Re: [WISPA] Interesting BGP Redundancy Opton for FREE
Butch, You completely missed my point, ot the background to the thread.. Of course you can build a tunnel of just about any MTU size on your network. The issue at hand is what max MTU size OTHER upstream ISPs allow on their network. Scott was talkng about doing a tunnel accross an end user Comcast circuit. With the open Internet, the two end point end users don't really have control of what ISPs in between gets traversed from End Point A to B. The ISPs in the middle could chance at any time. This is not a new problem For example A number of years back Universities built a private experimental transport network to support high MTU above 9600, so that their GB and 10GB networks could pass full capacity. As you know, max transfer rate is directly proportional to latency times packet size. Most common ISPs only passed 1500MTU, therefore the Universities had to make their own net. This has been a challenge for years for even passing VLAN tags or MPLS data, where layer2 fiber carriers would only pass a 1512 packet. When you are the end user, the answer is to shrink your MTU, so after the tunnel overhead it fits into the ISP's max 1512 MTU. But when one is an tranport ISP that transports many customer's data, it is not appropriate for the ISP to shrink his MTU below 1500, as all the other end users would not know that the MTU was shrunk, and would not have their routers set to a smaller MTU to fit. Sure you can allow fragmentation, and TCP will automatically split the packets to fit, but it has been common ISP management practice to disallow fragmentation for various reasons that I don't want to get into in this thread. And yes, there is MTU autolearning, but again, not supported by everyone or all protocols. So sure, the ISP can make a tunnel setting a lower MTU, so after tunel overhead, it will fit in the uipstream's 1512 MTU. But then full size packets (because packets comming from end user customers will be 1512 size) inside the tunnel will get fragmented to fit into the tunnel. For long haul backhauls, there can be side effects of just simply allowing fragmentation on the routers without any further consideration. Again, we have a good solution for this... It is called CIPE. Its a tunneling protocol that splits the packets appropriately for optimal efficiency. I understand how CIPE works because it is what we use. I can't say I understand the methods that Mikrotik may use. So, what I asked is how Mikrotik can deal with that problem, because Mikrotik does not support CIPE. Tom DeReggi RapidDSL Wireless, Inc IntAirNet- Fixed Wireless Broadband - Original Message - From: Butch Evans but...@butchevans.com To: WISPA General List wireless@wispa.org Sent: Friday, April 24, 2009 11:03 PM Subject: Re: [WISPA] Interesting BGP Redundancy Opton for FREE On Fri, 2009-04-24 at 19:37 -0400, Tom DeReggi wrote: Over a Layer2 PTP its usually not an issue, but it is over a standard transit connection. (customer and Internet needs to see 1500 bytes, but an ISP's tunnel causes packet size to exceed 1500 MTU. I have built tunnels that carry 12000 byte packets. Not sure where this idea comes from. They can be built that will carry as much as 65k bytes. We use Cipe tunnels to solve that. To split the full size packets before it enters the tunnel, so tunnel stays at 1500MTU or less, required by the transit provider.. How do you do it with Mikrotik ? Of the tunnels I've done with MT, you just use PPtP and set the MRRU (just like your tunnels). I've done this with standard Linux, too. It is actually quite an elegant solution. -- * Butch Evans * Professional Network Consultation* * http://www.butchevans.com/* Network Engineering * * http://www.wispa.org/ * WISPA Board Member * * http://blog.butchevans.com/ * Wired or Wireless Networks * WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] Interesting BGP Redundancy Opton for FREE
Butch, Of the tunnels I've done with MT, you just use PPtP and set the MRRU (just like your tunnels). I've done this with standard Linux, too. It is actually quite an elegant solution. Actually I missed this part of your post, before making my last post Am I understanding correctly Are you saying. When using PPTP and you set the MRRU to the same as your tunnels, both your tunnel ethernet packet size can be 1512, while the ethernet packet size for data inside the tunnel also can be 1512? Meaning that PPTP does not increase the Ethernet packet size, in order to be implemented? (PS, I don't recall the details of PPTP. We generally use IPSEC, OpenVPN, VLANs, MPLS, all of which increase ethernet packetsize above 1512, unless IP payload MTU is reduced..) Tom DeReggi RapidDSL Wireless, Inc IntAirNet- Fixed Wireless Broadband - Original Message - From: Butch Evans but...@butchevans.com To: WISPA General List wireless@wispa.org Sent: Friday, April 24, 2009 11:03 PM Subject: Re: [WISPA] Interesting BGP Redundancy Opton for FREE On Fri, 2009-04-24 at 19:37 -0400, Tom DeReggi wrote: Over a Layer2 PTP its usually not an issue, but it is over a standard transit connection. (customer and Internet needs to see 1500 bytes, but an ISP's tunnel causes packet size to exceed 1500 MTU. I have built tunnels that carry 12000 byte packets. Not sure where this idea comes from. They can be built that will carry as much as 65k bytes. We use Cipe tunnels to solve that. To split the full size packets before it enters the tunnel, so tunnel stays at 1500MTU or less, required by the transit provider.. How do you do it with Mikrotik ? Of the tunnels I've done with MT, you just use PPtP and set the MRRU (just like your tunnels). I've done this with standard Linux, too. It is actually quite an elegant solution. -- * Butch Evans * Professional Network Consultation* * http://www.butchevans.com/* Network Engineering * * http://www.wispa.org/ * WISPA Board Member * * http://blog.butchevans.com/ * Wired or Wireless Networks * WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] Interesting BGP Redundancy Opton for FREE
Hello again... I didn't specify comcast but in the context of our discussion it doesn't matter much :) Tom... Lets just do a test from your network to mine. A learning experience if nothing else - can't go wrong there. I've never heard of CIPE but I assure you that MT has no problem whatsoever passing traffic from anyone over a tunnel between us, I think you are hung up on something that is a non-issue and what Butch mentioned was not about over one's own network - he understood that it was from some end user provider to another with multiple possible ISPs in the middle... its a mute point who's in the middle really with whats being proposed and how it works. I have a router ready to go, you? Latency between us is good, less than 30ms. I 60MB on any given day/time still available not doing anything, usually a little more. Scott Carullo Brevard Wireless 321-205-1100 x102 Original Message From: Tom DeReggi wirelessn...@rapiddsl.net Sent: Sunday, April 26, 2009 6:49 PM To: WISPA General List wireless@wispa.org Subject: Re: [WISPA] Interesting BGP Redundancy Opton for FREE Butch, You completely missed my point, ot the background to the thread.. Of course you can build a tunnel of just about any MTU size on your network. The issue at hand is what max MTU size OTHER upstream ISPs allow on their network. Scott was talkng about doing a tunnel accross an end user Comcast circuit. With the open Internet, the two end point end users don't really have control of what ISPs in between gets traversed from End Point A to B. The ISPs in the middle could chance at any time. This is not a new problem For example A number of years back Universities built a private experimental transport network to support high MTU above 9600, so that their GB and 10GB networks could pass full capacity. As you know, max transfer rate is directly proportional to latency times packet size. Most common ISPs only passed 1500MTU, therefore the Universities had to make their own net. This has been a challenge for years for even passing VLAN tags or MPLS data, where layer2 fiber carriers would only pass a 1512 packet. When you are the end user, the answer is to shrink your MTU, so after the tunnel overhead it fits into the ISP's max 1512 MTU. But when one is an tranport ISP that transports many customer's data, it is not appropriate for the ISP to shrink his MTU below 1500, as all the other end users would not know that the MTU was shrunk, and would not have their routers set to a smaller MTU to fit. Sure you can allow fragmentation, and TCP will automatically split the packets to fit, but it has been common ISP management practice to disallow fragmentation for various reasons that I don't want to get into in this thread. And yes, there is MTU autolearning, but again, not supported by everyone or all protocols. So sure, the ISP can make a tunnel setting a lower MTU, so after tunel overhead, it will fit in the uipstream's 1512 MTU. But then full size packets (because packets comming from end user customers will be 1512 size) inside the tunnel will get fragmented to fit into the tunnel. For long haul backhauls, there can be side effects of just simply allowing fragmentation on the routers without any further consideration. Again, we have a good solution for this... It is called CIPE. Its a tunneling protocol that splits the packets appropriately for optimal efficiency. I understand how CIPE works because it is what we use. I can't say I understand the methods that Mikrotik may use. So, what I asked is how Mikrotik can deal with that problem, because Mikrotik does not support CIPE. Tom DeReggi RapidDSL Wireless, Inc IntAirNet- Fixed Wireless Broadband - Original Message - From: Butch Evans but...@butchevans.com To: WISPA General List wireless@wispa.org Sent: Friday, April 24, 2009 11:03 PM Subject: Re: [WISPA] Interesting BGP Redundancy Opton for FREE On Fri, 2009-04-24 at 19:37 -0400, Tom DeReggi wrote: Over a Layer2 PTP its usually not an issue, but it is over a standard transit connection. (customer and Internet needs to see 1500 bytes, but an ISP's tunnel causes packet size to exceed 1500 MTU. I have built tunnels that carry 12000 byte packets. Not sure where this idea comes from. They can be built that will carry as much as 65k bytes. We use Cipe tunnels to solve that. To split the full size packets before it enters the tunnel, so tunnel stays at 1500MTU or less, required by the transit provider.. How do you do it with Mikrotik ? Of the tunnels I've done with MT, you just use PPtP and set the MRRU (just like your tunnels). I've done this with standard Linux, too. It is actually quite an elegant solution. -- * Butch Evans
Re: [WISPA] Interesting BGP Redundancy Opton for FREE
On Sun, 2009-04-26 at 18:57 -0400, Tom DeReggi wrote: Of the tunnels I've done with MT, you just use PPtP and set the MRRU (just like your tunnels). I've done this with standard Linux, too. It is actually quite an elegant solution. Actually I missed this part of your post, before making my last post Am I understanding correctly Are you saying. When using PPTP and you set the MRRU to the same as your tunnels, both your tunnel ethernet packet size can be 1512, while the ethernet packet size for data inside the tunnel also can be 1512? Meaning that PPTP does not increase the Ethernet packet size, in order to be implemented? You can set the MRRU to 65535 if you want. (PS, I don't recall the details of PPTP. We generally use IPSEC, OpenVPN, VLANs, MPLS, all of which increase ethernet packetsize above 1512, unless IP payload MTU is reduced..) The tunnel itself will be whatever the transport MTU is. You can even do (if you desire) a PPtP over OpenVPN to get the added encryption. For what it's worth, it is documented: http://www.mikrotik.com/testdocs/ros/3.0/vpn/pptp.php -- * Butch Evans * Professional Network Consultation* * http://www.butchevans.com/* Network Engineering * * http://www.wispa.org/ * WISPA Board Member * * http://blog.butchevans.com/ * Wired or Wireless Networks * WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] Interesting BGP Redundancy Opton for FREE
Scott, Actually, I originally missed the part about mikrotik router. We don't use Mikrotik routers currently, as they can not accommodate us loading our custom management software code. But all our servers are Linux based, so can likely do anything that Mikrotik can, (with a little bit of effort). Butch was suggesting using PPTP. I need to double check that we have a PPTP package loaded on our routers, and if not, load one first. (I could always get a MT box to do the tunnel, and just allocate an Ethernet port on my Linux router to it, but I'd need to procure a MT unit first. ) I agree, at minimum, it would be a fun experiment,with no disadvantage. We have plenty of free bandwidth. We should probably take this offlist, at this point. We can always share the results with the list, after the fact. Tom DeReggi RapidDSL Wireless, Inc IntAirNet- Fixed Wireless Broadband - Original Message - From: Scott Carullo sc...@brevardwireless.com To: WISPA General List wireless@wispa.org Sent: Sunday, April 26, 2009 6:58 PM Subject: Re: [WISPA] Interesting BGP Redundancy Opton for FREE Hello again... I didn't specify comcast but in the context of our discussion it doesn't matter much :) Tom... Lets just do a test from your network to mine. A learning experience if nothing else - can't go wrong there. I've never heard of CIPE but I assure you that MT has no problem whatsoever passing traffic from anyone over a tunnel between us, I think you are hung up on something that is a non-issue and what Butch mentioned was not about over one's own network - he understood that it was from some end user provider to another with multiple possible ISPs in the middle... its a mute point who's in the middle really with whats being proposed and how it works. I have a router ready to go, you? Latency between us is good, less than 30ms. I 60MB on any given day/time still available not doing anything, usually a little more. Scott Carullo Brevard Wireless 321-205-1100 x102 Original Message From: Tom DeReggi wirelessn...@rapiddsl.net Sent: Sunday, April 26, 2009 6:49 PM To: WISPA General List wireless@wispa.org Subject: Re: [WISPA] Interesting BGP Redundancy Opton for FREE Butch, You completely missed my point, ot the background to the thread.. Of course you can build a tunnel of just about any MTU size on your network. The issue at hand is what max MTU size OTHER upstream ISPs allow on their network. Scott was talkng about doing a tunnel accross an end user Comcast circuit. With the open Internet, the two end point end users don't really have control of what ISPs in between gets traversed from End Point A to B. The ISPs in the middle could chance at any time. This is not a new problem For example A number of years back Universities built a private experimental transport network to support high MTU above 9600, so that their GB and 10GB networks could pass full capacity. As you know, max transfer rate is directly proportional to latency times packet size. Most common ISPs only passed 1500MTU, therefore the Universities had to make their own net. This has been a challenge for years for even passing VLAN tags or MPLS data, where layer2 fiber carriers would only pass a 1512 packet. When you are the end user, the answer is to shrink your MTU, so after the tunnel overhead it fits into the ISP's max 1512 MTU. But when one is an tranport ISP that transports many customer's data, it is not appropriate for the ISP to shrink his MTU below 1500, as all the other end users would not know that the MTU was shrunk, and would not have their routers set to a smaller MTU to fit. Sure you can allow fragmentation, and TCP will automatically split the packets to fit, but it has been common ISP management practice to disallow fragmentation for various reasons that I don't want to get into in this thread. And yes, there is MTU autolearning, but again, not supported by everyone or all protocols. So sure, the ISP can make a tunnel setting a lower MTU, so after tunel overhead, it will fit in the uipstream's 1512 MTU. But then full size packets (because packets comming from end user customers will be 1512 size) inside the tunnel will get fragmented to fit into the tunnel. For long haul backhauls, there can be side effects of just simply allowing fragmentation on the routers without any further consideration. Again, we have a good solution for this... It is called CIPE. Its a tunneling protocol that splits the packets appropriately for optimal efficiency. I understand how CIPE works because it is what we use. I can't say I understand the methods that Mikrotik may use. So, what I asked is how Mikrotik can deal with that problem, because Mikrotik does not support CIPE. Tom DeReggi RapidDSL Wireless, Inc IntAirNet- Fixed Wireless Broadband - Original Message - From: Butch Evans but...@butchevans.com
Re: [WISPA] Interesting BGP Redundancy Opton for FREE
On Fri, 2009-04-24 at 19:37 -0400, Tom DeReggi wrote: Over a Layer2 PTP its usually not an issue, but it is over a standard transit connection. (customer and Internet needs to see 1500 bytes, but an ISP's tunnel causes packet size to exceed 1500 MTU. I have built tunnels that carry 12000 byte packets. Not sure where this idea comes from. They can be built that will carry as much as 65k bytes. We use Cipe tunnels to solve that. To split the full size packets before it enters the tunnel, so tunnel stays at 1500MTU or less, required by the transit provider.. How do you do it with Mikrotik ? Of the tunnels I've done with MT, you just use PPtP and set the MRRU (just like your tunnels). I've done this with standard Linux, too. It is actually quite an elegant solution. -- * Butch Evans * Professional Network Consultation* * http://www.butchevans.com/* Network Engineering * * http://www.wispa.org/ * WISPA Board Member * * http://blog.butchevans.com/ * Wired or Wireless Networks * WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
