Troubleshooting DMVPN

Troubleshooting DMVPN

Problems on the DMVPN network can categorized as follows:

Most of the problems that occur in these areas are caused by misconfiguration or a bug in the code. This section helps you identify and troubleshoot configuration-related issues. Most of the problem areas can be identified with show commands output. You might end up running debug commands to find additional details about the DMVPN problem.

NHRP Mapping Problem

NHRP (cache) Mapping problems can be identified by executing show ip nhrp command as shown in Example 6-34.

Example 6-34. Showing the Successful Mappings of NHRP with show ip nhrp Command

Hub1# show ip nhrp
! This is the first dynamic NHRP Mapping
! Tunnel0 is the interface of the NHRP cache entry that was created. 00:11:03 is the time
! since the NHRP entry was created. 00:04:52 is the time in which the positive and
! negative authoritative NBMA address will expire (hours:minutes:seconds). This value is
! based on the ip nhrp holdtime command.
10.0.0.11/32 via 10.0.0.11, Tunnel0 created 00:11:03, expire 00:04:52
! Type dynamic means NBMA address was obtained from NHRP Request packet. staticNBMA
! address means statically configured.
! The flag in the following shows Authoritative unique registered which means
! that the NHRP information was obtained from the Next Hop Server or router that
! maintains the NBMA-to-IP address mapping for a particular destination. Implicit
! Indicates that the information was learned not from an NHRP request generated from the
! local router, but from an NHRP packet being forwarded or from an NHRP request being
! received by the local router. Negative caching indicates that the requested NBMA
! mapping could not be obtained.
 Type: dynamic, Flags: authoritative unique registered
! The following shows the NBMA (Nonbroadcast Multi-access Address). The address format is
! Appropriate for the type of network being used (for example, ATM, Ethernet, Switched
! Multimegabit Data Service (SMDS), or multipoint tunnel).
 NBMA address: 172.16.1.1
! This is the Second dynamic NHRP Mapping
10.0.0.12/32 via 10.0.0.12, Tunnel0 created 01:03:31, expire 00:05:46
 Type: dynamic, Flags: authoritative unique registered
 NBMA address: 172.16.2.1
. . .
Hub1#

If the NHRP does not work correctly, analyze the problem further with the debug nhrp command.

Following is a list of some of the important NHRP-related issues that you need to keep in mind: