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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 ! 

 

7 REPLIES 7
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VIP Advisor

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

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 ?

BB
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Beginner

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

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

Beginner

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

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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Beginner

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

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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Beginner

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

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

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Beginner

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

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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Beginner

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

Please see attached.Capture.PNGCapture1.PNG