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RS0015 - NHRP Phase 1
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Routing & Switching
The video looks at Next Hop Resolution Protocol (NHRP) Phase 1 with Hub-and-Spoke topology and explains the differences from point-to-point GRE tunnel. NHRP is the basis of widely-used DMVPN. Without the IPSec encryption in DMVPN, we are able see the actual NHRP packets in action, which helps to understand how the protocol operates (ie. Spoke Registration Request/Reply). We will analyze these packets in Wireshark.
Topic includes
- NHRP Phase 1 - Hub-and-Spoke
- NHRP Registration Request/Reply
Notes:
- Next Hop Server (NHS) maintains dynamic mappings between logical and physical endpoint addresses learnt at the time of endpoint registration
- Next Hop Client (NHC) queries NHS for a physical IP address of the other spoke to build spoke-to-spoke tunnel
- Registration message is sent every one-third of NHRP holdtime by default unless specified
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NHRP Phases
- Phase 1 – Hub-and-Spoke only
- Phase 2 - Spoke-to-Spoke. Each spoke maintain next-hop information of the other spokes
- Phase 3 – Spoke-to-Spoke with enhancement (Hierarchical Topology, Route Summarization)
About Author
Metha Chiewanichakorn, CCIE#23585 (Ent. Infra, Sec, SP), is a Cisco networking enthusiast with years of experience in the industry. He is currently working as a consulting engineer for a Cisco partner. As a founder of and an instructor at labminutes.com, Metha enjoys learning and challenges himself with new technologies.
5 comments
great video...thanks
great video...thanks
the switch
i am running the configuration in gns3 so i wonder the switch, what kind or should i use a router instead ?
the switch
Last we checked GNS3 still does not have L3 switch. There might be a switch module on the router but even so it still L2 so you will need to use router as an L3 device for the config.
L3 device
if i use L3 devices, do i need to perform any routing on that device
L3 device
You may need routing if you don't use directly connected interfaces on Hub and Spoke.