WAN and VPN - jibingl/CCNA-CCNP GitHub Wiki

WAN

WAN connection services include leased line, Ethernet, DSL, CATV, Fiber, and WLAN.

Glossary	Explanation
Hub-and-Spoke	A WAN topology like center-branches
DSL	Digital Subscriber Line
Modem	Modulator-demodulator
PSTN	Public Switched Telephone Network
CATV	Cable Television
CE router	Customer Edge router
PE router	Provider Edge router
P router	Provider router
MPLS	Multi-Protocol Label Switching
Single-homed	Customer's 1 connection to 1 ISP
Dual-homed	Customer's 2 connections to 1 ISP
Multihomed	Customer's 2 connections to 2 ISPs
Dual Multihomed	Customer's 2 connections to each 2 ISPs
DMVPN	Dynamic Multipoint VPN

MPLS VPN

Label switching - forwarding decision based on labels, not destination IP. Create VPNs over MPLS infrastructure.

                     .---------ISP-MPLS-net--.
                    /                         \
     CE-R1         |PE-R2       P-R1      PE-R3|           CE-R2
      (+)---------(+)-----------(+)-----------(+)----------(+)
                   |===========================|
                    \   L3-MPLS-VPN-tunnel    /
                     `-----------------------`

                     .-------ISP-(like a SW)-.
                    /                         \
     CE-R1         |PE-R2       P-R1      PE-R3|           CE-R2
      (+)---------(+)-----------(+)-----------(+)----------(+)
         ==========|===========================|===========
                    \   L2-MPLS-VPN-tunnel    /
                     `-----------------------`

DMVPN, FlexVPN, and GETVPN

Feature	DMVPN	FlexVPN	GETVPN
Encryption	IPsec	IPsec (IKEv2)	IPsec (GDOI)
Tunneling	GRE/mGRE	GRE, IPsec	No tunnels (uses native IP forwarding)
Topology	Hub-and-Spoke, Full-Mesh	Any (Point-to-Point, Hub-Spoke, Full-Mesh)	Full-Mesh
Scalability	High (Dynamic Tunnels)	High (Modular Design)	Very High (No Tunnel Overhead)
Dynamic Spoke-to-Spoke	✅ Yes (NHRP)	✅ Yes	❌ No
Key Feature	Dynamic VPN with NHRP	Unified IKEv2 VPN framework	Group Encryption
Interoperability	Cisco-centric	✅ Better interoperability	Cisco-centric
Best for	Branch Networks, Remote Offices	Flexible VPN needs, Mobile Users	MPLS Encryption, Large-Scale WANs
Advantages	✅ Dynamic tunnels ✅ Reduces config overhead ✅ Works over the internet	✅ IKEv2 support ✅ Modular & unified ✅ Better security & mobility	✅ No tunnel overhead ✅ Consistent security policy ✅ Scales well over MPLS
Disadvantages	❌ Hub dependency ❌ NHRP complexity	❌ More complex than DMVPN ❌ Requires IKEv2 knowledge	❌ Needs private backbone (MPLS) ❌ Not for public internet