Annotation of embedaddon/mpd/doc/mpd19.html, revision 1.1
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! 2: <HTML>
! 3: <HEAD>
! 4: <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
! 5: <TITLE>Mpd Layers</TITLE>
! 6: </HEAD>
! 7: <BODY text="#000000" bgcolor="#ffffff">
! 8:
! 9: <A HREF="mpd.html"><EM>Mpd 5.6 User Manual</EM></A>
! 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>
! 26: <A HREF="mpd28.html#interface">interface</A></b> ->
! 27: <b>
! 28: <A HREF="mpd26.html#ipcp">ipcp</A></b> ->
! 29: <b>
! 30: <A HREF="mpd24.html#compression">compression</A></b> ->
! 31: <b>
! 32: <A HREF="mpd23.html#encryption">encryption</A></b> ->
! 33: <b>
! 34: <A HREF="mpd22.html#bundle">bundle</A></b> ->
! 35: <b>
! 36: <A HREF="mpd20.html#links">links</A></b></p>
! 37: <p>In "ppp repeater" mode different hierarchy used:
! 38: <b>
! 39: <A HREF="mpd20.html#links">links</A></b> ->
! 40: <b>Repeater</b> ->
! 41: <b>
! 42: <A HREF="mpd20.html#links">links</A></b></p>
! 43: <p>A <b>
! 44: <A HREF="mpd20.html#links">links</A></b> is a single point-to-point
! 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>
! 84: <A HREF="mpd26.html#ipcp">ipcp</A></b> and
! 85: <b>
! 86: <A HREF="mpd27.html#ipv6cp">ipv6cp</A></b>,
! 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>
! 93: <A HREF="mpd24.html#compression">compression</A></b> and
! 94: <b>
! 95: <A HREF="mpd23.html#encryption">encryption</A></b> layers, which
! 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>
! 110: <A HREF="mpd.html"><EM>Mpd 5.6 User Manual</EM></A>
! 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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