CIS 656, Dr Ott, Fall 2004, Network Description. Network Description, ``project B''. Composition of teams is due 10/23 or soon after. Maximum teamsize = 2, Minimum = 1. Recommended size is 2. This is a hypothetical private network inside NJIT, with a private address space, connected through a NAT Router (Network Address Translation) to the rest of the NJIT network, and thus to the rest of the Internet. A drawing of this network is available on Dr Ott's web page. For a computer (router) the drawing is not necessary: all relevant information is given below. But the drawing makes life easier for us humans! There are 9 Routers inside the private network (R1, ... , R9). There are 12 subnetworks inside the private network (I, ... , XII). The NAT router is outside the private network. Network I is the boundary and has only two interfaces on it: it is a ``point to point link'', see Forouzan page 369. This is irrellevant to the project. Network addresses and MTUs: Netw address MTU I 10.1.0.0/24 65535 II 10.10.0.0/20 65535 III 10.2.16.0/20 65535 IV 10.2.32.0/20 17914 V 10.10.128.0/20 4352 VI 10.1.1.0/24 65535 VII 10.10.16.0/22 4464 VIII 10.10.24.0/22 576 IX 10.5.128.0/22 1500 X 10.5.192.0/22 65535 XI 10.5.132.0/22 65535 XII 10.5.136.0/22 1500 Interfaces: NAT: A1 to I R1: A2 to I, A3 to II. R2: A4 to II, A5 to III. R3: A6 to III, A7 to IV, A8 to V, A9 to VI, A10 to VII, A11 to VIII. R4: A12 to IV, A13 to IX. R5: A14 to V, A15 to IX. R6: A16 to VII, A17 to XII. R7: A18 to VI, A19 to X. R8: A20 to X, A21 to XI. R9: A22 to XI, A23 to XII. The other port(s) on the NAT router do not concern us. Addresses of interfaces. (If I goofed, like using an address twice, or give an address not in the subnework the interface is on, please let me and Mr Jain know). A1 10.1.0.1 A2 10.1.0.254 A3 10.10.0.1 A4 10.10.0.254 A5 10.2.16.1 A6 10.2.16.254 A7 10.2.32.1 A8 10.10.128.1 A9 10.1.1.1 A10 10.10.16.1 A11 10.10.24.1 A12 10.2.32.254 A13 10.5.128.1 A14 10.10.128.254 A15 10.5.128.254 A16 10.10.16.254 A17 10.5.136.1 A18 10.1.1.254 A19 10.5.192.1 A20 10.5.192.254 A21 10.5.132.1 A22 10.5.132.254 A23 10.5.136.254 Routing is ``min-hop'': Routers always try to use the route that has the smallest number of intermediate routers. There are some ties: From R3 to IX routing could go over either R4 or R5. The decision is to go over (IV, R4). (Larger MTU, must be a static route put in by hand!). From R3 to XI routing could go over either (R6, R9) or over (R7, R8). The decision is to go over (VI, R7, X, R8). (Larger minimal MTU, must be a static route put in by hand!). Note: This way of breaking ties can be done by a human using static routing, not by routers using RIP or OSPF ! All routers (but R1) have a default route to or toward R1. R1 does not have a default route. All packets with destination outside 10.0.0.0/8 it forwards to the NAT router. All packets with destination address in one of the subnetworks I, ... , XII it handles as the theory says it must. (For network II it also checks existence of the destination, using ARP or some such mechanism). Packets with destination A2 or A3 it sends to its own higher level software. Packets with destination A1 it delivers to A1. (Direct Delivery). All other packets with destination in 10.0.0.0/8 it drops on the floor and (if possible) it sends an ICMP error message for these. (The NAT Router uses state information to do address translation. Not your concern in this project). For project B: You will create forwarding tables for R1 and R3, using the prescriptions above. In project B, you will write a program that for packets deliverd to one of the interfaces A2, A3, A6, A7, A8, A9, A10, A11 (Routers R1 and R3): Prints the content of the packet (as in project A); Decides how to handle the packet (direct delivery, forwarding, drop, ICMP error message, fragmentation, etc), prints the outgoing fragments. (ALL of them.) The only IP options present will be No-Op and Strict Source Route. Example input and output files will soon appear on this website. For the time being you can use the examples on the websites for previous semesters of CIS 656. While the networks are different, the complications you have to take care of will be similar. R1 ``knows'' that on network I there are only two interfaces: A1 and A2. Further, assume that whenever direct delivery is required, the destination interface indeed exists, and that an entry in the arp cache already exists.