1. Basics
   1. Have you tried switching it off & on again?
2. OSI Layers
   1. Application
      1. Layer 7
      2. SMTP
      3. HTTP
   2. Presenetation
      1. Layer 6
      2. XML / HTML
      3. GIF / JPEG
   3. Session
      1. Layer 5
      2. Controls Connections... i.e. source port to destination port.. and source port tied to applications
   4. Transport
      1. Layer 4
      2. TCP
      3. UDP
      4. ICMP
   5. Network
      1. Layer 3
      2. Logical Addressing
      3. IP
      4. Routing
   6. Data-Link
      1. Layer 2
      2. MAC Addresses
      3. ARP
      4. Switching
   7. Physical
      1. Layer 1
      2. Physical Connections, plugs
      3. Fibre / Copper
3. Routing Protocols
   1. RIP
      1. Distance Vector
      2. UDP 520
      3. Admin Distance 120
      4. Load Balance upto 16 paths
      5. Version 1
         1. Broadcast Updates
         2. Classfull
         3. No Authentication
      6. Version 2
         1. Classless, VLSM = ok!
         2. Auto Summary on Class
         3. MULTICAST - 224.0.0.8
         4. Authentication
   2. EIGRP
      1. Enhanced Interior Gateway Routing Protocol
      2. Routing protocol designed and developed by Cisco
      3. EIGRP is an advanced distance-vector routing protocol, with optimizations to minimize both the routing instability incurred after topology changes, as well as the use of bandwidth and processing power in the router.
      4. Mixture of Distance Vector & Link state
      5. Fast Convergence via DUAL (Diffusing Update Algorithm)
      6. VLSM Support
      7. Triggered partial routing updates
      8. Multiple network layer supports
         1. Supports IP, AppleTalk, IPX, Novell NetWare
      9. Route States
         1. Passive
         2. Active
         3. A route is considered "active" when route recomputation is taking place, i.e. a routing decision has not yet been made.
         4. Passive is the operational "normal" state
      10. Terminology
          1. Neighbour Table
             1. Router uses "hello packets" to discover neighbors
             2. The Neighbour Tables stores a list of directly connected neighbours
          2. Topology Table
             1. When a new neighbour is discovered they update each other with details on all the routes they know about.
             2. The topology table contains all the destination networks learned by other routers.
          3. Advertised Distance
             1. Advertised Distance (AD) is the total metric along a path to a destination network as advertised by an upstream neighbor
          4. Feasible Distance
             1. A Feasible Distance (FD) is the lowest known distance from a router to a particular destination
             2. This is the Advertised Distance (AD) + the cost to reach the neighboring router from which the AD was sent
          5. Sucessor
             1. Also known as Current Sucessor
             2. Is a neighbour that has least-coset path to a destination (and not part of a routing loop)
          6. Feasible Sucessor
             1. is the backup "next hop" if a sucessor fails
             2. (also not part of a routing loop)
          7. Routing table
             1. Stores the best routes to all destinations
      11. multi data-link protocol / topology support
          1. Multicast Neighbours on Ethernet
             1. 224.0.0.10
             2. Support for Unicast Multi-Cast comminucation
          2. Support for point to point & non-broadcast multi-access (NBMA)
      12. EIGRP Packets are IP Protocol Number 88
      13. Admin Distance 90
      14. EIGRP Message Authentication Configuration Example
          1. Routing authentication relies on a key on a keychain to function
          2. ip authentication mode eigrp 10 md5
          3. ip authentication key-chain eigrp 10 MYCHAIN
   3. IGRP
      1. Interior Gateway Routing Protocol
      2. Distance Vector
      3. Cisco Proprietary
      4. IGRP was created in part to overcome the limitations of RIP (maximum hop count of only 15, and a single routing metric) when used within large networks
      5. CLASS_FULL_
      6. Periodically each gateway broadcasts its entire routing table (with some censoring because of the split horizon rule) to all adjacent gateways.
      7. Admin Distance 100
   4. OSPF
      1. Open Shortest Path First
      2. Terminology
         1. Router Types
            1. Internal
            2. All routers have identical LSDBs
            3. Backbone
            4. A router with at least one connection to Area 0
            5. ABR
            6. A router with a connection to 2 or more areas
            7. ASBR
            8. A router with a connectio to an external area
            9. External Area would be re-distributing routes from another protocol
         2. LSDB
            1. Link State DB
            2. A Database of routes within a given area
            3. Routers may have many LSDBs
      3. Admin Distance 110
      4. Multicast
         1. 224.0.0.5 (all SPF/link state routers, also known as AllSPFRouters)
         2. 224.0.0.6 (all Designated Routers, AllDRouters)
      5. OSPF does not use TCP or UDP but uses IP directly, via IP protocol 89
      6. Classless, VLSM = ok!
      7. Link-State Routing Protocol
      8. LSA
         1. Link State Announcement
         2. Types
            1. LSA 1
            2. Router LSA
            3. Describe the state of the routers links to the area
            4. Only Flooded within a particular Area
            5. LSA 2
            6. Network LSA
            7. Generated by DR in multi-acess networks (ethernet)
            8. Describe the routers connected to the multi-access area
            9. LSA3
            10. Summary LSA
            11. Describe routes to the Area's Networks
            12. Flooded thru Backbone (Area 0)
            13. Not flodded thru Totally Stubby or NSSAs
            14. LSA4
            15. Summary LSA
            16. Describe routes to the ASBRs
            17. Flooded thru Backbone (Area 0)
            18. Not flodded thru Totally Stubby or NSSAs
            19. LSA 5
            20. AS External LSA
            21. Generated by ASBRs
            22. Describe routes to external Areas
            23. Not Flooded to Stub, totally stubby or NSSAs
            24. LSA 6
            25. Multicase OSPF LSA
            26. Used in multicase applications
            27. LSA 7
            28. NSSA LSA
            29. LSA 8
            30. External LSA for BGP
            31. Used to OSPF <-> BGP internetworking
            32. LSA 9, 10 or 11
            33. Opaque LSA
            34. Designed for future upgrades
      9. IGP (Interior gateway protocol)
      10. Areas
          1. Backbone
             1. Area 0 is the backbone area
             2. Virtual Link can create a temp link to area 0
             3. All Areas must connect to Area 0
          2. Stub Area
             1. A stub area is an area which does not receive external routes except the default route
             2. Does recieve internal routes
             3. Cannot contain an ASBR
          3. Totally Stubby Area
             1. Does not receive internal or external routes
          4. No So Stubby Area
             1. NSSA
             2. Can send external routes to back bone
             3. Does not accept external routes from other areas
             4. _CAN_ contain an ASBR
      11. Configuring OSPF Authentication on a Virtual Link
          1. ip ospf authentication-key cisco
          2. area 1 virtual-link 3.3.3.3 authentication-key cisco
      12. Sample Configuration for Authentication in OSPF
          1. Types
             1. Null Authentication
             2. Plain Text Authentication
             3. MD5 Authentication
          2. show ip ospf interface serial0
   5. BGP
      1. TCP 179
      2. Border Gateway Protocol
      3. Exterior Gateway Protocol
         1. A routing protocol which exchanges routes _between_ AS's
         2. Also known as: Interdomain routing protocol (IDRP)
      4. AS = Autonomous System
         1. Private AS Numbers = 64512 -> 65535
         2. Transit AS
            1. An AS that routes traffic from one external AS to another External AS
         3. Non-Transit AS
            1. An AS which has an ISP multihoming connection, but does not transfer routes between them
      5. iBGP
         1. Internal BGP
         2. BGP runs within an AS
      6. eBGP
         1. External BGP
         2. BGP is exchanging routes _between_ AS's
      7. Attributes
         1. Well-Known Mandatory
            1. Next hop
            2. Origin
            3. AS_path
         2. Well-Known discretionary
            1. Local Preference
            2. Influences _OUTBOUND_ Traffic
            3. Higher value preferred
            4. Atomic Aggregate
         3. Optional transitive
            1. Community
            2. Aggregator
         4. Optional nontransitive
            1. MED
            2. Multi-Exit Discriminator
            3. Influences _INBOUND_ traffic
            4. Lower value preferred
         5. Cisco Defined
            1. Weight
      8. Path Vector Protocol
      9. BGP is the core routing protocol of the Internet. It maintains a table of IP networks or 'prefixes' which designate network reachability among autonomous systems (AS).
      10. BGP is an interautonomous system routing protocol.
      11. ISP Multihoming Options
          1. Each ISP passes only a default route to the AS
          2. Each ISP passes only a default route and provider-owned specific routes to AS
          3. Each ISP passes all routes to the AS
      12. BGP Authentication
4. Switching
   1. Spanning Tree
      1. BPDU
         1. Notication Frames
            1. Note Generated by spanning-tree portfast
         2. Config Frames
         3. Set with Source Mac & root bridge MAC
      2. Security
         1. Root Gurad
            1. Stops new root Bridge BPDUs, allows switches to connect
         2. BPDU Guard
            1. Rejects ANY BPDU
         3. Loop Gurad
            1. Stops Loops forming if no BPDU recieved
         4. UDLC
            1. UNI-Directional Loop Detection
            2. used to detect if tx or rx breaks
            3. Normal Mode = Log
            4. Aggressive Mode = Err_Disable Port
         5. BPDU Filter
            1. Filters Outbound BPDU
   2. VLANS
      1. VLAN Trunking
         1. Trunk Link carries many VLANS over a single switch port
         2. Switch Frames are "tagged" with a VLAN ID, so receiving device can determine where Frames were destine
         3. ISL
            1. Inter-Switch Link Protocol
            2. Cisco-proprietary protocol that maintains VLAN information as traffic flows between switches and routers
            3. Performs frame identification in Layer2 by encapsulating each frame between a header and trailer.
            4. Referred to as FRAME double tagging
            5. Not the same as Security Layer2 attach "double tagging"
         4. 802.1q
            1. IEEE 802.1Q Protocol
            2. EEE 802.1Q (also known as VLAN Tagging) was a project in the IEEE 802 standards process to develop a mechanism to allow multiple bridged networks to transparently share the same physical network link without leakage of information between networks
            3. Each Frame is tagged within the layer2 frame.... not encapsulated
            4. Single Tagging
            5. Internal Tagging
            6. Native VLAN
            7. VLAN where "untagged" frames should reside.
         5. VTP
            1. VLAN Trunking Protocol
            2. Modes
            3. Server
            4. DEFAULT!
            5. Client
            6. Transparent
            7. All VLANS are local
            8. Layer 2 Frames
            9. Domains
            10. Revision Number
            11. To re-Set to 0
            12. Change Domain Name
            13. Change Switch Mode
            14. VLANS in domain
            15. Paramaters
            16. Mode
            17. Version 2
            18. Version 2
            19. Pruning
         6. DTP
            1. Dynamic Trunking Protocol
            2. The Dynamic Trunking Protocol (DTP) is a proprietary networking protocol developed by Cisco Systems for the purpose of negotiating trunking on a link between two VLAN-aware switches, and for negotiating the type of trunking encapsulation to be used
      2. Virtual LAN
         1. LAN = Local Area Network
      3. A group of hosts with a common set of requirements that communicate as if they were attached to the Broadcast domain, regardless of their physical location.
      4. Static VLAN Assignment
         1. Port Based Membership
         2. This is the "normal"
         3. Steps
            1. Step 1
            2. Create VLAN
            3. vlan <number>
            4. name <vlan-name>
            5. Step 2
            6. Assign Port to VLAN
            7. switchport mode access
            8. switchport access vlan <number>
      5. Dynamic VLAN Assignment
         1. VLANs are assigned based on the MAC address of the end-user device
         2. Switch must query VLAM Membership Policy Server (VMPS)
      6. End to End VLANS
         1. A vlan switch spans a large geographical area
         2. examples would be a single vlan across a whole building or campus
      7. Local VLANS
         1. A vlan restricted by "something"
         2. Example, local to switch or local to room or local to floor
5. TCP/IP Protocols
   1. ICMP
      1. Protocol 1
      2. Types
         1. 0 Echo Reply
         2. 3 Destination Unreachable
         3. 4 Source Quench
         4. 5 Redirect
         5. 8 Echo Request
         6. 11 TTL Expired
   2. TCP
      1. Protocol 6
      2. Connection-Orientated
   3. UDP
      1. Protocol 17
      2. Connection LESS
   4. IP v6
      1. Internet Protocol version 6 (IPv6) is the next-generation Internet Layer protocol for packet-switched internetworks and the Internet.
      2. IPv6 is a new IP protocol designed to replace IPv4, the Internet protocol that is predominantly deployed and extensively used throughout the world. IPv6 quadruples the number of network address bits from 32 bits (in IPv4) to 128 bits or approximately 3.4 x 1038 addressable nodes, which provides more than enough globally unique IP addresses for every network device on the planet.
      3. Key Features
         1. Lager Address Space
         2. Simplified Protocol Header
         3. Built-in Support for Security & Mobility
         4. Transition Richness
            1. Dual Stack
            2. Tunneling
            3. 6 in 4
            4. 6 to 4
            5. Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)
            6. Teredo
      4. Address representation
         1. 2001:0002:2CB5:0000:0000:077A:0000:0000:0007
         2. Addresses can be shortened with :: which replace sucessive 0s
         3. 2001:2:2CB5::77A:0:0:7
         4. Only _ONE_ pair of colons can be used
         5. Leading 0s can be removed
      5. Address Types
         1. Unicast
            1. similar to V4 unicast
            2. Glocal Unicast
            3. = Global Routing Prefix + Subnet ID + Interface ID
            4. Link-Local Unicast
            5. Stateless Auto Config
         2. Anycast
            1. is the "closest" ip address
         3. Mulicast
            1. Similar to v4 mulicast
      6. Routing Protocols
         1. OSPF v3
         2. IS-IS for IPv6
         3. RIPng
         4. EIGRP for IPv6
         5. BGP4
   5. IP v4
      1. Class A
      2. Class B
      3. Class C
      4. Class D
         1. MultiCast
      5. Class E
         1. Experimental
      6. RFC 1918
      7. RFC 2827
6. IP Multicast
   1. IP multicast is a method of forwarding IP datagrams to a group of interested receivers
      1. Multicast Groups are identified by Class D IP addresses
      2. 224.0.0.0 -> 239.255.255.255
         1. 224.0.0.1 = All Hosts
         2. 224.0.0.2 = All Multicast Routers
         3. 224.0.0.4 = All DVMRP Routers
         4. 224.0.0.5 = All OSPF Routers
         5. 224.0.0.6 = All OSPF DR's
         6. 224.0.0.9 = All RIP v2 Routers
         7. 224.0.0.10 = All EIGRP Routers
         8. 239.0.0.0 -> 239.255.255.255 = PRIVATE Internal
   2. Cisco's Securing Multicast
   3. IGMP
      1. Internet Group Management Protocol
      2. Hosts use IGMP to register with a router to Join & Leave multicast groups; the router then "knows" that it needs to forward multicast datastreams to that host
   4. CGMP
      1. Cisco Group Management Protocol
      2. Cisco propiarty protocol which runs between a router & a switch
      3. The router informs directly connected switches about which hosts have joined multi-cast groups to help limit flooding on the switch
   5. PIM
      1. Protocol Independent Multicast
      2. Used by Routers that are forwarding Multicast Traffic
      3. Modes
         1. Sparse Mode
            1. PIM-SM
            2. Hosts/Sources register with the RP
            3. Routers along the path, explicitly Join the group so data can be passed from the RP to the Host
         2. Dense Mode
            1. PIM-DM
            2. All routers are initially "joined" to the multicast group
            3. Routers then request pruning, if no hosts wish to join.
         3. PIM Sparse-dense mode
            1. Hybrid of PIM-SM & PIM-DM
            2. Allows routers to run both PIM-SM & PIM-DM for different multicast groups
            3. Supports automatic RP discovery
      4. RP
         1. Rendezvous Point
         2. Source of the Multicase Tree, i.e. data source.
   6. DVMRP
      1. Distance Vector Multicast Routing Protocol