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Sidewinder G2 6.1.2 Administration Guide - Glossary of Technical ...

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Appendix D: Configuring Dynamic Routing with RIP<br />

RIP with <strong>Sidewinder</strong> <strong>G2</strong> not using transparent IP addressing<br />

620<br />

generic TCP proxy. Also, to pass the RIP information through the <strong>Sidewinder</strong><br />

<strong>G2</strong>s, both systems must configure and enable the routed server.<br />

Again for discussion purposes, the administrator must use the Admin Console<br />

to configure routed on the Internet burb for the following options:<br />

• Advertise routing information: yes<br />

• Advertise as default gateway: no<br />

• Receive routing information from other routers: yes<br />

• Routes from burbs: none<br />

Also, routed on the trusted burb must be configured as follows:<br />

• Advertise routing information: yes<br />

• Advertise as default gateway: no<br />

• Receive routing information from other routers: no<br />

• Routes from burbs: Internet (2)<br />

When the Telnet client needs to connect to the Telnet server, it sends a TCP<br />

connection request to Router_b which forwards the frame on to<br />

<strong>Sidewinder</strong><strong>G2</strong>_b. The <strong>Sidewinder</strong><strong>G2</strong>_b IP services receives the frame and<br />

passes it up to the generic_TCP proxy, which validates the connection request<br />

and issues a new, independent TCP connection request to the Telnet server<br />

(on the external network).<br />

This new request, however, contains the originating IP address <strong>of</strong> the real<br />

client, not the external <strong>Sidewinder</strong> <strong>G2</strong> IP address. The request gets sent to<br />

Router_a and is forwarded to the Telnet server in the Bizco network. Next, the<br />

Bizco Telnet server builds and sends a reply to Router_a, expecting it to be<br />

delivered on to the client. Router_a receives the reply and looks at its routing<br />

table to find a route to CorpCity’s client network. Router_a will not find one,<br />

and the packet will be dropped.<br />

Because the <strong>Sidewinder</strong> <strong>G2</strong> is NOT advertising its internal routes Router_a<br />

does NOT know how to get to CorpCity’s networks. What the administrator<br />

should do is set “Routes from Burb to Internal (0)” on the external side. This will<br />

cause the routed server in the external burb to also advertise all the routes it<br />

finds on the internal burb. What happens now is Router_a gets additional<br />

information about internal routes available on the <strong>Sidewinder</strong> <strong>G2</strong>.<br />

Does this solve the problem? The answer is NO. Since the internal routed<br />

server is NOT updating the internal route table (“Receive routing information<br />

from other routers” was set to NO), no routes about CorpCity’s network will be<br />

available. The <strong>Sidewinder</strong> <strong>G2</strong> administrator must set as “Receive routing<br />

information from other routers to YES” on the internal routed server. Now the<br />

<strong>Sidewinder</strong> <strong>G2</strong> will advertise CorpCity’s routes to router_a, and when Router_a<br />

receives the packet for CorpCity it will understand how to route it.

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