Just an additional FYI: My company uses TFTP for end-users of our telephone service for configuration of their Linksys ATAs. We have had very little issues with our customers (home and business end-users over the internet). Of course, we have our ATAs only pulling configs every once in a while, not upon boot every time, as the Sipura-SPA might (although Linksys's ATAs have sipura-spa backends, AFAIK, let me know if I'm wrong).
I do agree though, with the point of multiple traversals of segements and firewalls, and even the point of US to Japan being a possible problem. My $0.02 Sherwood McGowan ->-----Original Message----- ->From: [EMAIL PROTECTED] ->[mailto:[EMAIL PROTECTED] On Behalf Of ->Gary Guthary ->Sent: Thursday, August 04, 2005 1:29 PM ->To: [email protected] ->Subject: [Asterisk-Users] TFTP - Good or Bad? -> ->Hi Guys/Gals - -> ->I don't post here often but I read with interest all the ->postings. - I've been on a lot of mailing lists, but this one ->is by far the most interesting. -> ->I've been doing a lot of work with 'tftp' loading Cisco 79xx ->phones with firmware, configs. for asterisk, etc. -> ->And I see where a lot of folks have trouble with 'tftp', use ->alternate port numbers (probably to get around firewall ->issues), etc. - And I've even seen where some folks complain ->that 'tftp' is one of the 'worst' protocols on the Internet. -> ->At the end of this posting, I've included a little tid-bit on ->'primary/alternate' 'tftp' servers for the Cisco 79xx phone setup. -> ->This next part is mainly for 'newbies' who are new to ->asterisk & haven't got a clue as to what 'tftp' is. - ->Advanced users, geeks, etc., please disregard the next part ->if you want. -> ->Apologize in advance if this is boring. -> ->Going back to 'Networking 101', just exactly what is 'tftp'? ->- Is there any reason WHY it came into being in the first place? -> ->'tftp' stands for 'Trivial File Transfer Protocol'. - Unlike ->the more popular 'ftp' protocol, 'tftp' is considered ->'non-secure'. - Meaning that no login name/password challenge ->is require. - The 'device' (computer, phone, ->whatever) sends a request to the 'tftp' server for the file & ->the server sends it. - Plain and simple. -> ->'tftp' also uses the 'UDP' (User Datagram Protocol). - The ->main difference between 'UDP' and 'TCP' is that 'UDP' uses NO ->ERROR CORRECTION. - No 'acks' ->& 'naks' to make sure all the packets arrive okay at the ->receiving end. - It's up the receiving end to make sure ->everything was received okay. -> ->Why tftp? - Back in the 'olden' days.... When hard disk ->drives were expensive, the Unix folks (i.e. the folks at Sun ->Microsystems) came up with the idea of 'diskless ->workstations'. - But for a 'diskless workstation' to boot up ->& load an operating system, enter 'tftp'. -> ->When you fired up your diskless work station, it would start ->up, DHCP it's network stuff then go out to the 'tftp' server ->for it's O/S. - The 'tftp' ->server would send the 'boot image' and your workstation would ->be up and running. - Simple as that. -> ->Well, not really that simple. - Here's a couple of 'Hows?' ->and 'What ifs?'. -> ->How did the workstation lean the IP address of the 'tftp' ->server when it booted? -> ->When the workstation DHCP'd it's IP address, netmask, ->gateway, etc., it ALSO got the "PRIMARY TFTP SERVER ADDRESS". ->- This part is STILL part of the DHCP protocol but a lot of ->folks don't know it. - Also, for historical purposes, in the ->olden days we didn't call it DHCP. - It was called 'bootp' - ->or 'bootpset'. -> ->What if the 'boot image' got mangled when the workstation loaded it? -> ->Good question. - When the workstation received the 'boot ->image', the 'boot image' also included a 'checksum' (much ->similar to our present day md5-checksum). - This checksum was ->verified. - If it didn't match, the workstation simply asked ->for the 'boot image' file again. -> ->In those days, 'tftp' usually worked very well. - Mainly ->because all the 'devices' were on the same segment of Ethernet. -> ->For newbies.- We asterisk/IP-Phone folks use 'tftp' to let ->our phones/devices download their configs. when logging into ->asterisk. - I'm not going into detail here how it works. - ->There's plenty of docs., readmes, & man pages covering this. -> ->Today, when we start doing 'tftp' transfers over several ->hundred/thousand miles of 'Internet', things can get ->complicated. - I have a 'Broadvoice' ->account and hit it with a Sipura ATA. - This means that I ->'tftp' whenever I fire up my Sipura. - But I live in JAPAN. - ->And that's not a short-haul from me to the 'Broadvoice' ->'tftp' server. - But most of the times, I boot up just fine. -> ->If your phones/devices are on the same local Ethernet ->segment, you should be okay. - But if you have long distances ->or firewalls between your devices and the 'tftp' server, you ->might encounter some difficulties. -> ->If you have 'tftp' problems, take a good hard look at your ->network. But don't blame your problems on the protocol itself. -> ->Cisco 79xx phones & 'tftp' server addresses. -> ->When configuring a Cisco 79xx phone, you'll probably see ->configs. for 'primary' and 'alternate' 'tftp' server. - ->Especially if the phone is configured for DHCP. - You'll also ->notice that you CANNOT make any changes to the 'primary tftp' ->server but you can define an 'alternate tftp' server. -> ->Reason - If the Cisco phone DHCP's a 'tftp' server address, ->it will become the phone's 'primary tftp' server. - In most ->cases, it probably won't (but that's up to your network ->admin). - If you wish to manually define a 'tftp' ->server, you have to set it up as an 'alternate tftp' server. ->- If this is the case, the phone will let the 'alternate ->tftp' server's address OVERRIDE the 'primary tftp' server's ->address (if you DHCP'd one or not). -> ->Bottom line. - If you want to force your Cisco 79xx phone to ->go to a specific 'tftp' server, set that server's address as ->the 'alternate tftp' ->server. -> ->Gary Guthary ->[EMAIL PROTECTED] -> -> -> ->_______________________________________________ ->Asterisk-Users mailing list ->[email protected] ->http://lists.digium.com/mailman/listinfo/asterisk-users ->To UNSUBSCRIBE or update options visit: -> http://lists.digium.com/mailman/listinfo/asterisk-users -> _______________________________________________ Asterisk-Users mailing list [email protected] http://lists.digium.com/mailman/listinfo/asterisk-users To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
