Default forwarding mode?

hedhrts

For a 2950. I'm trying to find documentation on the cisco web site, or the command on the switch to find out what it defaults to.

1. store and forward
2. fragment-free
3. cut through

Does anyone have a link or an answer?

steve-o87

Hi,

2950's only support store and forward, I think.

If I am wrong someone please correct me

Good Luck

Humper

I believe all switches now use store and forward because of the speed. Dont quote me on that, someone else will be able to provide you more information.

loboernesto

I remember reading something about it somewhere there, it said is store and forward...
I also think that they do only store and forward.

http://www.cisco.com/en/US/products/hw/switches/ps628/products_configuration_guide_book09186a00801a6b78.html

cheers

hedhrts

loboernesto wrote:

I remember reading something about it somewhere there, it said is store and forward...
I also think that they do only store and forward.

http://www.cisco.com/en/US/products/hw/switches/ps628/products_configuration_guide_book09186a00801a6b78.html

cheers

Thanks for the link. So far it looks like you're right.

Building the Address Table
With multiple MAC addresses supported on all ports, you can connect any port on the switch to
individual workstations, repeaters, switches, routers, or other network devices. The switch provides
dynamic addressing by learning the source address of packets it receives on each port and adding the
address and its associated port number to the address table. As stations are added or removed from the
network, the switch updates the address table, adding new dynamic addresses and aging out those that
are not in use.
The aging interval is configured on a per-switch basis. However, the switch maintains an address table
for each VLAN, and STP can accelerate the aging interval on a per-VLAN basis.
The switch sends packets between any combination of ports, based on the destination address of the
received packet. Using the MAC address table, the switch forwards the packet only to the port or ports
associated with the destination address. If the destination address is on the port that sent the packet, the
packet is filtered and not forwarded. The switch always uses the store-and-forward method: complete
packets are stored and checked for errors before transmission

.

Danman32

Cut-through and fragment free have the least latency, but have least control over the frames as well. With store and forward, the appliance (switch) can fully analyze and manage the frame before forwarding it out.
Since Cisco is all about full management and security, only store and forward would make sense.

bmauro

I was just leafing through Lammle's CCNA book - and came across Fragment-Free switching and he mentions that 1900 series switches use this method as the default.

News to me.