N-Series DHCP Failure after Upgrading to 6.x Firmware

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  • Updated 5 years ago
Article ID: 10499 

Products
Matrix N-Series DFE, firmware 6.01.01.0020 and higher 

Changes
Configured DHCP with a pool subnet mask of less than 22 bits (e.g. 'ip local pool myPool 10.8.13.0 255.255.0.0').
Upgraded from 5.x or earlier firmware to 6.x firmware. 

Symptoms
DHCP does not function.
Upon upgrade, all DHCP configuration commands have been erased. 

Cause
The defined pool of DHCP addresses exceeds the amount currently supported, which is 1024 addresses. 

Firmware 6.01.01.0020 release notes state, in the "Software Changes and Enhancements" section:
The DHCP configuration CLI now enforces lease capacity limits. Two new messages may be displayed when configuring DHCP: "The Maximum number of DHCP Leases has been reached." and "The specified pool exceeds the amount of DHCP Leases remaining." Previously the DHCP server might stop processing DHCP requests if its configuration exceeded supported capacities.

Solution/Workaround
The local DHCP pools can contain no more than a total of 1024 addresses, and will need to be reconfigured accordingly. 

Ensure that the specified subnet mask within the 'ip local pool' command is within the range of 255.255.192.0 (22-bit = 1022 addresses) and 255.255.255.252 (30-bit = 2 addresses), which will prevent any given pool from exceeding the limit.
Also ensure that the total number of addresses as defined by all local DHCP pools does not exceed the limit.
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Posted 5 years ago

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