AdTran Netvanta 3140 - negotiation issues, packet loss, etc.

[Anonymous]

Hello all,

I recently purchased an AdTran Netvanta 3140 to replace an end-of-life Cisco 2801 router. This is a very basic configuration where I am routing between two networks (no NAT, no telco stuff, etc).

When I attempted to install the new device this morning, I ran into a lot of issues with my local-side connection (configured on port 0/1). I am connecting this device to Extreme Networks switches. On one device, I couldn't get 1GB negotiation to occur at all. It kept dropping to 100Mb full. If I forced 1GB on the Adtran, it would drop connection entirely. On the Extreme side, I am not able to enforce 1GB Full Duplex due to a restriction of the OS.

When connecting it to my other Extreme Switch of a different model, it connected at 1000 Full Duplex without a problem. But the device started dropping packets, and there was a lot of lag when trying to use the Interface. I ran a speed test with this device connected, and I was getting between 1 and 3 Mbps (we have a 200Mb connection with the ISP).

Perhaps I am doing something wrong with the config? Can someone please have a look? I am attaching a scrubbed config.

[jayh · Accepted solution]

On the local-side connection I would suspect bad wiring. I've seen situations where the physical RJ-45 plug contact separators are just a slight bit tweaked or the jack has a tighter tolerance. For gigabit connections you shouldn't have to specify speed or duplex. It sounds as if either pair 1 (pins 4-5) or pair 4 (pins 7-8) isn't making good contact. Gigabit needs all four pairs but 100 only needs two. To make things worse, some cheap patch cords or crossover cables are only populated with two pair. I'd try a different cable and set it to speed auto. If the Extreme side is hard-coded to 1G full, then set the Adtran to that as well, but these days both sides to auto should just work.

For the ISP side, pretty much the same thing. Also if they're sending jumbo frames and you have the ip mtu set to 1500 you'll get fragmentation which can be an issue.

What would be very useful is to see a "show interface" on both interfaces when it's been in the bad state for a while.

Also note that there's a cosmetic bug that Adtran hasn't been able to squash for over a year when it comes to LLDP. It will constantly spam the console with speed and duplex mismatch errors when in fact negotiation is fine. You can turn off LLDP to get it to shut up. I'd try turning off LLDP anyway just to see if Exreme doesn't like what you're sending. "no lldp send-and-receive" at the interface level.

How were speed and duplex configured on the interfaces of the Cisco device that it is replacing?

[Anonymous]

Hello Jay, thanks for the advice. The cables are all brand new CAT-6e. I did try using a different one, but it was the difference between a brand new Belkin cable and a brand new Tripp-Lite. I would like to say that the Tripp-Lite made some difference. But it was still dropping packets, so it's probably just circumstantial. And at this point, the speed it all set to auto on the Extreme switch since I didn't have an option. But I can set it back to auto on the AdTran as well.

I will have to see about Jumbo Frames. I doubt that they are using them. I had a conversation a few weeks back with a tech, and he said they set everything to 1500 on their MPLS circuitry. Since this runs on the same equipment and alongside my MPLS stuff, I would think it's all set to MTU of 1500.

I will also look into disabling lldp, as I was not aware of that bug.

With speed and duplex on the Cisco - it's sort of irrelevant because I am not duplicating it. The Cisco 2801 is a 100Mb device. And I am switching it out with a gig device (because my ISP speed is 200Mb). When switching between the Cisco and the AdTran, I am also switching out the SFP module from a 100 to a 1000. Now you have me thinking that I need to call the ISP and see what sort of speed and duplex they are laying down when I switch out the modules. Perhaps that is the issue!!

[jayh]

I'd suggest setting the 3140 back to auto, clear counters and then let it run for 15 minutes or so. Then capture the result of "show interface" and post the results here.

[Anonymous]

Thanks for the advice. I spoke with the ISP this afternoon and they confirmed that they would need to make some changes to their router in regards to port negotiation - after - I install the 1GB SFP module. So I will try this again in the early hours of a weekday next week. This time I will have them on the line when I make the switch.

[Anonymous]

After calling the ISP to make the change I was told (by a different tech) at that all of these settings are automatic and negotiation shouldn't be an issue. Nonetheless, he idled by on the phone watching the interface on the ISP equipment while I installed the router.

The router went into place without a hitch. The only change that I made to the configuration was to add "no lldp send-and-receive" on both interfaces. Thank you for that advice. I have marked this answer as the solution.