Question on V. 35 Router

[SecureBlob]

I was reading the following link on configuring Frame Relay. I am not into this field so I was trying to gain some knowledge on how Frame relay is setup in real world. I also understand that Frame Relay is not a popular technology anymore. I am asking this question to get some concepts clear. Hope someone would be able to clarify my doubt.

https://www.cisco.com/c/en/us/td/docs/ios/12_2/wan/configuration/guide/fwan_c/wcffrely.html

I am pasting a picture (Figure 22) from the above link. If you look at it, you can see 2 V. 35 routers. One is connected directly to Frame Relay cloud and another via a CSU/DSU. My question is on the V.35 router which is directly connected to Frame Relay cloud. Here are my questions.

• What kind of physical media is connected between the V. 35 router and the Frame Relay cloud??
• Is it a serial cable?
• If it is a serial cable, in which all instances a serial cable is used to connect to a Frame Relay cloud? I ask this question as I believe there is limitation on the length of Serial cable.
• What is the maximum length it supports?

Here is the picture.

[chrihussey · Accepted solution]

Hello,

• What kind of physical media is connected between the V. 35 router and the Frame Relay cloud?

        My impression that it represents a router that is in the same location as the frame relay switch. In most instances, when customers use a providers frame-relay service they connected via the CSU/DSU scenario

• Is it a serial cable?

        Yes it is a large multi pin connector that can operate at multiple speeds  that top out at 2Mbps.

• If it is a serial cable, in which all instances a serial cable is used to connect to a Frame Relay cloud? I ask this question as I believe there is limitation on the length of Serial cable.

         As stated earlier, the connection would only be used if the router was in close enough proximity to the frame relay switch to allow for that type of connection.       

• What is the maximum length it supports?

See below link for V.35 specs

https://www.cisco.com/c/en/us/support/docs/switches/igx-8400-series-switches/10795-70.html

Hope this helps

[SecureBlob]

You said "the connection would only be used if the router was in close enough proximity to the frame relay switch to allow for that type of connection."

I have some follow up question.

1) When the router is connected to frame relay via Serial cable does the router should have an inbuilt CSU/DSU? 

2) Or is it that a CSU/DSU is required only when the connection goes via a T1 /E1 line?