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Author Topic: Determine Trunk Ports  (Read 205 times)

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Offline bobo

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Determine Trunk Ports
« on: February 22, 2018, 02:14:47 PM »
Hello,
I have Nortel switches in my environment and trying to see how they are trunked. Using cli command "show autotopology nmm-table" it shows on one of my switches port 1/47 actually connects to 2 different switches. How can 1 port link to 2 different switches? Also, port 1/47 is a trunk port but so is 1/48, but 1/48 doesnt show up in the above command.

Port 1/47 is copper and what it links to on the other switches is fiber, how can that be? Could it be that 1/47 and 1/48 are port-channeled?

Any explanation would be helpful,
Thank you.
« Last Edit: February 22, 2018, 02:19:09 PM by bobo »


Offline orgitnized

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Re: Determine Trunk Ports
« Reply #1 on: March 17, 2018, 11:45:29 PM »
I'm not a Nortel guy, but I can tell you that this behavior also exists on ERS 3500 switches.
Using that command will show you other switches that are connected to neighboring switches.  So, you aren't seeing 2 switches on the same port, but that's what it looks like.
Here's the table on my ERS 3510
Code: [Select]
switch1#show autotopology nmm-table
LSlot                                                                     RSlot
LPort IP Addr          Seg ID  MAC Addr     Chassis Type     BT LS   CS   RPort
----- --------------- -------- ------------ ---------------- -- --- ----  -----
 0/ 0 10.16.101.110   0x000000 00:00:00:00:00:00 3510GT-PWR+      12 Yes HTBT    NA
 1/ 8 10.16.1.1       0x000101 00:00:00:00:00:00 VSP 4850GTS-PWR+ 12 Yes HTBT   1/ 1
 1/ 8 10.16.1.1       0x000114 00:00:00:00:00:00 VSP 4850GTS-PWR+ 12 Yes HTBT   1/20
 1/ 8 10.16.1.1       0x000115 00:00:00:00:00:00 VSP 4850GTS-PWR+ 12 Yes HTBT   1/21
 1/ 8 10.16.1.1       0x000116 00:00:00:00:00:00 VSP 4850GTS-PWR+ 12 Yes HTBT   1/22
 1/ 8 10.16.101.105   0x000130 00:00:00:00:00:00 3549GTS-PWR+     12 Yes HTBT   1/48

Note that my local ports are the same, showing 1/8 for at least 2 devices, right?
Now let's do another command...
Code: [Select]
switch1#sh lldp neighbor
-------------------------------------------------------------------------------
                            LLDP neighbor
-------------------------------------------------------------------------------
Port: 1     Index: 15                 Time: 0 days, 01:04:16
        ChassisId: MAC address        00:00:00:00:00:00
        PortId:    MAC address        00:00:00:00:00:00
-------------------------------------------------------------------------------
Port: 8     Index: 171                Time: 1 day, 12:43:58
        ChassisId: MAC address        00:00:00:00:00:00
        PortId:    Interface name     Gi1/0/25
        SysName:   switch2
        SysCap:    rB / B             (Supported/Enabled)
        PortDesc:  GigabitEthernet1/0/25
        SysDescr:
Cisco IOS Software, C2960S Software (C2960S-UNIVERSALK9-M), Version 15.0(1)SE3,
 RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2012 by Cisco Systems, Inc.
Compiled Wed 30-May-12 14:35 by prod_rel_team
And take note...that switch wasn't even detected via the first command.  And, even the LLDP query would not have worked either, unless I had set LLDP to manually run on the cisco switch.
If that's what you're seeing, it's normal.  It simply means that multiple devices are being detected out the same interface.  To get to those devices, you need to exit through [said] interface to get more information about how they are all connected.
That's where the 2 commands come in handy.