load balancing for static route (unequal links)

Unanswered Question
May 8th, 2007

We have 2 leased line. first leased line capacity is 2Mb 2. is 512 Kbps. We would like to work load balancing an these lines. We must use static routing. How can we make a load balancing? We tried multilink. But dont work.

interface Multilink1

bandwidth 3072

ip address 195.155.2.162 255.255.255.252

load-interval 30

ppp multilink

multilink-group 1

interface Serial5/0

bandwidth 2024

no ip address

encapsulation ppp

no ip route-cache cef

no ip mroute-cache

load-interval 30

serial restart_delay 0

ppp multilink

multilink-group 1

interface Serial5/3

bandwidth 1024

no ip address

encapsulation ppp

no ip route-cache cef

no ip mroute-cache

load-interval 30

serial restart_delay 0

ppp multilink

multilink-group 1

I have this problem too.
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bjornarsb Tue, 05/08/2007 - 01:22

Hi,

If PPP multilink is going to work it has to be configured on both ends. The customer router and on the provider edge router.

Both links need to be terminated at the same provider edge router ( even though its possible to run Multichassis Multilink PPP )

So you need to contact your service provider.

If they do not support PPP multilink ask for OSPF load balancing.

HTH

Regards,

Bjornarsb

Danilo Dy Tue, 05/08/2007 - 01:24

Hi,

IF you must use STATIC Routing, then you should use CEF. However, if you must load balance on unequal link, you should use OSPF, EIGRP.

Dandy

bjornarsb Tue, 05/08/2007 - 01:55

Hi,

When you have your M-PPP setup corectly, CEF load balancing is configured on a per-packet round robin or on a per session (source and destination pair) basis.

Regards,

Bjornarsb

mohammedmahmoud Tue, 05/08/2007 - 02:12

Hi,

Why not just using CEF load balancing, without using MLPPP (MLPPP is more CPU intensive), make sure that "ip cef" is under the global configuration and then just add 2 default routes pointing to the 2 interfaces (and make sure that your provider routes your LAN back by the 2 interfaces), but note that having 2 unequal bandwidth interfaces might introduce problems and it is not recommended with this setup (it will be better using EIGRP variance), use per destination load balancing not per packet.

http://www.cisco.com/en/US/products/hw/modules/ps2033/prod_technical_reference09186a00800afeb7.html

HTH, please rate all helpful posts,

Mohammed Mahmoud.

bjornarsb Tue, 05/08/2007 - 02:44

Hi,

CPU is actually not your problem, its a provider problem. I quess this turns out to be a question on how your links are billed.

I quess you have bought 2 separate links and then you cannot claim 3 Mbit per session.

It depends on your need. Concering load balancing efficiency just CEF is fairly - good. MLPPP is very good. Keep in mind that MLPPP is done at layer 2.

Hope this was clarifying.

Regards,

Bjornarsb

Paolo Bevilacqua Tue, 05/08/2007 - 05:22

Excuse me, MLPPP on links of such large different speed is not an option. Neither is OSPF, and EIGRP does dot work satisfactorily on unequal links, despite whatever documentation saying otherwise.

All the above becomes even more true in the case these are internet links so no routing protocol is there.

The only choice is to send some less traffic via the slower link, and default via the faster. Of course with static routes. This can work with or without NAT.

bjornarsb Wed, 05/09/2007 - 03:05

Hi,

I'm very sorry! It's been a while since I've set up MLPPP, and of cource you have right.

It is recommended that member links in a bundle have the same bandwidth. If you add unequal bandwidth links to the bundle, it will lead to lot of packet reordering, which will cause overall bundle throughput to diminish.

BR,

Bjornarsb

guruprasadr Wed, 05/09/2007 - 04:13

HI siladeniz, [PLs Rate if Helps]

On Un-equal Cost Load Balancing using static routes - U need to abopt a Techniq called:

1.Per Packet Load Balancing

(or)

2.Per Destionation Load Balancing

Pls Refer Cisco Docs on this. This will resolve your Issue.

Pls Rate if Helps

Best Regards,

Guru Prasad R

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