We're Sorry, Full Content Access is for Members Only...

If you like to keep on reading, Become a Member Now! Here is Why:

  • Learn any CCNA, CCNP and CCIE R&S Topic. Explained As Simple As Possible.
  • Try for Just $1. The Best Dollar You've Ever Spent on Your Cisco Career!
  • Full Access to our 557 Lessons. More Lessons Added Every Week!
  • Content created by Rene Molenaar (CCIE #41726)

 

317 New Members signed up the last 30 days!

satisfaction-guaranteed

100% Satisfaction Guaranteed!
You may cancel your monthly membership at any time.
No Questions Asked!

Tags:


Notable Replies

  1. Hey Rene,

    I have found one of Swisscom BGP router from that expressions:

    AS path access list 1
        permit ^$
        permit 650[0-9][0-9][)]$

    permit ^$ : I think this one is written for locally originating routes

    I can't get a meaning the last one's " [)] "section ? You have an idea?
    By the way ; these ip as-path access lists , bgp filtering commands just filtering the AS's that advertising from another BGP routers right?

    Deniz

  2. Hi Deniz,

    The first entry will match on prefixes that originated in this AS. The second one will match on everything that ends with 650XX). Anything in the 64512 – 65535 range are private AS numbers. The [)] is a bit strange, normally you use the [] for a range (like 0-9). I'm guessing that they use it to match on sub-AS numbers in a confederation? That's the only time you will see a ) in the AS path:

    https://networklessons.com/bgp/bgp-confederation-explained/

    Rene

  3. Hi Rene,
    Just looked at BGP looking glass server. How can one practice regular expression on this site? Thanks!
    A.

  4. Hi A,

    Most of the looking glass servers support regular expressions so that would be the best option to get some practice. If you want to practice this "locally" then I would configure some BGP routers and use route-maps for things like AS path prepending, this can be used as a nice simulation of the Internet.

    Rene

Continue the discussion forum.networklessons.com

Participants