CCIE Exam: Enterprise Infrastructure

Period: 1st October to 31st October

Hours Studied: 47 hours

Total Hours Studied To Date: 545 hours

Study Resources:

  • CBT Nuggets: Implement an SD-Access Fabric with Cisco DNA Center [link]
  • Cisco Learning Network: Designing Cisco Enterprise Networks (ENSLD) v1.0 [link]
  • Cisco Live: Digital 2020 – DGTL-BRKIPM-1261 – Introduction to IP Multicast by Timothy McConnaughy [link]
  • Cisco Press: CCNP Enterprise Design ENSLD 300-420 Official Cert Guide: Designing Cisco Enterprise Networks [link]
  • Cisco Press: IP Multicast Volume 1 – Cisco IP Multicast Networking [link]
  • Cisco Press: IP Multicast Volume 2 – Advanced Multicast Concepts and Large-Scale Multicast Design [link]
  • Cisco Press: The LISP Network [link]
  • Cisco Press: Cisco Software-Defined Access [link]

Study Sprint: None

Previous Period Goals Status:

  1. Pass the Designing Cisco Enterprise Networks (300-420) specialist certification exam
    I originally had this exam booked for October 31st, but I have had to push it back to November. I am not too sure how I feel about my preparation with ENSLD as the exam feels like it’s going to consist of a lot of “trivia” questions that the old CCNP Routing & Switching exams were known for. Two hurdles I have encountered include developing a solid foundational understanding of the technologies which support Cisco Software-Defined Access, and developing memory exercises/flashcards to help me become “exam ready”.
  2. Complete Multicast and QoS items on the blueprint
    I completed the multicast and QoS items on the blueprint from a theoretical perspective but need to lab them more.
  3. Complete the Transport Technologies & Solutions domain on the blueprint by finishing off FlexVPN topic
    I got sidetracked with Software-Defined Access, so I did not even look at FlexVPN this month. Whoops!


Topics Studied: Cisco Software-Defined Access (inc. IS-IS, LISP, VXLAN), Multicast, QoS


I watched Tim McConnaughly’s excellent Cisco Live 2020 Digital Introduction to Multicast talk about getting a different perspective on technology. I finished off the theory for multicast by reading “IP Multicast Volume 1” cover-to-cover and even strayed outside of the blueprint slightly by reading half of the follow-up title “IP Multicast Volume 2”. While MSDP is not on the blueprint, I feel like knowing how to design a multicast network that supports routing multicast traffic over the WAN could be tested upon in the design section of the lab.

  • 1.6.a Layer 2 multicast
    • 1.6.a i IGMPv2, IGMPv3
    • 1.6.a ii IGMP Snooping, PIM Snooping
    • 1.6.a iii IGMP Querier
    • 1.6.a iv IGMP Filter
    • 1.6.a v MLD
  • 1.6.b Reverse path forwarding check
  • 1.6.c PIM
    • 1.6.c i Sparse Mode
    • 1.6.c ii Static RP, BSR, AutoRP
    • 1.6.c iii Group to RP Mapping
    • 1.6.c iv Bidirectional PIM
    • 1.6.c v Source-Specific Multicast
    • 1.6.c vi Multicast boundary, RP announcement filter
    • 1.6.c vii PIMv6 Anycast RP
    • 1.6.c viii IPv4 Anycast RP using MSDP
    • 1.6.c ix Multicast multipath

Cisco Software-Defined Access

I covered elements of Cisco SDA that do not require interaction with Cisco DNA Center. CBT Nuggets SDA skills covered by Jeff Kish broke down the theory in these areas excellently. I am going to attempt building an SDA fabric in CML2 during November/December while I wait on access to a Cisco DNA Center appliance.

  • 2.1.a Design a Cisco SD-Access solution
    • 2.1.a i Underlay network (IS-IS, manual/PnP)
    • 2.1.a ii Overlay fabric design (LISP, VXLAN, Cisco TrustSec)
    • 2.1.a iii Fabric domains (single-site and multi-site using SD-WAN transit)
  • 2.1.c Segmentation
    • 2.1.c i Macro-level segmentation using VNs
    • 2.1.c ii Micro-level segmentation using SGTs (using Cisco ISE)


I understand QoS but good lord there seems to be a lot to memorise here. I am thinking of buying some cheap Cisco IP Phones to integrate into my physical lab, so I can play around with QoS and see whether I can hear a difference in call quality when it’s not in use, and I flood a network with traffic. If anyone has some “fun” QoS labs, please reach out to me!

  • 4.4.a End to end L3 QoS using MQC
    • 4.4.a i DiffServ
    • 4.4.a ii CoS and DSCP Mapping
    • 4.4.a iii Classification
    • 4.4.a iv Network Based Application Recognition (NBAR)
    • 4.4.a v Marking using IP Precedence, DSCP, CoS
    • 4.4.a vi Policing, shaping
    • 4.4.a vii Congestion management and avoidance

Top 5 Weaknesses

I have removed MPLS from my Top 5 weaknesses as I feel “exam ready” for the MPLS topics on the blueprint now. Yay!

  1. Route filtering with any routing protocol: No changes. Knowledge Rating: 3.5/5
  2. Redistribution between any pair of routing protocols: No changes – still waiting on labs. Knowledge Rating: 3.5/5
  3. Multicast: I understand all of the topics on the lab blueprint for multicast and need to lab them. Knowledge Rating: 3.5/5 [+1.5]
  4. QoS: I think I have rounded out the basic theory required for the lab blueprint but do not feel confident with designing an enterprise QoS solution. More reading and labbing required. Knowledge Rating: 2.5/5 [+0.5]
  5. Network Programmability & Automation: I have covered almost all of the programmability topics thanks to my DevNet Associate exam preparation. I need to play around with EEM, guest shell and Linux environments, and of course – lab everything. Labbing these topics should be fairly easy considering I’m involved with some pretty cool DevNet and automation projects at work. Knowledge Rating: 2/5.

Top 3 Goals for Next Period:

  1. Pass the Designing Cisco Enterprise Networks (300-420) specialist certification exam
  2. Lab the Multicast and QoS items on the blueprint
  3. Build an SDA fabric manually within CML2 to develop familiarity with IS-IS, LISP, and VXLAN.


October marks the 6-month mark of my CCIE Enterprise Infrastructure journey – huzzah!

After taking some time off from the CCIE in September, I felt reinvigorated to continue studying throughout October. I am, however, starting to feel some of the “wear and tear” associated with preparing for the lab exam. I kept feeling like I had some form of “brain fog” lingering in my head as I found myself re-reading and revisiting the same topics frequently this month. To combat this, I elected to hold smaller 1-2 hour highly focused study sessions, as opposed to the usual 8-12 hour marathon days. As the next couple of months progress, I believe that maintaining a flexible schedule which factors in rest is going to become critical, as I do not want to be one of the many candidates who burns out just before they sit the lab!

I have found preparing for the “Designing Cisco Enterprise Networks (300-420 ENSLD)” to be an interesting experience. Putting on my design hat forces me to think about why I would choose a particular technology to solve a business problem intelligently. Most of the course content heavily overlaps with content that I have covered throughout my CCIE journey thus far; however, being reminded to think at a higher level has definitely been beneficial. I was posed with a problem in my new role where my colleagues and I need to consider re-addressing an entire network due to a legacy design decision that no longer makes sense. Until ENSLD, I honestly did not think of standing up new SVIs within the desired address space and then slowly migrate end-devices over to them. It’s a good example of how thinking simply and at a high level can yield an effective solution.

I have had to tangent in my ENSLD studies because I have run into the beast that is Cisco’s Software-Defined Access. An SDN solution that essentially cranks the L3 routed access design up to 11 by throwing in technologies such as LISP, VXLAN, Cisco TrustSec, and Cisco ISE. I was dreading this exam topic because I have absolutely no hands-on experience with Cisco SDA. The technologies used to build the fabric also seemed rather complex. However, with the help of CBT Nugget’s phenomenal SDA course and the RouterGods CCIE-EI community channel, I am slowly making progress with this exam blueprint item. I intend to manually provision a fabric throughout November and December better to appreciate Cisco DNA Center’s role within Cisco SDA. I may have some Catalyst 9K switches, and a DNAC appliance headed my way to help with my studies. More on that in the future, though…

Last but not least, I started my new role at work on the 26th of October. Preparing for the CCIE EI lab exam has made it incredibly easy to “hit the ground running”. It’s been quite refreshing to know what to look for to get up to speed in a new networking environment quickly. I am very much looking forward to seeing how I can use my DevNet, network programmability, and automation knowledge to simplify further the administration and maintenance of all the networks that I have inherited in this position.

Key Takeaway

A flexible study schedule makes it easier to remain sustainable.

From the Whiteboard

Missing! The whiteboard is currently in use for other purposes right now. It will be back in November’s update post!