Port Speed

 
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ehuang
Super Advisor

Port Speed

A quick and easy question:

On my Storageworks SAN FC Switch 4/32, I see different port speed settings. 2, 4, N2, and N4. 2 and 4 stands for 2Gb/s and 4Gb/s, what is "N2" and "N4"?

Thanks.
8 REPLIES 8
marsh_1
Honored Contributor
Solution

Re: Port Speed

hi,

you can either set the speed 2 or 4 or set it to negotiate the speed 2gb or 4gb (n2 and n4 respectively)

hth

IBaltay
Honored Contributor

Re: Port Speed

Hi,
the speed can be fixed (1, 2, 4, 8) or negotiated (N1, N2, N4, N8, or AN - autonegotiated)
the pain is one part of the reality
ehuang
Super Advisor

Re: Port Speed

Would N2 better than 2 (or vice versa) if the max speed on the device is known a certain 2G?
marsh_1
Honored Contributor

Re: Port Speed

hi,

only set the port to negotiate if the hba at the other end supports negotiation otherwise hard set the speed, most newer hbas support negotiation.

hth

IBaltay
Honored Contributor

Re: Port Speed

maybe the SAN performance consideration section (from page 157) of

http://h20000.www2.hp.com/bc/docs/support/SupportManual/c00403562/c00403562.pdf?jumpid=reg_R1002_USEN

could help you here
the pain is one part of the reality
ehuang
Super Advisor

Re: Port Speed

thanks guys. do i have performance issue if i set the speed on the device end as "auto" but the swtich end as "n2" or "2" instead of "an"?
marsh_1
Honored Contributor

Re: Port Speed

hi,

a lot of this is a mix of personal preference and some manufacturer recommendations, some people prefer to hard set the speeds to save the negotiation time when the link comes up, a number of the manufacturers of the hbas/switches recommend auto both ends, while the link is up there is no difference.

hth
ehuang
Super Advisor

Re: Port Speed

question answered.