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New Member

Can IP Routing be extended to one subnet within a LAN

  • LAN Switching and Routing
Cisco Employee

Whats the actual question?why

Whats the actual question?

why do you need roiuting in one subnet that would work fine without the routing.

routing is required when you want to communicate between the subnets and going over the wan for internet or to reach any other external networks by using the routing protocols.



New Member

I'm sorry insharie, it looks

I'm sorry insharie, it looks like what I posted yesterday didn't even show up in the question.  Here's the original question which I hope makes it more clear as to why I'm asking.  Simply using a Default-Gateway doesn't pass the entire 7 layers back to the access layer switches on the right side of the diagram:


The left side of the cloud is the Core of the Network which has a Fiber Agg Switch to connect 9 different LAN's (Districts), of the network on a fiber backbone.  EIGRP is running at the Core and on the Edge.  OSPF along with EIGRP is running on the Core for the Data Center because of non-Cisco switches in the DC (not my choice).

The right side of the cloud shows 1 LAN starting with a Fiber Edge Sw connected to a Distribution Stack of 2 Switches which has 5 separate Access Layer switches for the different departments.  I left out the rest of the connections coming out of the Dist Sw because my question concentrates on a Wireless Ring Network for IP Surveillance Cameras in remote locations.  2 of the remote locations need Access Layer Switches for end-user connectivity and the other 2 are exclusive for video.  The radio's are UMX IP radios for the transport.  The switches to connect the radios and to the Access Layer Switches are exclusive Layer 2 industrial grade N-Tron Switches.  I broke the Wireless Ring after the last Access Layer point going to the 2 endpoints which shows in the bottom right corner of the drawying.  1 N-Tron switch in the top right of the drawing (Network) is temporarily being replaced with a hub for connectivity since the N-Tron isn't working correctly and will be replaced.  All switches involved in this setup have IPServices (layer 3) IOS'.

My question is: Can I take out the Default Gateway on all the Access Layer Switches and put IP Routing with EIGRP in this segment without creating a routing loop?  If so, do I have to set this end up as a Stub?

I hope all you Guru's can understand all of this and thank you in advance.



Hall of Fame Super Silver

I am not clear from the

I am not clear from the diagram how many of the devices on the right you classify as access switches. And it is not clear in the drawing whether all of the access switches support running dynamic routing protocols. So I will answer your question in this way - assuming that the access switches do support running a dynamic routing protocol such as OSPF or EIGRP then you could extend dynamic routing into the section of the network on the right. OSPF and EIGRP each have mechanisms to prevent routing loops so routing loops will not be an issue if you extend dynamic routing to the access switches. If you choose EIGRP then you may have an option to set some of the access switches as stub, but that is an option and not a requirement.





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