Took a couple of days off to get our house ready to sell.  I am hoping the brownie point that I earned from the with go a long way!

On section 23 of 39 but there are quite a few long sections coming up which make up about 50% of the estimated time of the course.  Slowly but surely I will get there!!

Section 23: DHCP – Dynamic Host Configuration Protocol

• Beside forwarding DHCP requests, I am not really sure why this is even a section… Do people really use their routers as a DHCP server?
• DHCP Server Configuration Commands
  • (config#ip dhcp excluded-addess [IP address start range] [IP address end]
  • (config)#ip dncp pool [text description]
  • (dhcp-config)#network [network address] [network subnet]
  • dhcp-config)#default-router 10.10.10.1
  • (dhcp-config)#dns-server 10.10.20.10
• DHCP Server Verification Commands
  • show ip dhcp pool
    • Details fo the DHCP
  • show ip dhcp binding
    • DHCP client informaiton assignment
• External DHCP Server
  • DHCP ip helper-address Commands, set on a interface hosting the subment.
    • (config)#interface f0/1
    • (config-if)#ip helper-address [DHCP IP address]
• Cisco Router as a DHCP Client
  • Used in case that the router needs to pull IP address from ISP
  • Config commands
    • (config)#interface f0/0
    • (config-if)#ip address dhcp
    • (config-if)#no sutdown
  • Verification Commands
    • #show dhcp lease

Section 24: HSRP – Hot Standby Router Protocol

• Backup routes will be given a higher AD (administration Distance) as this is backup and not load balancing
• FHRP: First Hop Redundancy Protocols
  • Use VIP (Virtual IP) and MAC address to allow for automated gateway failover.
  • Devices use the VIP as the gateway
  • Protocols
    • HSRP – Hot Standby Router Protocol:
      • Cisco proprietary
      • Deployed in active/standby pair
      • Default is version 1
        • Version 2 introduces minor improvements
      • Both routers must be running the same version
    • VRRP – Virtual Router Redundancy Protocol
      • Open standard
      • Deployed in active/standby (Similar to HSRP)
    • GLBP – Gateway Load Balancing Protocol
      • Cisco proprietary
      • Supports active active load balancing acrossmultiple routers
• Virtual IP and MAC addresses will be configured on the same interface on the routers that are used for standard traffic.
• On device will be elected as the HSRP active router and the other will be come the standby reouter
• The active router will respond to ARP requests and will own the virtual IP and MAC address
• All traffic will go to the active router
• If the standby router stops receiving hellos from the active router it will take on the responsibility of the IP and MAC addresses beconing the primary router.
• The higher IP address with win election to be active if priority the same or left at default (100).  The higher priority will become active
• If pre-emption is enable (disabled by default), when primary router comes back online the active router will be transfered back to the the higher priority router.
  • Leaving pre-emption disabled may be more stable in the case a router is flapping
• Commands Example
  • First Router
    • (config)#interface g0/1
    • (config-if)#ip address 10.10.10.2 255.255.255.0
    • (config-if)#no shutdown
    • (config-if)#standby 1 ip 10.10.10.1
  • Second Rtouer
    • (config)#interface g0/1
    • (config-if)#ip address 10.10.10.3 255.255.255.0
    • (config-if)#no shutdown
    • (config-if)#standby 1 ip 10.10.10.1
• Verification Command
  • #show standby
• Priority, Pre-emption and version Commands examples
  • (config)#interdace g0/1
  • (config-if)#ip address 10.10.10.2 255.255.255.0
  • (config-if)#no shutdown
  • (config-if)#standby 1 ip 10.10.10.1
  • (config-if)#standby 1 pritory 110
  • (config-if)#standby 1 preempt
  • (config-if)#standby version 2
• Active/Active
  • You can have an active/active HSRP for separate different IP subnets.  For the same IP subnet, it will be active/passive.

Section 25: STP – Spanning Tree Protocol

• Layer 2 technology to avoid loop on layer 2 switches.
• Used to prevent looping arp broadcast storms when requests between switches while attempting to populate the ARP table.
• STP physically shuts down interfaces to prevent the broadcast storm. 
• If the STP link goes down the switch will detect the outage and change a disabled port to an active forwarding port.
• Switches sends BPDU (bride protocol data units) out all ports when they come online
  • Used to detect other switches and potential loops
• A switch will not forward traffic out any port until it is certain it is loop-free.
  • Port starts in a ‘Blocking State’
  • Will detect if the port forms a potential loop
  • When determined no loop the port is changed to a ‘forwarding’ port
  • Can take up to 50 seconds
• Bridge ID
  • BPDU contains Bride ID which identifies the switch
  • Bridge ID is made up of the switch’s unique MAC and a defined Bridge Priority value
    • The bridge priority is a number from 0-65535, but is defaulted to 32768
• Root Bridge
  • Elected based on the switches’ Bride ID values
  • The Switch with the lowest Priority value is preferred
  • When the priority is the same the switch with the lowest MAC address will win the election
  • The switches build a loop-free forwarding path Tree leading back to the Root Bridge
• Spanning Tree Cost
  • Switch calculates its best path towards the Root bridge
  • Higher bandwidth links are preferred
  • Date Rate – STP Cost
    • 4 Mbps – 5,000,000
    • 10 Mbps – 2,000,000
    • 16 Mbps – 1,250,000
    • 100 Mbps – 200,000
    • 1 Gbps – 20,000
    • 2 Gbps – 10,000
    • 10 Gbps – 2,000
• Load Balancing
  • STP instance does not load balance
  • If a switch has multiple equal-cost paths, it will select eh neighbor with lowest Bridge ID
  • If the requesting switch has multiple paths to the same neighbor (two ethernet connection to the same switch) it will select the port with the lowest Port ID
• Designated Ports
  • These are ports coming from the root switch
    • Root Ports point toward the Root Bridge
    • Designated Ports point away from the Root Bridge.
    • All ports on the Root Bridge are always Designated ports
  • Designated ports can exist on switches that are not the Root Bridge Switch, in these cases, they will be switches that are between the requesting switch and the Root Bridge Switch.
    • Root and Designated ports are the most direct paths to and from the root bridge.
    • Designated ports are also the lowest cost Bridge ID on links that have been blocked because the are not the most direct paths.
• Blocking Ports
  • Any ports which have not be selected as a Root Port or Designated Port Pair and would be a potential loop
  • BPDUs continue to be sent over the link but other traffic is dropped
  • STP only blocks ports on one side of the the link
• 7-Steps to determine port types
  • Determine the Root Bridge
    • Lowest Priority and in case of a tie, the lowest MAC
  • All ports on the Root Bridge are Designated Ports
  • Determine the Root Ports on the other switches
    • Lowest cost to root port based on link cost (lowest wins)
  • Ports on the other side of the Root Ports are Designated ports
  • On links that are not determined Root or Designated ports, will be determined as Blocking ports
    • Determined the block port by highest cost path to root bridge or highest bridge ID
  • The port on the other side of the blocking port is Designated Ports.
• Spanning Tree Versions
  • IEEE Open Standards
    • STP – 802.1D Spanning Tree Protocol
      • Uses one Spanning Tree for all VLANs in the LAN
    • RSTP – 802.1w Rapid Spanning Tree Protocol
      • Imporved convergence time
    • MSTP – 802.1s Multiple Spanning Tree Protocol
      • Enables grouping and mapping VLANs into different spanning-tree instances for load balancing.
  • Cisco Proprietary versions
    • PVST+ – Per VLAN Sapnning Tree Plus
      • Enhancement to 802.1D
      • uses a separate Spanning Tree instance for every VLAN
      • Default on Cisco Switches
    • RPVST+ – Rapid Per VLAN Spanning Tree Plus
      • Enhancement to 802.1w TSPT
      • Improved Convergence time over PVST+
      • Uses a separate Spanning Tree instance for every VLAN
    • Cisco versions do not support grouping multiple VLANs into the same instance, so you must configure each VLAN separately.
• Verification of STP
  • Verification Commands
    • show spanning-tree vlan
      • Include VLAN# at the the end of the command to look at a single VLAN:
        • Example: show spanning-tree vlan 1
    • show mac address-table
      • Use this to determine the path of traffic
• Manipulate the Root Bridge Election
  • Reasons to manipulate the Root Bridge
    • Root bridge acts as ta center point of the LAN
    • Ensure a pair of high-end core switches are selected as 1st and 2nd most preferred Root bridge
    • Lowest MAC address has the chance of being the oldest switch on the network, so make sure that the oldest switch is not the root bridge may want to be reviewed.
  • Command
    • (config)#spanning-tree vlan 1 root primary
      • Set the switch to be the primary switch to STP
      • Set priority of 24576
    • (config)#spanning-tree vlan 1 root secondary
      • set the switch to be the secondary switch for STP
      • Set priority of 28672
• STP and HSRP Alignment
  • HSRP should be configured to match the STP path
  • Ensure that VLAN HSRP and Root Bridge match accordingly.
• Portfast, BPDU Guard and Root Guard
  • STP Portfast
    • On ports that have a single host, you can turn off STP so the convergence time can be avoided and have the port come up ASAP as opposed to the 50 second wait time.
    • Command Examples
      • Set a single port for portfast 
        • (config)# interface f0/10
        • config-if# spanning-tree portfast
      • Set all port to a default of portfast on
        • (config)# spanning-tree portfast default
      • If a ‘portfast default’ is configured and a switch is configured using the following example to remove portfast on the interface
        • (config)# interface f0/1
        • (config-if)# no spanning-tree portfast
  • BPDU Guard
    • Enable BPDU Guard on Portfast ports to guard against un-authorized switches being added.
    • This will shutdown the port if a switch is detected.
    • Command Example
      • Turn on BPDU guard on a single port 
        • (config)#int f0/10
        • (config-if)#spanning-tree portfast
        • (config-if)#spanning-tree bpduguard enable
      • Set all ports as BPDU default on all ports
        • (config)#spanning-tree portfast bpduguard default
  • STP Root Guard
    • Prevents an unintended switch from becoming the root bridge
    • If the interface receives a superior BPDU it will transition the port to root-inconsistent, it will not forward any traffic over the port and in sense shut the port down
    • Set on ports that would not expect a higher priority, and protect from an un-authorized switch trying to take priority of STP root.
    • Command
      • (config)#int fa0/2
      • (config-if)#spanning-tree guard root

Section 26: EtherChannel

• Oversubscription
  • Recommendation for oversubscription is 20:1 from the access layer to the distribution layer
    • 20 PCs connect with 1 Gbps NICs at the access layer, you would require 1Gbps uplink to the distribution layer
  • 4:1 ratio is recommended from the distribution layer to the core layer
  • These are general rules and should be analyzed on each network and configured as necessary
  • Example
    • 48 port 1Gbps switch with a pair of 10GBps
    • subscription ratio = 2.4:1
      • 48/20=2.4
    • STP cause a problem as it by defaults disables a single port providing a with on one link and a ratio of 4.8
• Etherchannel (AKA Port Channel, LAG Link Aggregation, Link bundle)
  • Groups multiple physical interfaces into a single logical interface
  • STP see the EtherChannel as a single interface, providing all bandwidth
  • Traffic is load-balanced across all the links in the EtherChannel
  • If the interface goes down all remaining links will remain up.
  • NIC Teaming
    • AKA – Bonding, NIC balancing, Link aggregation
• EtherChannel Load Balancing
  • Packet in a single session all go over the same port-channel/link
    • If packets were round robined it could cause packets being delivered out of order.
    • This means that each session is only allowed 1 gig but there are multiple links for additional connections.
• EtherChannel Protocols and Configuration
  • LACP – Link Aggregation Control Protocol
    • Open standard
    • Switches on both sides negotiate the port-channel creation and maintenance
    • Most widely used
    • Configuration
      • Can be set as either Active or Passive
      • If both interfaces set to passive the channel will not come up
      • Recommended that both sides are set to Active, that way you do not have to worry about which side is active and which is passive.
    • Commands
      • This creates interface port-channel 1
        • (config)#int range f0/23 – 24
        • (config-if-range)#channel-group 1 mode active
      • Configure the interface setting on the port channel, this is where you would set all other settings such as VLANs, IP, etc…
        • (config)#interface port-channel 1
        • (config-if)#switchport mode trunk
  • PAgP – Port Aggregation Protocol
    • Cisco proprietary
    • Switches on both sides negotiate the port-channel creation and maintenance
    • Interfaces can be set to desirable or auto
      • Will not come up if both are set ‘Auto’ it will not come up
      • Recommended that both sides be set as ‘desirable’
    • Command Example
      • Create PAgP port channel 
        • (config)#interface range f0/23 – 24
        • (config-if-range)#channel-group 1 mode desireable
      • Configure port channel, this is where you would set all other settings 
        • (config)#int port-channel 1
        • (config-if)#switchport mode trunk
  • Static EtherChannel
    • Switches do not negotiate the creation and maintenance
    • Settings must match on both sides for the port channel to work
    • Use is LACP is not supported on both sides
    • Command Example
      • Create port channel 
        • (config)#interface range f0/23 – 24
        • (config-if-range)#channel-group 1 mode on
      • Configure port channel, this is where you would set all other settings 
        • (config)#int port-channel 1
        • (config-if)#switchport mode trunk
  • Command
    • Verification
      • #show etherchannel summary
      • #show spanning-tree vlan 1
  • Parameters
    • Both sides must have matching configs
      • Speed and duplex
      • Access or Trunk mode
      • Native VLAN and allowed VLANs on trunks
      • Access VLAN on access ports
  • StackWise, VSS, and vPC
    • When you have two port-channels set up going between two different switches, spanning tree sees this as two different paths and will shut one of the port-channels down to protect against loops.
    • Multi-chassis EtherChannel
      • Support a shared EtherChannel from different switches
      • Supported on some switches (must be advance level switches that support Multi-chassis EtherChannel)
      • STP see a single link from switch that is connected to the two core switches and on those two switches it see a single channel that is shared on two switches.
      • The switch that supports Multi-chassis EtherChannel will have one of the following three
        • StackWise
          • Catalyst switch families 3750, 2850 and 9000 
        • VSS
          • Catalyst switch families 4500 and 6500 
        • vPC
          • Nexus switch family
  • Layer 3 EtherChannel
    • Command examples
      • (config)#interface range GigabitEthernet 1/0/1 – 2
      • (config-if-range)#no switchport
      • (config-if0range)#channel-group 1 [mode | active | auto |desireable | on | passive]
      • (config)#interface port-channel 1
      • (config-if)#ip address [ip address] [subnet]
      • (config-if)#no shutdown
    • This is used more no days as layer 3 switches were much more expensive in the past
    • Same as layer two as far as configuration and fast convergence times
    • Using layer 3 EtherChannel will affect the end-users default gateway to be the port on the switch since each link between the switches will be a different IP address range.

I was hoping to more than halfway done at this point, but there is a lot to learn and the labs are taking a little longer than I was hoping, but this is a good thing as the more I use the commands the better off I will be for the test and plus this will all be a reference for future review when I can’t remember commands 🙂

Section 20: OSPF – Open Shortest Path First

• OSPF Adjacencies
  • Focus on the first three steps in the OSPF Operations
    • OSPF Operations Review
      • Discover neighbors
      • Form adjacencies
      • Flood LSDB (Link State Database)
      • Compute the shortest path
      • Install best routes in the routing table
      • Respond to network changes
    • OSPF Packet Types Review
      • Hello – Used to find adjacent routers
      • DBD (DataBase Description) packets – Used for adjacent routers to tell each other the networks they know about.
      • LSR Link State Request – Used to populated missing info in the received DBD
      • LSA (Link State Advertisement) – Route Update
      • LSU (Link State Update) – List of LSA’s which should be updated, used during flooding
      • LSAck – LSA acknowledgment
  • Hello Packets
    • OSPF routers discover each other and form adjacencies via Hello packets
    • Hello packets our sent out non-passive OSPF enabled interfaces.
    • Multicast on 224.0.0.5 every 10 seconds
    • Hello Packet Contents
      • Router ID
      • Hello Interval – Default 10 seconds
      • Dead Interval – Default 4x Hello Interval
      • Neighbors – list of adjacent OSPF routers that it has received Hello packets from
      • Area ID – 
      • Router Priority – 8 bit number used to select DR (Designated Router) and BDR (Backup Designated Router)
      • DR and BDR IPv4 Address – If known
      • Authentication Flag – Auth details
      • Stub Area Flag – uses ABR to connect two OSPF areas
    • Routers must match for adjacency
      • Must be each other’s Neighbor list
      • Following must match
        • Hello and Dead Intervals
        • Area IDs
        • IP Subnet 
        • Auth Flag
        • Stub Area Flag
  • OSPF DR and BDR Designated Routers
    • When there are multiple routers in a multiaccess segment/subnet it is not effective for the routers to create a 1 to 1 link between each router to pass information.
    • DR (Designated Router)
      • Will control all replication for all routers on the segment
    • BDR (Backup Designated Router)
      • In place, if the DR goes down
    • The DR and BDR are elected
      • Router with the highest priority (0-255) becomes DR and the second-highest priority becomes BDR with the highest Router ID breaking a tie.  Priority is set manually if not left at default which is 1.
        • Set Priority to zero if you wish the router to not become a DR or BDR
      • Ethernet interfaces will be considered a multiaccess segment and a DR/BDR will be designated, but serial connections are point to point and no DR/BDR will be advertised/elected.
    • OSPF Priority Command
      • (config#interface [interface]
      • (config-if)#ip ospf priority [0-255]
        • OSPF restart on the interface for change to take place
          • Restart router
          • Disable/Enable interface
          • Clear OSPF
            • command: #clear ip ospf process
            • This does not cause a full election and the BDR will remain the same and the command would need to be restarted on the old BDR or the old DR for the BDR to change.
    • In the case of four routers on a segment, the DR and BDR will be in a full state communication with all the routers to pass information, the two routers that are not a DR or BDR, they will reside in a 2-way state to ensure each other are up and running but will not passing routing information.
      • If there is a link-state change an LSU packet is sent multicast over 224.0.0.6 to all designated routers
      • DR will multicast the update on 224.0.0.5 to all OSPF routers
  • OSPF Areas
    • Potential issues
      • Too many routes can use up to much memory
      • Network changes on large networks can take a long time to reconverge and use a lot of CPU resources
    • Resolution for large networks
      • OSPF supports a hierarchical design, large networks into smaller areas
        • Transit area (backbone/area 0), generally does not contain users
        • Regular areas connect end-users to the transit area to connect to other areas
      • Routers maintains full info about its own area and summary info about other areas
    • Router types
      • Backbone contains all routes for area 0
      • ABR (Area Border Router) and contains multiple areas
        • Separates LSA flooding zones
        • Summarizes area address
        • Source for default routes
        • Maintains the LSDB for each area that is it connected to
        • Recommended that it is only connected to two areas
        • Summarisation is not automatic and needs to be configured manually
          • (config-router)#area [area id] range [network address] [subnet]
    • Summary routes will show in the ‘#show ip route’ as ‘O IA’ which is OSPF inter area
    • ASBR (Autonomous System Boundry Router)
      • it is running OSPF but it is providing routes from another source
        • Example: RIP, EIGRP or static routes being distributed from another source
        • From “#show ip route’ it will show up as O*E1 or O*E2 route

Section 21: VLANs Virtual Local Area Networks

• VLAN
  • Operate at Layer 3
  • Separate IP subnets and need a router to be able to communicate.
  • Provide performance and security by splitting networks into smaller domains
  • Layer 2 Switches broadcast traffic everywhere including between different IP subnets
• VLAN Access Ports
  • Where end hosts are plugged in.
  • Have one VLAN
  • end host is not VLAN aware
• VLAN commands
  • Create VLAN
    • (config)#vlan [vlan#]
    • (config-vlan)#name [text]
  • Assign interface to VLAN
    • (config)#interface [interface] – Single interface
      • For multiple interfaces: (config)#interface range [interface range]
    • (config-if)#switchport mode access
    • (config-if)#switchport access vlan [vlan#]
  • Trunk Ports
    • Dot1Q Trunk Port
      • Tags layer 2 Dot1Q header with correct VLAN
      • Receiving switch only forwards traffic out to requested VLAN ports
      • Dot1Q tad is removed from frame when it sends to the end host
    • Trunk Commands
      • (config)#interface [interface]
      • (config-interface)#description [text]
      • (config-interface)#switchport trunk encapsulation dot1q
      • (config-interface)#switchport mode trunk
    • Access Trunk Port
      • (config)#interface [interface]
      • (config-interface)#description [text]
      • (config-interface)#switchport mode access
      • (config-interface)#switchport access vlan 10
      • (config-interface)#switchport voice vlan 20
    • Native VLAN
      • Switch needs to know which VLAN to assign to any traffic which is untagged on a trunk port
      • Default VLAN is VLAN 1
        • It is recommended to change to a different VLAN then VLAN 1 for security concerns.
      • native VLAN must match on both sides of a trunk for it to come up
      • Native VLAN Configuration Command
        • Create VLAN
          • (config)#vlan [vlan#]
          • (config-vlan)#name [test description: Native]
        • Configure Trunk Port
          • (config)#interface [interface]
          • (config-interface)#description [text]
          • (config-interface)#switchport trunk encapsulation dot1q
          • (config-interface)#switchport mode trunk
          • (config-interface)#switchport trunk native vlan 199
      • Allow VLAN over Trunk
        • (config)# interface [interface]
        • (config-interface)#switchport trunk allowed vlan [vlan#s separated by a comma]
    • DTP Dynamic Trunking Protocol
      • It is recommended not to use DTP and to manually configure the access and trunk ports
      • DTP configuration commands
        • #Switchport mode dynamic auto
          • Will form a trunk if the neighbor switch port is set to trunk or desirable.
        • #Switchport mode dynamic desirable
          • Will form a trunk if the neighbor switch port is set to trunk, desirable or auto
        • #Switchport nonegotiate
          • disables DTP
    • VTP VLAN Trunking Protocol
      • Allows you to add, edit or delete VLANs on switches configured as VTP server
      • Switches configured as VTP clients synchronize their VLAN database with VTP servers
      • Good for large campus
      • If switch with a hight VLAN database revision number in the domain it can wipe out all your production VLANs
      • VTP domain name has to match on neighbor switches for DTP trunks to be formed.
      • VTP Modes
        • VTP Server
          • Can add, edit or delete VLANs
          • Sync VLAN database from another server with a higher revision number
        • VTP Client
          • Cannot add, edit or delete VLANs
          • Sync VLAN database from the server with the highest revision number
        • VTP Transparent
          • Does not participate in the VTP domain
          • Can add, edit or delete VLANs in its own local VLAN database
      • VTP Commands
        • Create a VTP domain
          • (config)#vtp domain [Domain name]
        • Assign device VTP mode
          • Server
            • (config)#vtp mode server
          • Client
            • (config#vtp mode client
          • Transpaent
            • (config)#vtp mode transparent
        • Verification
          • #show vtp status

Section 22: Inter-VLAN Routing

• Router with separate Interfaces
  • Config like it is a regular setup, no special setup.
• Router on a Stick
  • Create a sub interface on the router and use the same setting as a physical interface
  • Commands
    • Enable router the interface that will be used
      • (config)#interface [interface: example: f0/1]
      • (config-interface)#no ip address
      • (config-interface)#no shutdown
    • Create VLAN interface
      • (config)#interface [interface: example: f0/1.10]
      • (config)#encapsulation dot1q 10
      • (config-interface)#ip address [ip address] [subnet]
      • (config)#interface [interface: example: f0/1.10]
      • (config)#encapsulation dot1q 20
      • (config-interface)#ip address [ip address] [subnet]
    • Set switch trunk
      • (config)#interface [interface]
      • (config-if)#switchport mode trunk
• Layer 3 Switch
  • Use SVI (Switched Virtual Interfaces) for the gateways interfaces
  • Inter-VLAN Routing Configuration Commands
    • (config)#ip routing
    • (config)#interface vlan [vlan1#]
    • (config-if)#ip address [gateway ip address] [gateway subnet]
    • (config)#interface vlan [vlan2#]
    • (config-if)#ip address [gateway ip address] [gateway subnet]
  • WAN Routing Configuration
    • Switch Example
      • (config)#interface F0/1
      • (config-if)#no switchport
      • (config-if#ip address 10.10.100.1 255.255.255.0
      • (config)#ip route 0.0.0.0 0.0.0.0 10.10.100.2
    • Router
      • (config)#interface f0/1
      • (config-interface)#ip address 10.10.100.2 255.255.255.0
      • (config)#interface f0/2
      • (config-interface)#ip address 203.0.113.1 255.255.255.0
      • (config)#ip route 0.0.0.0 0.0.0.0 203.0.113.2
      • (config)#ip route 10.10.0.0 255.255.0.0.10.10.100.1

And the fun continues as I continue to prep for my CCNA certificate.

Lab 17 – So many commands that but by the end I think that I got them all

• #show ip route
• #show ip protocols
• #show ip rip database
• #show eigrp neighbor
• debug [protocol]
• (config)# router [protocol] {number for eigrp and OSPF which I have not learned about yet}
  • (config-router)# network [IP] [subnet | reverse subnet] {area for OSPF}
  • (config-router)# no auto-summary — This is for testing purposes
• ip route with AD setting for fall back route

After writing them down, there aren’t that many but it sure felt like it when using all of the different protocols and how the AD (Administrative Distance) prioritizes one protocol over another.

Section 18 Connectivity Troubleshooting

• Extended ping – very nice tool that I was not aware of.
  • Enter “ping” without an address will bring up other options such as
    • Protocol [ip]
    • Target IP address
    • Repeat count [5]
    • Datagram size [100]
    • Timeout in seconds [2]
    • Extended commands [n]
      • Source address or interface
      • Type of service [0]
      • Set DF bit in IP header [no]
      • Validate reply data [no]
      • Data pattern [0xABCD]
      • Loose, Strict, Record Timestamp, Verbose [none]
      • Sweep range of sizes [n]
• Extended Traceroute – started the same way but due to the difference in functionality the options differ
  • Protocol [ip]
  • Target IP address
  • Source address
  • Numeric display [n]
  • Timeout in seconds [3]
  • Prove count [3]
  • Minimum Time to Live [1]
  • Maximum Time to Live [30]

Section 18 Lab – Use ping and traceroute to discover which router is missing a static route

Section 19 IGP Interior Gateway Protocol Fundamentals

• RIP
  • Distance Vector
  • Hop Count Metric
  • Max hop count is 15
  • Summarise routes to the classful boundary by default
    • This can cause issues so it is recommended to use the “no auto-summary” to ensure that routes are not changed in undesirable ways.  If left on making sure that the routes are confirmed correct.
    • Use “ip summary-address rip” to manually summarize route at the interface level
  • Perform ECMP (Equal Cost Multi Path)
    • 4 paths by default
      • Can it have more and can it be set to less?
  • Version
    • Version 1
      • Not usually used much as version 2 has many advantages
      • Uses Broadcast every 30 seconds
      • Does not support authentication
      • Does not support Variable Length Subnet Masking (VLSM)
    • Version 2
      • Use multicast address 224.0.0.9 instead of broadcast
      • Supports authentication
  • RIPng
    • Not covered but should know that it is for IPv6
  • Verification commands
    • #show ip protocols
    • #show run | section rip
    • #show ip route
    • #sho ip rip database
  • Default Route Injection
    • (config-router)# default-information originate
• EIGRP (Enhanced Interior Gateway Routing Protocol)
  • Advanced Distance Vector routing protocol
  • Very fast convergence time
  • Multicast – sent to routers affected by the changes through bounded updates
  • ECMP 4 paths by default but can be increased to 16
  • Can perform unequal cost load balancing
  • Autonomous System (AS) Number
    • This is to enforce independent administrative domains, each router much have the same AS number to pass routing information but this allows separate administrative domains.
  • Use a wild card mask when specifying the subnet
    • If no subnet mask is specified a classful boundary will be used. Class A 0.255.255.255, B 0.0.255.255 or C 0.0.0.255 will be used.
  • The interface subnet is what will be advertised and not the network that was setup.
    • Example
      • EIGRP used network 10.0.0.0 does not share 10.0.0.0/8 but will share any interfaces that are shared in the 10.0.0.0/8 range.  So interface with IP range of 10.10.0.0/24 will be shared.
  • Router identify themselves with an EIGRP Router ID which is a form of an IP address
    • Being the highest IP address of any loopback interface or highest other IP address if no loopback exists.
    • You can manually specify the Router ID
    • Recommended to use Loopback or manually set the routed ID
      • Manual ID command: (config-router)#eigrp router-id [ID]
  • Commands
    • #show run | section eigrp
    • #show ip protocols
    • #show ip eigrp interfaces
    • #show ip eigrp neighbors
    • #show ip route

Section 20: OSPF – Open Shortest Path First

• Link State routing protocol
  • Each router describes itself and its interfaces to its direct neighbors
  • Each router learns the full network
• Used for large networks
• Fast convergence time
• Multicast
• Open standard so used by most vendors, for this reason, it is the most common internal routing protocol used.
• Uses Dijkstra’s Shortest path algorithm to learn the network.
• OSPF uses LSA (Link State Advertisements) to pass on the routing updates
• OSPF Router ID
  • Being the highest IP address of any loopback interface or highest other IP address if no loopback exists.
  • You can manually specify the Router ID
  • To change the Router ID the service will need to be restarted
  • Recommended to use Loopback or manually set the routed ID
    • Manual ID command:
      • (config)#router ospf [process ID]
      • (config-router)#router-id [ID]
• Uses a wild card mask when specifying the subnet
  • A wild card mask has to be specified or it will error upon entry
• OSPF Operations
  • Discover neighbors
  • Form adjacencies
  • Flood LSDB (Link State Database)
  • Compute the shortest path
  • Install best routes in the routing table
  • Respond to network changes
• OSPF Packet Types
  • Hello – Used to find adjacent routers
  • DBD (DataBase Description) packets – Used for adjacent routers to tell each other the networks they know about.
  • LSR Link State Request – Used to populated missing info in the received DBD
  • LSA (Link State Advertisement) – Route Update
  • LSU (Link State Update) – List of LSA’s which should be updated, used during flooding
  • LSAck – LSA acknowledgment
• OSPF commands
  • (config)#router ospf [Process ID]
    • Process ID does not have to match to work with the neighboring routers
    • Routes will however not be propagated to other routers in the network since the process ID does not match.
  • (config-router)#network [network ip] [subnet wildcard mask] [area]
    • Example
      • OSPF used network 10.0.0.0 does not share 10.0.0.0/8 but will share any interfaces that fall into the 10.0.0.0/8 range.  An example: interfaces with IP range of 10.10.0.0/24 will be shared.
  • #sh run | section ospf
    • show ospf in the running-config
  • Identification and troubleshooting commands
    • #show ip protocols
    • #show ip ospf interface brief
    • #show ip ospf neighbor
    • #show ip ospf database
    • #show ip route
  • Manual ID command:
    • (config)#router ospf [process ID]
    • (config-router)#router-id [ID]
  • Passive Interfaces
    • (config)#router ospf [process ID]
    • (config-router)#passive-interface [interface]
    • (config-router)#passive-interface [interface]
    • (config-router)#passive-interface default
      • set all interfaces to passive
    • (config-router)#no passive-interface [interface]
      • Turns on the interface to use OSPF
  • Default Route Injection
    • (config)#ip route 0.0.0.0 0.0.0.0 [gateway IP]
    • (config)#router ospf [process ID]
    • (config-router)#default-information originate
  • Bandwidth vs Clock Rate and Speed
    • Speed Command
      • Used for network interfaces 
      • if ‘speed 10’ is set it will only transmit at 10 Mbps
    • Clock rate command
      • Used for Serial interfaces physical transmit
      • Serial interfaces transmit at 1.544 Mbps by default
      • If ‘clock rate 64000’ is set if will physically transmit at 64 Kbps
    • Bandwidth command
      • Setting ‘bandwidth’ does not affect the physical transmission rate.
      • If you set the bandwidth to 50 Mbps on a FastEthernet interface, it will still transmit at the default 100 Mbps or the set ‘speed’
      • ‘Bandwidth’ command affects software policy on the router
        • EIGRP
        • OSPF
        • QoS
      • It can influence software policy by setting the bandwidth on an interface.
  • OSPF Cost Metric
    • The router will learn about all destinations in its area and select routes based on its lowest to get to the destination.
    • Reference Bandwidth
      • Cost is automatically derived from the interface bandwidth.
        • Cost = Reference Bandwidth/Interface Bandwidth
          • Default reference bandwidth is 100 Mbps
          • FastEthernet link cost defaults to 1 (100/100)
          • t1 link cost defaults to 64 (100/1.544)
        • The reference bandwidth should be changed on all routers to compensate for speeds faster than FastEthernet otherwise all interfaces will be seen as a cost of 1
          • (config) #router ospf 1
          • (config-router)#auto-cost reference-bandwidth 100000
    • Manipulating the OSPF Metic
      • If manipulation is needed it is recommended to change OSPF cost on interfaces opposed to bandwidth as changing bandwidth can affect features other than OSPF such as QoS.
      • Cost change commands
        • (config)#interface [interface]
        • (config-if)#ip ospf cost 50
      • To review OSPF cost commands
        • #show ip ospf interface
          • To see full details for all interfaces
        • #show ip ospf interface [interface]
          • To see an individual interface
        • #show ip ospf interface brief
          • To see a summary of all interfaces

Another day in the book.  I am on week three but I have a feeling since I am not just reviewing OSI model items and now focusing on Cisco commands along with the Cisco Functionality I will be working more closely with the timeline that is laid out on the study plan calender.

So I am on vacation and while most people go out and see new sites or at least get out of the house, I am working on getting through as much as the CCNA training that I can before going back to the day job, so without further ado…

13. The Cisco Troubleshooting Methodology – Who knew that I was doing this without knowing the Cisco Methodology

Something fun to know, if you need end a traceroute in Cisco Packet Tracer is the command ctrl+Shift+6, I found this in the lab but when it was being demoed I kind of fix it before the getting to the lab or even through the lab demo.

14. Cisco Router and Switch Basics – Lots of talk of the setup wizard, “Shutdown”, “No shutdown”, full and half-duplex troubleshooting.  As well as CDP and LLDP.

15. Cisco Device Management – Boot up, Factory Reset, backup, and upgrades.

16. Routing Fundamentals – Lots of routes and how to set them along with a lot of labs to watch.

17. Dynamic Routing Protocols – The section that I really start learning/reviewing items that I haven’t used before.  I was somewhat familiar with RIP, EIGRP, and OSPF, but not IS-IS, loopbacks, or passive interfaces.

Looking at the schedule that came with the course, I didn’t quite finish week 2 on day two as I still need to complete the lab for section 17 and do all of 18 and 19 with their labs.  Will I be ready to take the test on Friday before I head back to work a week from tomorrow?

I have decided that I needed to get another piece of paper to continue on proving myself to the unknown masses of tomorrow.

I feel that with my experience that the CCNA test is something that I should be able to tackle in a fair amount of time since my daily workday is full of Wireshark captures and troubleshooting network issues of the customer.

It has been some time since I have logged into a Cisco device as recent jobs have had me working a Fortinet Firewalls and switches as well as Symantec Proxy, Content Analysis, Management Center and Reporter devices.  The Symantec devices at least retain many of the Cisco formats with the enable, config t type layout.

I first looked through the LinkedIn Learning library as that is something that is offered through my current employment but the only CCNA course that I saw was the CCNA security lesson.  I am sure that will be great but wanting to make sure that I have all my bases covered before I drop $300 on a test I went over to Udemy and decided to go with Neil Anderson @flackboxtv and his Cisco CCNA 200-301 – The Complete Guide to Getting Certified.

I appreciate that he has a Study plan setup and there is some solid steps laid out to follow, as I am one of those set path types of guys.

Now granted I did do the first weeks of lessons on day 1 as there was little that was new to me here as the OSI model is something that I was studying back in 1999 (man I am old, lol)

I think the only thing that might have made this a little better is if he explained some of the network details with Packet Capture program like Wireshark.

Here is a review of the sections in the course:

1. Welcome – Discuss how and why he has set up the program in the layout he has.
2. How to set up the Lab – Cisco Packet Tracer setup.  It has been quite a while since I have used this but it is a great free tool to learn the Cisco devices
3. Host to host communications – A high level overview of the OSI model, a bit boring for veterans but good review and some new acronyms that I hadn’t heard before… Please Do Not Take Sales People’s Advice – Please Do Not Touch Superman’s Private Area
4. The Cisco IOS Operating System – Summary of the structure and review of the different OSs from the past and current.
5. OSI Layer 4 Summary
6. OSI Layer 3 Summary
7. IP Address Classes
8. Subnetting – I haven’t had to do this manually for so long, I didn’t realize how rusty I was.  I will say I appreciate a good IP calculator
9. OSI Layer 2 Summary
10. OSI Layer 1 Summary
11. Cisco Device Function – Switches, Hubs, and Routers oh my…
12. The Life of a Packet – I will say the last two parts were overkill.  If you don’t understand ARP after this you either don’t want to or you should be looking at a different profession.

Bring on Week/Day 2!!