NETGEAR is aware of a growing number of phone and online scams. To learn how to stay safe click here.
Forum Discussion
Solved
I can not add /31 subnet mask 255.255.255.254 in WAN ISP > static IP setting in VPN Firewall SRX5308
Hi, I can not add /31 subnet mask 255.255.255.254 in WAN ISP > static IP setting in VPN Firewall SRX5308. When I try to apply it, I get the error message popup as "Invalid IP subnet mask. Please ...
/31 would be used in specific scenarios where you *really* need to conserve address space and only on point-to-point links. To be fair I've never come across anyone, or any ISP, that uses it. It works on point to point because well, there's no need for broadcast address since there are only two devices on the link (one on each side of the cable).. IP ranges would be; .0 - .1, .2 - .3, etc.
Most (if not all) Netgear devices will prevent you from setting /31, but you'll probably be able to use /30 without issues anyways, depending on the ISP setup I don't think it would cause you any issues really. But if you can, I'd definitely ask for a /30 instead.
/31 would be used in specific scenarios where you *really* need to conserve address space and only on point-to-point links. To be fair I've never come across anyone, or any ISP, that uses it. It works on point to point because well, there's no need for broadcast address since there are only two devices on the link (one on each side of the cable).. IP ranges would be; .0 - .1, .2 - .3, etc.
Most (if not all) Netgear devices will prevent you from setting /31, but you'll probably be able to use /30 without issues anyways, depending on the ISP setup I don't think it would cause you any issues really. But if you can, I'd definitely ask for a /30 instead.
Thank you Danthem and DaneA for your kind replies. Yes, I can confirm to you that although /31 subnet is very restrictive, it works well from the SnapGear SG560 firewall and note that this firewall is so old that you can't even buy it now! It surely didn't work from the Netgear firewall in question because it wouldn't even allow the /31 subnet mask IP 255.255.255.254 in its WAN ISP > static IP setting. Anyway, my ISP today gave me a /30 IP block with its subnet mask IP of 255.255.255.252 which is accepted in Netgear's WAN ISP > static IP setting, it's all working for me now, I am happy but it's a pity about the restriction of /31 subnet mask, IMO it shouldn't have had that.
regards
Ridwan
NETGEAR Academy
Boost your skills with the Netgear Academy - Get trained, certified and stay ahead with the latest Netgear technology!
Join Us!
