# OSPF Broadcast Design Considerations

**URL:** <https://forum.networklessons.com/t/ospf-broadcast-design-considerations/7715>\
**Category:** OSPF\
**Created:** [July 17, 2019, 8:28pm UTC](https://forum.networklessons.com/t/ospf-broadcast-design-considerations/7715 "2019-07-17T20:28:06Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![alias\_617](https://cdn-forum.networklessons.com/user_avatar/forum.networklessons.com/alias_617/32/765_2.png) [@alias\_617](https://forum.networklessons.com/u/alias_617)\
**Post date:** [July 17, 2019, 8:28pm UTC](https://forum.networklessons.com/t/ospf-broadcast-design-considerations/7715/1 "2019-07-17T20:28:06Z")

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I’m designing an OSPF network for a client’s new VPLS cloud. I’ve done this before using a /24 for the interface uplink to the VPLS. I’m curious if anyone has experience with larger (or even this large) of a subnet for OSPF broadcasts.

The client already has around 100 routers running OSPF, all in area 0. Not the best design, I know - but until we can redesign their entire network we’re stuck with it. The VPLS deployment will be for edge devices and I’d like to know if anyone has had successful deployments with 100+ routers in a single broadcast and OSPF area.

Routers are ISR 4331 and ASR 1004s (for the DR and BDR).

Thanks in advance!

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**Author:** ![alias\_617](https://cdn-forum.networklessons.com/user_avatar/forum.networklessons.com/alias_617/32/765_2.png) [@alias\_617](https://forum.networklessons.com/u/alias_617)\
**Post date:** [July 19, 2019, 1:39am UTC](https://forum.networklessons.com/t/ospf-broadcast-design-considerations/7715/2 "2019-07-19T01:39:32Z")

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I posed the same question on the Cisco Community Forum and thought I’d share the responses, since it doesn’t immediately come up when searching…

> **[OSPF Design Considerations for Broadcast Networks](https://community.cisco.com/t5/routing/ospf-design-considerations-for-broadcast-networks/m-p/3892912/highlight/false#M318453)**
>
> I’m designing an OSPF network for a new VPLS cloud. I’ve done this before using a /24 for the interface uplinks to the VPLS. I’m curious if anyone has experience with larger (or even this large) of a subnet for OSPF broadcasts.   We have around...

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**Author:** ![ReneMolenaar](https://cdn-forum.networklessons.com/user_avatar/forum.networklessons.com/renemolenaar/32/488_2.png) [@ReneMolenaar](https://forum.networklessons.com/u/ReneMolenaar)\
**Post date:** [July 19, 2019, 6:09am UTC](https://forum.networklessons.com/t/ospf-broadcast-design-considerations/7715/3 "2019-07-19T06:09:33Z")

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Hi Richard,

You got some good replies there, I learned something too from that.

If you haven’t seen incremental OSPF before, here’s an example:

[https://networklessons.com/cisco/ccie-enterprise-infrastructureospf-incremental-spf](https://networklessons.com/cisco/ccie-enterprise-infrastructureospf-incremental-spf)

Rene