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Community Member

Problem with L3 to Router Redundency

Hi

I am busy with a project for my 3rd year on university and currently I am stuck at a point and would like some one to help me if possible.

I have a netwotk design as shown above Network.JPG

My problem I have at this stage is to be able to connect both Layer 3 switches to the one single Router. I have enabled IP routing on the L3 switches so the 5 different vlans can comunicate with each other but I cant setup exactly the same subinterfaces on both ports of the router. How would I have to go about to be able to connect the two L3 switches to the one router so that all the vlans can access internet on other side of the router.

I have watched multiple videos but cant seem to get a explenation of what to use.

Any help would be greatly appreciated.

Kindest Regards

Petrus Delport

2 ACCEPTED SOLUTIONS

Accepted Solutions
VIP Super Bronze

Problem with L3 to Router Redundency

Hi,

You already have the SVIs assigned on both switches.  You need to run HSRP or VRRP between the 2 layer-3 switches for redundancy and from each switch a layer-3 routed link with /30s to the router.  You can  run OSPF, EIGRP, etc... on both switches and the router.  No need for sub-interfaces on the router.

HTH

Problem with L3 to Router Redundency

Hello.

Totally agree with Reza.

1- Configure SVI in the layer 3 switches, since switches do at wire-speed they are much faster than the router.

2- If you configure the router as default gateway for the computer you will only have a single point of failure, so configure the l3 switches for that.

3- Do not configure just one switch to take over all the responsability. Configure first hop redundancy protocol in each switch like HSRP, VRRP or GLBP, here's good documentation if you are not familiar with that

http://www.cisco.com/en/US/products/ps6644/products_ios_protocol_option_home.html

4-  Load-balance traffic within the Layer 3 switches for best performance.

How would I have to go about to be able to connect the two L3 switches to the one router so that all the vlans can access internet on other side of the router.

Think about redundancy, high availability, fault tolerance and scalability: configure dynamic routing is the best option independently which protocol to use they all will dynamically failover over one route or the other without human intervantion.

Regards.

Wilson B

3 REPLIES
VIP Super Bronze

Problem with L3 to Router Redundency

Hi,

You already have the SVIs assigned on both switches.  You need to run HSRP or VRRP between the 2 layer-3 switches for redundancy and from each switch a layer-3 routed link with /30s to the router.  You can  run OSPF, EIGRP, etc... on both switches and the router.  No need for sub-interfaces on the router.

HTH

Problem with L3 to Router Redundency

Hello.

Totally agree with Reza.

1- Configure SVI in the layer 3 switches, since switches do at wire-speed they are much faster than the router.

2- If you configure the router as default gateway for the computer you will only have a single point of failure, so configure the l3 switches for that.

3- Do not configure just one switch to take over all the responsability. Configure first hop redundancy protocol in each switch like HSRP, VRRP or GLBP, here's good documentation if you are not familiar with that

http://www.cisco.com/en/US/products/ps6644/products_ios_protocol_option_home.html

4-  Load-balance traffic within the Layer 3 switches for best performance.

How would I have to go about to be able to connect the two L3 switches to the one router so that all the vlans can access internet on other side of the router.

Think about redundancy, high availability, fault tolerance and scalability: configure dynamic routing is the best option independently which protocol to use they all will dynamically failover over one route or the other without human intervantion.

Regards.

Wilson B

Community Member

Problem with L3 to Router Redundency

Thank you for the help. I used a mix between STP to block loops and then the HSRP mentioned above and everything works smoothly.

Thank you for the fast response guys.

Hope has been restored in humanity

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