PTM Failure when connected to a Redhat/Centos 7 Server


A common way to configure a Prescriptive Topology Manager topology.dot file is as follows

graph G {
graph [hostnametype="hostname", version="1:0", date="04/12/2013"]; "leaf1":"swp32s0" -- "server1":"em1"; "leaf2":"swp32s0" -- "server2":"eth2"; }
PTM may fail to identify the topology when a Cumulus Switch is connected to a Redhat/Centos 7 Server with the following error

cumulus@leaf1:~$ sudo ptmctl -d  ----------------------------------------------------------------------------------------------------------------------------------------------------------------  port     cbl     exp           act                        sysname  portID             portDescr              match   last  BFD     BFD   BFD    BFD   BFD                  status  nbr           nbr                                                                           on      upd   status  peer  local  type  DownDiag    ----------------------------------------------------------------------------------------------------------------------------------------------------------------  swp32s0  fail    server1:em1  server1:52:54:00:c3:a5:34  server1  52:54:00:c3:a5:34  Interface   3 as em1  IfName   5s   N/A     N/A   N/A    N/A   N/A       
To resolve this issue, set lldpad to send the PortID TLV with subtype=ifName/5

admin@rhel7$ sudo lldptool -i em1 -T -V portid -c subtype=5
The RHEL server should change the PortID TLV from the mac address to the interface name (ifName)

admin@rhel7$ lldptool -i em1 -t  Chassis ID TLV          MAC: 52:54:00:c3:a5:34  Port ID TLV          Ifname: em1  Time to Live TLV          120  Port Description TLV          Interface   3 as em1  System Name TLV          server1  End of LLDPDU TLV
And PTM will report a success.

cumulus@leaf1:~$ sudo ptmctl -d  ----------------------------------------------------------------------------------------------------------------------------------------  port     cbl     exp           act           sysname  portID  portDescr              match   last  BFD     BFD   BFD    BFD   BFD                  status  nbr           nbr                                                   on      upd   status  peer  local  type  DownDiag    ----------------------------------------------------------------------------------------------------------------------------------------  swp32s0  pass    server1:em1  server1:em1  server1  em1    Interface   3 as em1  IfName  60s   N/A     N/A   N/A    N/A   N/A       
A suggested initial config for LLDP on RHEL/Centos for a port is as follows. If one does not delete /var/lib/lldpad/lldpad.conf, the config should not change

lldptool set-lldp -i  adminStatus=rxtx  lldptool -T -i  -V sysName enableTx=yes  lldptool -T -i  -V portDesc enableTx=yes  lldptool -T -i  -V portid -c subtype=5


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