Mailing List Archive

Though not had any experience with MX's, we were never successful in getting DAC's to work with our EX's.
Had to go for optics.
We learned to just not bother with DAC's in future due to off-list anecdotes of such behavior - not just with Juniper (HPE, Cisco...)

-----Original Message-----
From: juniper-nsp [mailto:juniper-nsp-bounces@puck.nether.net] On Behalf Of Chris Adams
Sent: Friday, June 12, 2020 11:39 AM
To: juniper-nsp@puck.nether.net
Subject: [j-nsp] MX routers and DAC cables?

Is anybody using DAC cables on MX routers? We have a customer with an
MX10003 connected to EX4600 switches with 40G DAC cables (Juniper parts,
not third-party). Upon upgrading the router JUNOS to 18.2R3-S3, none of
the interfaces with a DAC cable would come up on the router end.

JTAC's response was that no DAC cables are supported on any MX routers.

That seems a little odd to me... I thought DAC cables are a part of the
various specs, so saying they're not supported is saying those aren't
actually Ethernet ports to me.

--
Chris Adams <cma@cmadams.net>
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I've used SFP+ DACs on MX, EX and QFX without problems. I have not tried QSFP DACs on MX, but they work on EX/QFX.

On Fri, Jun 12, 2020 at 01:39:11PM -0500, Chris Adams wrote:
> Is anybody using DAC cables on MX routers? We have a customer with an
> MX10003 connected to EX4600 switches with 40G DAC cables (Juniper parts,
> not third-party). Upon upgrading the router JUNOS to 18.2R3-S3, none of
> the interfaces with a DAC cable would come up on the router end.
>
> JTAC's response was that no DAC cables are supported on any MX routers.
>
> That seems a little odd to me... I thought DAC cables are a part of the
> various specs, so saying they're not supported is saying those aren't
> actually Ethernet ports to me.
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Hi,

On 12.06.2020 20:39, Chris Adams wrote:
> Is anybody using DAC cables on MX routers? We have a customer with an
> MX10003 connected to EX4600 switches with 40G DAC cables (Juniper parts,
> not third-party). Upon upgrading the router JUNOS to 18.2R3-S3, none of
> the interfaces with a DAC cable would come up on the router end.
>
> JTAC's response was that no DAC cables are supported on any MX routers.
>
> That seems a little odd to me... I thought DAC cables are a part of the
> various specs, so saying they're not supported is saying those aren't
> actually Ethernet ports to me.

DAC and AOC are transceivers, and officially only a specific set of
transceivers are supported per platform.

For MX10003 you can check here:
https://apps.juniper.net/hct/product/#prd=MX10003

There are 40GE AOC supported for that box, but not 40GE DAC. For 100GE
DAC are actually supported in later Junos version.

That being said typically DAC worked in MX for 10G and even 40G on most
noxes, but on MX10003 we had a lot of problems with 40G DACs and
eventually replaced most/all of of them with optical transceivers.

Even on 100GE you might need to set the FEC config depending on what and
where you connect the other DAC end.

While 10G mostly worked everywhere we had a fair share of trouble on 40
and 100GE on various vendors and platforms.

--
regards
Tobias
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Juniper's official Hardware Compatibility Guide lists 100G DACs as
officially supported on MX10003, so "no DACs" being officially
supported is not true.
https://apps.juniper.net/hct/product/#prd=MX10003

We have used DAC cables (10G, 40G, & 40G -> 4x10G) with MX204s up to
18.4R3. I have also labbed up 40G DACs with EX4300s (for VC and
uplink to MX) with no issues.

--
______________________
David Miller
dmiller@tiggee.com

On Fri, Jun 12, 2020 at 2:41 PM Chris Adams <cma@cmadams.net> wrote:
>
> Is anybody using DAC cables on MX routers? We have a customer with an
> MX10003 connected to EX4600 switches with 40G DAC cables (Juniper parts,
> not third-party). Upon upgrading the router JUNOS to 18.2R3-S3, none of
> the interfaces with a DAC cable would come up on the router end.
>
> JTAC's response was that no DAC cables are supported on any MX routers.
>
> That seems a little odd to me... I thought DAC cables are a part of the
> various specs, so saying they're not supported is saying those aren't
> actually Ethernet ports to me.
>
> --
> Chris Adams <cma@cmadams.net>
> _______________________________________________
> juniper-nsp mailing list juniper-nsp@puck.nether.net
> https://puck.nether.net/mailman/listinfo/juniper-nsp
_______________________________________________
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That's what I was going to chime in on. Behaviour differences between
software versions have done different defaults.

ekrichbaum@atl-bdr1> show interfaces et-0/0/1 | grep FEC
Active defects : None
Ethernet FEC Mode : NONE

eric@cht-bdr2> show interfaces et-0/0/1 | grep FEC
Active defects : None
Ethernet FEC Mode : FEC91

These are 204s with a difference in default from 17.4 to 18.2 somewhere.
Manually setting FEC on both ends seems to correct and bring up the links.


-----Original Message-----
From: juniper-nsp <juniper-nsp-bounces@puck.nether.net> On Behalf Of Tobias
Heister
Sent: Friday, June 12, 2020 2:03 PM
To: juniper-nsp@puck.nether.net
Subject: Re: [j-nsp] MX routers and DAC cables?

Hi,

On 12.06.2020 20:39, Chris Adams wrote:
> Is anybody using DAC cables on MX routers? We have a customer with an
> MX10003 connected to EX4600 switches with 40G DAC cables (Juniper
> parts, not third-party). Upon upgrading the router JUNOS to
> 18.2R3-S3, none of the interfaces with a DAC cable would come up on the
router end.
>
> JTAC's response was that no DAC cables are supported on any MX routers.
>
> That seems a little odd to me... I thought DAC cables are a part of
> the various specs, so saying they're not supported is saying those
> aren't actually Ethernet ports to me.

DAC and AOC are transceivers, and officially only a specific set of
transceivers are supported per platform.

For MX10003 you can check here:
https://apps.juniper.net/hct/product/#prd=MX10003

There are 40GE AOC supported for that box, but not 40GE DAC. For 100GE DAC
are actually supported in later Junos version.

That being said typically DAC worked in MX for 10G and even 40G on most
noxes, but on MX10003 we had a lot of problems with 40G DACs and eventually
replaced most/all of of them with optical transceivers.

Even on 100GE you might need to set the FEC config depending on what and
where you connect the other DAC end.

While 10G mostly worked everywhere we had a fair share of trouble on 40 and
100GE on various vendors and platforms.

--
regards
Tobias
_______________________________________________
juniper-nsp mailing list juniper-nsp@puck.nether.net
https://puck.nether.net/mailman/listinfo/juniper-nsp


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