508 lines
8.5 KiB
HTML
508 lines
8.5 KiB
HTML
<HTML
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><HEAD
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><TITLE
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>Common Problems</TITLE
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CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
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TITLE="Bridging mini-HOWTO"
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>Bridging mini-HOWTO</TH
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WIDTH="10%"
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="SECT1"
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><H1
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CLASS="SECT1"
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><A
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NAME="AEN72">2. Common Problems</H1
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><DIV
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CLASS="QANDASET"
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><DL
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><DT
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>Q: <A
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HREF="x72.html#AEN76"
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>I get the message <SPAN
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CLASS="ERRORNAME"
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>ioctl(SIOCGIFBR) failed: Package not installed
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</SPAN
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>. What does this mean?</A
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></DT
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><DT
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>Q: <A
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HREF="x72.html#AEN83"
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>Machines on one side cannot ping the other side!</A
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></DT
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><DT
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>Q: <A
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HREF="x72.html#AEN99"
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>I cannot <SPAN
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CLASS="APPLICATION"
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>telnet</SPAN
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>/<SPAN
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CLASS="APPLICATION"
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>ftp</SPAN
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> from the bridge! Why?</A
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></DT
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><DT
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>Q: <A
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HREF="x72.html#AEN106"
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>What do I need to set up in the way of routing?</A
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></DT
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><DT
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>Q: <A
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HREF="x72.html#AEN113"
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>The bridge appears to work, but why doesn't <SPAN
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CLASS="APPLICATION"
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>traceroute</SPAN
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> show the bridge as a part of the path?</A
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></DT
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><DT
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>Q: <A
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HREF="x72.html#AEN120"
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>Is it necessary to compile <TT
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CLASS="ENVAR"
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>IP_FORWARD</TT
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> into the kernel?</A
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></DT
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><DT
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>Q: <A
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HREF="x72.html#AEN127"
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>Why are the physical ethernet addresses for port 1 and port 2 the
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same according to the <SPAN
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CLASS="APPLICATION"
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>brcfg</SPAN
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> program?
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Shouldn't they be different?</A
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></DT
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><DT
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>Q: <A
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HREF="x72.html#AEN133"
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>Bridging does not appear to be an option when performing a make
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config on the kernel. How does one enable it?</A
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></DT
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><DT
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>Q: <A
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HREF="x72.html#AEN140"
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>Too many hubs (4 or more) are chained one after another in series,
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cause timing problems on an ethernet. What effect does a bridge
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have in a subnet that is layered with hubs?</A
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></DT
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><DT
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>Q: <A
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HREF="x72.html#AEN145"
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>Can a bridge interface to both 10Mb and 100Mb ethernet segments?
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Will such a configuration slow down the rest of the traffic on the
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high speed side?</A
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></DT
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></DL
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><DIV
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CLASS="QANDAENTRY"
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><DIV
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CLASS="QUESTION"
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><P
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><A
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NAME="AEN76"><B
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>Q: </B
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>I get the message <SPAN
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CLASS="ERRORNAME"
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>ioctl(SIOCGIFBR) failed: Package not installed
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</SPAN
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>. What does this mean?</P
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></DIV
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><DIV
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CLASS="ANSWER"
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><P
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><B
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>A: </B
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>You don't have bridging capability in your kernel.
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Get a 2.0 or greater kernel,
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and recompile with the <TT
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CLASS="ENVAR"
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>BRIDGING</TT
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> option enabled.</P
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></DIV
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></DIV
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><DIV
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CLASS="QANDAENTRY"
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><DIV
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CLASS="QUESTION"
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><P
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><A
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NAME="AEN83"><B
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>Q: </B
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>Machines on one side cannot ping the other side!</P
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></DIV
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><DIV
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CLASS="ANSWER"
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><P
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><B
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>A: </B
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><LI
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><SPAN
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>Did you enable bridging using <SPAN
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CLASS="APPLICATION"
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>brcfg -ena</SPAN
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>? (<SPAN
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CLASS="APPLICATION"
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>brcfg</SPAN
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> should say <SPAN
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CLASS="RETURNVALUE"
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>bridging is ENABLED</SPAN
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>)</SPAN
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></LI
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><LI
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><SPAN
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>Did you put the interfaces into promiscuous mode?
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(issue the <SPAN
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CLASS="APPLICATION"
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>ifconfig</SPAN
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> command.
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The <SPAN
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CLASS="PROPERTY"
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>PROMISC</SPAN
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> flag should be on for
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both interfaces.)</SPAN
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></LI
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><LI
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><SPAN
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>If using multiple-media interface adapters,
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make sure that the correct one is enabled.
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You may need to use the config/setup program that
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came with the network interface card.</SPAN
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></LI
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></P
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></DIV
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></DIV
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><DIV
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CLASS="QANDAENTRY"
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><DIV
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CLASS="QUESTION"
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><P
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><A
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NAME="AEN99"><B
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>Q: </B
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>I cannot <SPAN
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CLASS="APPLICATION"
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>telnet</SPAN
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>/<SPAN
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CLASS="APPLICATION"
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>ftp</SPAN
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> from the bridge! Why?</P
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></DIV
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><DIV
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CLASS="ANSWER"
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><P
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><B
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>A: </B
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>This is because there is no IP address bound to any of bridge
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interfaces. A bridge is to be a transparent part of a network.</P
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></DIV
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></DIV
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><DIV
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CLASS="QANDAENTRY"
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><DIV
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CLASS="QUESTION"
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><P
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><A
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NAME="AEN106"><B
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>Q: </B
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>What do I need to set up in the way of routing?</P
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></DIV
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><DIV
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CLASS="ANSWER"
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><P
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><B
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>A: </B
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>Nothing!
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All routing intelligence is handled by
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the bridging code in the kernel.
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To see the ethernet addresses as they are learned by the bridge,
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use the <SPAN
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CLASS="APPLICATION"
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>brcfg</SPAN
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> program in debug mode:</P
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><TABLE
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BORDER="1"
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BGCOLOR="#E0E0E0"
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WIDTH="100%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="SCREEN"
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>brcfg -deb
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</PRE
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></FONT
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></TD
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></TR
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></TABLE
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></DIV
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></DIV
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><DIV
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CLASS="QANDAENTRY"
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><DIV
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CLASS="QUESTION"
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><P
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><A
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NAME="AEN113"><B
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>Q: </B
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>The bridge appears to work, but why doesn't <SPAN
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CLASS="APPLICATION"
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>traceroute</SPAN
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> show the bridge as a part of the path?</P
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></DIV
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><DIV
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CLASS="ANSWER"
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><P
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><B
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>A: </B
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>Due to the nature of a bridge, a <SPAN
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CLASS="APPLICATION"
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>traceroute</SPAN
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> should NOT show the bridge as a part of the path. A bridge is to be a transparent component of the network.</P
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></DIV
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></DIV
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><DIV
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CLASS="QANDAENTRY"
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><DIV
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CLASS="QUESTION"
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><P
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><A
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NAME="AEN120"><B
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>Q: </B
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>Is it necessary to compile <TT
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CLASS="ENVAR"
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>IP_FORWARD</TT
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> into the kernel?</P
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></DIV
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><DIV
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CLASS="ANSWER"
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><P
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><B
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>A: </B
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>No. The bridging code in the kernel takes care of the packet
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transport.
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<TT
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CLASS="ENVAR"
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>IP_FORWARD</TT
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> is for a gateway that has IP addresses
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bound to its interfaces.</P
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></DIV
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></DIV
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><DIV
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CLASS="QANDAENTRY"
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><DIV
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CLASS="QUESTION"
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><P
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><A
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NAME="AEN127"><B
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>Q: </B
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>Why are the physical ethernet addresses for port 1 and port 2 the
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same according to the <SPAN
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CLASS="APPLICATION"
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>brcfg</SPAN
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> program?
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Shouldn't they be different?</P
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></DIV
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><DIV
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CLASS="ANSWER"
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><P
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><B
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>A: </B
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>No. Every port on a bridge intentionally is assigned the same
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physical ethernet address by the bridging code.</P
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></DIV
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></DIV
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><DIV
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CLASS="QANDAENTRY"
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><DIV
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CLASS="QUESTION"
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><P
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><A
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NAME="AEN133"><B
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>Q: </B
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>Bridging does not appear to be an option when performing a make
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config on the kernel. How does one enable it?</P
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></DIV
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><DIV
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CLASS="ANSWER"
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><P
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><B
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>A: </B
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>During the kernel config, answer <SPAN
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CLASS="QUOTE"
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>"Y"</SPAN
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> to the question, <TT
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CLASS="PROMPT"
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>Prompt for
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development and/or incomplete code/drivers (CONFIG_EXPERIMENTAL) [Y/n/?]</TT
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>.</P
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></DIV
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></DIV
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><DIV
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CLASS="QANDAENTRY"
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><DIV
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CLASS="QUESTION"
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><P
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><A
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NAME="AEN140"><B
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>Q: </B
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>Too many hubs (4 or more) are chained one after another in series,
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cause timing problems on an ethernet. What effect does a bridge
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have in a subnet that is layered with hubs?</P
|
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></DIV
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><DIV
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CLASS="ANSWER"
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><P
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><B
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>A: </B
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>A bridge resets the 3/4/5 hubs rule. A bridge does not deal with
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packets the way a hub does, and is therefore not a contributor to
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timing problems on a network.</P
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></DIV
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></DIV
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><DIV
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CLASS="QANDAENTRY"
|
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><DIV
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CLASS="QUESTION"
|
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><P
|
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><A
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NAME="AEN145"><B
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>Q: </B
|
|
>Can a bridge interface to both 10Mb and 100Mb ethernet segments?
|
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Will such a configuration slow down the rest of the traffic on the
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high speed side?</P
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></DIV
|
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><DIV
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CLASS="ANSWER"
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><P
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><B
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>A: </B
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>Yes, a bridge can tie together a 10Mb segment with a 100Mb segment.
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As long as the network card on the fast network is 100Mb capable,
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TCP takes care of the rest. While it's true that the
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packets from a host in the 100Mb network communicating to a host
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in the 10Mb network are moving at only 10Mb/s, the rest of the
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traffic on the fast ethernet is not slowed down.</P
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></DIV
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></DIV
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></DIV
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></DIV
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HREF="x23.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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VALIGN="top"
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HREF="x149.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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>Setup</TD
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