There are several things I didn't get in the slides, some of them being just typos, I think.
in archi.ppt on top left of page 39, there is the formula T = L/D, shouldn't it be T = L/b ?
in tcp.ppt on pages 43, there are several things I don't understand :
"Reset timers for packets 4, 5, 6", as packet 6 is an ack, shouldn't it be "Reset timers for packets 4, 5" ?
then at event 8, why does the sender waits for the ack (event 9) before sending the next packet ? Is it because it's usable window is empty ?
there is something I don't understand with the "win" field (same on page 57). It is supposed to be the offered Window Size so I suppose that on the acks, it represents the window's size the sender should use (credits). And on the data, it represents the window's size the sender is actually using. So why don't they match ? After receiving an ack, the window's size should be set the the received value, and then the next sent packet should piggyback this same value.
in dv.ppt on page 9, I think there is a typo on the 3rd (should add B4 at the end) and 4th routes (should add B2 between R2 and R3).
on page 36, the statement "Just before B updates its table..." shouldn't it be "Just before B broadcasts its table..." ?
on page 42, I don't understand what the "bounce effect" is. Is it just a synonym for slow convergence ?
on page 43, I think the starting scenario is: link 1 fails -> the system converge to a new stable state -> link 6 fails -> D updates its table (sets costs to INF). Then the entry "B l3 INF" on table D is not logical, is should be : "B l6 INF" (same for pages 46, 47, 48)
Are these statements true ?:
split horizon can fail only if there is a loop;
even if there is a loop, the order of the broadcasts will determine failure or success of split horizon (success if all routers with correct infinite values are able to broadcast their values to all neighbors before receiving incorrect values);
even if split horizon fails, the routers will just count toward infinity, thus (slowly) converging to a stable state.
in bgp.ppt on page 5, it is said that ARD D and B are transit. It's ok for D since it serves as a relay between A and C. But it's not the case for B so shouldn't B be multihomed instead of transit ?
on page 12, the last line states that : "ISP 1 announces to ISP3 only routes to ISP3?s customers". But it doesn't make sense to me, so shouldn't it be "... only routes to ISP1?s customers" ? This way, ISP3 is not aware of the connection between ISP2 and ISP1 and therefore cannot send its packet to ISP2 through ISP1.
on page 20, the import policy accepts or rejects routes. But what is the point of rejecting some routes ? Are there incorrect routes ? And if yes, how can they be detected ?
on pages 34, 35, 79, 80, the address 126.96.36.199 is the external address of router R5 and not R6 ?
on page 80, shouldn't R1 also inject the route in its forwarding table ?
Posted by René Giller on Saturday 16 December 2006 at 1:37