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Tuesday, December 12, 2017
Lab Gear * CCNA * Topologies

CCNA Topologies

Before buying your first Cisco lab gear, it can be helpful to think about the topologies of gear you would use when practicing for the exam. Then, you can let the topologies drive the number of routers and switches you need to buy or borrow. This page examines several alternative topologies that can be useful for CCNA preparation.


Some of the sample topologies shown here focus on routers, and some focus on switches. The topologies can of course be combined, but for the sake of discussion, the topologies listed on this page keep either a router or switch focus. Also, all topologies assume at that you have one PC that can be connected via Ethernet and to the device consoles for testing and configuration.


Click in the following list to scroll down to the area of this page for the various topologies:


Router Centric Topologies   Switch Centric Topologies
Router Pair   Solo Switch
Router Triangle   Switch Pair
Router WAN Square   Switch Triangle
Router LAN Square      


more Topologies...

Router Pair


Notable Benefits: Related Notes:
  • Real Cisco IOS CLI
  • Basic Routing Protocol configuration                 
  • Very Basic Layer 3 redundancy
  • NAT
  • DHCP 
  • IPv4 and IPv6
  • SSH
  • Static routes
  • RIP, EIGRP, and OSPF
  • HDLC, PPP                                     
  • ACLs                                                                                                                                                 
  • With a single 2950 switch added, can support 802.1Q trunking between a router and switch

more Topologies...

Router Triangle


Additional Benefits
(Compared to Router Pair):
Related Notes:
  • Much Better routing protocol redundancy
    (See this blog series)
  • Supports more OSPF areas
  • Allows better experiments with automatic summarization 
  • With 2 serial interfaces per router, supports basic Frame Relay (shown)
  • Give 1 router 4 serial interfaces, and you can configure so one router acts as FR switch, with 3 routers as FR DTEs (not shown)

more Topologies...

Router WAN Square


Additional Benefits
(Compared to Router Triangle):
Related notes:
  • Even better routing protocol redundancy 
  • Easier support for 3 Frame Relay DTEs
  • Can create a 4 Frame Relay DTE design by giving one router 5 serial interfaces (not shown)
  • Probably overkill for CCNA; 3 routers should be enough

more Topologies...

Router LAN Square


Additional Benefits
(Compared to Router triangle):
Related Notes:
  • Demonstrates OSPF DR/BDR/DROther much better than other topologies 
  • Best design (so far) for testing routing protocol neighborship issues
  • Doesn't add a lot of possibilities compared to router triangle, at least for CCNA topics

more Topologies...

Solo Switch


Notable Benefits: Related Notes:
  • Switch admin
  • VLANs 
  • VTP 
  • 802.1Q trunking from switch to router
  • VLAN configuration
  • Voice VLANs
  • Port Security
  • DHCP client 
  • Many CCNA-level LAN switch features require a single switch for lab experiments
  • The topology shows two routers as devices for testing
  • Most CCNA labs will have at least two routers anyway, so these are not “additional” routers

more Topologies...

Switch Pair


Additional Benefits
(Compared to Solo Switch):
Related Notes:
  • Allows configuration of all CCNA Spanning Tree features
  • Etherchannel
  • Supports meaningful VTP experiments
  • Switch-to-switch trunking (802.1Q)
  • You do not need a layer 3 switch

more Topologies...

Switch Triangle


Additional Benefits
(Compared to Solo Switch):
Related Notes:
  • Uses the triangle design suggested by Cisco LAN design documents
  • Much more interesting Spanning Tree Topology; harder to predict
  • Can run even more meaningful VTP experiments (eg 2 servers, 1 client)
  • Not really necessary, but useful

See below for additional CCNA products and guides...

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