VLSM'd Static Routing

[joshuadukes0]

I am working on a practice Packet tracer activity and I'm unsure what they are asking for in this requirement:

Configure on each router, static routes for the local, VLSM’ed subnets for VLAN’s 10 and 20.

Background:

I have created x2 sub interfaces on both routers which correspond to VLAN 10 and VLAN 20 on each router.

I have added a default static route between R1 & R2.

Its just the above request that's confusing me, is it just that it needs a static route adding using 'next hop static route' or 'full specified static route' 

If so how do I specify this with sub interfaces involved for both subnets/vlans configured on each router.

[Lasse_Jensen]

Which packet tracer is this? and what's the goal? one sub-interface per router? Doesn't seem to make much sense to create a sub-interface on both, because only one of them can be gateway.

[joshuadukes0]

Hi, 

Thanks for getting back to me. 

They are asking for two vlans on either network with a sub-interface on both to act as the gateway, even though there is only one of the vlans in use on either network (1 pc on either). 

I think this just for VSLM & sub-interface practice. 

• Configure Einstein to point to Newton with a default route. - I have done this no issues using the default route command 
• Configure Newton to point to Einstein with a default route. - I have done this no issues using the default route command

"Configure on each router, static routes for the local, VLSM’ed subnets for VLAN’s 10 and 20". - I think I may understand now and was overthinking it maybe....

I did some research and this is what I need to do, just a normal static route....

The below is what I believe I need for: "Configure on each router, static routes for the local, VLSM’ed subnets for VLAN’s 10 and 20

[Joseph W. Doherty]

• Configure Einstein to point to Newton with a default route. - I have done this no issues using the default route command 
• Configure Newton to point to Einstein with a default route. - I have done this no issues using the default route command

BTW, that creates a routing loop, if the default route is used.

Also, what's to be done, in both OP and your follow on reply is unclear, so I agree what's requested is confusing.

If your follow on reply is quoting from the lab, it shows two "subnets" on each router each on a physical interface, not a sub interface.  The 192.168.#.0/24 address blocks being used are not subnets.  VLSM isn't shown being used.  (Also BTW, subnets and VLSM have specific meanings, which are often misused since CIDR, which actually makes those terms obsolete, although "subnet" has perhaps acquired a new meaning.)

[joshuadukes0]

Hi, 

Thanks for taking time to get back to me.

This is the background on the College requirement for this packet tracer. 

The first part is the router on stick configuration which I fully understand: 

VLSM for 4 further subnets on Newton and 32 on Einstein.

On Newton:

• Create two sub interfaces, for VLANs 10 and 20. - Enable dot1q trunking for each sub interface
• Using VLSM, split 172.16.0.0/24 into (see above selection method ) further subnets. VLAN 10 will be in Subnet 0, VLAN 20 will be in Subnet 1. Create suitable interface IP addresses and subnet masks to reflect this configuration requirement.

On Heisenberg:

• Create VLANS 10 and 20, associate interfaces 6 thru 12 with VLAN 10 and associate interfaces 13 thru 18 with VLAN 20.
• Enable dot1q trunking for VLAN’s 10 and 20 via Fa0/5

The second part is the Static and Default routes between the two routers: 

This must be completed on both routers only. Create a static routed network that will allow full connectivity for the topology seen in Figures 2 and 3. You will need to create a manually converged system. To accomplish this, you must:

• Configure Einstein to point to Newton with a default route.
• Configure Newton to point to Einstein with a default route.
• Configure on each router, static routes for the local, VLSM’ed subnets for VLAN’s 10 and 20.
• Ensure that each PC is be able to ping each other.

This is another diagram of the network topology: 

The links between both switches is for EtherChannel config which i understand and is a task later on, cables not connected yet as this a later task in the requirements. 

I hope this further information makes this more clear.

[Joseph W. Doherty]

"I hope this further information makes this more clear."

Unfortunately, not a whole lot.

If the following is verbatim:

• Configure Einstein to point to Newton with a default route.

• Configure Newton to point to Einstein with a default route.

Again, that makes for a routing loop, if the default route is used.  Such an obvious error sort of makes questionable the quality of this lab.  (BTW, you could use default routing in this lab, but not as described.)

Taking all the information you've provided, it's conflicting and incomplete.  You've shown two different topologies, both also lacking detailed information, and information like using a series of 192.168.x.0/24s vs. subneting 172.16.0.0/24.

All the foregoing makes it very difficult to provide good advise.

[joshuadukes0]

Apologies for the confusion. 

I have configured part 1 of this activity into a PT file and added the configuration and details to the file. - This is attached

This is exactly as they are asking for in terms of the sub-interfaces on G0/1.10 and G0/1.20 on both routers .10 for VLAN 10 and 0.20 for VLAN 20.

This is exactly as they are asking from part 1 of this activity. 

Only VLAN 10 on either network is used, VLAN 20 is not used against any host devices. (just a part of the activity practice + there's only 1 PC on either network) 

Newton

They want 172.16.0.0/24 to be VSLM'd into 4 subnets with the first 2 ranges used against VLAN 10 & 20 on Newton network. 

So my two ranges in use are:

VLAN 10 - 172.16.0.0/26 Default Gateway - G0/1.10 - 172.16.0.1

VLAN 20 - 170.16.0.64/26 - Default Gateway - G0/1.20 - 172.16.0.65

Einstein

They want 1192.168.0.0/24 to be VSLM'd into 32 subnets with the first 2 ranges used against VLAN 10 & 20 on Newton network. 

VLAN 10 - 192.168.0.0/29 - Default Gateway - G0/1.10 - 192.168.0.1

VLAN 20 - 192.168.0.8/29 Default Gateway - G0/1.20 - 192.168.0.9

So this has all been configured on this PT in terms of: 

- Sub-interfaces on router with encapsulation dot1q and relevant VLAN ID 

- VLAN creation on both switches and assigned against required switchports.

- trunk port assigned between switch and router 

Where I'm stuck? - I know how to configure variation of static routes from my learning on NETCAD, its just the VLSM'ed part mainly....

I maybe overthinking the whole thing and worrying about the sub interfaces too much. 

Part 2 

This must be completed on both routers only. Create a static routed network that will allow full connectivity for the topology seen in Figures 2 and 3. You will need to create a manually converged system. To accomplish this, you must

• Configure Einstein to point to Newton with a default route.
• Configure Newton to point to Einstein with a default route.
• Configure on each router, static routes for the local, VLSM’ed subnets for VLAN’s 10 and 20.
• Ensure (and prove) that each PC is be able to ping each other.

Then add a loopback interface to Einstein, using the following commands

enable

configure terminal

interface Loopback0

ip address 123.0.0.1 255.255.255.0

no shutdown

Also add another loopback interface to Newton, using the following commands

enable

configure terminal

interface Loopback0

ip address 100.0.0.1 255.255.255.0

no shutdown

I hope this makes much sense now.

Thanks Josh

[Joseph W. Doherty · Accepted solution]

The attachment is very helpful.

"I maybe overthinking the whole thing and worrying about the sub interfaces too much. "

Yup, from a routing perspective, it doesn't much matter that the interfaces are subinterfaces.  Also, although the static routing statement allows for providing an interface, in my experience, often it's just the next hop that's provided.

What you need to do is inform each router about networks not directly connected to that router, and what's the next hop to reach the specified network.

So, for example, on Newton/R1 you need to inform it of any networks you wish to reach on the "far side" of Einstein/R2, which are:

192.168.0.0/29 and 192.168.0.8/29.

From R1, what's the next hop to reach those?  It's R2's 99.0.0.2.  BTW, first time I've seen a /8 used for a p2p link. ; )

So given the foregoing information, can you construct the necessary route statement(s) on R1?

Don't forget, you'll need to do similar for R2.

Also BTW, you PCs don't appear to have IP information.

Interestingly, using default routes, as noted in your reply, should allow the two PCs to ping each other, and would negate the need for additional static routes, but again, it allows routing loops.

[Joseph W. Doherty]

If you're still stuck or confused by my prior reply, let us know.

[joshuadukes0]

Hi Joseph, 

Thanks for your help over the past couple of days. 

Your advice has been really helpful. - I saved some of your advice in my OneNote, especially this: 

An important thing to remember about routing, "somehow" the router needs to know where to send packets for destination networks.  Generally, a router implicitly knows about the networks it's direction connected to, so something like

Which clicks now and really makes it easier.

Does the router know this network (show IP route) - if not forward onto the next hop interface. 

I applied static config to my PCs and added the routers for both networks to either router and I have connectivity!

Thanks again for your advice Joseph