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New Member

Loose ping packets when I roam

I've setup 22 ap's in a building. When I perform a constant ping to my gateway, I notice I will drop a packet when I move from one ap to another. Is this normal? If not, what would fix this?

  • Getting Started with Wireless
7 REPLIES
Green

Re: Loose ping packets when I roam

What kind of security (encryption, authorization) have you implemented?

Let us know.

Scott

New Member

Re: Loose ping packets when I roam

WPA/LEAP. Here is part of my config:

************************************

interface Dot11Radio0

no ip address

no ip route-cache

!

encryption mode ciphers tkip

!

ssid WLAN

authentication open eap eap_methods

authentication network-eap eap_methods

authentication key-management wpa

New Member

Re: Loose ping packets when I roam

We have an issue very similar. Would be interested in how you resolved. Thanks.

Bronze

Re: Loose ping packets when I roam

This is normal. The act of roaming requires you to lose one signal while picking up another.

Sometimes you will not lose any, sometimes one or two. Anymore than that would indicate a problem.

Silver

Re: Loose ping packets when I roam

I assume you mean WPA/PEAP not LEAP, because LEAP is a Cisco proprietary modification to WEP and does not support WPA/WPA2.

If you are using a Cisco ACS or Microsoft IAS server as your RADIUS server, then WPA1/PEAP roam times will be 1 to 2 seconds, depending on load on the RADIUS server, because of a complete re-auth. As if you were authenticating all over again to the Microsoft AD.

There are two solutions to this problem:

1. Using Cisco autonomous (standalone) APs (as it appears you have configured) and configure the APs to be members of a WDS. Also, your clients must support CCKM in one form or another.

Depending on your client wireless NIC and driver capabilities, you may be able to use WPA1 with CCKM or may be forced to use EAP-FAST and/or a Cisco wireless NIC. The Intel 2200BG, 2915ABG, and 3945ABG NICs have good support for Cisco radios and CCX standards. Most others do not.

You will NOT be able to use the MS zero-config client, you MUST use the driver supplied by the NIC vendor.

2. Upgrade your autonomous APs to the centralized model using a Cisco Airespace controller.

The Cisco WLCs have always supported WPA2/PEAP-MSCHAPv2 with fast roaming (configured on your client, controller, and RADIUS server) and recently have supported CCKM as above.

The important note is the fast roaming (under 100 ms) is ONLY supported with

1. Cisco's proprietary CCKM (with WPA1/WPA2 and PEAP-MSCHAPv2 or EAP-FAST), depending on client NIC and wireless driver. This NOT supported by the MS zero-config client.

2. WPA2/MSCHAPv2 with 'fast reconnect' enabled on the client, controller and RADIUS server. This is supported with the MS zero-config client with nearly any wireless NIC and wireless driver but requires XP SP2 with several hotfixes (NOT SECURITY PATCHES).

In short, there is nothing you can do with an autonomous AP and WPA1 with the MS zero-config client for fast roaming. Depending on the load on the AP, RADIUS server and MS AD DC(s), you may experience roam times measured in tens of seconds to a minute...

New Member

Re: Loose ping packets when I roam

You may be losing the pings because of coverage holes. To detect the holes I would recommend walking with your laptop watching ping responses as well as signal strength by some means (Cisco Aironet Client Utility, NetStumbler, or AirMagnet). If there is a correlation between bad signal strength and ping failures you have coverage holes. If the strength of the signal is good but ping still fails you may be experiencing interference between the channels and you may want to revisit your channel allocation plan. Depending on your AP vendor request them few seamless roaming suggestions.

New Member

Re: Loose ping packets when I roam

We experience the same problems. The Intel clients usually have zero problem re-authenticating and connecting, while other/older cards can take minutes or sometimes don't re-authenticate at all and have to do it manually.

You can try 3rd party software or use WDS as others said.

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