[c-nsp] LX GBIC at half duplex?

Reuben Farrelly reuben-cisco-nsp at reub.net
Wed Oct 24 06:40:25 EDT 2012


On 24/10/2012 7:44 PM, Phil Mayers wrote:
> The only places we disable autoneg in our network are to connect to same
> $FORMER_GOVT_TELCO, which makes me sad :o(

A bit OT, but a similar $FORMER_GOVT_TELCO here in Australia does the 
same thing on their business grade ethernet products.

They attempt to disable autoneg on 1000TX by hard setting speed and 
duplex (likely because this 'worked' for 10/100TX), but in practice this 
then forces autonegotiation but disables anything other than 1000/FULL. 
  A device with a 100M port connected won't even link up let alone pass 
data.

It seems to work this way on the ME3400E switches (and I think many others).

It's a royal pain if the customer has a low end branch router such as an 
1841 or an 881 that can't do 1000TX but does 100TX just fine - and the 
customer only needs a 10M or 20M circuit so can't justify a bigger 
router.  Or they need to do an emergency swap out and only have a low 
end router available at hand.

Of course we could just force upstream $TELCO to do 100/FULL for those 
customers who can't get link up, but, well, it must generate far more 
support work both on our side and the telco side to do this rather than 
the 'auto-by-default' approach and fall back to hard-set if all else fails.

Reuben






More information about the cisco-nsp mailing list