RE: Lists and Maps

Jared,

I thought I would add an order of operations to that as well, at least for filtering, taken from the BGP FAQs.

http://www.cisco.com/en/US/tech/tk365/technologies_q_and_a_item09186a00800949e8.shtml#one

A. The order of preference varies based on whether the attributes are applied for inbound updates or outbound updates.

For inbound updates the order of preference is:

   1.

      route-map
   2.

      filter-list
   3.

      prefix-list, distribute-list

For outbound updates the order of preference is:

   1.

      prefix-list, distribute-list
   2.

      filter-list
   3.

      route-map

Note: The attributes prefix-list and distribute-list are mutually exclusive, and only one command (neighbor prefix-list or neighbor distribute-list) can be applied to each inbound or outbound direction for a particular neighbor.

-ryan

-----Original Message-----
From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of Jared Scrivener
Sent: Wednesday, May 13, 2009 11:23 PM
To: 'kevin dalby'; 'Cisco certification'
Subject: RE: Lists and Maps

My answer is inline below. If there are any errors please let me know.
Imprecision is not acceptable to me for myself. I think I just wrote half
the R&S self-study notes inadvertently for free here...

Oh, one of my students taught me that if you are Cisco, RFP's come in. For
example, with BGP inbound updates we process Route-map, Filter-lists,
Prefix-lists then distribute lists in that order. Outbound is the opposite.

Cheers,
 
Jared Scrivener CCIE3 #16983 (R&S, Security, SP), CISSP
Sr. Technical Instructor - IPexpert, Inc.
URL: http://www.IPexpert.com
Telephone: +1.810.326.1444
Fax: +1.810.454.0130
Mailto: jscrivener_at_ipexpert.com

-----Original Message-----
From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
kevin dalby
Sent: Wednesday, 13 May 2009 10:58 PM
To: Cisco certification
Subject: Lists and Maps

Hi Experts,

I have a question about all the lists & maps. How do you keep them all
straight? I get confused on what to use when.

   1. distribute-list: filter routing updates for Distance Vector routing
protocols and BGP using an ACL. Filter updates from the OSPF database into
the routing table.
   2. prefix-list: filter routing updates for BGP to neighbors or in a
route-map using a prefix-list. Filter OSPF announcements on an ABR into an
area.
   3. filter-list: filter BGP updates between neighbors or in a route-map.
   4. access-list: where do I begin? I'll leave that one for you someone
else to explain as I don't have the time. :)
   5. as-path access-list: Same thing as number 3.
   6. offset list: Adds to the metric of Distance Vector protocols.
   7. advertise-list: conditional bgp routing - was that a question or an
answer? It's correct.
   8. MQC: class map, policy map, service policy - classify types of
traffic, do something to the traffic, apply the policy
   9. route-map: Used as input in a number of different functions. Broken
into statements that either permit or deny themselves to be processed. Each
statement matches traffic (explicitly or all if not specified) and can then
optionally set a parameter.
   10. table-map: modifies BGP update information prior to copying it to the
appropriate RIB depending on address family (that's how it works for IPv4
and should be designed for other protocols if it is not already)
   11. advertise map: Advertises a specific network based on a conditional
statement being true.
   12. unsuppress map: Takes a BGP update that is already suppressed
generally to all neighbors due to an aggregate-address and then allows it to
be sent to particular neighbors.

Thanks in advance

Blogs and organic groups at http://www.ccie.net
Received on Thu May 14 2009 - 11:02:51 ART