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Default Gateway - more than one?

Posted on 2013-01-30
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Last Modified: 2013-01-31
HI,

Can you have multiple default gateways and if so, can you run multiple default gateways at the same time?

Thanks
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Question by:fredostare
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by:IntegrityOffice
ID: 38837471
Go to the advanced tab on your TCP/IP4 ( I am assuming Windows here ) and add separate default gateways, you need to weight them (add metric ) for the priority
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by:fredostare
ID: 38837485
Thanks! Would you use more than one default gateway for redundency? And is it actually advisable? I've heard it shouldn't be done, and others say it's fine...
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by:IntegrityOffice
ID: 38837512
I often have a piece of hardware ( such as a watchguard firewall ) and I let that do the load balancing across the two broadbands. I can then use it to do "policy based routing"

Eg

Fast broadband Internet, VPN connectios
Slow one mail and maybe webmailHTTPs access, DNS

The advantage here is that I setup the lines to use the above protocols but there is also a what happens if BB1 fails it all flicks to BB2 in less than 45 seconds. ( that is configurable )

If you are really worried about a hardware failure you can HA ( high availability ) link two filrewalls together so you do not need to worry about a single point of failure.

Also if you are using something like a Watchguard you can use all the wonderful features of UTM. There are many firweall operators that do this but I have been using it on sites with WG for several years now.
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by:Don Johnston
ID: 38837609
Can you have multiple default gateways and if so, can you run multiple default gateways at the same time?

You can have multiple default gateways defined, but only one will be used at any given time.

If you want first hop redundancy then a FHRP (First Hop Redundant Protocol) such as VRRP, HSRP or GPBP would be used on the layer three devices which are the default gateways.
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Rob Williams earned 500 total points
ID: 38838447
Multiple default gateways in Windows do not work as they should.  Firstly "default" by definition can only be one, but Windows allows a failover default gateway.  Unfortunately if the higher metric gateway fails, even for a second, the lower metric gateway takes over, but under no condition does it ever switch back as it should, without a reboot.  This in no way allows for load balancing between the two gateways.  That requires a dual WAN port router.
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by:fredostare
ID: 38839186
Hi all, so is best practice to avoid having a client point to two default gateways on a windows system, and rather deal with redundancy at the gateway itself instead?
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by:Don Johnston
ID: 38839221
Hi all, so is best practice to avoid having a client point to two default gateways on a windows system, and rather deal with redundancy at the gateway itself instead?
Correct.
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by:Rob Williams
ID: 38839511
Windows will even warn you of that if you try to add a second agteway, though it will accept it.
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