Spanning Tree Protocol: BPDU and Root Bridge Election Fundamentals

BPDU and Root Bridge Election Fundamentals

The Source MAC address is the first thing that the switch looks at on incoming frames.

Unknown unicast, broadcast and multicast frames are forwarded out all ports excluding the one that came in on.

Known unicast frames are unicast via the port listed in the MAC address table

Broadcasts traditionally result in more broadcasts, hence a broadcast storm!

Switching loops cause 3 issues, frames don’t reach destination – strain on CPU, wasted bandwidth

BPDUs are sent every 2 seconds to multicast MAC address 01-80-c2-00-00-00


Once root bridge is elected, only RB will originate a CONFIGURATION BPDU, all non root bridge switches will send COPIES only.

BID = 2 byte Priority value and 6 byte MAC address

If a tie in the priority value, then the mac address breaks the tie (Priority and MAC making up the entire BID)


CCNP Revision

Ok so as previously stated I am going to go back to the past and revise all of the routing and switching concepts to NP level. I made a smart a decision a year or so to purchase the excellent CCNP training material from Chris Bryant at Chris teaches with incredible depth and  offers a good prerequisite of knowledge required for the IE. I will try and fit as much as this in as possible over the next few weeks. I am also going to document notes from the training videos so this website will grow into a full on repository of NP/IE concepts.

CCIE Links

Whilst I was surfing this morning I came across a few other CCIE related links that were worth noting: – (This is a brilliant resource from Paul Alexander)

Some videos:

Time to go back..

Ok so I reviewed the check list and left a lot of blanks. The problem is I am scared to commit to being an ‘expert’ at any concept, let alone ones I am good at. I have decided to go back to my CCNP R&S Videos to recap a lot of concepts, then I hopefully can begin to tick those boxes.

Materials Used:

Chris Bryant in my opinion is the best instructor I have come across for video based traning. Jeremy Cioara of CBT Nuggets does enough to open the door on a concept and show you enough to probably get away with it, but Chris Bryant offers far more depth and even quotes a lot of time ‘if you want to get your IE, you want to know this!’

My intention is to catch up on a lot of CCNP concepts, then begin the training for the written exam. I am not sure at this point what materials I will use. We will cross that bridge in time..

Written Exam Topics

Here is the rather long list from Cisco on all concepts you need to know for CCIE Written.
Exam Sections and Sub-task Objectives
1.00 Implement Layer 2 Technologies
1.10 Implement Spanning Tree Protocol (STP)
(a) 802.1d
(b) 802.1w
(c) 802.1s
(d) Loop guard
(e) Root guard
(f) Bridge protocol data unit (BPDU) guard
(g) Storm control
(h) Unicast flooding
(i) Port roles,  failure propagation, and loop guard operation
1.20 Implement VLAN and VLAN Trunking Protocol (VTP)
1.30 Implement trunk and trunk protocols, EtherChannel, and load-balance
1.40 Implement Ethernet technologies
(a) Speed and duplex
(b) Ethernet, Fast Ethernet, and Gigabit Ethernet
(c) PPP over Ethernet  (PPPoE)
1.50 Implement Switched Port Analyzer (SPAN), Remote Switched Port Analyzer (RSPAN), and flow control
1.60 Implement Frame Relay
(a) Local Management   Interface (LMI)
(b) Traffic shaping
(c) Full mesh
(d) Hub and spoke
(e) Discard eligible   (DE)
1.70 Implement High-Level   Data Link Control (HDLC) and PPP
2.00 Implement IPv4
2.10 Implement IP version 4 (IPv4) addressing, subnetting, and variable-length subnet masking (VLSM)
2.20 Implement IPv4 tunneling and Generic Routing Encapsulation (GRE)
2.30 Implement IPv4 RIP version 2 (RIPv2)
2.40 Implement IPv4 Open Shortest Path First (OSPF)
(a) Standard OSPF areas
(b) Stub area
(c) Totally stubby area
(d) Not-so-stubby-area (NSSA)
(e) Totally NSSA
(f) Link-state  advertisement (LSA) types
(g) Adjacency on a  point-to-point and on a multi-access network
(h) OSPF graceful restart
2.50 Implement IPv4 Enhanced Interior Gateway Routing Protocol (EIGRP)
(a) Best path
(b) Loop-free paths
(c) EIGRP operations when alternate loop-free paths are available, and when they are not available
(d) EIGRP queries
(e) Manual   summarization and autosummarization
(f) EIGRP stubs
2.60 Implement IPv4 Border Gateway Protocol (BGP)
(a) Next hop
(b) Peering
(c) Internal BorderGateway Protocol (IBGP) and External Border Gateway Protocol (EBGP)
2.70 Implement policy routing
2.80 Implement Performance Routing (PfR) and Cisco Optimized Edge Routing (OER)
2.90 Implement filtering, route redistribution, summarization, synchronization, attributes, and other advanced features
3.00 Implement IPv6
3.10 Implement IP version 6 (IPv6) addressing and different addressing types
3.20 Implement IPv6 neighbor discovery
3.30 Implement basic IPv6 functionality protocols
3.40 Implement tunneling techniques
3.50 Implement OSPF version 3 (OSPFv3)
3.60 Implement EIGRP version 6 (EIGRPv6)
3.70 Implement filtering and route redistribution
4.00 Implement MPLS Layer 3 VPNs
4.10 Implement   Multiprotocol Label Switching (MPLS)
4.20 Implement Layer 3 virtual private networks (VPNs) on provider edge (PE), provider (P), and customer edge (CE) routers
4.30 Implement virtual   routing and forwarding (VRF) and Multi-VRF Customer Edge (VRF-Lite)
5.00 Implement IP Multicast
5.10 Implement Protocol Independent Multicast (PIM) sparse mode
5.20 Implement Multicast Source Discovery Protocol (MSDP)
5.30 Implement interdomain multicast routing
5.40 Implement PIM Auto-Rendezvous Point (Auto-RP), unicast rendezvous point (RP), and   bootstrap router (BSR)
5.50 Implementmulticast tools, features, and source-specific multicast
5.60 Implement IPv6 multicast, PIM, and related multicast protocols, such as Multicast Listener Discovery (MLD)
6.00 Implement Network   Security
6.01 Implement access lists
6.02 Implement Zone Based Firewall
6.03 Implement Unicast Reverse Path Forwarding (uRPF)
6.04 Implement IP Source Guard
6.05 Implement authentication, authorization, and accounting (AAA) (configuring the AAA server is not required, only the client-side (IOS) is configured)
6.06 Implement Control Plane Policing (CoPP)
6.07 Implement Cisco IOS Firewall
6.08 Implement Cisco IOS Intrusion Prevention System (IPS)
6.09 Implement Secure Shell (SSH)
6.10 Implement 802.1x
6.11 Implement NAT
6.12 Implement routing protocol authentication
6.13 Implement device access control
6.14 Implement security features
7.00 Implement Network   Services
7.10 Implement Hot Standby Router Protocol (HSRP)
7.20 Implement Gateway Load Balancing Protocol (GLBP)
7.30 Implement Virtual Router Redundancy Protocol (VRRP)
7.40 Implement Network Time Protocol (NTP)
7.50 Implement DHCP
7.60 Implement Web Cache Communication Protocol (WCCP)
8.00 Implement Quality of   Service (QoS)
8.10 Implement Modular QoS CLI (MQC)
(a) Network-Based Application Recognition (NBAR)
(b) Class-based weighted fair queuing (CBWFQ),  modified deficit round robin (MDRR), and low latency queuing (LLQ)
(c) Classification
(d) Policing
(e) Shaping
(f) Marking
(g) Weighted random early detection (WRED) and random early detection (RED)
(h) Compression
8.20 Implement Layer 2 QoS: weighted round robin (WRR), shaped round robin (SRR), and policies
8.30 Implement link fragmentation and interleaving (LFI) for Frame Relay
8.40 Implement generic traffic shaping
8.50 Implement Resource Reservation Protocol (RSVP)
8.60 Implement Cisco AutoQoS
9.00 Troubleshoot a  Network
9.10 Troubleshoot complex Layer 2 network issues
9.20 Troubleshoot complex Layer 3 network issues
9.30 Troubleshoot a network in response to application problems
9.40 Troubleshoot network services
9.50 Troubleshoot network security
10.00 Optimize the Network
10.01 Implement syslog and local logging
10.02 Implement IP Service Level Agreement SLA
10.03 Implement NetFlow
10.04 Implement SPAN, RSPAN, and router IP traffic export (RITE)
10.05 Implement Simple Network Management Protocol (SNMP)
10.06 Implement Cisco IOS Embedded Event Manager (EEM)
10.07 Implement Remote Monitoring (RMON)
10.08 Implement FTP
10.09 Implement TFTP
10.10 Implement TFTP server   on router
10.11 Implement  Secure Copy Protocol (SCP)
10.12 Implement HTTP and   HTTPS
10.13 Implement Telnet
11.00 Evaluate proposed changes to a Network
11.01 Evaluate interoperability of proposed technologies against deployed technologies
(a) Changes to routing protocol parameters
(b) Migrate parts of a network to IPv6
(c) Routing Protocol migration
(d) Adding multicast support
(e) Migrate spanning tree protocol
(f) Evaluate impact of new traffic on existing QoS design
11.02 Determine operational impact of proposed changes to an existing network
(a) Downtime of network or portions of network
(b) Performance degradation
(c) Introducing security breaches
11.03 Suggest Alternative solutions when incompatible changes are proposed to an existing network
(a) Hardware/Software upgrades
(b) Topology shifts
(c) Reconfigurations

CCIE R&S Written Exam

So Step One is to pass the written exam. Here are the details:

CCIE® Routing & Switching Written

350-001 CCIE Exam v4.0

Exam Number: 350-001
Associated Certifications: CCIE RS
Duration: 120 minutes (90-110 questions)
Available Languages: English
Click Here to Register: Pearson VUE
Exam Policies: Read current policies and requirements
Exam Tutorial: Review type of exam questions
CCIE Policies: Review the current CCIE Policies.

Exam Description

The CCIE written exam is a two-hour qualification exam, taken at a Cisco authorized Pearson VUE testing center. The exam uses a combination of multiple choice questions and simulations to assess the skills listed under Exam Topics.  Exams are closed book and no reference materials are allowed.

I expect more ‘typical’ Cisco questions, however my instinct is that this will be more ‘up my alley’ and hopefully I won’t find the questions as awkward. :/ Heres hoping!

More info..

Written Exam Topics (Blueprint) v4.0

The Routing and Switching written exam (#350-001) has 100 multiple-choice questions and is two hours in duration. The topic areas listed are general guidelines for the type of content that is likely to appear on the exam. Please note, however, that other relevant or related topic areas may also appear.

Suggested Training

Cisco provides a flexible and integrated learning program using instructor-led and self-paced training, hands-on exercises, assessments, and practice exams to build the expert skills required for CCIE certification.  The Cisco 360 Learning Program for CCIE R&S is available from specially trained and authorized learning partners.  Other individual Cisco training courses can fill in gaps in a candidate’s experience or knowledge.

Reading List

This page lists reading materials on topics appearing on the CCIE exam blueprints. They are not required study resources, however, they can be used to build knowledge in certain areas.

Online Resources

Similar to the book list, the list of online resources provides links to articles, white papers, and documentation on topics covered in the blueprint.

Quick Learning Modules

The following Module(s) has been identified to cover content found in the Exam Topics.

Study Documents

Community-Generated Content

This content was created by community members, and has not been reviewed by Cisco.  Be sure to rate the content and provide your comments.

CCIE Introduction

Here are extracts from Cisco themselves on what the CCIE R&S is all about:

Cisco Certified Internetwork Expert Routing and Switching (CCIE Routing and Switching) certifies the skills required of expert-level network engineers to plan, operate and troubleshoot complex, converged network infrastructure.


There are no formal prerequisites for CCIE certification. Other professional certifications or training courses are not required. Instead, candidates must first pass a written qualification exam and then the corresponding hands-on lab exam. You are expected to have an in-depth understanding of the topics in the exam blueprints and strongly encouraged to have three to five years of job experience before attempting certification.

Step One: CCIE Routing and Switching Written Exam

You must pass the two-hour, written qualification exam, which covers networking concepts and some equipment commands before you are eligible to schedule the lab exam.

Step Two: CCIE Routing and Switching Lab Exam

The eight-hour lab exam tests your ability to configure actual equipment and troubleshoot the network in a timed test situation. You must make an initial attempt of the CCIE lab exam within 18-months of passing the CCIE written exam. If you do not pass the lab exam within three years of passing the written exam, you must retake the written exam before being allowed to attempt the lab exam again.