><SPAN
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CLASS="PRODUCTNAME"
|
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>Cisco 2511</SPAN
|
|
></TD
|
|
></TR
|
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></TABLE
|
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></DIV
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></BODY
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></HTML
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> |