Annotation of embedaddon/mpd/doc/mpd19.html, revision 1.1.1.4

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                      5: <TITLE>Mpd Layers</TITLE>
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1.1.1.4 ! misho       9: <A HREF="mpd.html"><EM>Mpd 5.9 User Manual</EM></A>
1.1       misho      10:  <b>:</b> <A HREF="mpd17.html"><EM>Configuring Mpd</EM></A>
                     11:  <b>:</b> <EM>Mpd Layers</EM><BR>
                     12: <b>Previous:</b> <A HREF="mpd18.html"><EM>General mpd commands</EM></A><BR>
                     13: <b>Next:</b> <A HREF="mpd20.html"><EM>Link layer</EM></A>
                     14: 
                     15: 
                     16: <HR NOSHADE>
                     17:   <H2><A NAME="19"></A>4.2. Mpd Layers<A NAME="layers"></A></H2>
                     18: <p>Mpd consists of several <b>layers</b>, corresponding
                     19: to the layered nature of the PPP protocol. There are two
                     20: types of layers hierarchy connected with two different 
                     21: operation modes as "ppp terminator" and "ppp repeater".
                     22: Operation mode is getting chosen dynamically depending on link
                     23: configuration and user auth name (see 'set link action ...' command).</p>
                     24: <p>In "ppp terminator" mode such hierarchy used:
                     25: <b>
1.1.1.4 ! misho      26: <A HREF="mpd28.html#interface">Interface</A></b> -&gt;
1.1       misho      27: <b>
1.1.1.4 ! misho      28: <A HREF="mpd26.html#ipcp">NCPs</A></b> -&gt;
1.1       misho      29: <b>
1.1.1.4 ! misho      30: <A HREF="mpd24.html#compression">Compression</A></b> -&gt;
1.1       misho      31: <b>
1.1.1.4 ! misho      32: <A HREF="mpd23.html#encryption">Encryption</A></b> -&gt;
1.1       misho      33: <b>
1.1.1.4 ! misho      34: <A HREF="mpd22.html#bundle">Bundle</A></b> -&gt; 
1.1       misho      35: <b>
1.1.1.4 ! misho      36: <A HREF="mpd20.html#links">Links</A></b></p>
1.1       misho      37: <p>In "ppp repeater" mode different hierarchy used:
                     38: <b>
1.1.1.4 ! misho      39: <A HREF="mpd20.html#links">Link1</A></b> -&gt;
1.1       misho      40: <b>Repeater</b> -&gt; 
                     41: <b>
1.1.1.4 ! misho      42: <A HREF="mpd20.html#links">Link2</A></b></p>
1.1       misho      43: <p>A <b>
1.1.1.4 ! misho      44: <A HREF="mpd20.html#links">link</A></b> is a single point-to-point
1.1       misho      45: connection between the local machine and a remote peer machine, 
                     46: implemented by some kind of physical device, 
                     47: such as a serial modem connection or a virtual PPTP connection.</p>
                     48: <p>Link parameters include whether authentication is enabled in
                     49: either direction, the authentication type (PAP or CHAP)
                     50: used, keep-alive packets, multilink negotiation options
                     51: and various other link specific parameters.</p>
                     52: <p>Lower half of the link layer is the physical devices layer.
                     53: Configuration of device type specific parameters happens at this layer. 
                     54: Each device has a specific <em>type</em>
                     55: corresponding to one of the supported device types in mpd.
                     56: The type dictates how the device dependent part
                     57: is configured and what it's capabilities are.</p>
                     58: <p>A <b>
                     59: <A HREF="mpd22.html#bundle">bundle</A></b> is a collection 
                     60: of one or more links, all connecting
                     61: to the same remote peer, that together form a single
                     62: multi-link PPP connection whose effective bandwidth is
                     63: the sum of the bandwidths of the individual links.</p>
                     64: <p>The bundle layer in effect lies just above the link layer.
                     65: The bundle layer handles the task of making multiple 
                     66: physical links appear as a single virtual link.</p>
                     67: <p>At the bundle layer you configure multi-link
                     68: PPP settings and the link management policy. The link management
                     69: policy determines whether mpd tries to keep all the links
                     70: connected all the time, or whether it adds and subtracts
                     71: links depending on demand, and if so, according to what parameters.</p>
                     72: <p>With each bundle is a corresponding 
                     73: <b>
                     74: <A HREF="mpd28.html#interface">interface</A></b> layer,
                     75: which corresponds directly to a system network interface
                     76: accessible via <code>ifconfig(8)</code>, such as <code>ng0</code>.
                     77: The interface layer handles configuring the interface,
                     78: bringing it up or down as appropriate, assigning
                     79: IP addresses, setting up static routes and configuring proxy-ARP.
                     80: The interface layer is also responsible for implementing
                     81: Dial-on-Demand and idle timeout functionality.</p>
                     82: <p>Each bundle has several corresponding NCP layers as
                     83: <b>
1.1.1.4 ! misho      84: <A HREF="mpd26.html#ipcp">IP Control Protocol (IPCP)</A></b> and
1.1       misho      85: <b>
1.1.1.4 ! misho      86: <A HREF="mpd27.html#ipv6cp">IPv6 Control Protocol (IPv6CP)</A></b>,
1.1       misho      87: which manages the protocol specific configuration of the interface.
                     88: This layers handle the negotiation of local and remote addresses
                     89: and TCP header compression, as well as other optional 
                     90: IP related information such as DNS servers and NBNS servers.</p>
                     91: <p>Each bundle also has corresponding
                     92: <b>
1.1.1.4 ! misho      93: <A HREF="mpd24.html#compression">compression (CCP)</A></b> and
1.1       misho      94: <b>
1.1.1.4 ! misho      95: <A HREF="mpd23.html#encryption">encryption (ECP)</A></b> layers, which
1.1       misho      96: allow you to enable and configure compression and encryption
                     97: for data sent and received over the bundle.</p>
                     98: <p>A <b>repeater</b> is a collection of two physical devices 
                     99: (links). It is getting created when there is need to forward 
                    100: connection coming from one physical device to another without
                    101: modification. This technology is also known as LAC 
                    102: (L2TP Access Concentrator) and PAC (PPTP Access Concentrator).</p>
                    103: <p>While the combination of all the various layers presents
                    104: a large number of configuration options, mpd tries to
                    105: have reasonable defaults for everything.</p>
                    106: 
                    107: 
                    108: 
                    109:  <HR NOSHADE>
1.1.1.4 ! misho     110: <A HREF="mpd.html"><EM>Mpd 5.9 User Manual</EM></A>
1.1       misho     111:  <b>:</b> <A HREF="mpd17.html"><EM>Configuring Mpd</EM></A>
                    112:  <b>:</b> <EM>Mpd Layers</EM><BR>
                    113: <b>Previous:</b> <A HREF="mpd18.html"><EM>General mpd commands</EM></A><BR>
                    114: <b>Next:</b> <A HREF="mpd20.html"><EM>Link layer</EM></A>
                    115: 
                    116: 
                    117: 
                    118: </BODY>
                    119: </HTML>

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