Hi,

I was digging into this topic a little more today and found out that by now NAV reports MACs correct again on all Nexus5K direct ports and on Switches attached behind a Nexus6000. The only thing that still doesn't seem to work is the directly attached "access ports" on the Nex6K. I found out that indeed the cam table in postgres was not filled at all with data for these devices:

nav=# select * from cam where netboxid='1577'

;

---------+----------+-------------------------------------+-----------+--------+----------------+-------------------+----------------------------+----------------------------+---------

1955887 | 1577 | nex6-urz1XXX | 369098762 | | port-channel11 | 1c:12:d3:22:cb:40 | 2014-04-03 16:17:27.153232 | 2014-04-03 16:43:57.396658 |

(1 row)

same for the other 3 nexus6k. I tried to fiend out what the problem is but actually could snmp-query these devices to retrieve the CAM information:

# snmpwalk -v2c -cpublic@2 nex6-urz1XXX.unibas.ch .1.3.6.1.2.1.17.4.3.1.

...

iso.3.6.1.2.1.17.4.3.1.1.24.3.115.217.149.63 = Hex-STRING: XX 03 XX D9 XX 3F

...

gives me a lot of these.

I wonder if I did the wrong query or if anyone has an idea what the problem could be with getting the inforamtion out of n6k? I checked all the logfiles and couldn't find any errors there either. Any ideas?

Cheers,

Mischa

Mischa Diehm | Network Operations Center (NOC)

UniBasel | UniRechenZentrum (URZ)

Klingebergstr. 70 | CH-4056 Basel

Tel. +41 61 267 1574 | http://urz.unibas.ch

From: Mischa Diehm <mischa.diehm@unibas.ch>
Date: Freitag, 4. April 2014 10:36
To: Morten Brekkevold <morten.brekkevold@uninett.no>
Cc: "nav-users@uninett.no" <nav-users@uninett.no>
Subject: Re: NAV mac-search with Nexus and FabricPath

Hi,

On Mon, 31 Mar 2014 10:28:50 +0000 Mischa Diehm <mischa.diehm@unibas.ch> wrote:

 we have FP activated in our datacenter and use Cisco Nexus (5,6,7)k. I'm not
 sure what caused the problem but NAV can't find MAC-addresses on these
 devices and even on catalysts behind them anymore. I don't know what
 algorithm is used to figure out where a MAC-address is attached but maybe
 someone who knows can clarify what is needed for that to work?

Not being a network engineer, I have no experience with FabricPath. I
had to Google it, and from what I could glean from [1], it appears
FabricPath throws traditional layer 2 bridging off the boat.

NAV collects MAC addresses from the forwarding tables in your switches.
It appears that Cisco FabricPath doesn't using forwarding tables, but
instead employs a proprietary system for routing ethernet frames.

In light of that, there is nothing the current version of NAV that will
help you get layer 2 information out of this proprietary system. Cisco
may have some MIBs available to get the relevant information, but I
could not say how/when or if we would put support for in on our roadmap.

Cisco has released information for FP-MIBS under:

ftp://ftp.cisco.com/pub/mibs/v2/CISCO-FABRICPATH-TOPOLOGY-MIB.my
ftp://ftp.cisco.com/pub/mibs/v2/CISCO-FABRICPATH-TOPOLOGY-CAPABILITY.my

Unfortunately I can't find any of this information supported on our Nexus 5K/6K yet.

ftp://ftp.cisco.com/pub/mibs/supportlists/nexus6000/Nexus6000MIBSupportList.html

Checking in a retrieved snmpwalk on a 6K. First check for a MAC-Adress behind a Portchannel trunk. Second grep for Mac behind a FabricPath Port:

root@m:~# grep -i "00 1e 7a cb d1 00" /root/tmp/nex6.txt
iso.3.6.1.2.1.4.22.1.2.151060481.10.33.1.254 = Hex-STRING: 00 1E 7A CB D1 00
iso.3.6.1.2.1.4.35.1.4.151060481.1.4.10.33.1.254 = Hex-STRING: 00 1E 7A CB D1 00
iso.3.6.1.2.1.17.4.3.1.1.0.30.122.203.209.0 = Hex-STRING: 00 1E 7A CB D1 00
root@m:~# grep -i "00 50 56 b3 02 5a" /root/tmp/nex6.txt
root@m:~#

This looks like the following running "show mac address-table" on the n6k:

* 3200     001e.7acb.d100    dynamic   40         F    F  Po2
* 3200     0050.56b3.025a    dynamic   40         F    F  1810.0.0

In the end of the second line 1810.0.0 is the FP ID of the neighbour n6k.

This said I guess once there is support for the MIBs it should be possible to retrieve and work with this information on NAV. What I don't understand is how NAV decides if the MAC is actually directly attached (Access Port Check?) and what the algorithm in place is. Finally it is not clear to me if it would be possible to adapt and include the FP information?

Cheers,
Mischa