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Issue with my OSPF and connectivity

potsy017
Level 1
Level 1

Hi I'm new to the community and networking so kindly bare with me,

I'm currently doing an assignment for my university, OSPF Routing. I've not done routing before but the assignment is is such that they gave a bunch of subnets and asked us to use them by further creating more subnets to accommodate the design, the network is made up of  routers, layer 3 switch, servers, WAPs 

even after I entered the ospf and default route commands I'm unable to ping across the network nor access the webpages, nor be able to use the WAP. I'm lost.

I'm attaching my packet tracer so if possible kindly look at it and let me know where I'm going wrong

Thank You

1 Accepted Solution

Accepted Solutions

Joseph W. Doherty
Hall of Fame
Hall of Fame

Yup, you've got several problems.

Firstly, /30s are fine for p2p links between L3 devices, but not too useful for LAN subnets.

In you network, likely you don't need a default route, as every subnet should be made known to OSPF.

Your OSPF network statements need to match interface IPs, if show "ip ospf int b" doesn't show your interfaces, likely your network statements are incorrect.

BTW, OSPF network statements work like ACEs for matching interface IPs.  I.e. one network statement can match multiple interface IPs.

Also BTW, later OSPF IOSs support defining an interface to OSPF with an interface command in lieu of the OSPF network statement.

See if you can fix the above problem areas, and if still stuck, post a follow up.

View solution in original post

4 Replies 4

Joseph W. Doherty
Hall of Fame
Hall of Fame

Yup, you've got several problems.

Firstly, /30s are fine for p2p links between L3 devices, but not too useful for LAN subnets.

In you network, likely you don't need a default route, as every subnet should be made known to OSPF.

Your OSPF network statements need to match interface IPs, if show "ip ospf int b" doesn't show your interfaces, likely your network statements are incorrect.

BTW, OSPF network statements work like ACEs for matching interface IPs.  I.e. one network statement can match multiple interface IPs.

Also BTW, later OSPF IOSs support defining an interface to OSPF with an interface command in lieu of the OSPF network statement.

See if you can fix the above problem areas, and if still stuck, post a follow up.

Hey Joseph Thanks for the reply, I believe I solved my subnetting issue now as you mentioned, I've reset my switches, routers and started OSPF routing again, but I'm still unable to ping outside a subnet, also facing issue trying to ping through the layer 3 switch, as it's not loading the ospf neighbors

Your L3 switch only has one OSPF neighbor, and it formed an adjacency with it.

However, still using /30s for all the LAN subnets?

When first introduced to L3 switches, they can be a bit confusing, as they support L2 and L3.

Your L3 switch should interact with its two L2 switches, much like your branch routers interact with their L2 switches.

As to the servers directly connected to the L3 switch, it should interact with them like your L2 switches.

Given the above, see how far you get in resolving those issues.

Again, if stuck again, post again.

(BTW, well done on your successful changes.  I see you used the OSPF interface option, which is fine, but for bonus learning and understanding, would like to see you use, on your 4331, in lieu of the interface statements, a configuration using 3 OSPF network statements and using just 1 OSPF network statement. [This can wait until you have a fully working topology - but I think it worthwhile to learn too, especially as you might see the network statements being used in existing OSPF topologies.)

yeah I looked into the Layer 3 switch and it was more than I could handle currently, luckily i wasn't forced t choose the layer switch alone hence I used a regular layer 2 switch, and finally understood what you meant by the /30 subnet i was using.

thank you for the reply, and the suggestions. now will invest myself to learn about the layer 3 switch