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Cisco Bug: CSCur44103 - ASR1k: Port leak while using NAT with interface mappings

Last Modified

Sep 14, 2019

Products (1)

  • Cisco ASR 1000 Series Aggregation Services Routers

Known Affected Releases

15.2(4)S

Description (partial)

Symptom:
An ASR1k router will run out of internal ports to be allocated for a given application. This can impact applications such as telnet, FTP, TACACs, etc.

For example, when trying to telnet to a locally defined IP address, the following will be seen if all the internal ports are leaked:
ASR1k#telnet 1.1.1.1
Trying 1.1.1.1 ...
% Out of local ports

Conditions:
This issue is seen when overloading NAT and using an interface-based mapping
"ip nat inside source list ACLNAME interface GigabitEthernet0/0/0 overload"

This issue is only applicable to ASR1k routers.
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Bug Details Include

  • Full Description (including symptoms, conditions and workarounds)
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