ISDN load balancing

[mo shea]

We have two routers at our main site and two at the remote site. Each pair is connected via 128k isdn lines (one Bri interface per router).

What is the approach to enable load balancing so that these lines appear as a single line.

Thanks

[spremkumar]

hi

r u using ur isdn as a backup kinda connectivity or is that ur primary connectivity between ur locations ?

do u want to club ur isdn lines connected in 2 different routers as a single logical link ??

AFAIK and upto my knowledge its not possible at this point of time to hv a setup like this...

but ofcourse u can club the channels in a single isdn line and make use of the total B/W avl.

regds

[mo shea]

Thanks for the reply

We need to club the in a single isdn to use the total bandwidth. Could you tell me how to do it.

If a 8-port isdn module is used at one site so that two isdn lines terminate in one router at the main site, can GLBP be used on the two routers at the remote site. Only static routes are being used

[Richard Burts]

I am not sure that GLBP is a good solution for this.

If what you need is to combine two ISDN connections (one BRI on each router with two routers at each site) so that they effectively act as one connection then I think the solution that you should look at is the Multi Chassis Multilink PPP implementation.

This URL has information to help understand the concepts:

http://www.cisco.com/en/US/tech/tk713/tk507/technologies_tech_note09186a008009408f.shtml

and this URL has more detail about how to configure:

http://www.cisco.com/en/US/products/sw/iosswrel/ps1826/products_configuration_guide_chapter09186a00800d9bdb.html

HTH

Rick

[mo shea]

Thanks for the reply...

Each bri interface on the routers in the remote sites dials a different string. How is it possible to combine both of these interfaces into a single logical dialer interface?

Is it possible to use two dialer map commands or dial string commands under one logical dialer?

I would like to know as well why glbp is not a good choice for this senario.

Thanks

[Richard Burts]

The main reason that I think GLBP would not be such a good choice in your situation is that GLBP (much like HSRP) controls load balancing on outbound traffic but has no control on inbound traffic. Also its control over outbound traffic is to assign a member of the GLBP group as the default gateway for each host on the LAN. So if some of the hosts generate lots of outbound traffic and some hosts generate small amounts of outbound traffic then the distribution on the links will be unequal.

Multilink PPP and multichassis multilink PPP control traffic in both inbound and outbound directions and will distribute the load equally over the members of the multilink bundle.

If you configure multilink PPP or multichassis multilink PPP it creates a virtual interface and binds the two physical interfaces to the virtual interface.

You probably want each bri to dial a different number. It is possible to configure two dialer maps or two dialer strings on the interface, but the router will dial the first one and only dial the second one if there is no answer on the first.

HTH

Rick