[cisco-voip] slow 7936 boot times (packet capture added)

[Lelio Fulgenzi]

Interestingly enough, it seems it wasn't the lack of option 150 or option 66 having an IP address instead of a name. It had to do mainly with the fact that the phones did not have DNS access. This lack of access caused the retries. Once we enabled access (via ACL), even though there was no DNS entry for "ciscocm1", we're guessing it received the negative DNS answer and then it tried the IP address in option 66. 


We actually removed option 66 and added option 150 and the boot time went from 5 min to 3 min - so it did have a positive affect. 

The plan is to modify all DHCP ranges to use option 150 instead of 66 (since that's the recommended approach) and to update the ACLs to allow ping and DNS access to the DNS servers. 

Thanks for your help on this. 

Lelio 


--- 
Lelio Fulgenzi, B.A. 
Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1 
(519) 824-4120 x56354 (519) 767-1060 FAX (JNHN) 
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 
Cooking with unix is easy. You just sed it and forget it. 
- LFJ (with apologies to Mr. Popeil) 


----- Original Message ----- 
From: "Wes Sisk" <wsisk at cisco.com> 
To: "Lelio Fulgenzi" <lelio at uoguelph.ca> 
Cc: "cisco-voip voyp list" <cisco-voip at puck.nether.net> 
Sent: Tuesday, July 13, 2010 2:14:07 PM GMT -05:00 US/Canada Eastern 
Subject: Re: [cisco-voip] slow 7936 boot times (packet capture added) 

The DHCP Offer does not include an option 150 which would normally identify the TFTP server address. DHCP offer does include Option 66. Option 66 is usually a DNS name to be resolved. In this capture option 66 is an IP address. Based on the phone repeatedly querying CiscoCM1 it seems pretty clear that the phone did not take the option 66 or option 150 for TFTP server. CiscoCM1 is the default DNS name that is queried to get TFTP address if one is not identified by other means. 

/Wes 

On Tuesday, July 13, 2010 12:56:09 PM, Lelio Fulgenzi <lelio at uoguelph.ca> wrote: 



Find two packet captures, one raw and one filtered with the IPADDR and MAC of the phone. 

Interesting how the phone is asking for CiscoCM1.uoguelph.ca over and over again. 

I plugged in the conference phone about 50 seconds or so after the capture started. 

Filter: (ip.addr == 10.104.25.100) or (eth.addr == 00:e0:75:24:dc:da) 

--- 
Lelio Fulgenzi, B.A. 
Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1 
(519) 824-4120 x56354 (519) 767-1060 FAX (JNHN) 
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 
Cooking with unix is easy. You just sed it and forget it. 
- LFJ (with apologies to Mr. Popeil) 


----- Original Message ----- 
From: "Wes Sisk" <wsisk at cisco.com> 
To: "Lelio Fulgenzi" <lelio at uoguelph.ca> 
Cc: "cisco-voip voyp list" <cisco-voip at puck.nether.net> 
Sent: Tuesday, July 13, 2010 11:56:37 AM GMT -05:00 US/Canada Eastern 
Subject: Re: [cisco-voip] slow 7936 boot times 

Packet capture please. 

2 things come to mind: 
* Phone is waiting for CDP exchange with switch. The phone waits for quite some time to receive CDP so it knows what voice vlan to use. Eventually it times out and assumes no CDP/trunk and behaves as access device. 
* DHCP server never completes the DHCP transaction or the transaction is significantly delayed. Along the same lines I saw some challenges with the options returned from a DHCP server that caused 7936 phone to not parse dhcp response. 

Packet Capture :) 

/Wes 

On Tuesday, July 13, 2010 11:30:51 AM, Lelio Fulgenzi <lelio at uoguelph.ca> wrote: 



We have had issues raised with 7936 conference phones taking between 10 and 15 minutes to boot up. I'm testing one right now that is taking 5 1/2 minutes. This was never the case. The only difference we can remember making is switching from Windows DHCP to central DHCP (Infoblox solution). I'll be doing some sniffing soon, but essentially what we see is the following: 


    • power up 
    • Cisco logo on screen for a bit 
    • "Configuring IP... Press Menu to reconfigure" (5 1/2 min) 
    • "Station IP: <ipaddr> Contacting: <tftpipaddr>" (quick) 
    • "Registering: <subipaddr>" (quick) 

I am able to ping the phone from the sub very quickly after power up (even after a config erase). 

Any ideas? 



--- 
Lelio Fulgenzi, B.A. 
Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1 
(519) 824-4120 x56354 (519) 767-1060 FAX (JNHN) 
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 
Cooking with unix is easy. You just sed it and forget it. 
- LFJ (with apologies to Mr. Popeil) 


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