setting up a ratio routing 80-20 over 1Mb and 54Mb connection

[krybabie]

Hi everyone

I am having a problem setting up on my 2600 router a 80-20 ratio routing over 2 routes.

This is the senario:

i have 2 lines 1 X 1Mb and 1 X 54Mb

1mb - serial0

54Mb - e0.1 (subinterface)

e0 (connection to my lan)

i need to balance the routing that the 54Mb line carries at least 80% and the 1Mb line carries at most 20%

If one goes down the other must go to 100% for the time that the other is down.

Thanks for your time

Hope you can help me

Regards

Malcolm

[Kevin Dorrell]

If you are running EIGRP, that will set up parallel routes with unequal-cost load balancing. If you really want 80:20, then I think you will have to fiddle the metrics to do so, and set a variance factor of at least 4. Otherwise it will be 54:1 and you will have to set a variance of at least 54.

Kevin Dorrell

Luxembourg

[krybabie]

hi, forgot one thing all routes are static and directly connected.

[Kevin Dorrell]

Ah, that makes it more of a challenge.

You say static and directly connected, but what exactly do you mean by that? The serial route can be static to the interface, but the Ethernet route must be static to the IP address of the next gateway. Both of these have an AD of 1 (contrary to popular opinion), but for some reason best known to the IOS writers, the static-to-interface wins. The only chance you have of getting them both to appear in the routing table is to configure both as static-to-gateway-address.

Then comes the question of load sharing. I think normally this config will distribute the traffic flows about 50:50. I really don't know how you would go about unequal load-balancing between static routes. You might be able to do something fancy with route maps. You will need someone else to advise you about this; I am out of my depth. Sorry!

Kevin Dorrell

Luxembourg

[krybabie]

correct on both counts - now you see my problem.

The serial is connected to a router on the other side a 1600. The ether will also be connected to the 1600 via the 54Mb ether.

i am just trying to find out how to load balance directly connected/static routes

Malcolm

[Kevin Dorrell]

If you configure the destination of serial static to be the other IP address of end of the link, and not the interface name, then both should appear in the routing table. But the flows will be shared 50:50.

You would need to do the same at the other end of course; load-sharing is only for translission.

Kevin Dorrell

Luxembourg

[krybabie]

yes, but i need 80-20 otherwise the 54Mb line is wasted maybe even 90:10

malcolm

[Kevin Dorrell]

Malcolm,

I've been thinking some more about your problem.

I cannot really imagine why you you would want to load-balance between two lines of such different bandwidths, but I suppose you must have your reasons, so I guess it is up to us to suggest a solution.

I would try setting up EIGRP just between the two routers. On each side, declare just the networks of the serial line and the 54 Mbps connection. Redistribute the connected networks into eigrp, and give them a credible default seed metric. You might want to redistribute some statics and maybe a default as well. Set up the variance so that EIGRP gets each route twice, and then compare the metrics. Then you will have to fiddle the connection costs so that the load gets distributed in the ratio you want.

Beware that this is normally flow balancing (or "per-destination" as the literature has it). Where the bandwidths are as lopsided as in this case, you are unlikely to get the ratios you are expecting. On the other hand, you could do per-packet load balancing, but then you run the risk of packets arriving severely out of sequence. Here is a good discussion of these issues:

http://www.cisco.com/en/US/tech/tk827/tk831/technologies_tech_note09186a0080094806.shtml

Kevin Dorrell

Luxembourg

[Craig Norborg]

Of course I'm wondering about something else. 54Mb is a odd number for WAN bandwidth, sounds more like something wireless, either 802.11 "a" or "g". In either one of those cases, the actual bandwidth is going to be quite a bit less than 54Mbit, more like "less than" 20Mbit, not to mention its half-duplex. I would guess that this could potentially run into problems since wireless could add odd latency problems into the connection that a wired connection wouldn't have.

If its not wireless, just ignore this, but it would be good to give everyone the whole picture here...

[Kevin Dorrell]

Good thinking. But that strengthens the case for EIGRP, as you can set both latency and bandwidth in the metric. I was thinking more in terms of ATM bandwidths.

Kevin Dorrell

Luxembourg

[krybabie]

Ok i am starting to get a grip on the picture i have at hand as it has been

a very long day baffling me.

This is the situation as it stands:

Side one.

2600 Router - one Serial - 1Mb connection

- one ether slot with a live IP.

Problem - need to subinterface for the wireless.

can't get an IP address to hold on the subinterface without vlan protocol

running.

The wireless consists of 2 router boards running Mikrotik OS and they are

working 100% connection distance less than 1 Km 5G network secure running at

54Mb no packet loss. Antenna are the best you can get for 5G around 100Km or

so distance wise.

Each routerboard can route so not worried how to get traffic across the

boards - just created a bridge between the ether ports on either Board.

I have 2 sets of live IP's in play. Mine and my ISP's lets say 196.a.b.? (my

range) and 196.c.d.?(isp range)

my router has ip 196.a.b.1

i was trying to use a private Ip range to route but that now won't work as i

can not add an ip to the sub interface.

Side 2 1600 router serial 0 1MB

Ether0 is the connection to the PIX at our Upstream provider also is

subinterfaced to the wireless - managed to get an ip address on the

subinterface working there.

This side is working perfectly.

Hope this all makes sense

Thanks

Malcolm

[Kevin Dorrell]

Malcolm,

I've just seen your network diagram on another section, and now I understand your architecture better. I wasn't previously aware of the 4 Mbps link from C to B. This really is a case for EIGRP between the three routers. EIGRP would give you almost exactly what you want. EIGRP would know that the path A-C-B has a bandwidth of 4 Mbps, and that A-C has 1 Mbps, and would share the traffic almost exactly 20:80.

You would start with a variance parameter of about 10 than because the 1 Mbps path is shorter, so the metric ratio may be slightly more than 4. You could tell it about the delay on the 54 Mbps path to adjust the sharing slightly.

Kevin Dorrell

Luxembourg

[Craig Norborg]

Ok, that explains something else I saw but forgot to mention. You can't run two "LANS" off the same ethernet interface having one as a subinterface and the other as the main interface, just doesn't work. However, you can do it by trunking the router to the switch, then have a seperate layer-2 domain in each VLAN. I've also had problems trunking on a regular Ethernet port, but not on FastEthernet ports, so that could be a limiting factor. Also, to do trunking you need to run the IOS Plus image at least.

Example for you:

Router:

interface fa0/0 (***ONLY HARDWARE CONFIGURATION GOES HERE!!)

speed 100

duplex full

interface fa0/0.1

encapsulation dot1q 1 native (*** Native VLAN - Not tagged!!)

description User VLAN

ip address 10.X.X.1 255.255.255.0

end

interface fa0/0.200

encapsulation dot1q 200

description Wireless Router VLAN

ip address 192.168.X.1 255.255.255.252

end

Switch:

interface fa0/0

description Trunked Port To Router

switchport mode trunk

speed 100

duplex full

end

interface fa0/1

description Connection to Wireless Router

switchport access vlan 200

end

Note that on a 2950 switch, it only does dot1q encapsulation, but on a 3500XL or similar you will also need a "switchport trunk encapsulation dot1q" on your trunked port. Also, on the router the VLAN # (determined by the "encapsulation" command) doesn't have to be the same number as the sub-interface, but that does make things easier to remember/debug...

After you get this working, you'll need to follow the unequal cost EIGRP or similar methods others have spoken of here...