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$ 100-300 |
| Status: |
Closed
for Bidding (selected
user daizisheng)
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Description
Write a program for GNU Linux that simulates the IP routing. The following algorithm MUST be used:
Algorithm:
RouteDatagram ( Datagram, Routing Table)
Extract destination IP address, D, from the datagram
And compute the network prefix, N;
if N matches any directly connected network address
deliver datagram to destination D over that network
(This involves resolving D to a physical address,
encapsulating the datagram, and sending the frame.)
else if the table contains a host-specific route for D
send datagram to nest-hop specified in table
else if the table contains a route for network N
send datagram to next-hop specified in table
else if the table contains a default route
send datagram to the default router specified in table
else declare a routing error.
The algorithm uses IP to forward a datagram. If this program is given an IP datagram and a routing table, this algorithm selects the next hop to which the datagram should be sent. All routes must specify a next hop that lies on a directly connected network. Network topology must vary. The simulation needs to be fairly detailed, with statistics from the routing table like next hop.
Here is sample data for routing test:
M_ENTRIES table = { 4,
{ {1, 0xc0a80016, 0xffffffff},
{2, 0xabf34718, 0xabf30001},
{3, 0xc0a801ff, 0xc0a80101},
{4, 0xffffffff, 0xc0a80001}
}
}
unsigned char data1[] = {0x45, 0x20, 0x00, 0x80, 0xD3, 0xD5, 0x00,
0x00, 0x72, 0x11, 0xC5, 0xC9, 0xab, 0xf3,
0x47, 0x18, 0xC0, 0xA8, 0x00, 0x05, 0x98,
0xED, 0x9C, 0x86, 0x00, 0x6C, 0xD7, 0x1A,
0x98, 0xED, 0xC5, 0x1A, 0x00, 0x00, 0x48,
0x23, 0x62, 0x1A, 0x71, 0x78, 0x00, 0x03,
0x00, 0x55, 0x00, 0x00, 0x23, 0x7D, 0x00,
0x00, 0x01, 0x7B, 0x00, 0x00, 0x00, 0x00,
0x17, 0x03, 0x00, 0x00, 0x40, 0x1D, 0x02,
0xEC, 0x77, 0x6C, 0xC9, 0xBF, 0x1A, 0x8C,
0x7F, 0x57, 0xB7, 0xC7, 0x5A, 0x00, 0xE5,
0xB3, 0xF4, 0x2B, 0x35, 0x64, 0x2B, 0x0F,
0xD9, 0x5E, 0x0A, 0xBB, 0xEB, 0x4B, 0x67,
0x25, 0x1A, 0xF4, 0x78, 0xCB, 0x36, 0x06,
0x7F, 0xC2, 0xC6, 0xFC, 0xCE, 0x7C, 0x83,
0xFE, 0xB0, 0x9B, 0xC9, 0x0D, 0x8A, 0xB0,
0x21, 0x88, 0x35, 0xAD, 0x15, 0xFD, 0xF3,
0xF0, 0x45, 0x03, 0x5A, 0x86, 0x85, 0x00,
0x00, 0x00 };
here is what program might look like:
/* A structure that defines a single entry
The first byte specifies the type of entry.
There are three types of entries,
1. A host specific entry
2. A routed network entry
3. A default entry
see for more info:
http://computer.howstuffworks.com/routing-algorithm2.htm
http://en.wikipedia.org/wiki/Distance-vector for more info
a directly connected networks are only determined
by looking at the machines IP address and the destination
IP address. If they both are on the same N then the
destination is considered to be on the same network.
*/
typedef struct entry{
#define DIRECT_NETWORK_ENTRY 1
#define HOST_SPECIFIC_ENTRY 2
#define ROUTED_NETWORK_ENTRY 3
#define DEFAULT_GETEWAY_ENTRY 4
unsigned char type_of_entry;
unsigned char matching_criteria[4]; /* routing decision is based if it
matches this address */
unsigned char forwarding_address[4]; /* forwarding or next hop address */
} ENTRY;
typedef struct entry * PENTRY;
/* A structure that defines a table of entries
The first element specifies how many entries
exist in the table
Each entry that follows is of type ENTRY
*/
typedef struct multiple_entries
{
int number_of_entries;
PENTRY* entries;
} M_ENTRIES;
typedef struct multiple_entries * P_MENTRIES;
/* An example of a Table
---------------------
M_ENTRIES table = { 3,
{ {2, 192.168.0.20, 192.168.0.2},
{3, 192.168.1.* , 192.168.1.2},
{4, 192.168.0.* , 192.168.0.1}
}
}
*/
Reminder
You may not start working in this and any project before
your bid is accepted. Any user who violates this policy
may have their account permanently suspended.
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