08-01-2019 03:05 PM
Hi,
I have cisco ASR 1002 X router with 1000Base SX SFP MMF and
Cisco 3850 switch with 10GBase SR SFP+ MMF
Now, I want to connect router to switch with the use of this modules. when I connect I am unable to see link status up.
what are the possibilities to make the connectivity up.
Need some suggestion.
Regards,
Santosh
08-01-2019 04:06 PM
Hello santosh kumar,
Please try using same optic on both sides of link. Either both 1000Base-SX. Or both 10Gbase-SR.
Using different speed optics on both sides of link would not allow for link up in this situation.
08-01-2019 04:07 PM
Let me try this.
08-01-2019 04:28 PM
08-01-2019 04:55 PM
Hi Summant,
I connected 1000Base SX SPF MMF card on both cisco ASR 1002 x and Cisco 3850 switch. But still, ports are showing down.
Also, it's observed that at the switch end its showing as not connected.
I changed speed 1000 but no luck.
Regards,
Santosh
08-01-2019 05:07 PM
08-03-2019 11:07 AM
08-03-2019 06:44 PM
Hi Santosh,
When you 'no shut' interfaces on both sides, what exact logs do you see for interface bring up? Please enable console logging and share syslogs from both sides while interface bring up. Need to know what is the configuration on both side as well.
When you are saying 3850 side shows 'down/down' that means it is not even receiving any signal- link is down. But at same time the ASR1K side if showing as 'up/up' per your confirmation, it doesn't seem logical. See if there is negotiation disabled on ASR1k side (assuming this is Copper connection you are trying?) Else, this would not be the case.
More details on logs would help. Also, try using same cable you used on working connection if possible to rule out cable issue.
Additional things that you can try:
- Connect both SFPs on two interfaces on ASR1K side only (loop on same spa 2 interfaces, e.g. Gi0/0/0 --- Gi0/0/1). And check if link comes up properly on both interfaces.
- Try above same test by using the same SFPs on 3850 side on two interfaces there. See if the external cable loop brings back the links on 3850 side.
This way you can isolate which side configuration has problem. And in all of the tests listed, syslogs are the key thing to observe. They will hint you towards root cause.
Good luck!
Cheers,
Sumant
08-03-2019 08:10 PM
08-01-2019 05:10 PM
Hello santosh kumar,
Down/down (notconnect) usually indicates problem with physical layer.
Make sure of the following:
08-02-2019 07:30 AM
Hello Santosh,
as explained by other colleagues optics SFP have no speed negotiation capabilities as we can see on a RJ-45 connection.
so a 1 Gbps SFP is not compatible with a 10 Gbps SFP+ and the second one is not able to fall back to 1 Gbps speed.
Physical layer is different , different modulation schemas are used for 1 Gbps over fiber and for 10 Gbps over fiber.
So even if the two SFPs may be working at the same wavelength they are not able to inter-operate.
The C3850 port may be able to support both SFP or SFP+ so you just need to put a matching SFP on the C3850 to achieve a working link.
Hope to help
Giuseppe
08-02-2019 03:28 AM
Hello
The interoperability between these two sfp's wont work, as suggested try using the same optical speed sfps for a successful connection
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