We are having some issues configuring the VVX500 handset with Cisco switches in a secure environment.
Where it’s at now is we have the VVX500 handsets authenticating via dot1x MAB and connecting to the voice VLAN; when a workstation connects behind a handset it will authenticate with dot1x (EAP-MSCHAPv2) and be placed on the data VLAN as follows (PVID=100, VVID=900):
SWITCH01#sh mac add | inc 1/0/20
100 2c41.38xx.xxxx STATIC Gi1/0/20
900 0004.f2aa.aaaa STATIC Gi1/0/20
CDP Neighbour information:
SWITCH01#sh cdp nei gi1/0/20
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone,
D - Remote, C - CVTA, M - Two-port Mac Relay
Device ID Local Intrfce Holdtme Capability Platform Port ID
SEP0004f2aaaaaa Gig 1/0/20 143 H P Polycom V Port 1
description *** VOICE ***
switchport access vlan 100
switchport mode access
switchport voice vlan 900
srr-queue bandwidth share 1 30 35 5
authentication host-mode multi-domain
authentication port-control auto
authentication violation restrict
no snmp trap link-status
mls qos trust cos
dot1x pae authenticator
dot1x timeout tx-period 5
dot1x timeout supp-timeout 5
auto qos trust
spanning-tree bpduguard enable
Included in handset configuration file:
The issue is that when the workstation behind the handset is physically disconnected there is no ‘EAPOL-logoff’ or ‘CDP disconnect’ sent to the authenticator and as such the workstation’s MAC address is still assigned to the handset’s interface. This in turn does not allow a new workstation to connect behind the handset and the switch will not allow the original workstation to connect to any other interface. (There is also a security issue with an authenticated MAC being behind the handset with no authenticated workstation present).
Without an ‘EAPOL-logoff’ or ‘CDP disconnect’ the MAC address of the workstation appears to stay assigned to the interface until manually cleared (>24hr).
From what I’ve read there is a way around it using inactivity timers dynamically assigned to the switch via the RADIUS ‘Idle-Timeout Attribute ’, however, this will also require the configuration ‘IP device tracking’ within the switch to ensure quiet devices (such as printers) are not disconnected from the network. I’m not sure that this is the best solution.
Any assistance or best practice recommendations would be greatly appreciated.
To clarify roles:
Supplicant: Voice Handset/Workstation
Authenticator: Cisco Switch 2960X 15.0(2)EX1 (Access Layer)
Authentication Server: Cisco ACS 4.2