Layer-3 EtherChannel issue on Packet tracer ..

[gohussai]

I made a simple Topology in Packet Tracer.

Two Layer-3 Switches and one computer connected to each switch.

Created  Layer-3 ether-channel as mentioned.

Switch-1

interface FastEthernet0/1

no switchport

channel-group 1 mode on

no ip address

duplex auto

speed auto

!

interface FastEthernet0/2

no switchport

channel-group 1 mode on

no ip address

duplex auto

speed auto

interface Port-channel 1

no switchport

ip address 10.10.10.1 255.0.0.0

Switch-2

Same as above with ether channel ip : 10.10.10.2

NOW if i ping from computer to etherchannel logical interface (10.10.10.1) why ping fails ???

NOTE:- I can ping SVI if i create on the switch, I can ping L3 port ip address if i define on this switch. Ether-channel is logical interface same as SVI why i can't ping it from computer.

              Switches can ping each other.

[Jon Marshall]

Forget about etherchannel for a minute and think of the connection between the switches as just a L3 link.

That L3 link terminates on the physical ports on each switch.  Those ports are L3 ports which means the IP subnet can only exist between those ports on each switch.

In effect what you are trying to do is extend the IP subnet past the L3 ports and you can't do this.

Making it an etherchannel does not change this, ie. etherchannel is a logical interface for a bundle of physical links but that logical interface is still a L3 interface.

When you change it to an SVI that is now a L3 interface that is not tied to any specific port so you can ping from your clients.

Jon

[gohussai]

I get what you mentioned. Is there any way to bind SVI with Etherchannel ? So I don't have to configure extra interface/SVI.

[Jon Marshall]

Not sure what you mean.

A L3 etherchannel and an SVI are both L3 interfaces.

Can you perhaps give an example ?

Jon

[gohussai]

Thanks Jon , I check in LAB its not possible what i'am thinking as physcial port is indeed at the back end of etherchannel so we need SVI.

One thing more Jon I would like to know , In order to reach from PC2 to PC1 in diagram, Do I have to define RIP on both Switch? because IP routing on both switches can't let me reach that end (PC1).

[devils_advocate]

You have used 10.0.0.0 /8 on both sides of the L3 link which is not going to work.

In a network, you cannot have the same IP Subnet in two different places, otherwise routing will not work properly.

If you need the interface between the switches to be a L3 link, you need to ensure the IP Subnets are different both sides. Try and use 10.10.10.1 on the left with a subnet mask of 255.255.255.0 and 10.10.20.1 with a mask of 255.255.255.0 on the right. 

As it is a L3 link, you are correct in that you need Routing for the PC's to be able to communicate. This can be Dynamic Routing in the form of RIP/OSPF/EIGRP or Static Routes. If you are practicing routing then go with dynamic but if you are concentrating on learning switching then just put a static route on each switch.

Thanks

[gohussai]

Thanks alot.

Please mention the command for adding static route and also shed light on "default network" and "default gateway" in L3 switch.