Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
New Member

Access Point ROAMING between Cisco and other vendors

Hello,

I would like to know if the Cisco's roaming technology between two Aironet Access Points is interoperable with other vendors (eg: Symbol, AVAYA, etc.).

Thank you

Paolo

2 REPLIES
New Member

Re: Access Point ROAMING between Cisco and other vendors

Keep an eye on the status of 802.11f. As far as I know for now, you're better if you stick to a single brand.

New Member

Re: Access Point ROAMING between Cisco and other vendors

Paolo, Dave,

802.11(b) doesn't cover the roaming yet; 802.11f should cover the Inter Access Point Protocol (IAPP). As such, any roaming process today is proprietary.

The roaming between CISCO/AIRONET AP's and devices is proprietary and improves the performances of the roaming itself (by msec.). When a client leaves an AP A for an AP B, the AP B sends a CISCO/AIRONET MULTICAST (014096FFFFF0) to warn all CISCO/AIRONET AP's on the segment (Distribution System), that this client arrived, noticing so the AP A to remove the terminal from its association table. Should a message for the terminal have arrived in AP A while PTC was not yet on AP B, the message is buffered on AP A and upon reception of the MULTICAST, the AP A will "mail forward" the pending message over the Distribution System.

The roaming is handled at the AP level while the terminal is briefly absent, moving to the new AP. This process is proprietary, the Multicast address that addresses only CISCO/AIRONET devices (4096).

When it comes to other vendors, the process is not "so" proprietary and the recovery process for pending messages relies on a recovery at a higher level, TCP i.e. . This is a bit less performant (in the absolute), again looking at the very last millisecond, but in practice it doesn't make a perceptible difference. This way of doing is however more "open" or "interoperable", allowing any 802.11 devices to roam amongst any vendor's AP's on the backbone.

I ran some testing combining CISCO/AIRONET AP's (AP4800/AP350) with another vendor's AP and both vendor's clients and noticed that the roaming goes fast and "transparent", on a functional standpoint, going from one to another AP back and forth. This was with AP's connected to a "multiport repeater" hub.

I should still check what would happen when the roaming occurs while AP's are connected to switches and the roaming occurs from a CISCO/AIRONET AP to another vendor AP. In this case, the original AP (CISCO) will not receive the "proprietary" MULTICAST from the other vendor's AP and as such will not be able to remove the terminal from its association table. Fortunately, this situation is temporary since on CISCO/AIRONET AP's, any wireless device is staled out after something like 10 sec. of absence.

The problem I suspect here, relates to the switched environment in the sense that during these +/- 10 sec. the roaming terminal's MAC address will be present on 2 ports in the switch infrastructure.

Impact: either the communication can be blocked, the switch refusing such a "duplicate address" situation, it might also prevent the roaming to occur, or the message for the terminal will be sent to both AP's and sent in both cells in parallel, up to when the CISCO/AIRONET AP will "stale" the terminal out.

Bottom line:

- Cisco/AIRONET client amongst Cisco/AIRONET homogenous backbone --> proprietary seamless roaming

- Cisco/AIRONET client amongst other vendor's AP's homogenous backbone --> recovery at higher level protocol layer, but it works transparent.

- Cisco/AIRONET client amongst heterogenous backbone -> works when roaming from other vendor's AP to Cisco/ AIRONET AP. But roaming in switched environment from Cisco/AIRONET AP to other vendor to be checked. --> recovery at higher level protocol layer

- Other vendor's client amongst Cisco/AIRONET homogenous backbone --> roaming works fine --> recovery at higher level protocol layer

- Other vendor's client amongst other vendor's AP's homogenous backbone --> roaming works fine. --> recovery at higher level protocol layer.

- Other vendor's client amongst heterogenous backbone -> roaming works, but in switched environment from Cisco/AIRONET AP to other vendor's AP, to be checked. --> recovery at higher level protocol layer

I hope this clarifies....

Guy

492
Views
0
Helpful
2
Replies
CreatePlease to create content