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Cisco Bug: CSCvi52166 - ASR does not understand untagged CDP packets in native vlan

Last Modified

Jun 18, 2018

Products (1)

  • Cisco IOS

Known Affected Releases

16.6.4 Everest-16.6.1

Description (partial)

Symptom:
After upgrade 3k switch from 3.6/3.7 to 16.3 if ASR connected to this switch and trunk is configured, ASR can stop see 3 switch in CDP neighbors.

Reason is

with the following config on 3k switch

interface TenGigabitEthernet3/1/3
 switchport trunk native vlan 10
 switchport mode trunk
 switchport nonegotiate
 ip arp inspection trust
 ip dhcp snooping trust
end

switch sends CDP packets
1. 3.6 - tagged
2. 16.3.5b untagged
3. 16.6.2 tagged

Conditions:
trunk between ASR and 3k switch
3k switch on 16.3
no native vlan in trunk list on ASR or no ""vlan dot1q tag native" 3850/3650
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