So the docs
http://www.cisco.com/en/US/docs/wireless/access_point/12.4_10b_JA/configuration/guide/scg12410b-chap17-cdp.html
say:
"CDP is sent on the lowest VLAN number configured on the access point.
When more than on VLAN is used in a wireless network, Cisco recommends
that the lowest VLAN number configured be used as the native VLAN"
This is not quite accurate ... here's the *real* story on how WNBU IOS
sends CDP:
* if the LAN interface is not configured for VLANs (dot1q
subinterfaces), then CDP is always sent untagged of course
* if the LAN interface is configured for VLANs, then CDP is always
sent in VLAN 1:
o if VLAN 1 is configured as the native VLAN, then CDP is
always sent in VLAN 1 (i.e. untagged)
o otherwise - regardless of whether VLAN 1 is explicitly
configured on the AP - CDP is sent tagged in VLAN 1
Pretty simple, really!
References:
CSCef35717 CDP Packets not sent over non-1 Native VLANs
I'll file a doc bug on this.
Cheers,
Aaron
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