Autonegotiation on MX-80

[pk]

Hi All

Should be a stupid question, but I'm confused with the way autonegotiation works in Junos. On one side (mxA-1), I have

ge-1/1/2 {
    unit 0 {
        family inet {
            address 172.18.112.1/30;
        }
    }
}

while on the other (mxA-2),

ge-1/1/2 {
    speed 10m;
    unit 0 {
        family inet {
            address 172.18.112.2/30;
        }
    }
}

On both sides, autonegotiation is enabled,

lab@mxA-1> show interfaces ge-1/1/2 detail | match Auto 
  Source filtering: Disabled, Flow control: Enabled, Auto-negotiation: Enabled, Remote fault: Online

lab@mxA-2> show interfaces ge-1/1/2 detail | match Auto   
  Source filtering: Disabled, Flow control: Enabled, Auto-negotiation: Enabled, Remote fault: Online

But the link is down. It goes up if I delete "10m" setting from one side or put "10m" also on the other. The devices are MX80's with Juniper SFP-T and Junos 11.2R6.3 but it does not seem to depend on version.

I do not understand why autonegotiation is in fact not working. Is it by design?

[tgoncalves]

Hi PK,

Despite this link is on Cisco website, I think it will clarify your doubts about Autonegotiation.

Troubleshooting Cisco Catalyst Switches to NIC Compatibility Issues

http://www.cisco.com/en/US/products/hw/switches/ps708/products_tech_note09186a00800a7af0.shtml

[pk]

Hi tgoncalves,

Thanks for your reply. However, from Table 1 of your link it follows that if I have 10M on one side and AUTO on the other, then link is established at 10M, which I would also expect, but the problem is that I don't see it.

So my original question remains.

[jtb · Accepted solution]

hi,

just a hint:  is it  SFP-1GE-T or SFP-1GE-FE-E-T ? Based on http://www.juniper.net/techpubs/en_US/release-independent/junos/topics/reference/general/dpc-mx-seri...

• 1000BASE-T (model number: SFP-1GE-T)
  
• 10/100/1000BASE-T (model number: SFP-1GE-FE-E-T)
  

Note: SFP-1GE-FE-E-T supports tri-rate 10/100/1000 mode in Junos OS Release 9.4 and later

jtb

[pk]

Hi jtb,

It is SFP-1GE-T. But with "speed 10m" on both ends, the link works.

I also tried with EX switches (not SFP, just 10/100/1000 ports), and there autonegotiation works as expected (speed 10m on one side and AUTO on the other => link up at 10m).

So I think you are right and the problem is in SFP here. I will mark it as a solution but kudos to anyone who can shed some more light on this.

[ChadM]

Since going between switches are you using a crossover cable or straight through cable?  I've seen some hardware where manually setting speed would disable auto-mdix.  It's possible this is a bug.

There was also a config requirement at some point to explicitly disable auto-negotiation when setting speed manually.  Leaving it enabled, the default, would cause the interface to not come up.

set interfaces ge-x/y/z speed 100m
set interfaces ge-x/y/z link-mode full-duplex
set interfaces ge-x/y/z gigether-options no-auto-negotiation

-Chad

[Johnson P Liu]

Dear all:

  Is anyone can tell me how to differentiate the two SFP ?

Because I cannot tell by it outlook (same part number) and show chassis hardware command (all called SFP-T), the only difference I can tell is S/N C072XXX was my new purchase SFP(SFP-1GE-FE-E-T), others are old SFP-1GE-T

Xcvr 0 REV 02 740-013111 C072022 SFP-T
Xcvr 1 REV 01 740-013111 8166763 SFP-T
Xcvr 2 REV 02 740-013111 C072184 SFP-T
Xcvr 3 REV 01 740-013111 8166669 SFP-T
Xcvr 5 REV 02 740-013111 C072779 SFP-T

Xcvr 4 REV 02 740-013111 C072852 SFP-T
Xcvr 5 REV 02 740-013111 C072308 SFP-T
Xcvr 6 REV 02 740-013111 C072744 SFP-T
Xcvr 7 REV 01 740-013111 8166732 SFP-T

[mdheavy]

http://etherealmind.com/ethernet-autonegotiation-works-why-how-standard-should-be-set/

/thread