Load Sharing between LL and ISDN

[ayram23]

Dear all,

Is there by any means we can configure a router to share the load between LL and ISDN.....?

Regards,

R.Rajaraman

[lgijssel]

Load balancing is automatic when you have equal cost paths. If the paths are not equal (512kb LL vs 64kb ISDN) you'd better not attempt load balancing.

It will make the overall performance worse due to the difference in delay and the increased risk for out-of-sequence packets.

You also have to make sure the ISDN is always up (never mind the $$$) and not up/down/up every few mins to make this work well.

Regards,

Leo

[nihal.akbulut]

If you have eigrp you can make unequal-path load-balancing with "variance" command..

[ayram23]

Hi,

Thanks for your reply.

My exact query is, i have a static route in my LL. When the load in this link goes up certain level then the ISDN should be made up and the load should be shared nbow between LL and ISDN. When the load is under control, then the ISDN should be made down automatically by the router. For this query i'm looking for a configuration. Plz help me in resolving this issue.

Regards,

R.Rajaraman

[steve.wadge]

You should be able to achieve what you want by first configuring ISDN backup of the leased line using the backup interface command & then using backup load command to set a percentage load for the ISDN line to come up.

See here for ISDN backup details:

http://www.cisco.com/en/US/customer/tech/tk801/tk133/technologies_configuration_example09186a008009455d.shtml

[ayram23]

Thanks for your reply.

Its asking for a CCO Login.I dont have a CCO Login.....Can you please send me that document as an attachment to the following id: rraja@hclinsys.com ? Please do this favour for me.....

Regards,

R.Rajaraman

[Kevin Dorrell]

Here is that same document on a guest URL:

http://www.cisco.com/warp/public/793/access_dial/backup_11047.html

Kevin Dorrell

Luxembourg

[ayram23]

Thanks a lot for the document.

we have configured the primary link (leased line p2p) with the backup interface command and also the load back up command. the back up interface is bri. the problem is that as an absolute back up it is working, ie when the serial link goes down, bri is activated. but when the load reaches or exceeds the configured value in the primary link, the bri is not activated at all. please do let me know any troubleshhoting techniques so that we can sort out this issue.

Regards,

R.Rajaraman

[nbhandarkar]

Hi,

You could achieve the desired feature by using the following commands:

interface serial 0

backup int bri0/0

backup load 75 5

where 75 is the percentage load on the primary link ie serial 0 at which ISDN should be fired and 5 is the percentage load on serial as well as ISDN link combined at which ISDN should be brought down.

Since you also mentioned that you are using static route via serial link.......you also have to add a static route with outgoing interface bri0/0 for the backup load feature to work properly.

rgds,

Nitin