Double Gateway Issue

[firoz.raj]

Hi Friends,again i have set Default Gateways for 10.64.49.22 and 10.64.49.2 the problem is that
10.64.49.2 is working fine .but 10.64.49.22 is not working . let me know please .Attachment 96169

[Nightwalker83]

Is "10.64.49.22" the correct address?

[firoz.raj]

10.64.49.22 is the correct IP .

[MagellanTX]

By not working do you mean that your computer is preferring 10.64.49.2 over 10.64.49.22? This is a common problem in Windows 7.

Try adjusting your metrics so that your preferred network is more desirable and the other will be a backup.



In this example, Windows will prefer 10.64.49.22 unless DGD determines it’s down and then will use the alternate 10.64.49.2.

[firoz.raj]

In this example, Windows will prefer 10.64.49.22 unless DGD determines it’s down and then will use the alternate 10.64.49.2.

what is DGD ?

[MagellanTX]

Dead Gateway Detection.

It’s a mechanism that comes with the IPv4 stack that allows windows to determine if a particular gateway is down. If so, Windows will fail that gateway and will move to the next preferred (if one is available).

The one thing that trips people up about DGD is that there is no mechanism to determine if a gateway has come back up.

The way you had your routes before would technically work, Windows would try to load balance between the two gateways but Windows workstation wasn’t really designed with load-balancing in mind and it doesn’t have a good algorithm to balance the traffic equally. If you put Wireshark on your machine you’d see that while there is some traffic spread across the two links it would largely favor one over the other.

DGD still comes into play even if you have equal cost routing (links with the same metric), if one of those gateways is down then Windows will no longer send to it.

[firoz.raj]

both the ip is pinging as well .i have added both the ip via route command . another point both the ip is pinging as well .i want both the ip needs to work .it is not like that if one is down other will work .both are pinging and it needs to work both . let me know please .any help would be highly appreciated .Attachment 96343

[MagellanTX]

In that case you need to adjust your metric back to automatic and windows will add both gateways to your routing table as equal cost. However, like I said, Windows workstation doesn’t load balance very well and only contains limited routing intelligence. I’m willing to bet that you’ll see traffic favoring one interface and only sparse traffic on the other.

The only exception to this is if you happen to be running Windows 7 Enterprise. Because of its support for DirectAccess the routing engine inside is a bit more featured but I still don’t think the load balancing is any better. I’ve never tested balancing using W7ENT and the only reason I mention it here is because you’re requirement for equal cost balancing and if you’re in an environment to where you can get your hands on a copy it might be worth testing.

There is load balancing software out there that you can install on your computer to achieve load balancing and, depending on your environment, you can install a firewall on a VM and the firewall does load balancing.

Check out PFSENSE, this might be an option for you if you can’t get the native equal cost routing to work the way you want.

http://bora.bilg.in/blog/04/multi-wa...s-with-pfsense

[firoz.raj]

both gateways to your routing table as equal cost. However, like I said, Windows workstation doesn’t load balance very well and only contains limited routing intelligence.

what is routing table ? and how should i access it . let me know please .

[MagellanTX]

The routing table is what Windows (or any other routing device) uses to determine the next hop for a particular path. You can access the routing table with the route.exe command

C:\> route print
C:\> route add
C:\> route delete

Look at the screenshot I posted in my first message which shows the gateways with a metric of 1 and 200. Modify those gateways to use automatic metric and that will set equal cost routing which you can verify with the route print command. You should see two lines with routes of 0.0.0.0. One with a destination of 10.64.49.22 and one with a destination of 10.64.49.2. If the metric in the last column is the same for both 0.0.0.0 routes then the cost is equal.