Which parameter must match on all routers in a DMVPN Phase 3 cloud?
Which parameter must match on all routers in a DMVPN Phase 3 cloud?
In a DMVPN Phase 3 cloud, the parameter that must match on all routers is the NHRP (Next Hop Resolution Protocol) Network ID. This ID identifies and groups routers within the same DMVPN network, ensuring they can communicate and exchange routing information correctly. While the GRE tunnel key can be used when configured, it is not mandatory for operation, making the NHRP network ID the essential matching parameter.
Es A, probado en mi Lab ,no se por que en algunas partes dice que el nhrp network id debe hacer match . Cuando puse diferentes tunnel key si bien el SA se formaba exitosamente el tráfico no pasaba.
A is optional. The question is "must match". Therefore B
A. Note NHRP network IDs are locally significant and can be different. It makes sense from a deployment and maintenance perspective to use unique network ID numbers (using the ip nhrp network-id command) across all routers in a DMVPN network, but it is not necessary that they be the same. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/sec_conn_dmvpn/configuration/15-mt/sec-conn-dmvpn-15-mt-book/sec-conn-dmvpn-dmvpn.html
A is correct
Tunnel key is optional in phase 3, but if you have one it must match on all routers in an NHRP domain, and if you do not use a tunnel key, you must not use it on any router in the NHRP domain (meaning technically it has to match, whether it's there or not). I vote A. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/sec_conn_dmvpn/configuration/15-mt/sec-conn-dmvpn-15-mt-book/sec-conn-dmvpn-dmvpn.html
Name ip nhrp network-id — interface Synopsis ip nhrp network-id id no ip nhrp network-id id Configures Enables NHRP Default Disabled Description This command enables NHRP on an interface by assigning a unique identifier for the network. All hosts participating in NHRP on a logical NBMA network must use the same network ID. id can be from 1 to 4,294,967,295.
Interesting. This appears to be pulled from an Oreilly book. However, Cisco says: "The NHRP network ID is a local only parameter. It is significant only to the local router and is not transmitted in NHRP packets to other NHRP nodes. For this reason the actual value of the NHRP network ID configured on a router need not match the same NHRP network ID on another router where both of these routers are in the same NHRP domain. As NHRP packets arrive on a GRE interface, they are assigned to the local NHRP domain in the NHRP network ID that is configured on that interface." See: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_nhrp/configuration/xe-16/nhrp-xe-16-book.pdf
Interfaces configured with the same ID are part of the same logical NBMA network. The ID is a local only parameter and is not sent to other NHRP nodes and so IDs on different nodes do not need to match
NHRP Configuration Guide, Cisco IOS XE Gibraltar 16.11.x Cisco https://www.cisco.com › ... › Configuration Guides 25 Apr 2019 — The NHRP network ID is a local only parameter. It is significant only to the local router and is not transmitted in NHRP packets to other NHRP ...
In a DMVPN (Dynamic Multipoint Virtual Private Network) Phase 3 cloud, the parameter that must match on all routers is the NHRP (Next Hop Resolution Protocol) Network ID. The NHRP Network ID is used to identify and group routers together within the DMVPN network. It ensures that routers can communicate with each other and exchange routing information correctly. On the other hand, the GRE (Generic Routing Encapsulation) Tunnel Key is used to differentiate multiple tunnels between the same source and destination IP addresses. Each tunnel will have a unique GRE Tunnel Key, which helps in identifying and forwarding traffic correctly within the DMVPN network. So, to summarize, the parameter that needs to match on all routers in a DMVPN Phase 3 cloud is the NHRP Network ID. If this parameter is consistent across all routers, they will be able to establish connectivity and exchange routing information seamlessly.
Answer correct is B The NHRP (Next Hop Resolution Protocol) network ID is a critical parameter that identifies the DMVPN network. It must be the same on all routers participating in the DMVPN Phase 3 deployment. The NHRP network ID is specified within the configuration and is used to group routers within the same DMVPN network.
It is B. https://journey2theccie.wordpress.com/2020/04/17/dmvpn-phase-3-configuration/ tunnel key is optional
NHRP Network ID needs to match
Ignore my comment, I am complete wrong. Network ID is locally significant.
using a tunnel key on the GRE interfaces places each GRE interface into a different NHRP domain, which is equivalent to each being in a unique DMVPN network.