Backup route - from 1 router to 2 switches

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Apr 18th, 2007
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Problem: I would like to connect our 3845 MPLS router into two 3560 switches for redundancy.

Current scenario: We currently have ge0/0 from the 3845 connected only to 3560-1. There is a 1Gig link between the 3560-1 and 3560-2. Each of the 3560's then has a separate path back to our main office.

Desired scenario: Utilize both ge0/0 and ge0/1 ports on 3845 with ge0/0 going to 3560-1 switch and 3845 port ge0/1 going to 3560-2 switch to provide better redundancy.

What is the best way to accomplish this. We currently have a static route pointing to ge0/0. Should I simply create another static route pointing to ge0/1 with a higher AD or should I set IP address of ge0/0 and ge0/1 to the same address and configure one as a backup with the backup interface command or is there a much better way?

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Anand Narayana Thu, 04/19/2007 - 02:19
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Hi Prem,

i am thorough with the HSRP & implemented in my organization 3 yearz b4, i juz happen to see this post today with the link you provided, in that i could see MHSRP & load balancing with the config, that thing is really making me confuse. can u juz explain me that. bcoz in that link, Router-A also got the standby 1 ip & standby 2 ip & same thing for Router-B, but my question is, what IP address will the client hav as a gateway? bcoz this configuration sayz it does load balancing that is why i am confussed.

"figure 38-2" & "configuring MHSRP" which i was referring to.

just1byte Thu, 04/19/2007 - 06:07
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HSRP is currently configured between the 2 3560 switches but there is currently only one physical cable going from ge0/0 on the 3845 to 3560-1. I would like to connect the second gig port from ge0/1 on the 3845 to the second 3560 (3560-2). What would the commands be to make this happen on the 3845. Currently only ge0/0 has an IP address and is turned up. As previously stated we are currently using a static route on the 3845 to point to the "virtual HSRP router" ip address used between 3560-1 and 3560-2 but there is only one physical connection to 3560-1 and no connection going from the 3845 to 3560-2 so if 3560-1 goes down hard HSRP doesnt really help since there is no additional physical connect from the 3845 to 3560-2. What would be the best way to configure this second port on the 3845?

Anand Narayana Thu, 04/19/2007 - 23:38
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The best way what i would suggest is follow the diagram.

3650-1 -----> 3650-2(ur existing connection)

3650-1 -----> 3845(ur existing connection)

3650-1 -----> 2960-1(suggested)

3560-2 -----> 2960-1(suggested)

2960-1 -----> 3845(suggested)

Note: Since you say that 3845 has got only 1 physical interface, you need to hav a L2 switch eg. 2960 has to get connected to the main switches 3560-1 & 3560-2, which means even if 3560-1 failz ,3845 will b reached via 3560-2.

hope this helps, rate this post if satisfied.


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