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New Member

Connection Issues with Point to Multipoint Bridge

Hello,

First off, my experience with wireless networks so far has been basic AP configuration - multiple VLANs and SSIDs directly connected to the network.

I've inherited a small wireless network that contains 3 Aironet 1240ag access points configured in a point-to-mulipoint configuration.  Here's a quick description of the network:

  • Two APs(Point1 and Point2) are configured to bridge with a central AP(Base1).
  • All 3 APs provide wireless connectivity to clients on dot11radio0 in the 2.4Ghz range.  Channel overlap does not appear to be an issue when I performed a quick wireless survey.
  • The point-to-multipoint bridge uses the 5Ghz range.
  • Point1 and Point2 have two external antennas.  One directional patch antenna to Base1, and one omni-directional antenna to service wireless clients.
  • Base1 has 3 antenna - Two directional square antenna to connect to Point1 and Point2, and one omni-direcitonal antenna to service wireless clients.
  • There are 3 VLANs carried across the bridge.

Occasionally we run into issues where:

  • Clients cannot connect
  • Clients to not receive a DHCP address, or it takes a long time.
  • Signal strength is very low even when standing very close to an access point.
  • The bridge from Base1 to one of the two points fails.

I have some theories about why the network isn't work the way it's supposed to, but I'm not sure how to test the theories, and I don't want to change things without getting other options from people who know more:

  • The omni-directional antennas could be overlapping and confusing the clients.  The site is not very large, maybe 100m x 100m.  I ran a basic wireless sniffer, and found that while standing next to one access point I was receving a DBi of 80, the other access points were between 50 and 70.
  • The bridge antenna are note aligned correctly.  Are there any commands that I can run on the base or point APs to gague the bridge antenna signal strength.
  • The network is being saturated with broadcasts.  I'm not sure how to test this.

I'd be happy to post configs, diagrams or outputs of commands.  Let me know what you think.

1 ACCEPTED SOLUTION

Accepted Solutions
Bronze

Re: Connection Issues with Point to Multipoint Bridge

Hi Kelly, 
 
As per your info this is a wireless setup you just inherited. 
All the devices being used are 1240 which are indoor access points that can work as
bridges and be set for a point to point link how you have them setup.
 
You are using the A radio between the root to the 2 non root units. 
Since you are using the A radio all the channels are non overlapping, 
I would advise you to set the channel statically on the A radio on the root since by default
it comes as least congested so due to this the root unit may be changing the channel and
every time it does this the radio will go down and come back up creating connectivity issues
between the point to point link.
 
I would also set the data rates to best range on the A radio. 
 
Then on the G radio which is set as access point to allow your wireless clients 
to connect we only have 3 non overlapping channels that are 1-6-11 and as we know access points
create interference to other access points so since you have 3 units I would advise you
to set 1 channel to each AP (1-6-11) so that they do not create interference between them
and also avoid the issue of the radio going down and coming back up every time it changes the channel.
 
Also I would set the data rates to best range. 
 
This is just some options you could try to see if the issue stops or continues. 

3 REPLIES
Bronze

Re: Connection Issues with Point to Multipoint Bridge

Hi Kelly, 
 
As per your info this is a wireless setup you just inherited. 
All the devices being used are 1240 which are indoor access points that can work as
bridges and be set for a point to point link how you have them setup.
 
You are using the A radio between the root to the 2 non root units. 
Since you are using the A radio all the channels are non overlapping, 
I would advise you to set the channel statically on the A radio on the root since by default
it comes as least congested so due to this the root unit may be changing the channel and
every time it does this the radio will go down and come back up creating connectivity issues
between the point to point link.
 
I would also set the data rates to best range on the A radio. 
 
Then on the G radio which is set as access point to allow your wireless clients 
to connect we only have 3 non overlapping channels that are 1-6-11 and as we know access points
create interference to other access points so since you have 3 units I would advise you
to set 1 channel to each AP (1-6-11) so that they do not create interference between them
and also avoid the issue of the radio going down and coming back up every time it changes the channel.
 
Also I would set the data rates to best range. 
 
This is just some options you could try to see if the issue stops or continues. 

New Member

Re: Connection Issues with Point to Multipoint Bridge

Thank you for the advice.

The A radio is currently set to "channel dfs", and is using 5220MHz/Channel 44.  If I set the channel to 44 manually, will the bridge APs disconnect and have to reassosicate?

The G radios are set to use non-overlapping channels.

Everything seems to be working fine at the moment, so I'm not going to make any changes as this is a remote hotel site with live users.  If it has trouble in the future I'll make sure to give this a try.

Thank you for your help.

KB

Bronze

Re: Connection Issues with Point to Multipoint Bridge

Yes, any change we make on the radio it will make the radio go down and come back up. The changes can be data rates , encryption , channel , etc

Sent from Cisco Technical Support iPhone App

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