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Load Balancing

Unanswered Question
Feb 6th, 2003
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I have 2 T1's that I want my networks to load balance and have reduncy at the same time. Now I am unsure as to what I need to do. Any suggestions would be appreciated.

Here is a brief discrpition as to what my network looks like:

T1-----2600a-----LAN

T1-----2600b-----LAN-------7204----School #1 of 16

I dont have any routing protocols running because the access routers at the school do not support any routing protocol except RIPv1

Regards,

Cao

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thisisshanky Thu, 02/06/2003 - 15:27
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To achieve redudancy you can run HSRP between the two 2600s. If you do this, at a time, only one T1 will be utilised ( the T1 on the active 2600) while the other T1 will be used as backup. (for this you need to enable HSRP interface tracking).


IF 2600a lan ip add is 10.10.10.1, and 2600b lan ip add is 10.10.10.2, choose, 10.10.10.3 as the HSRP virtual ip. On the 7200, use a static default route as follows,


ip route 0.0.0.0 0.0.0.0 10.10.10.3


Run RIP v1 between the school access routers and 7200 and 2600s.

c.mac Fri, 02/07/2003 - 06:58
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To achieve redundacy through HSRP I am well aware of that possibility. But I want to be able to utilize both T1s at the same time with load balancing but am unsure if this is done through static routing. In addition to utilizing both T1s, I would also like to have some sort of redundacy in case one of the T1s go downs. Is this possible. Thanks in advance.



s.vautour Fri, 02/07/2003 - 12:21
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I've never actually done this but here's how I understand it. You're best bet would be to run a routing protocol that would allow load balancing between equal cost paths (OSPF) or unequal cost paths (EIGRP). Since you can't run a routing protocol, you could configure 2 static routes on you're router with the same admin distance. Your router should load balance equally between the two links on outbound traffic. The route on the other end will also require 2 static routes back to you for inbound traffic. However, you're return traffic may not load balance equally. If the router is running CEF, it should always send traffic to the same destination out the same interface. In other words, traffic for 1 host on your network will not be devided between the links. Makes sense?


These articles should explain it a little more. Don't worry about the routing protocol part, you can replace it with static routes if you have too. Check out:


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


http://www.cisco.com/en/US/partner/tech/tk648/tk365/technologies_tech_note09186a0080094806.shtml


Serge

sachin@infoteci... Thu, 02/06/2003 - 19:42
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Can't we do policy routing with HSRP????????

I mean to say keep policy routing statements on both the 2600 routers with HSRP enabled.

By the way ,thisisshanky can u give me your mail ID????

9mmurphy Fri, 02/07/2003 - 12:35
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Try this...


Run RIPv1 on all three routers

advertise static routes from 2600a and 2600b with same metric

redistribute static

7204 will have both routes in its routing table and will round robin between the two T1's on a per-destination basis


This will work as long as it is router to router communication.


If you have access clients on the LAN between the 2600's and the 7204, you will have to use multiple instances of HSRP and point different groups of users to the different instance of HSRP( poor mans load balancing) for hosts on that segment. Of course, you would track the T1 in order to fail over when the T1 went down.


HTH

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