Answers: Serial Config 1

By certskills September 9, 2015 09:05

Time to check your config for a back-to-back serial link in a lab. Check out the requirements back in the lab post, create your answers, and come back here to check your work.



Figure 1: Two Routers with IP Subnets


Example 1: R1 Config

Example 2: R2 Config



Cisco serial interfaces use a default encapsulation of High-Level Data Link Control (HDLC); It is however also important to note that this is a Cisco proprietary version of HDLC. Most serial interfaces on Cisco devices support a number of different encapsulation types including the three most common: HDLC, Point-to-Point Protocol (PPP) and Frame-Relay. This lab asks for HDLC, so no configuration is necessary to set the type of data link protocol with the encapsulation command.

For a link in the lab, created with a back-to-back serial cable, the clock rate defines the speed at which the router acting as DCE clocks the link. At later IOS versions, IOS defaults to clock at 2Mbps. However, in this case, the lab asks for 512Kbps. The clock rate needs to be set only on the router acting as DCE, so only R1 should list a clock rate 512000 command, meaning 512,000 bps.

Serial Config 1
Basic NetFlow 1
By certskills September 9, 2015 09:05
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  1. Mit May 8, 07:17

    Hi Wendell,

    One quick question!

    Are L3 Etherchannel and MLPPP mean the same thing?

    Reply to this comment
    • Mit May 8, 07:53

      Hi Wendell, was a bad question, got the answer actually.

      Layer 3 Etherchannel bundles switch links, whereas MLPPP bundles serial links using PPP.

      Sorry to bother you, and please correct me if I am wrong 🙂

      Reply to this comment
      • certskills Author May 16, 10:04

        Hi Mit,
        Been out sick, sorry for the delay.
        Yes, that’s one fundamental difference. They definitely solve similar problems. MLPPP does so on links that use PPP as the data link protocol (eg serial links), whereas EC does so on links that use Ethernet. Note that they originated from the context of their respective data link protocols, so while they solve similar problems, it’s not like someone started with a “how do we deal with multiple parallel layer 2 links” and found solutions for all layer 2 protocols. They were each created once the market saw a need in the context of serial+PPP and with Ethernet.

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