network design and interface matters

Diagram A.

subnet A ---------|
                         |                                             web server
                         |                                                      \  
                         |                                                        \
subnet B  -------router 1------ Firewall 1-------------------- Boundary router (subnet E)
                         |                                                        /                                                                               |
                         |                                                      /               |
                         |                                            mail server          |
subnet C ---------|                                                                      |
                                                                                           Firewall 2
                                                                                                |
                                                                                                |
                                                                                                |
                                                                                              router 2
                                                                                                |                                                                                                
                                                                                                |
                                                                                                |
                                                                                             subnet D

I intend to connect 3 subnets to router 1, den from router 1, connect to firewall 1.
wat would be the interface for firewall 1? i believe 1 IP will be from subnet E, how abt the other one?
LVL 1
kebeenAsked:
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ShineOnCommented:
Are the subnets A B and C all part of network D?  For example: A=10.1.1.0  B=10.1.2.0  C=10.1.3.0   A,B & C use netmask 255.255.0.0.  Interface X on router is 10.1.254.254 with netmask 255.0.0.0.  That makes the 3 subnets AB&C all part of the same higher-level network which is what that end of router1 is defined to.


Is that the scenario?

If yes, then one end of firewall 1 would be on subnet E and the other end would be on subnet whatever the heck you want to make it.  All you need to do is route what's going in and out of subnets A,B&C through the firewall 1 private interface using a route provided by router 1.  If the ABC subnets each would have a separate interface, it wouldn't matter what network or address you use for the interface between router 1 and Firewall 1 as long as you set up the routes and any NATs appropriately.

Regardless, in this diagram, one interface of Firewall 1 is going to be in the subnet E in order to connect to the boundary router.

What firewall services did you plan to provide through Firewall 1?  Proxy?  NAT?  Packet filtering?  ???

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ShineOnCommented:
Sorry, it should read "Are the subnets on A B and C all part of network X, with X being the "private" side of router 1?"
kebeenAuthor Commented:
I have a class C network.
all these subnets R all all classless. perhaps.


x.y.z are all the same........ say 140.151.23.subnet/host.

subnet A  x.y.z.a/26
subnet B  x.y.z.b/26
subnet C x.y.z.c/27
subnet D x.y.z.d/27
subnet E x.y.z.E/28

>If yes, then one end of firewall 1 would be on subnet E and the other end would be on >subnet whatever the heck you want to make it.

I have 3 subnets on the other side...... so..... must i create a new subnet just for the router n firewall?
b'coz the router interface with 3 subnets on one side.... n ?? on the other.....
while the firewall interface with subnet E on one side n ???? on the other.....
ShineOnCommented:
Yes, if I understand correctly...
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