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The ns Manual (formerly ns Notes and Documentation)1 - NM Lab at ...

The ns Manual (formerly ns Notes and Documentation)1 - NM Lab at ...

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<strong>The</strong> final object th<strong>at</strong> a received packet passes through is an object of class NetworkInterface. This object stampsthe iface_ field in the common header with the network stack’s unique index value. This is used to keep track of whichnetwork stack a packet arrived on. <strong>The</strong> packet then goes to the entry of the S<strong>at</strong>Node (usually, an address classifier).Finally, “geo-repe<strong>at</strong>er” s<strong>at</strong>ellites exist, as described earlier in this chapter. Geo-repe<strong>at</strong>er network stacks are very simple– theyonly contain a Phy_tx <strong>and</strong> a Phy_rx of class Repe<strong>at</strong>erPhy, <strong>and</strong> a S<strong>at</strong>LinkHead. Packets received by a Phy_rx are sentto the Phy_tx without delay. <strong>The</strong> geo-repe<strong>at</strong>er s<strong>at</strong>ellite is a degener<strong>at</strong>e s<strong>at</strong>ellite node, in th<strong>at</strong> it does not contain things liketracing elements, h<strong>and</strong>off managers, routing agents, or any other link interfaces other than repe<strong>at</strong>er interfaces.17.4 Comm<strong>and</strong>s <strong>at</strong> a glanceFollowing is a list of comm<strong>and</strong>s rel<strong>at</strong>ed to s<strong>at</strong>ellite networking:$<strong>ns</strong>_ node-config -s<strong>at</strong>NodeType This node configur<strong>at</strong>ion declares th<strong>at</strong> the subsequent new nodes cre<strong>at</strong>ed will be of type , where can be one ofthe following: geo, geo-repe<strong>at</strong>er, polar, terminal. Other required fields for s<strong>at</strong>ellite nodes (for setting upinitial links <strong>and</strong> channels) are as follows (see Section 5.3): $<strong>ns</strong>_ node-config -llType $<strong>ns</strong>_ node-config -ifqType $<strong>ns</strong>_ node-config -ifqLen $<strong>ns</strong>_ node-config -macType $<strong>ns</strong>_ node-config -channelType $<strong>ns</strong>_ node-config -downlinkBW (note– s<strong>at</strong>NodeType geo-repe<strong>at</strong>er only requires specifying the channelType– all other optio<strong>ns</strong> are disregarded. Seetcl/ex/s<strong>at</strong>-repe<strong>at</strong>er.tcl for an example.)$<strong>ns</strong>_ s<strong>at</strong>node-polar This a simul<strong>at</strong>or wrapper method for cre<strong>at</strong>ing a polar s<strong>at</strong>ellite node. Two links, uplink <strong>and</strong> downlink, are cre<strong>at</strong>ed along withtwo channels, uplink channel <strong>and</strong> downlink channel. is the polar s<strong>at</strong>ellite altitude, is orbit inclin<strong>at</strong>ion w.r.tequ<strong>at</strong>or, is the longitude of ascending node, gives the initial position of the s<strong>at</strong>ellite along this orbit, defines the plane of the polar s<strong>at</strong>ellite. is a list of link argument optio<strong>ns</strong> th<strong>at</strong> defines the network interface (likeLL, Qtype, Qlim, PHY, MAC etc).$<strong>ns</strong>_ s<strong>at</strong>node-geo This is a wrapper method for cre<strong>at</strong>ing a geo s<strong>at</strong>ellite node th<strong>at</strong> first cre<strong>at</strong>es a s<strong>at</strong>node plus two link interfaces (uplink <strong>and</strong>downlink) plus two s<strong>at</strong>ellite channels (uplink <strong>and</strong> downlink). defines the type of channel.$<strong>ns</strong>_ s<strong>at</strong>node-geo-repe<strong>at</strong>er This is a wrapper method for making a geo s<strong>at</strong>ellite repe<strong>at</strong>er node th<strong>at</strong> first cre<strong>at</strong>es a s<strong>at</strong>node plus two link interfaces (uplink<strong>and</strong> downlink) plus two s<strong>at</strong>ellite channels (uplink <strong>and</strong> downlink).$<strong>ns</strong>_ s<strong>at</strong>node-terminal This is a wrapper method th<strong>at</strong> simply cre<strong>at</strong>es a terminal node. <strong>The</strong> <strong>and</strong> defines the l<strong>at</strong>itude <strong>and</strong> longituderespectively of the terminal.$<strong>ns</strong>_ s<strong>at</strong>node This is a more primitive method for cre<strong>at</strong>ing s<strong>at</strong>nodes of type which can be polar, geo or terminal.$s<strong>at</strong>node add-interface This is an internal method of Node/S<strong>at</strong>Node th<strong>at</strong> sets up link layer, mac layer, interface queue <strong>and</strong> physical layer structuresfor the s<strong>at</strong>ellite nodes.185

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