Routers Configuration

[Oz1]

Hello Everyone,

I have a quick question. I'm new to cisco packet tracer and not very good at configuring the routers and switch with each other... (Is it possible to connect 4 routers with one switch? ) For example For Router A ( the IP 202.120.8.1 255.255.255.240 ) For router b ( the IP 202.120.8.2 255.255.255.240) Router C (the IP 202.120.8.3 255.255.255.240) which VLAN and what IP address subnet mask and default-gateway  I should use in switch to do the trunking with all the routers. So, it can ping successfully

looking forward for a reply!

[Joseph W. Doherty]

If all your routers are on the same subnet, you can attach each to an access port, where all ports are configured with the same VLAN.

[Oz1]

I tried to use VLAN 99 with IP address 202.120.8.0 255.255.255.240 and assign VLAN 99 to those specific ports which are connected to routers. But unfortunately, still failed to ping

[Joseph W. Doherty]

Ping what - from one router to another? Or from between switch and router(s)?

What "model" switch are you using? If it's a L3 switch, is it configured for L2 or L3?

[Oz1]

The scenario is like this (given in the picture) Pinf grom RA to RC AND RA RB (The 2960-24TT switch is between these three routers...

[Joseph W. Doherty]

Router D takes a bit more work to integrate. We can get into that after you get your switch and the other routers to be able to ping each other.

A 2960 is a L2 switch, so when you defined a VLAN and IP, you're defining the management IP for the switch. That said, if the VLAN interface is also defined as being used by routers A, B and C and if they share a subnet, those routers and the switch should be able to ping each other in any combination.

Oh, I just noticed, something you're doing that's usually best avoided, you're using the network address as a host IP. That's something that might "confuse" Packet Tracer, which doesn't always support all the capabilities of the devices it emulates.

[Oz1]

I see Sir! How about you help me to create the IPs and Subnet Masks for this whole Network ?? so I can try your given IPs to see how this infrastructure really works.

[Raja_D]

Firstly it would not be possible for you to configure vlan 99 on L2 switch with ip 202.120.8.0 255.255.255.240 as its a network which holds the ip range from 202-120.8.1 till 202.120.8.14 and even if you try to configure vlan 99 on switch with ip 202.120.8.0 255.255.255.240 it would end up with error message as "Bad mask /28 for address 202.120.8.0"

Since you have Router A , B and C all in same subnet its not specifically necessary for you to create a vlan in the L2 switch as Router A would be able to ping Router B and Router C without any issues through the L2 switch and vice versa.

L2 switch that you have in between the router's do not contain any routing table as it cannot do any Routing through it.

[Joseph W. Doherty]

Well, as I wrote earlier, let's try to get things to work in stages.

Can the routers A, B and C ping each other?

If you move the switch's IPs to another host IP, rather than zero, can you now ping between it and any of the routers?

[Oz1]

Yes Sir, Router A, B, C able to ping with each other successfully by using (Router A IP address 202.120.8.1 255.255.255.240. Router B IP address 202.120.8.2 255.255.240. Router C IP address 202.120.8.3 255.255.255.240). But now the question is how can I ping Router A with Switch (2960-24TT) (Because when i try to ping it says the switch has no functional ports...)

[Joseph W. Doherty · Accepted solution]

The switch should be able to interact with the directly connected routers if you provide it a SVI on the same VLAN that hosts the routers and a host IP on that network. (NB: BTW, Packet Tracer is always a bit of a crapshoot, what works or not. I.e. a valid configuration on real devices might not work on it.) Also BTW, again, you probably want to avoid using the network address as a host IP,