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Beginner

FTD 6.2.3 on ASA5506-X - unable to use /31 mask on ipv4 data interface

Hi, the FTD software (6.2.3.10) on ASA 5506-X does not seem to support point-to-point (/31) ipv4 subnets. When trying to set my static /31 public ip on the outside interface in FDM the error message "You cannot assign a broadcast address as the IP address of an interface" is raised. A fix would be most appriciated ! 

 

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VIP Expert

This message is clearly says you can not assign ""You cannot assign a broadcast address as the IP address of an interface"

 

can you please show us more information, what is the exactly IP address you trying to Assign ?



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Hi, any attempt to assign an ip address with netmask 255.255.255.254 to an interface in FDM will either raise the error message above or "You cannot assign a network address "x.x.x.x/255.255.255.254" as the IP address of an interface" based on whether you are using the first or last address in the point-to-point subnet.  

 

/31 subnets is not a problem on a IOS router or ASA:

 

interface GigabitEthernet1
ip address x.x.x.81 255.255.255.254

 

TB

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I just tried that on my FPR 2110 and it does work. What's the extact IPv4 address you are entering?

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I'm using a new ASA5506-X reimaged with FTD and FDM local management (no FMC avail). The smallest subnet possible on the interfaces is /30. If the problem is FDM, could the interface ip be configured from CLI Expert mode ?

 

TB

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... and every ip (i.e 10.20.30.40) with 31 bits mask (255.255.255.254) is rejected.

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Abhijeet- just got confirmed from TAC that the /31 addresses is a restriction on ALL devices running FTD due to limitations in FMC. This feature is planned implemented in a future FTD/FMC vesion. Could you share the running FTD/FMC version on your FPR2110 ?

 

Thanks,

Terje

 
 
 
 
 
 
 
 
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Please see attached.Capture.PNGCapture1.PNG

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