Frame-Relay

This may be kind of a stupid question, but

has anyone with gear ever used one router with 2 serial ports as 2 spokes or simulating 2 routers in frame-relay?

I was thinking about doing that with several routers, but it seems the only way to pull it off is with "point-to-point" frame-relay connections

The other thing is the routing tables would be kinda funky too. you would have a lot more directly connected routes and less learned routes. I just never thought about doing it that way for practicing purposes.

When you have real equipement in front of you, it kinda brings new light on what all you can do.

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Comments

mikej412

If all you have is 3 2501s, then you have to make do with what you have. If you use one as a frame-relay switch, you could do point-to-point configurations. And you could do the Hub and Spoke configurations, but with only one spoke you don't get the "full effect" so it would be harder to learn those lessons.

You can combine 2 2501s to make a 4 port frame-relay cloud.... but then you'd still need 3 routers with 1 serial port each to be the hub and 2 spokes.

Paul Boz

It's tough to simulate two spokes with one router unless you can run virtual routing instances. I can see possibly running two OSPF processes on one router with two serial interfaces, and connecting them to the hub router, but there's a number of reasons why it's a bad idea, wouldn't help you very much, and would really not work that well.

Netstudent

Well I have 3 2610's and they all have 2 Wic-1T. So thats 6 ports of 6 possible networks.
Then I have a 2620 with a Nm-4as and 2 wic-1t's. That gives me 6 ports on the 2620 for a frame-switch. SO I was thinking about connecting 2 serial interfaces on the same router to the frame switch just to simulate 2 point-to-point networks. But I think the routing tables would get screwy and probably just confuse me.

So I'll just go with 3 spokes for now. At least I can do a full-mesh, partial mesh, and hybrid.

I was trying to find little work arounds to simulate more devices.

dtlokee

You can connect the network the way you have stated. If you used point-to-point subinterfaces each P2P subinterface could be it's own subnet and any routes learned from other routers would just traverse this link. You could also set it up where you are using 2 multipoint subinterfaces on the same subnet. Implement FRF.16 (multilink frame-relay) if your IOS supports it, or finally MPP with virtual templates and Multilink interfaces. There's lots of fun you can have with multiple frame connections on a single router.

BTW most of this is way beyond the CCNA cert but you seem to be up to the challenge

Enjoy!

Netstudent

Ya I'm always trying to figure out new things or different methods. i find myself overstepping the CCNA boundries a lot, but I think it's just because I ask myself questions and I'm always thinking beyond, like I want to know everything. lol

the only thing that kinda gets me tripped up is trying to conceptualize what my lab would be like if it were a real network with geographic separation. The WAN aspect.

But lets say I did use mulpitple serial interfaces on one router as two spokes. Then I would have learned routes that were accessible via both of the serial interfaces. Because while I am simulating two routers, the single router only has one routing table.

So lets say I have an Ethernet host somewhere in layer 2 and it needs to send a packet to a learned subnet. Which interface will it choose? Will it load balance both physical interfaces unless I change the metric?

I think I'm just not seeing the logical topology because I haven't done it yet.

dtlokee

Ahh, if your goal is to "virtualize" 2 spokes on 1 router you would need VRF, that is multiple instances of a routing protocol on a single router(basically each instance functions a a seperate router). Each instance has a seperate routing table. I thought you were just looking to work with PVC's on multiple physical interfaces, I misunderstood the scenario.