difference between vlan management ip address and switch default-gatway address....

[chiragom2341]

what is the difference between management ip address and default-gateway according to the switch ? both are doing the same job, i.e. sends the frame into different network ! am I right ?

Suppose a switch has vlan 1 management ip address,will it need default-gateway ? assume that all hosts connected to switch have same subnet of vlan 1 management ip address.

thanks,

Chirag

[pradeep dhanasekaran]

Hi Chirag,

Management IP address is mostly used to access the device remotely, if you are asking about SVI it's used for inter vlan communication and  ip default-gateway is used to specify when routing is not enabled(ip routing command in switch) where to forward the unknown traffic.

I hope below documents will give you more details,

http://www.cisco.com/c/en/us/support/docs/lan-switching/inter-vlan-routing/41860-howto-L3-intervlanrouting.html 

https://supportforums.cisco.com/discussion/11138161/how-configure-management-vlan

HTH,

Pradeep Dhanasekaran

[Richard Burts · Accepted solution]

Chirag

There are several aspects to understand about switch management address and about switch default gateway address. First is that switch management address is an address on the switch while the default gateway address is an address on some device that is not the switch.

The switch management address allows the switch to communicate within that subnet (to any device in that subnet which is connected to the switch and to any device in that subnet that is not connected to that switch). As long as you do not need to communicate with other subnets then the switch does not need a default gateway. But if the switch does need to communicate with other subnets then the switch does need a default gateway.

So to summarize this points: the switch management address is an address on the switch which allows local communication and the default gateway is an address on a different device which allows remote communication.

HTH

Rick

[chiragom2341]

thank you for replying !

you are absolutely right. I have tried on cisco packet tracer by creating topology where a switch has three vlans - 1,32 and 33 and they are connected to a router through trunk link, sub interfaces(0/0.1, 0/0.32, 0.33) and dot1Q encapsulation.

I have also created SVI interface into switch - int vlan 1, int vlan 32 and int vlan 33 and assigned ip addresses to each SVI interfaces.

Also, each vlans has one host connected to it and assigned the ip address and default-gateway. I used the default-gateway into host as SVI interface ip address.

Now, it is interesting to see that - when I go into switch command line interface and ping to other SVI interface ip addresses, I can get reply so I assumed that I can also get reply from host, means I can communicate to other vlan host.

But when I tried, in result it didn't reply. it just failed - saying "request time out"

So, I have changed the default-gateway into host same as the router sub-interface ip address associated specifically to similar vlans. By doing this, finally when I ping reply comes from host connected into different subnet.

In summary, I can say switch it self can communicate to different subnets or vlans or networks through SVI but hosts connected to its vlan needs to communicate to other vlans, it has to have a default-gateway of router. if you insert default-gateway of SVI interface into host assuming that switch will transfer a frame to different vlan without sending to router, it just don't work !

you can do the telnet by using any address assigned to SVI. Suppose there are five SVI - five separate ip addresses assigned. you can use any ip address to do telnet.

Finally, a question arise to me - what is the purpose of only a switch can communicate (internally) to different vlans through SVI and host can not (without router) ? what I have understand is, it just use into telnet, that is all. Please clear me if I'm wrong here....

Thanks

Chirag