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Netwoking

What is Multi-point GRE (mGRE)?

mGRE is key ingredient to build the DMVPN tunnel. Without mGRE we can’t build the DMVPN tunnel. DMVPN uses a combination of the following technologies to build the tunnel : 1. Multi-point GRE (mGRE) 2. Next-Hop Resolution Protocol (NHRP) 3. Dynamic Routing Protocol (EIGRP, RIP, OSPF, BGP) 4. Dynamic IP-Sec encryption(Optional) Point-to-Point Generic Routing Encapsulation (GRE) Tunnels: The traditional […]

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Netwoking

Recovering from ErrDisabled in Cisco Devices

The ErrDisable feature is implemented to handle special situations where the switch detected excessive or late collisions on a port, port duplex misconfiguration, EtherChannel misconfiguration, Bridge Protocol Data Unit (BPDU) port-guard violation, UniDirectional Link Detection (UDLD), and other (miscellaneous) causes. The error-disable function allows the switch to shut down a port when it encounters physical, […]

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Netwoking

FlexVPN an introduction.

FlexVPN, unofficially called “DMVPN phase 4” is a newer “solution” for deployment of VPNs and for this you must have newer hardware to support the versions of IOS code which offer FlexVPN features. DMVPN is an option on almost every Cisco router. FlexVPN is a configuration framework (a collection of CLI/API commands) aimed to simplify […]