Connecting Cisco Nexus 3172T to Juniper QFX5100; will not connect at 10G/full

ssu · ‎10-18-2016

When connecting cisco nexus 3172T to juniper qfx5100, e.g. [QFX]----xe-1/0/47---------e1/47---[Nexus], they negotiate to 100/half only. With disabling auto negotiation, they connect at 100/full. Is there a way to get them to connect at 10G/full or is there a limitation on either nexus or qfx side? Thanks.

Jigar Dave · ‎10-21-2016

Hi ssu,

Nexus------------------------------
I assume you are using Nexus 5k.

nexus switches are coming with 10g/full duplex as default interface. if you need to set to 1000/full, you have to manually do it on interface

Juniper----------------------------
Juniper QFX, QFX5100-48S, QFX5100-24Q, QFX5100-96S

The following default configurations are available on 10-Gigabit Ethernet interfaces:

    All the 10-Gigabit Ethernet interfaces are set to auto-negotiation.
    Flow control for 10-Gigabit Ethernet interfaces is set to enabled by default. You can disable flow control by specifying the no-flow-control option.
    The speed cannot be configured.

    On QFX5100-48S, QFX5100-96S, and QFX5100-24Q devices using 10-Gigabit Ethernet SFP interfaces, the speed is set to 10 Gbps by default and cannot be configured to operate in a different speed.
    10-Gigabit Ethernet interfaces operate in full-duplex mode by default.
    Autonegotiation is enabled by default, and will autonegotiate the speed with the link partner. We recommend that you keep autonegotiation enabled for interfaces operating at 100M, 1G, and 10G.

    If for some reason you have disabled autonegotiation, you can enable it by issuing the set interfaces name ether-options auto-negotiate command.

    To disable autonegotiation, issue the delete interfaces name ether-options auto-negotiate command.
Issue the show interfaces name extensive command to see if autonegotiation is enabled or disabled and the negotiated speed of the interface.

hope this helps

Scott.Powell · ‎09-04-2018

SSU, thanks for the question. we are looking into mixing platforms as well. curious from a layer 2 how much special configuration was needed to make the two vendors work?

Jigar, you made the assumption of a Nexus 5k when in the title he told you it was a 3172T. Your statements are general in context but did not address the original question. Do you have any other specific replies to this matter?