4507R Module query

Answered Question
Feb 13th, 2007

Hi

I am in process of ordering a 6 port GBIC modlue or 18 port.I am confused about one thing in cisco docs it says 6 gbic module will have all the ports wire speed and on 18 gbic module its says 2 ports will have wire speed and 16 will have a ratio of 4:1.What is this ratio.

is it like this that 4 ports are going to have 1 gb bandwidth shared which equal to total speed of the module to 6gb.plz explian.

Thanks

Mahmood

I have this problem too.
0 votes
Correct Answer by Jon Marshall about 9 years 7 months ago

Hi Mahmood

It means that the port can give 1Gbps speed with no contention. So it can run at it's full capability and it will have access to the switch fabric at a full 1Gbps whereas a port within one of the 4:1 groups is contended in that it has to compete with three other ports so if all 4 ports were transmitting at same time each port could not reach it's 1Gbps speed.

Hope i've explained that clearly

Jon

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 4.8 (3 ratings)
Loading.
Jon Marshall Tue, 02/13/2007 - 00:17

Hi Mahmood

Yes in effect what it means is that 2 ports have a dedicated 1Gbps at wire speed. 4Gbps is then divided between the remaining 16 ports with each group of 4 ports having access to 1Gbps.

If you don't intend to fully populate the blade you can space the connections out to get less contention.

HTH

Jon

mahmoodmkl Tue, 02/13/2007 - 00:23

Hi Jon

Thanks for the reply i am confused abt this term wire speed does it mean that as the port is gbic it is going to give 1 gbps speed.

Thanks

Mahmood

Correct Answer
Jon Marshall Tue, 02/13/2007 - 00:28

Hi Mahmood

It means that the port can give 1Gbps speed with no contention. So it can run at it's full capability and it will have access to the switch fabric at a full 1Gbps whereas a port within one of the 4:1 groups is contended in that it has to compete with three other ports so if all 4 ports were transmitting at same time each port could not reach it's 1Gbps speed.

Hope i've explained that clearly

Jon

branfarm1 Thu, 02/15/2007 - 13:08

How is the 4:1 divided up? Can you expect the ports to be grouped as 3-6, 7-10, 11-14, 15-18?

Jon Marshall Thu, 02/15/2007 - 13:52

Hi

You would think so but unfortunately no :-).

The first 2 ports are the uncontended wire speed ports. After that, taken from Cisco doc:

==============================================

WS-X4418-GB Gigabit Ethernet Switching Module

The WS-X4418-GB Gigabit Ethernet switching module offers two dedicated 1000BASE-X (GBIC) ports (ports 1 and 2) and 16 oversubscribed (possibly blocking) 1000BASE-X (GBIC) Gigabit Ethernet ports. The module provides a Gigabit Ethernet network backbone connection for multiple servers and high-end workstations.

Ports 1 and 2 each have 1-Gbps dedicated bandwidth. These ports are typically used to connect to the network backbone.

The 16 oversubscribed ports (ports 3 through 18) are multiplexed in four groups of four ports each:

•Ports 3, 5, 7, 9

•Ports 4, 6, 8, 10

•Ports 11, 13, 15, 17

•Ports 12, 14, 16, 18

Lines on the front panel of the WS-X4418-GB are used to frame the port groups. (See Figure 1-30.)

Each group of four ports shares 1-Gbps of bandwidth.

The oversubscribed Gigabit ports are typically used to connect to clients or servers equipped with Gigabit Ethernet network interface cards (NICs

==============================================

HTH

Jon

Actions

This Discussion