RIP
Features:
Based on the distance vector
format (N, d, X) to the destination network N, a distance d, the next hop is XSwap adjacent information
exchange is that all of the information in this router that, in the exchange process will converge and stabilizeSuitable for small networks inside and
a large network to update the table will be high time complexity of
the internal network environment means without regard to excessive environmental factors, the algorithm is more theoretical comparison of ridiculousUsing a UDP packet
RIP update cycle all network information, still need a larger data packets
Direct host router to a non-direct distance is compared with the number of elapsed +1 router
address X with the neighboring routers RIP packet to the next hop X (see Dictionary 1 understand, is to d [x] = d [y] +1], to the rear of a you know from X, X denotes a distance through a network N is d [x])
Specifically:
IF project is not the destination network N, is added to the routing table, such as (N2,3, Y) === no N2 of> (N2,4, X-)
the else see next hop
---- next hop original IF X will be unconditionally updated to ensure the latest network topology state time
---- else next hop is not X, d need to see better is updated
You did not receive the update within 3min not set up to d = 16
As for the next hop usage, I think it was in response to the ARP packet is of no use, when a request query path, recognizable by the next hop to where to go and how much distance (router Ri in the project Subject to the first two hops constant determination condition was the last sent Rj) <==== because hand ARP packet is updated to immediately modify a packet to all the sender himself and d + 1
If R4 update sent (N, 5, R1) to the original R6 (N, 1, R7) == > update messages to update (N, 6, R4), comparative (N, 1, R7), go the third condition is not updated
if R4 update sent (N, 5, R1) to the original R6 (N, 9, R7) == > update messages to update (N,. 6, R4), comparative (N , 1, R7), take the third condition, updating (N, 6, R4), the current distance can be up to 6 N, go to the next step to R4!
The rest of empathy, more examples see [4-5] Total net example
OSPF
Open path limited
compared to more suitable for larger type of internal environment and RIP routing
1. flooding, comparative RIP only send information to several adjacent routers, the method is adjacent bracing for all (but not sent to the original input port)
2. link change only when updated, RIP is a regularly updated
3. send only adjacent to this router link status of all router (only those nodes measure to inform the next adjacent router itself), compared to all of the network is RIP
Some optimization:
1. Add area concept, dividing more autonomous systems, reducing traffic flooding
2. Direct use of IP packets (itself provide a reliable transmission, and therefore on this basis as small as possible so that packets )
3. (meter net P161, process is a bit vague ..)
Packet type
1.hello group, ask connectivity
2. database state, to the adjacent node's own summary information
3. Link state request, link-state request to the other
4. Update packet (the book mentioned here out)
5. link state acknowledgment
Process
1. connectivity status is obtained by Hello
2. By such a database to synchronize database description
3 link change case: Request -> Update -> Confirm
The book is not much concrete description, it should be the mechanism is more complex, as the understanding of it ( `· ω ·)