Can someone explain shortest path switch over in Multicast?

Can someone explain shortest path switch overin Multicast?

Hi,
Shortest path switchover is used in PIM Sparse mode.
The concept of Sparse Mode is the multicast traffic should only be delivered when there are active receivers in the network. To accomplish this SM has explicit Join and Prune mechanism rather than Flood and Prune used by Dense mode.
When the last hop router (where receiver is connected) receives an IGMP join message, it sends a PIM Join towards RP. This creates shared tree from the last hop router till RP along the routers.Thus a shared tree has been created from last hop router till RP.
At the same time the above procedure was taking place, the first hop router (where source is connected) starts sending PIM Register messages to RP (when source starts sending multicast traffic). This register messages are unicast so that the intermediate routers will not aware of multicast traffic. When the RP receives Register messages from first hop rotuer, it does below checks after decapsulation:
1. Are there any shared tree for the specific multicast group. If yes then send a SPT join towards first hop router so that the multicast traffic from source will be delivered to RP via native multicast rather than encapsualted packets. Also RP sends Register Stop message to inform first hop router to stop sending encapsulated multicast packets.
2. When there are no active groups in RP (i.e RP has not received any PIM join for the multicast group from any last hop router), RP sends a Register Stop message.
By this the traffic from source flows via SPT till RP. From RP it flows via shared tree till receiver. Everything is fine till now. But the drawback in SM is placement of RP and the load on it. Since RP is located in a central location chances are there that the multicast traffic from source takes a longer path to reach the receiver. This will result in increase in latency along with increase in RP load.
So in those cases, it is desirable for the multicast traffic from source flows to receiver on optimal path. This is done by SPT switchover and this is done when the multicast group traffic crosses the SPT threshold configured. In Cisco the default SPT threshold is Zero kbps. So when the last hop router receives first multicast packet via shared tree, it does SPT switchover. This is done by sending a SPT Join towards the source thus bypassing the RP. Now the traffic from source prefers the most optimal path to reach the receiver.
The same time, last hop router sends a PIM prune towards RP to inform it that it does not want multicast traffic over shared tree. This is done to avoid duplication of the multicast packets over SPT and shared tree.
Few facts:
1. Last hop router needs information about the source to send SPT Join and this can only happen when it receives few initial multicast packets via RP shared tree.
2. If you do not want the last hop router to fall back to SPT switchover, then configure SPT threshold to infinity in last hop router.
Sorry for the long post.
HTH.
thanks
Arun
Pls rate if it is helpful

Similar Messages

  • Can someone explain about frame header size in Ethernet over MPLS

    Can someone explain about frame header size in Ethernet over MPLS

    Hello Arun,
    Here is some explanation:
    http://cciethebeginning.wordpress.com/tag/eompls/
    Also I attached pcap file, you can open it in wireshark and look at entire packets. There are some pings 10.0.0.1 <-> 10.0.0.2 between CEs
    Best Regards
    Please rate all helpful posts and close solved questions

  • Please can someone explain how to delete email addresses?  I have people who when I type in their name it comes up with the correct email address but then when you hit return to confirm it promptly changes the name to someone else (always the same someone

    Please can someone explain how to delete and email address that when typed in brings up one name but when you hit return to confirm it jumps to another name.  I can't find them in my contacts list but they do come up when you type the first few letters of a name.
    EG If I type xyz and the name of the person comes up, when I press return to confirm that's the one I want then it jumps to [email protected],  always the same def address.
    I can't fathom it out.
    Thanks
    Terri

    Try this:
    Start a new email.  In the To address bar, type in xyz like you normally do, press return to confim, and when the address you want to remove shows up in the address bar, move your cursor over the address you want to delete.
    A small triangle next to the name will show up.  click on it, a drop down menu will open, click Remove from Previous Recipients List.  Then do the drop down menu again and Remove Address.
    Good luck.

  • Trying to understand RSTP - Please can someone explain this?

    Hi Group
    I am still confused about how RSTP is implemented. From what i understand the major difference is that STP
    used Timers for Loop prevention whereas RSTP coordinates between neighbors via messages (proposal/aggreement) to turn on links
    more quickly after topology changes and is "timer free".
    However, I have not noticed any difference in the configuration from the legacy STP
    configurations and the RSTP configuration on cisco devices. Or are there any differences??
    I have read in documentation that RSTP natively includes features like UplinkFast, BackboneFast and PortFast. So are these features now obsolete
    and not needed to be configured if you are running RSTP. (Although i have seen Portfast still configured along with RSTP on many switches)
    Also can someone explain the below Points from Cisco Documentation
    1) should STP be disabled on edge ports all together as suggested below?
    "STP edge ports are bridge ports that do not need STP enabled, where loop protection is not needed out
    of that port or an STP neighbor does not exist out of that port. For RSTP, it is important to disable STP
    on edge ports, which are typically front-side Ethernet ports, using the command bridge
    bridge-group-number spanning-disabled on the appropriate interface. If RSTP is not disabled on edge
    ports, convergence times will be excessive for packets traversing those ports."
    2) It seems RSTP relies on duplex setting to determine inter-switch links. What is the configuration to explicitly
    configure RSTP link types? (I couldnt find this in the documentation)
    "RSTP can only achieve rapid transition to the forwarding state on edge ports and on point-to-point links.
    The link type is automatically derived from the duplex mode of a port. A port that operates in fullduplex
    is assumed to be point-to-point, while a half-duplex port is considered as a shared port by
    default. This automatic link type setting can be overridden by explicit configuration. In switched
    networks today, most links operate in full-duplex mode and are treated as point-to-point links by RSTP.
    This makes them candidates for rapid transition to the forwarding state."
    Also i am a bit rough on my RSTP knowledge even after skimming a few Cisco documents. Can someone please explain this in simple way.
    Thanks in advance

    to configure it on a device:-
    spanning-tree mode rapid-pvst
    PortFast/UplinkFast & BackboneFast were cisco "Enhancements" to 802.1d STP. RSTP just incorperates them. If you want to configure portfast, the command is still "spanning-tree portfast"
    OK
    1) That is your choice - I have bitter experiance of users/IT admins just plugging hubs/switches in when ever they can. Also cabling the switch back to itself creating a cabled loop. So my advice to you is to leave STP enabled on all switch ports, BUT enable BPDUGuard - this is a life saver, if you have configured portfast.
    2) duplex auto! or duplex full (overiding)
    I really suggest that you read the 802.1d standard, once you understand normal spanning-tree - RSTP will come to you.
    http://www.cisco.com/en/US/tech/tk389/tk621/tsd_technology_support_protocol_home.html')">http://www.cisco.com/en/US/tech/tk389/tk621/tsd_technology_support_protocol_home.html')">http://www.cisco.com/en/US/tech/tk389/tk621/tsd_technology_support_protocol_home.html')">http://www.cisco.com/en/US/tech/tk389/tk621/tsd_technology_support_protocol_home.html
    http://en.wikipedia.org/wiki/Spanning_tree_protocol')">http://en.wikipedia.org/wiki/Spanning_tree_protocol')">http://en.wikipedia.org/wiki/Spanning_tree_protocol')">http://en.wikipedia.org/wiki/Spanning_tree_protocol
    HTH>

  • CAN SOMEONE EXPLAIN ME THE DISPLAY QUALITY

    I have just purchased a new macbook pro 15" 2.4ghz. Im a designer, i havent even created my appleid, im on my sisters... i made a sacrifice to buy this $2700 laptop.
    and Im so dissapointed...
    I CANT SEE SMOOTH GRADIENTS.. all i see are ugly lines... i dont get it, for such a high class LAPTOP.
    Apple support please help me solve this. ive been reading forums about 6bit screens for this laptop.. i dont want to believe that. can someone explain? im returning this...

    I can verify that all of Apple's laptops use 18 bit (6 bits per Red, Green Blue) color, which is about 260,000 colors. The OS then using dithering to fake the missing colors. Despite what you have read, they are incapable of 24 bit 'millions of colors'.
    The problem with this argument is that, when it comes down to it, the color displays are made up of dithered red, green, and blue elements anyway. We accept that this form of display gives us "full color", so it's difficult to argue that millions of colors can't be represented using the same mechanism. It's not quite 16.7 million (more like 16.3 or something) but Apple's text has always taken care to read "millions of colors" rather than 16.7 million (which you'll still see on the specifications for the Cinema displays).
    Just for informational sakes though, these kinds of 6-bit displays don't rely on OS spatial dithering; they actually make use of their very fast switching to perform temporal dithering, switching a pixel between two shades very quickly to generate an in-between shade. That's why for most people the result is usually visually indistinguishable from true 8-bit color, and doesn't look like what you'd see with traditional dithering.
    If the OP is noticing severe banding on gradients, it's more likely to be an issue with color profiles than with the display being 6-bit.

  • I have downloaded ios 5.1.1 and the wifi has stop working or it would stay on for less then 20min its only 9 months old can someone explain what is happening and if some know how to fix it

    I have downloaded ios 5.1.1 and the wifi has stop working or it would stay on for less then 20min its only 9 months old can someone explain what is happening and if some know how to fix it

    I have taken it back to the Apple store genius bar, but they say they don't see anything wrong. Well unless you use it all day and experience the problems when they happen, you wont see anything wrong. But there are lots wrong with it. But this would be the same store as I purchased the phone. And they backed up my old Iphone 4, but were not able to get anything to load back onto my new phone. So, I lost pretty much everything. But over time, some of my contacts have started showing up, although i am still missing over 800 of them.

  • Can someone explain how data is fed to the usage details screen in My Verizon?

    Can someone explain to me how I can view my data usage for a past date today and when I look at the same date a few days from now there will be additional data. Customer support were adamant that the data usage details come directly from my device so I commented that my device must be saving usage and sending it to Verizon arbitrarily to which I was met with silence on the line.
    Here's an example - on 4/1 I checked my data usage details for the date of 3/21 and it looked like this:
    03/21/12
    08:43:00 PM
    0.02518
    03/21/12
    09:17:00 AM
    0.01475
    03/21/12
    07:20:00 AM
    0.01730
    then on 4/7 when I checked my data usage details for the date 3/21 it looked like this:
    03/21/12
    11:45:00 PM
    1.15382
    03/21/12
    11:38:00 PM
    0.24853
    03/21/12
    08:43:00 PM
    0.02518
    03/21/12
    07:50:00 PM
    1.03191
    03/21/12
    06:55:00 PM
    1.18499
    03/21/12
    06:10:00 PM
    1.03968
    03/21/12
    09:17:00 AM
    0.01475
    03/21/12
    07:20:00 AM
    0.01730
    The red rows have been added between 4/1 & 4/7, but where did they come from? This is just one example, it's happening all over my bill and Verizon cannot justify the anomaly and certainly won't consider removing the $40 in overage charges I have this month. Which brings up another question, why doesn't Verizon offer more than 10GB for the mifi? If I want to use more data and am willing to pay for it, I have to go to another provider?

    Hi kellieh,
    When you had your data overage (and the additional spurious charges), how did Verizon respond to you?
    I have just reported a 2x discrepancy between individual device data usage (.89 GB total) and the reported 1.5 GB for my account.  They claim it will take 72 hours to get back to me after they research the problem.
    What avenues did you pursue to make contact?
    I caled 611, then emailed tech support, then sent a private message to Verizon Wireless support.

  • Can someone explain how .prel files work?

    Can someone explain how .prel files work?  My C drive is O/S and programs, my D drive is storage and the project file(s) (the .prel file) are on my E drive. 
    How is this supposed to be more efficient/faster?  P.E. (C drive) has to constantly communicate back and forth across drives with the .prel file and all the files in the subfolders?  It seems like it would be slower. 
    As I mentioned in a previous post; my zooms in/out of the Timeline are VERY slow.  It is almost 1 second before the Timeline gets bigger/smaller.  Any info would be great,thanks!
    Elwood
    Windows 7 64 bit, i7 980x @333 6 core processor, 12 GB ram DDR 1600, Radeon 5850 GPU PE 9

    By using multiple HDD's, one is spreading the I/O (Input/Output) load over various HDD's. The controller is faster than a single HDD, being tasked to read/write from/to multiple places. One of the first laws of physics is that an object cannot be in more than one place, at the same time. The heads on a HDD are no different. If requests for multiple reads are made, the heads will position themselves over on place on the platters, read, and then move to the next requested location, and so on. However, with multiple HDD's, and a good, fast controller, the heads of each HDD will be placed, where necessary, so reads are done at once, from multiple locations.
    For ultimate performance, a good setup would be as follows:
    C:\ system OS and programs (more reading being done here, than writing)
    D:\ Project files (PREL's in this case)
    E:\ RAID 0 Scratch Disks for Media Cache, but not Render files (both reading and writing)
    F:\ RAID 0 Media files (more reading, but also writing)
    G:\ RAID 0 Export/Share and Render files
    Some go so far as to separate out Audio Assets from Video Assets, and use a separate RAID 0 for each
    The downside of that "ultimate performance" setup, is that when a Project is completed, to clean up, one has to go to many HDD's, and locations. There can also be issues when Archiving a Project, because things are scattered about.
    I get "good performance" by having my Project, Copies of my Assets and all Scratch Disks on one HDD. What I give up in performance, I make up for with housekeeping chores, when the Project is done. I still spread my OS/programs from my Projects, with separate physical HDD's.
    Good luck, and hope that this helps,
    Hunt
    PS - Above, I mention RAID 0, but even greater speed can be achieved via many HDD's in the Array, and perhaps a RAID 50. RAID 0 is just two physical HDD's. Also, for RAID, I recommend a dedicated RAID controller card, and NOT software, or the MoBo's RAID capability.

  • Can someone explain how to set up an administrator account so that I can have my phone and my daughters have separate apple ids?

    I mistakenly updated to the latest version of iOS and ever since then I can send messages to my daughter and I receive them but she does not.  She has an iphone also and her phone is under my apple id also.  Someone told me that I could set up an Administrator Account so that she can still be under my account but she has her own ID and that will fix the problem with text/imessages.  I can't find anything on the website that explains how to do that.  Can someone explain that to me?
    Thanks!

    I'm still not clear on what you are trying to accomplish. If you have an iPhone and she does as well you should have your own Apple IDs.
    If you want to pay for any purchases she makes with her phone as far as apps/music goes than that is what Family sharing is for.
    In my case my Wife and I are setup for family sharing. When she purchases music/apps it charges my credit card. This setup also allows me to share my past music/app purchases with her and vice versa.

  • I cannot find a way to sort the bookmark folders themselves alphabetically by name.I am not talking about in a view mode but in the way they are displayed when I click on my bookmarks tab. Can someone explain to me how to accomplish this.

    I have a lot of various book mark folders with websites contained within each folder. I am able to sort the websites within each folder alphabetically by name but I cannot find a way to sort the bookmark folders themselves alphabetically by name.I am not talking about in a view mode but in the way they are displayed when I click on my bookmarks tab. Can someone explain to me how to accomplish this other than manually dragging them as this is extremely hard for me due to the fact that I am a quadriplegic with limited hand movement dexterity

    Bookmark folders that you created are in the Bookmarks Menu folder. "Sort" that folder.
    http://kb.mozillazine.org/Sorting_bookmarks_alphabetically

  • Can someone explain me this?

    Can someone explain me why LabVIEW embeds the graphic in sheet 1 if i specify location as "prueba"? The vi is for LV 5.0.1f1 and Excel 2000, it just creates a workbook, adds some data and creates a chart. I've tried to ask a NI engineer but i receive no answer.
    Thanks,
    Gorka
    Attachments:
    Untitled.llb ‏430 KB

    Hi Gorka,
    I am not sure if this helps but the help file for the add Sheets method says
    "Add Method (Sheets Collection)
    Creates a new worksheet, chart, or macro sheet.
    Syntax
    expression.Add(Before, After, Count, Type)
    expression Required. An expression that returns a Sheets object.
    Before Optional Variant. An object that specifies the sheet before which the new sheet is added.
    After Optional Variant. An object that specifies the sheet after which the new sheet is added.
    Count Optional Variant. The number of sheets to be added. The default value is one.
    Type Optional Variant. Specifies the sheet type. Can be one of the following XlSheetType constants: xlWorksheet, xlChart, xlExcel4MacroSheet, or xlExcel4IntlMacroS
    heet. The default value is xlWorksheet.
    Remarks
    If Before and After are both omitted, the new sheet is inserted before the active sheet.
    *******" (I added asterisks for emphesis).
    the help for the "location method" says,
    "Add Method (Sheets Collection)
    Creates a new worksheet, chart, or macro sheet.
    Syntax
    expression.Add(Before, After, Count, Type)
    expression Required. An expression that returns a Sheets object.
    Before Optional Variant. An object that specifies the sheet before which the new sheet is added.
    After Optional Variant. An object that specifies the sheet after which the new sheet is added.
    Count Optional Variant. The number of sheets to be added. The default value is one.
    Type Optional Variant. Specifies the sheet type. Can be one of the following XlSheetType constants: xlWorksheet, xlChart, xlExcel4MacroSheet, or xlExcel4IntlMacroSheet. The default value is xlWorksheet.
    Remarks
    If Before and After
    are both omitted, the new sheet is inserted before the active sheet.
    Just trying to help,
    Ben
    Ben Rayner
    I am currently active on.. MainStream Preppers
    Rayner's Ridge is under construction

  • Can someone explain European use of 3G in a new iPad?

    Can someone explain European use of 3G in a new iPad? Will it work in Europe? I am concerned.
    Will the keyboard, charger, case, dock from iPad2 work with the new iPad?

    yeah everything apart from LTE(4G) and the charger itself (if you buy it USA) will work

  • Can someone explain the use of a hashtable in java?

    can someone explain the use of a hashtable in java?

    Hashtable allows us to store values along with keys.
    One other advantage is, it provides Synchronised methods.
    Hope you got it.

  • I am getting cross border fee charges on my credit card that I believe to be assessed against my monthly fee, can someone explain?

    I am getting cross border fee charges on my credit card that I believe to be assessed against my monthly fee, can someone explain?

    This is an open forum, not Adobe support... you need Adobe staff to help
    Adobe contact information - http://helpx.adobe.com/contact.html
    -Select your product and what you need help with
    -Click on the blue box "Still need help? Contact us"
    -or by telephone http://helpx.adobe.com/x-productkb/global/phone-support-orders.html

  • Can Someone Explain the order of things Using Swingworker?

    Hi:
    Can someone explain very clearly the order of things using Swingworker? Please do not refer the SUN tutorials. I am totally dead in the water with a very large application and the order of things is not sensible. Also, if the worker thread is too long, the GUI gets updated, but my progress bar (killed right after in the finished method) remains running in some instances only.
    Can someone explain any debugging methods for thread work?
    I am a veteran programmer of 19 years and this one's got me. The event dispatch thread returns immediate, the GUI responds well, but the progress bar setVisible(false); ... just after in the finished() method (on Event Dispatch thread) does not go away, continues running, only on very long (large query) work. I'm truly stumped. I have successful applications of the Swingworker use, the progress bar, and everything works fine. Not this one.
    Debugging threads is what I need. Or some tool that visually shows threads as the program runs.
    Thanks for any help,
    PiratePete

    Thanks. I guess I should count my blessings when using free stuff. But I have been impressed with what the J2SDK has to offer. I have been writing a complicated application that I am going to market and most of my problems have been "design" in nature.
    Thanks again,
    PiratePete

Maybe you are looking for