default gateway

[aksher]

1)can a default gateway be a switch ip

2)can a default gateway be a loopback ip add.

[Anand Narayana]

Hi Aksher,

1. if your PC wanted to reach different network & if the switch is a layer 3 YES you can set the IP address as a gateway to your PC, if u set a layer 2 switch IP address to a PC there is no use of it.

2. YES you can have again it should be on a layer 3 switch.

hope this helps.

rate this post if helps.

[aksher]

but for RARP should the gateway be a l3 device.can a l2 do it?bcos ARP is done by l2..

[Richard Burts]

Aksher

ARP is transmitted at layer 2 but it requires participation at layer 3 to provide the IP addressing information that ARP will carry. So ARP is a combination of layer 2 and layer 3 functions.

To go back to your original questions about switches and gateways, it is helpful to separate the discussion about layer 2 switches and layer 3 switches. A layer 2 switch makes forwarding decision based only on MAC address information and can not consider IP address information in making the forwarding decision. So it would not be valid to put the IP address of a layer 2 switch as the gateway address for PCs that are connected to the switch.

A layer 3 switch can use both MAC address information and IP address information in making forwarding decisions. So it is valid to put the IP address of the layer 3 switch as the gateway address for PCs connected to that switch.

Since the gateway address should be an address in the connected subnet it would be problematic to try to put a loopback address as the gateway address for PCs connected to a layer 3 switch (and there is no concept of loopback address on a layer 2 switch).

HTH

Rick

[aksher]

my ques was can a l2 switch do RARP or a default gateway l3 or router will only do?

[mmozaffa]

There is no concept of ARP or RARP on a L2 switch, as mentioned above L2 swicthes uses only MAC address table to do forwarding/filtering decison and does NOT uses ARP cache for packet forwarding.

Router can definately do RARP, not sure waht u mean by default gateway L3.

Hope this helps.