A、A. by track<m>em>m>inm>em>m>g thm>em> status of objm>em>cts along thm>em> path to thm>em> <m>em>m>m>em>-commm>em>rcm>em>m>em>m> modulm>em> B、B. by dm>em>tm>em>ct<m>em>m>inm>em>m>g undm>em>sirablm>em> conditions along thm>em> path to thm>em> <m>em>m>m>em>-commm>em>rcm>em>m>em>m> modulm>em> C、C. by us<m>em>m>inm>em>m>g thm>em> Mm>Em>D to communicatm>em> thm>em> sitm>em> prm>em>fm>em>rm>em>ncm>em>s for traffic to multiplm>em> ISPs D、D. by communicat<m>em>m>inm>em>m>g thm>em> availablm>em> prm>em>fixm>em>s, rout<m>em>m>inm>em>m>g policim>em>s, and prm>em>fm>em>rm>em>ncm>em>s of m>em>ach sitm>em> to its ISP m>Em>、m>Em>. by mov<m>em>m>inm>em>m>g thm>em> SLB to a position whm>em>rm>em> sm>em>lm>em>ctm>em>d traffic to and from thm>em> sm>em>rvm>em>rs dom>em>s not go through thm>em> SLB