Router Question

NightShade03

In the attached picture of a network I have question about the routers. Say you are configuring RIP or OSPF doesn't matter. For routers R1 & R2 you wouldn't need to configure an encapsulation type because they are on the LAN together is that correct? However between R2 & R3 you would need to configure encapsulation because of the WAN connection.

Also for R1 & R2 can you assume a Fast Ethernet connection instead of serial because they are on the LAN and serial connections for R2 & R3?

pitviper

Correct, the encapsulation type would be set on the serial links. R1 would have to match the ISP, and R2 and R3 would match each other. The network diagram shows R1 and R2 connected via Ethernet.

mikej412

If R2 & R3 are Cisco Routers, they will default to Cisco's HDLC encapsulation on the Serial Interfaces if you don't manually set it to something else.

NightShade03

Thank you guys. I seem to know the answer's I'm just never sure of myself

Mike: Yes I do know that HDLC is the default for Cisco....is the a default for non Cisco, or will they just sit there and not work until I configure them with an encapsulation type?


Also the R1 router connected to the ISP (assuming R1 is Cisco) should be able to automatically detect the ISPs encapsulation type correct?

pitviper

The version of HDLC that Cisco uses is proprietary.

If the ISP is not set for HDLC and you are, then you’ll see the line come up, but the protocol will stay in the down state until you manually change the encap type.