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Linux - Networking This forum is for any issue related to networks or networking.
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Old 07-16-2004, 03:10 PM   #1
marc hall
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Registered: Jul 2004
Location: Dallas
Distribution: Fedora Core 2 (Kernel 2.6)
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Routing Issue


Hardware:

2 switches
4 Linux PC's(Fedora Core 2, Kernel 2.6)

Diagram(Currently):
Code:
 --------    Eth      --------
| X    1 | ------->  | 4    Y |
|        |   11g     |        |
| A 3  2 | ------->  | 5  6 D |
 --------             --------
    |                    |
    |Eth             Eth |
    |                    |
    |                    |
 --------     11b      --------
| 7    8 | ---------  | 10  12 |
|        |   SATCOM   |        |
| B    9 | ---------  | 11   C |
 --------              --------
(don't think the diagram will be formated correctly)

1 to 4, 3 to 7, 6 to 12 Eth(100)
2 to 5 11g (wireless)
8 to 10 11b
9 to 11 SatCom
X = Server
Y = Client

(Currently) 3 and 7 connect to one switch and 6 and 12 connect to the other switch. Trying to route from client to server.

subnets are set up as(cannot change):
A: 10.2.2.1 (Ethernet)
11.2.2.1 (Wire 11G)
B: 10.1.2.1 (Ethernet)
12.1.2.1 (Wire 11B)
13.1.2.1 (Sat Comm)
C: 10.1.1.1 (Ethernet)
12.1.1.1 (Wire 11B)
13.1.1.1 (Sat Comm)
D: 10.2.1.1 (Ethernet)
11.2.1.1 (Wire 11g)

The only data flow restriction is from the client to the server.No data can flow directly from the client to the server, only from the server to the client(drawn in the direction of the arrows). I am familiar with networking(not an expert) but have little experience with Linux).

Questions: Should(do) I need ip forwarding on all systems or just B and C?
Do I set B and C as gateways? and how are they configured?
(I read an article where, in my case example(using B), I would configure node B's ip address of 10.1.2.1 to have a the gateway of 12.1.2.1 and B's ip address of 12.1.2.1 to have a gateway of 10.1.2.1. Is this overdoing it?)
I have configured the systems to what I believe is the correct configuration but can never ping through from D to B or A(something I suspect being a gateway issue).
It does not matter how the switches come into play, but I would like to have no node's directly connected to each other.
In my current configuration I can ping all IP's from D to all IP's to C.
Is this possible?
Both switches being involved is not required.

I would appreciate any help given.

Thanks,
Marc

Last edited by david_ross; 07-16-2004 at 04:16 PM.
 
Old 07-16-2004, 04:20 PM   #2
david_ross
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Registered: Mar 2003
Location: Scotland
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Welcome to LQ.

I've fixed your diagram a bit but I'm still a bit confused.

You have asked questions but I don't understand what you are trying to acheive.
 
Old 07-17-2004, 11:02 AM   #3
zaphodiv
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Registered: Oct 2003
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Using ip addresses like 12.1.1.1 is bad practise. That address is allocated to AT&T who may be using it on the internet.

Is this a homework question?

What subnet masks are you using?

>No data can flow directly from the client to the server, only from the
>server to the client(drawn in the direction of the arrows).
So you want the data from Y to X, to flow via D and C?

>Should(do) I need ip forwarding on all systems or just B and C?
What are you trying to do?
Just to get data flowing between X and Y in your bizaire scheme then you need C and B to forward packets and you need the routing tables set correctly on B and C. Do you want all packets to go clockwise?

It depends on which ip addreses are being used for connections between X and Y. Client X could open a connection to 10.2.1.1 or 11.2.1.1 to contact the server.

Assuming /24 subnets, C is not in the same subnet as any of A's ip's so it will send packets to it's default gateway or to whereever it's routing table tells it to send it.

>Do I set B and C as gateways?
Setting D to use C as a gateway and setting C to use B as a gateway would seem to be what you are after.
 
Old 07-18-2004, 09:55 AM   #4
marc hall
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Registered: Jul 2004
Location: Dallas
Distribution: Fedora Core 2 (Kernel 2.6)
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Here's my situation:
new to a company and they asked me if I had any networking experience, what else could I say...
(I'm a software engineer)

to David:

Thanks for fixing the diagram.
I am trying to achieve data flow from the Server to the Client. I must send Eth and 11g directly to the client and both SatCom and 11b must go through nodes B and C.
All client data must go through node C to B.


to zaphodiv:

>Is this a homework question?
This is a lab environment preconfigured(with management not wanting to change anything) so conflicting addresses will not be a problem.

>What subnet masks are you using?
I am currently using /8 as to create a subnet for each node. Reason: If I set both of the nodes A nd D to /24 then the client will send directly to the server(bad).


>>Should(do) I need ip forwarding on all systems or just B and C?
>What are you trying to do?
>Just to get data flowing between X and Y in your bizaire scheme then you need C and B to >forward packets and you need the routing tables set correctly on B and C. Do you want all >packets to go clockwise?
Management messages and streaming data need to be sent quickly to the client(directly connected to the client).
Anything form the client, such as requests should be sent on slower links(SatCom, 11b).


>>No data can flow directly from the client to the server, only from the
>>server to the client(drawn in the direction of the arrows).
>So you want the data from Y to X, to flow via D and C?
Y(client) to X(server) should only flow via C to B then X.

Thanks for all the help.
Marc
 
Old 07-18-2004, 10:59 AM   #5
peter_robb
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Registered: Feb 2002
Location: Szczecin, Poland
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These configurations are set with static route tables..

These tables specify which router/gateway is used to reach a certain host or subnet..

To further complicate it, there are 2 or more possible routes, and you must ensure you use the same return path, or you will need to set up specific firewalling rules for accepting in on one interface and out on another.

The route programme of choice is iproute2, it can do these things elegantly..
Have a look at http://tldp.org/HOWTO/Adv-Routing-HOWTO/lartc.rpdb.html Chapter 4
It covers entry/exit routing.
You can add static routes from the same place..
 
  


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