ans_hw4 - (outside of the AS receiving the advertisement)...

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Homework #4 Answers Each problem/question worth 20 points Page 421-435 (Kurose and Ross) Review Questions: 11, 24, and 30 Problems: 9 and 24 Review Question : 11 HOL blocking – a queued packet in an input queue must wait for transfer through the fabric because it is blocked by another packet at the head of the line. It occurs at the input port. Review Question : 24 No. The advertisement tells D that it can get to z in 11 hops by way of A. However, D can already get to z by way of B in 7 hops. Therefore, there is no need to modify the entry for z in the table. If, on the other hand, the advertisement said that A was only 4 hops away from z by way of C, then D would indeed modify its forwarding table. Review Question : 30 Routers use the AS-PATH attribute to detect and prevent looping advertisements; they also use it in choosing among multiple paths to the same prefix. The NEXT-HOP attribute indicates the IP address of the first router along an advertised path
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Unformatted text preview: (outside of the AS receiving the advertisement) to a given prefix. When configuring its forwarding table, a router uses the NEXT-HOP attribute. Problem : 9 a) Prefix Match Link Interface 11100000 00 11100000 01000000 1 1110000 2 11100001 1 3 otherwise 3 b) Prefix match for first address is 5th entry: link interface 3 Prefix match for second address is 3rd entry: link interface 2 Prefix match for third address is 4th entry: link interface 3 Problem : 24 Step N D(t),p(t) D(u),p(u) D(v),p(v) D(w),p(w) D(y),p(y) D(z),p(z) x 3,x 6,x 6,x 8,x 1 x v 7,v 6,v 3,x 6,x 6,x 8,x 2 xv u 7,v 6,v 3,x 6,x 6,x 8,x 3 xvu w 7,v 6,v 3,x 6,x 6,x 8,x 4 xvuw y 7,v 6,v 3,x 6,x 6,x 8,x 5 xvuwy t 7,v 6,v 3,x 6,x 6,x 8,x 6 xvuwyt z 7,v 6,v 3,x 6,x 6,x 8,x...
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This note was uploaded on 11/01/2010 for the course INFS 612 taught by Professor Staff during the Fall '08 term at George Mason.

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ans_hw4 - (outside of the AS receiving the advertisement)...

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