Load share/ Redundant configuration question

[kope]

I have a question regarding load balance/redundant configuration. The topology of the network are two redundant links (1 Gig each). One end of the links are two Nortel Passport switches; the other end of the links are two Cisco Catalyst 6509 switches.

Do anyone has any experience on how to implement a load balance or standby/active config on this cross-platform settings?

I just want to throw out two ways here if it would work.

1. Use GLBP or HRSP on the Cisco side; and use whatever protocols it supports on the Nortel side. Would this work?

2. Implement universal routing protocols such as OSPF on the two links; does OSPF automatically sort of load balance these two links; if one link down, would other link pick up all the traffic?

Thanks.

[leighharrison]

Hi there,

The weapon of choice here is VRRP. VRRP is very similar to HSRP, but is an open standard - HSRP is Cisco's own. The command set is nearly identical to HSRP, if you go to an interface and type "vrrp ?" you'll see some very familiar commands.

Not too sure what your passports are, but I know that the 8600's run VRRP, so I guess they all should.

As for the routing, OSPF would find both ways to get through the network and then either traverse one link or load-balance over them, depending on what you tell it to do.

If you have 2 Nortel boxes and then 2 Cisco boxes with networks behind the two, then I would run OSPF every time.

Hope that helps - if it does, let me know.

LH

[kope]

Thank you so much your input. It definately helps. if I am running OSPF, it can do load-balance or traverse one link; in this case, I don't need running any redundancy protocol.

Yes, all the boxes behind Nortel are Nortels; and all the boxes behind Cisco are Cisco's. So, I think your suggestion is go with OSPF.

Thks.

[devang_etcom]

yes you have to go for OSPF load balanceing because HSRP and GLBP will supported by the Cisco...GLBP is the most preferable when ever you are talking about the redundancy as well as the loadbalancing...

and when ever we are talking about redundancy only then you will have HSRP and VRRP...again HSRP is of cisco and VRRP is of open standard but having disadvantag...

so you need to configure OSPF for the load balancing...

hope this will help you

rate this post if it helps

regards

Devang

[devang_etcom]

OSPF perform the equal cost path load balancing...cisco's router can have 4 equal-cost path in routing table and it can be very between 1 to 6 ...you can add specify the number of equal cost path in routing table by using command "maximum-paths n" where n is the number of path and its valur ranging form 1 to 6...

and if you have lets say 4 equal cost path then normally router will load share with all the 4 path ...but if you one path will go down then you will have 3 equal cost path so now router will have load balancing on that 3 path...

hope this will help you

rate this post if it helps

regards

Devang

[kope]

the two links have the same bandwidth; so it does not require any additional configuration. My assumption is they will automatically load balance between these two links since they have equal cost (same bandwidth). Is this a correct assumption?

[leighharrison]

Hi there,

Yes - you're completely right.

There is some tweaks that you can do such as "ip ospf cost xx" on the interface and "max-paths x" under the routing protocol. That is only for equal cost paths. If you want to load balance ofer unequal cost paths, then you'll need eigrp...

http://www.cisco.com/warp/public/105/loadbal_cef.html

Regards,

LH

Please rate all posts

[devang_etcom]

yes your assumption is perfect...as equal cost path donot need any configuration...load balancing will take place automatically...ospf install 4 equal cost path in routing table but if you want to have more then you have to use command "maximum-path" which will allow you to have maximum up to 6 equal cost path in your routing table..

rate this post if it works

regards

Devang