[c-nsp] defualt bandwidth range for Gig E interface on 3750 .

[Andre Beck]

On Mon, Apr 25, 2005 at 02:16:26AM -0700, Baldev Vaishnav wrote:
> What is the default bandwidth range on an Gig E interface on 3750 .
> if 2 interfaces are  down , down , we can see different interface bandwidth .
> What is the value it takes by defalt on a Gig E interface .
> And since this interface is Gigabit range , why it shows the interface BW in Megabit range .
>  
> model WS-C3750G-12S

Well, first guess would be 10BaseT/100BaseTX/1000BaseT auto sense, but
that is ruled out by the 12 SFP model. I had a look on a 3750 of ours
which has 3 SFPs plugged and one unplugged. The unplugged one says:

GigabitEthernet2/0/2 is down, line protocol is down (notconnect)
  Hardware is Gigabit Ethernet, address is 000f.9080.d782 (bia 000f.9080.d782)
  MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec, 

>  GigabitEthernet1/0/9 is down, line protocol is down (notconnect)
>   Hardware is Gigabit Ethernet, address is 0012.4394.3a89 (bia 0012.4394.3a89)
>   Description: *** Building Switch Trunk 9 ***
>   MTU 1500 bytes, BW 10000 Kbit

Any chance this is either SFP unplugged or never had a medium connected
that came up so far? Look on the following lines, like

  Full-duplex, 1000Mb/s, link type is auto, media type is LX

versus

  Auto-duplex, Auto-speed

where the latter is SFP-unplugged.
 
> GigabitEthernet1/0/2 is down, line protocol is down (notconnect)
>   Hardware is Gigabit Ethernet, address is 0012.4394.3a82 (bia 0012.4394.3a82)
>   Description: *** Building Switch Trunk 2 ***
>   MTU 1500 bytes, BW 1000000 Kbit

A chance this has an SFP and was up once in the uptime?

Maybe the BW internally just defaults to 10Mbps until the interface first
comes up and the real bandwidth is sensed. Doing this for SFPs may seem
semi-sick, but I've seen 1000BaseT SFPs somewhere lately, so there might
actually be a reason if they were capable of 10/100 (how they would do
that is a bit of a mystery to me considering that GMII is a fixed protocol).

-- 
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  or "how to turn a complete illusion into a neverending money source"

-> Andre Beck    +++ ABP-RIPE +++    IBH Prof. Dr. Horn GmbH, Dresden <-