Hi,
I am fairly new to RouterOS and am running a pair of hEXPoE routers connecting my internet demarc to my home. I currently have 1 wireless link between these 2 sites. I would like to gain the extra bandwidth and redundancy by running 2 wireless links between these 2 sites and am looking for advice on the most reliable way to configure this using these routers. I have read about both bonding and OSPF in the manual, the wiki and in the forums however have not really seen any clear guidance on what is the best way to configure this. Is anyone willing to share what they have done and what they would recommend?
Thanks in advance,
John
What you’re requesting is called “Equal Cost Multipath”
OSPF does this by default. Basically, if a destination is reachable via multiple paths with the same cost, then the same number of routes are activated in the routing table and the router will balance the two paths automatically. This is not perfect load balancing - you will often find one of the links using more or less than the others. This is because it is usually balanced “per connection” - meaning that once a connection flows through the router, the rest of the packets in that flow will continue to use the same interface, regardless of the load on that or other interfaces.
The basic way to set this up is to make sure that each wireless link is a separate layer 3 network (i.e. not bridged or switched in the same broadcast domain) - and typically you’ll put a /30 of IP addressing onto each one.
So if you have R1.ether1 <> R2.ether1 and R1.ether2 <> R2.ether2
You will put IPs like this:
R1:
ether1 = 192.168.255.1/30
ether2 = 192.168.255.5/30
R2:
ether1 = 192.168.255.2/30
ether2 = 192.168.255.6/30
Then suppose R1.ether3 = lan A (192.168.1.1/24) and R2.ether3 = lan B (192.168.2.1/24)
On each router, you will want to add at least the following networks to your /routing OSPF networks list:
R1: 192.168.1.0/24 and 192.168.255.0/24
R2: 192.168.2.0/24 and 192.168.255.0/24
This will get you going with equal cost multipath. Obviously, you’ll want the “upstream” router to “redistribute default information = always” (in a simple home configuration like yours, always is fine, but those of you with more dynamic needs should probably avoid that, as it’s not best practice for general networking needs)
Good luck!
I have a question. Can ospf doubld bandwidth?
OSPF is protocol for finding the best route/path for packets (kind of … to be honest). It does not doubles, triples bandwith.
You can also ask if RIP can double bandwith or if BGP could? No.
You can obserwe better bandwith as side effect of changed route to interface/path with better throughput.
The answer is both yes and no.
Yes, OSPF (and as BartozP points out) and other protocols can do equal-cost multipath. If you have 2 circuits, then you can “double” your bandwidth.
No, equal-cost multipath does not allow you to download twice as fast.
Basically, ECMP gives your network double the capacity, but any single data stream will be routed via one specific link, which means that this stream can go no faster than the available bandwidth on that link at that time. I haven’t looked into how it’s done in RouterOS, but in Cisco, you can set the load balancing as either per-connection or per-packet. If you were to configure per-packet load balancing, then you could get single data streams that approach the full bandwidth of both circuits combined. I tend to avoid per-packet load balancing because my network carries lots of VoIP, and per-packet load balancing would allow out-of-order packet delivery to be possible, which would totally kill voice quality.
Finally, ECMP doesn’t perfectly balance the circuits like MLPPP (or some other layer 2 mechanism) would.
I tend to think of ECMP as “poor man’s bonding”