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Cisco Bug: CSCum56808 - C880 - MTU calculation for ESP-NULL

Last Modified

Oct 14, 2019

Products (1)

  • Cisco IOS

Known Affected Releases

15.3(3)M1.9 15.4(1.1)T

Description (partial)

C880 uses 0-3 bytes padding in case of configuring ESP-NULL and esp-sha-hmac for encryption thereby overhead calculation results in 42-45 bytes. When MTU of interface with crypto-map has default ethernet value of 1500, the maximum size of data which can be encrypted with padding 0 is 1458 bytes. However it is calculated to be 1454 instead of 1458 bytes.

The issue has been observed with Cisco881 running later than 12.4(24)T4 up to the latest version.
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