cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
2249
Views
4
Helpful
5
Replies

Bonding WANs to increase bandwidth with GRE Tunnels

William Foster
Level 1
Level 1

How can I bond 2 WANs 50/5 to get a combined speed of 100/10 using GRE tunnels on a 3750 switch.

I am having a hard time finding anything on this. We also want to do this with our own company network.

If someone could point me to the right spot it would be greatly appreciated.  We also do not want to have to purchase any services to do this.

1 Accepted Solution

Accepted Solutions

Joseph W. Doherty
Hall of Fame
Hall of Fame

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

I can think of two ways that might work, but both are "messy" and probably not worth the effort especially to only increase your aggregate bandwidth by 10%.  Also depending on how they are implemented, either your short term load balancing wouldn't be really 10:1 unless you do packet-by-packet, which I would advise against.

First, as noted by Paolo, 3750s don't support GRE - although to be precise - he means GRE tunnel end points.  If GRE traffic is just passing through the 3750, then there's no problem.

Second, a single GRE tunnel is seen as one flow.  This means a single GRE tunnel's traffic cannot be sent across multiple paths unless you do packet-by-packet, again I would advise against that.  Also as a single flow, whose "flow" attributes don't change, all the traffic will normally take the same path (when not doing packet-by-packet) when there are multiple paths to chose from.

Both distribution methods I have in mind depend on both your links being routable.  In the first, you use 5 statics routes across the 100 Mbps path, and 1 static route across the 10 Mbps path.  To have 5 static routes on the one path, you'll need 5 destinations IPs.  This might be accomplished by using secondaries or making the 100 Mbps a trunk with 5 VLAN interfaces.

In the second method, you use EIGRP and its variance costing.

Also again, if not doing packet-by-packet, flows will pick one of the paths and use it regardless of actual traffic load.  This means any GRE flows running across the 10 Mbps link might congest even though much of the 100 Mbps link is currently not being used.

My recommendation would be to only use the 10 Mbps as a hot standby.  I.e. use the 100 Mbps for all traffic, only use the 10 Mbps if the 100 Mbps is down.

View solution in original post

5 Replies 5

paolo bevilacqua
Hall of Fame
Hall of Fame

It is not possible "to bond WANs". You can add multiple circuits for load sharing, but the single session bandwidth will remain the same. Same if you could use EthernetChannel, and is not even said that you can. Furthermore, the 3750 being a switch, does not support GRE.

Joseph W. Doherty
Hall of Fame
Hall of Fame

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

I can think of two ways that might work, but both are "messy" and probably not worth the effort especially to only increase your aggregate bandwidth by 10%.  Also depending on how they are implemented, either your short term load balancing wouldn't be really 10:1 unless you do packet-by-packet, which I would advise against.

First, as noted by Paolo, 3750s don't support GRE - although to be precise - he means GRE tunnel end points.  If GRE traffic is just passing through the 3750, then there's no problem.

Second, a single GRE tunnel is seen as one flow.  This means a single GRE tunnel's traffic cannot be sent across multiple paths unless you do packet-by-packet, again I would advise against that.  Also as a single flow, whose "flow" attributes don't change, all the traffic will normally take the same path (when not doing packet-by-packet) when there are multiple paths to chose from.

Both distribution methods I have in mind depend on both your links being routable.  In the first, you use 5 statics routes across the 100 Mbps path, and 1 static route across the 10 Mbps path.  To have 5 static routes on the one path, you'll need 5 destinations IPs.  This might be accomplished by using secondaries or making the 100 Mbps a trunk with 5 VLAN interfaces.

In the second method, you use EIGRP and its variance costing.

Also again, if not doing packet-by-packet, flows will pick one of the paths and use it regardless of actual traffic load.  This means any GRE flows running across the 10 Mbps link might congest even though much of the 100 Mbps link is currently not being used.

My recommendation would be to only use the 10 Mbps as a hot standby.  I.e. use the 100 Mbps for all traffic, only use the 10 Mbps if the 100 Mbps is down.

What about doing this with an ASA instead of a Switch?

ASAs are also very bad for balacing traffic etc. For that, you need routers.

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Sorry, can't say, I'm unfamilar with ASAs.

Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: