ATM Configuration and Troubleshooting Guide

Troubleshooting
Troubleshooting MPOA
Chapter 9262
If the destination is a LAN-legacy system located behind an
MPOA-capable edge device, consult the edge device’s documentation to
check its MPOA configuration.
If you think all the devices along the data path have been properly
configured and the MPOA feature is still not working, contact HP.
G Check for the MPC-MPS VC’s existence. Ensure that the VC from
the local ATM host’s MPC to the destination’s MPS exists. You can use
the atmmgr command to do this (see “D” on page 256—in that example,
you should look at the first two LLC LEC, MPC VCs [0,240 and 0,241]).
H Lower the threshold. Decrease the setting for the flow detection
threshold (see the list of assumptions after the flowchart [Figure 9-14 on
page 253]).
I Check for Resolve Reply Acks. Run the mpcstat command and look
for the counters Resolve Requests in the Tx section and Resolve
Reply Acks in the Rx section (both are shown as bold in the example
below). If the first counter (Resolve Requests) is increasing and the
second counter (Resolve Reply Acks) is still 0 or not keeping up with
the first counter, you can suspect that somewhere along the data path
you have a non-MPOA-capable device. This could, for example, be an
incompatibility between routers or their inability to forward/receive
NHRP packets, or your destination could be badly configured.
The mpcstat comand is also useful in verifying that packets are being
exchanged on the shortcut VCs established between your local ATM host
and the MPOA-capable destination systems. Also shown in bold in the
example below are two other counters—Total Tx packets over
shortcut and Total Rx Packets over shortcut. These show the total
number of packets sent (Tx) and the total number of packets received
(Rx) over the shortcuts established on a specific MPOA-capable LAN
Emulation interface. Note that these counters are for all of the shortcuts
on the LAN Emulation interface. This means that you cannot identify a
specific data flow from these counters.
Ingress/Egress Cache statistics of all of the MPCs on the system:
Ingress Cache
Total Tx Packets over shortcut : 1000
Egress Cache
Total Rx Packets over shortcut : 1234