Wireless Access

Hello-

Budding wireless engineer here.  Was hoping to run this issue by the message board to see if anyone has the same issue.  About 98% of our campus buildings are fed with fiber, but the remaining 2% are legacy HDSL circuits.  We are in the process of swapping out MSM gear with Aruba 6000's and AP-135's(yea!).  My questions are regarding HDSL and RAP.

Now, to add a little history.  We were never able to successfully configure an MSM460 over an HDSL circuit because of an issue of MTU packet size; HP could never fix it and the AP would never negotiate the link.  So, as a fix, we had to keep RP210's around to give the HDSL sites wireless access.  When we tested the AP-135's on HDSL, we configured them as a RAP and they worked!  It was sort of a deal breaker........ :)

Now, is there someone who can explain to me what is happening?  How can the AP negotiate this link?  If the AP is used heavily, won't it clog the link so much as to create network latency to the other vlans piped to the building? 

Matt Bonadies

Lead Network Engineer (Wireless)

Campus Network Infrastructure

Indiana University

mbonadie@iu.edu

(812) 855-2422

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@mbonadie wrote:

Hello-

 

Budding wireless engineer here.  Was hoping to run this issue by the message board to see if anyone has the same issue.  About 98% of our campus buildings are fed with fiber, but the remaining 2% are legacy HDSL circuits.  We are in the process of swapping out MSM gear with Aruba 6000's and AP-135's(yea!).  My questions are regarding HDSL and RAP.

 

Now, to add a little history.  We were never able to successfully configure an MSM460 over an HDSL circuit because of an issue of MTU packet size; HP could never fix it and the AP would never negotiate the link.  So, as a fix, we had to keep RP210's around to give the HDSL sites wireless access.  When we tested the AP-135's on HDSL, we configured them as a RAP and they worked!  It was sort of a deal breaker........ :)

 

Now, is there someone who can explain to me what is happening?  How can the AP negotiate this link?  If the AP is used heavily, won't it clog the link so much as to create network latency to the other vlans piped to the building? 

 

Matt Bonadies

Lead Network Engineer (Wireless)

Campus Network Infrastructure

Indiana University

mbonadie@iu.edu

(812) 855-2422

 

 

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When you say "someone who can explain what is happening".... what do you mean?  An AP configured as a RAP does use a different MTU than a Campus AP, so if I was guessing, that is what it is.

With regards to the latency, etc, you can have the Remote AP bridge the user traffic instead so the traffic is deposited locally to the switchport of the AP (trunked if you want multiple VLANS).  You could deal with the latency issue in that manner.

Thanks for the comment.  I guess what I meant was someone to explain RAP vs Campus AP's.  Each one of our buildings has it's own seperate VLANs for wired traffic/management and wireless.  With respect to latentcy, I do not want to cause it because the wireless tunnel is almost as large as the total HDSL bandwidth.  How much "space" am I saving with configuring the AP as a RAP?

Matt