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Multiple External Subnets

Hi All,

We have a Cisco ASA 5505; we have just upgraded our internet service with Comcast and with the information they have sent me, I'm not sure how i would configure our ASA with the two different subnets on the outside interface.

This is what they have sent:

IP Allocations:
Interconnect block – 50.100.77.96/30          
Netmask: 255.255.255.252
Comcast Internet gateway: .97
Customer’s WAN interface: .98

Primary DNS: 75.75.75.75   Secondary DNS: 75.75.76.76  

Customer’s useable IP block – 50.100.77.112/28
Netmask: 255.255.255.240
Usable IPs: 50.100.77.113 thru .126
The /28 of usable IP space is statically routed by Comcast to 50.100.77.98

Could someone please suggest how i would best go about this?

Many thanks,
Tarran

Everyone's tags (1)
2 REPLIES
Hall of Fame Super Silver

You can't have both

You can't have both simultaneously handling your traffic. The closest you can do directly on the ASA is to have one path as a backup route which only takes over when the first is not seen. Reference. (old guide but still valid)

Otherwise you need to use an upstream router.

VIP Purple

I read your post completely

I read your post completely different then Marvin ... It seems that you just got a second subnet so that you have more usable addresses? And your outside IP is 50.100.77.98? Then you can either use that new subnet as a DMZ-interface on the ASA, or you can use the addresses of this new range as public NAT-objects for incoming and outgoing traffic.

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