LAN Topology L2/L3 - Design

Unanswered Question
Apr 24th, 2010

Customer is looking at layer 3 switching design using RIPv2 between all LAN switches. Would using RIPv2 be a more stable design than using a traditional layer 2 design with MSTP/RPVST+ (see attached diagram).

note: Customer is not prepared to upgrade ios on Access Switches (ip base), so RIPv2 is the only option for dynamic routing.

### Switches ##

Core Layer - 2 * 6500 switches (ip services)

Access Layer - 4 * 3560E switches (ip base)

Please advise.

Regards,

Colm

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Reza Sharifi Sat, 04/24/2010 - 06:37

colmgrier wrote:

Customer is looking at layer 3 switching design using RIPv2 between all LAN switches. Would using RIPv2 be a more stable design than using a traditional layer 2 design with MSTP/RPVST+ (see attached diagram).

note: Customer is not prepared to upgrade ios on Access Switches (ip base), so RIPv2 is the only option for dynamic routing.

### Switches ##

Core Layer - 2 * 6500 switches (ip services)

Access Layer - 4 * 3560E switches (ip base)

Please advise.

Regards,

Colm

Hi Colm,

Right now you only have one uplink to your core device and one to the other access switch.  For redundancy you should have 2 uplinks from each switch (3560) to the core switches (6500) and no connection between access switches. If you want to keep the 3560s as layer-2, that is fine but you need to create an SVI for each vlan on the 6500s and have the 6500 do the inter vlan routing for you.  You also need a link between the 6500s and HSRP or VRRP should be running on them.  Since you have IP services license for the 6500 you can run OSPF.

HTH

Reza

Giuseppe Larosa Sat, 04/24/2010 - 15:53

Hello Colm,

as noted by Reza try to review design with each access switch with two uplinks one to core1 and one to core2.

RIPv2 convergence time is poor in comparison to Rapid STP, and it is even slower then old STP 802.1D

A L3 solution makes sense with EIGRP or OSPF not with RIPv2.

Hope to help

Giuseppe

colmgrier Sun, 04/25/2010 - 16:42

Thanks Guys for help to date.

Physically the network design cannot change as the two 3560E switches are in the same cabinet with only 1 uplink to each core switch.

I have decided not to use RIPv2 because of slow convergence etc...

Would EIGRP stub be an option on 3560E switches to provide redundant dynamic routing between all switches?

Please Advise,

Colm

Reza Sharifi Sun, 04/25/2010 - 19:21

Colm,

EIGRP Sub is commonly used in a hub and spoke topology in WAN environment where the spokes connect to hub.  Usually The remote router is adjacent only to one or more distribution routers and not to one another.

If you can not change the physical aspect of the design then you may upgrade your switches to fully support dynamic routing protocols so you can run EIGRP or OSPF.

HTH

Reza

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