CCNA Video Training Series

Instant Access, Web or Mobile!

Only $99 for 30 days...
Renew at half price!

Buy/Renew

Includes FREE Practice Exams!

Member Login

Lost your password?

Not a member yet? Sign Up!

Official Lammle User Forum

Results 1 to 4 of 4
  1. #1
    Join Date
    Sep 2011
    Posts
    1

    Default When does the Route Flush Timer start?

    Hello,

    It is not totally clear when the (RIP) Route Flush Timer starts.
    Is it after the route becomes invalid (so after the Route Invalid Timer times out)?
    Or is it when a route update is received (so when also the Route Invalid Timer starts)?

    In my book (CCNA, version 5) it seems to say that it starts when the route becomes invalid, but it also says that the value of the Route Invalid Timer must be less than that of the Route Flush Timer.
    That seems to contradict each other.

    Thanks in advance for your answer.

    Regards, Wim.

  2. #2
    Join Date
    Dec 2010
    Location
    Left Coast, California
    Posts
    306

    Default

    Quote Originally Posted by wim4 View Post
    Hello,

    It is not totally clear when the (RIP) Route Flush Timer starts.
    Is it after the route becomes invalid (so after the Route Invalid Timer times out)?
    Or is it when a route update is received (so when also the Route Invalid Timer starts)?

    In my book (CCNA, version 5) it seems to say that it starts when the route becomes invalid, but it also says that the value of the Route Invalid Timer must be less than that of the Route Flush Timer.
    That seems to contradict each other.

    Thanks in advance for your answer.

    Regards, Wim.
    The flush time deletes the dead route from the routing table at 240 secs (default), which is 60 seconds longer than the invalid timer.

    After the invalid time expires, rip needs time to advertise the down route -- thats why they say not to make the flush time LESS than the 180 sec invalid time -- otherwise there would be no time for rip to advertise the down route.

    Timers are tweakable (not recommended!!) so the point is, leave time for the router to advertise the down route before it flushes it.
    Last edited by ciscodaze; 01-02-2012 at 06:20 PM.
    Kevin NET+SEC+A+CCNA
    'All that is not eternal is eternally out of date' ~ C.S. Lewis

  3. #3
    Join Date
    Dec 2010
    Location
    Left Coast, California
    Posts
    306

    Default

    William, I should also add you are walking on some spooky ground here, as the holddown timer is not part of the RFC specification for rip, so searching for info on it in RFC wont yeild results (I did find one RFC about extensions that mentions holdtime, but not much help) . This has lead to a lot of confusion between the cisco implementation of the holddown time, and the invalid timer.

    I would explain it in 2 easy sentences if I could, but I can't. Maybe someone else can clarify.

    For the exam, just memorize whats in whatever book you are using and you will be fine. Otherwise, do some googling around, it will be a good learning experience.

    Then come back and tell us what you learned.
    Last edited by ciscodaze; 01-02-2012 at 10:28 PM. Reason: \
    Kevin NET+SEC+A+CCNA
    'All that is not eternal is eternally out of date' ~ C.S. Lewis

  4. #4
    Join Date
    Dec 2010
    Location
    Left Coast, California
    Posts
    306

    Default

    William, heres a good link to check out at the learning center, regarding rip timers.

    If 3 heavy-hitter CCIE dudes need to hash out how the hell rip timers work, dont feel bad that you dont get it all right now!

    https://learningnetwork.cisco.com/thread/20422
    Last edited by ciscodaze; 01-02-2012 at 11:21 PM.
    Kevin NET+SEC+A+CCNA
    'All that is not eternal is eternally out of date' ~ C.S. Lewis

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Pg. 392 - RIP Timers: confusion over Route Flush time
    By viprocon in forum Chapter 8: IP Routing
    Replies: 4
    Last Post: 01-19-2013, 10:16 AM
  2. Holddown Timer
    By nemiath in forum Chapter 8: IP Routing
    Replies: 4
    Last Post: 11-14-2011, 08:06 AM
  3. When to start labbing?
    By mid4 in forum CCNA Equipment
    Replies: 7
    Last Post: 06-16-2011, 08:25 PM
  4. Where to start?
    By lukeman3000 in forum General Questions (Any Chapter)
    Replies: 4
    Last Post: 07-07-2010, 11:55 AM
  5. Holddown Timer Question
    By typesh in forum Routing
    Replies: 4
    Last Post: 12-21-2009, 08:45 AM

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •