Fibre Channel (SAN)

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Contributor
Posts: 26
Registered: ‎03-11-2010

Measurement of ISL Link Distance

Hi,

The following is copied from the command reference.

In LD mode, the value of

desired_distance is the upper limit of the link

distance and is used to calculate buffer availability for other ports in the

same port group. When the measured distance exceeds the value of

desired_distance

, this value is used to allocate the buffers. In this case, the

port operates in degraded mode instead of being disabled due to insufficient

buffers.

We have a dark fibre connection between two buildings with an optical length of 10.4 km.

When I configured both ports of the ISL with portcfglongdistance port LD 1 50, we are getting a measured link distance of 47 km and 206 BB credits are awarded to the port.

How is the measurement done? Are there any reasons why the measured value differ from the actual value?

I can think of devices or cables.

Regards, Bart

Super Contributor
Posts: 644
Registered: ‎03-01-2007

Re: Measurement of ISL Link Distance

--->>> Are there any reasons why the measured value differ from the actual value?

what they mean whit: "measured value" .... "actual value"

Super Contributor
Posts: 425
Registered: ‎03-03-2010

Re: Measurement of ISL Link Distance

check portbuffershow, it will show you like this:

HDFC_UAT5_FAB1:user> portbuffershow
User     Port     Lx           Max/Resv    Buffer Needed          Link   Remaining
Port     Type    Mode          Buffers     Usage  Buffers     Distance  Buffers
----     ----    ----          -------     ------ -------     --------- ----------
  0        E      -               8         26      26             2km
  1        E      -               8         26      26             2km
  2        E      -               8         26      26             2km
  3        E      -               8         26      26             2km
  4               -               8          0       -             -
  5               -               8          0       -             -
  6               -               8          0       -             -
  7               -               8          0       -             -
  8        F      -               8          8       -             -
  9        F      -               8          8       -             -
10        F      -               8          8       -             -
11        F      -               8          8       -             -
12               -               8          0       -             -
13               -               8          0       -             -
14               -               8          0       -             -
15               -               8          0       -             -        220
=============================================================

Also check portcfgshow, portshow

pls find the pdf that may help you

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