From: Scott Morris (smorris@ipexpert.com)
Date: Thu Oct 25 2007 - 02:15:10 ART
If you have multiple routers redistributing the same routes adding the
device number to the tag may be a necessary thing, but in a simpler rule
does it help any? (e.g. personal choice) :)
Let's not make things more thought provoking than necessary. In my
experience watching people use tags and working through redistribution
problems, it's easier for them to remember AD values as that has more likely
been ingrained in their brains for years thereby reducing the thought
processes needed to come up with tags or watch things happen.
Both obviously work perfectly fine, I simply look at it for simplicity.
The tag for connected is an interesting idea.... I'd never thought of that,
but likely because I never worried about a routing look with connected
interfaces before. But an interesting idea!
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE-M
#153, JNCIS-ER, CISSP, et al.
CCSI/JNCI-M/JNCI-ER
VP - Technical Training - IPexpert, Inc.
IPexpert Sr. Technical Instructor
A Cisco Learning Partner - We Accept Learning Credits!
smorris@ipexpert.com
Telephone: +1.810.326.1444
Fax: +1.810.454.0130
http://www.ipexpert.com
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Brian Dennis
Sent: Wednesday, October 24, 2007 11:46 PM
To: Scott Vermillion
Cc: 'Herbert Maosa'; 'Joseph Brunner'; 'Jeffrey Biggs';
ccielab@groupstudy.com
Subject: Re: Redistribution with route tags are KILLING ME!!!`
If you are going to tag use the device number plus the administrative
distance of the routes being redistributed (i.e. R2 OSPF = 2110 or R6
connected = 60).
Also we have a free route redistribution vseminar on November 14th that's
open to everyone. We'll limit this vseminar to only 300 people so sign up
early if you are interested as the last one on Catalyst QoS pushed the
limits of the vseminar software ;-)
--Brian Dennis, CCIE4 #2210 (R&S/ISP-Dial/Security/SP) bdennis@internetworkexpert.com
Internetwork Expert, Inc. http://www.InternetworkExpert.com Toll Free: 877-224-8987 Direct: 775-852-3995 (Outside the US and Canada)
Scott Vermillion wrote: > I don't know, I thought Scott Morris's idea of tagging all routes with their > "native" AD was quite brilliant. Sure makes things easy to keep straight > (although I confess I haven't done too much in the way of redistribution > labs at this juncture in my studies, so I'm certainly no expert on the > subject). > > -----Original Message----- > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of > Herbert Maosa > Sent: Wednesday, October 24, 2007 4:37 PM > To: Joseph Brunner > Cc: Jeffrey Biggs; ccielab@groupstudy.com > Subject: Re: Redistribution with route tags are KILLING ME!!!` > > Actually, I use route-tags in two cases > > - one of the protocols is already carrying external routes from > elsewhere > - one of the protocols is RIP, which has no concept of External routes > > Except for these two cases, so far I successfullly implement loop free > redistribution by matching internal routes ( in the case of OSPF ) or > matching route-type Internal ( for the case of EIGRP ). > > I think the use of route-tags is generally overused, perhaps overtrained, so > much so that you end up using it on every redistribution scenario without > understanding what you are trying to accomplish. Could waste quite a lot of > time at the best, and you could get it all wrong at the worst ! > > . > Herbert. > > On 10/24/07, Joseph Brunner <joe@affirmedsystems.com> wrote: >> Wait slow down... >> >> You only NEED to use redistribution with route-tags when you have more >> than >> 1 router doing mutual route re-distribution. We use the tags to block >> route >> feedback. That is, if a route has been redistributed already at either >> router it wont be re-redistributed back to the source protocol at the >> other >> router. >> >> Here is an example... R3 and R4 are redistributing between EIGRP & OSPF. >> To >> prevent a loop we don't allow route feedback from a protocol back into a >> protocol. Anything going from OSPF to EIGRP, and EIGRP to OSPF is tagged >> and >> the redistribution at other router denies routes with that tag before >> redistribution. The tags allow us to know WHERE that route originally came >> from. >> >> Here is the topology >> >> R1---OSPF--- R3--- EIGRP-AS-10--- R5 >> | | >> R2---OSPF--- R4--- EIGRP-AS-10--- R6 >> >> >> R3&R4 >> >> Router ospf 1 >> Redis eigrp 10 subnets route-map watch-tag >> >> Router eigrp 10 >> Redistribute ospf 1 route-map watch-tag metric 1500 100 255 1 1500 >> >> Route-map watch-tag deny 5 >> Match tag 5 >> Route-map watch-tag permit 10 >> Set tag 5 >> >> >> Try it with my topology in your dynamips... >> >> >> -----Original Message----- >> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of >> Jeffrey Biggs >> Sent: Wednesday, October 24, 2007 4:48 PM >> To: ccielab@groupstudy.com >> Subject: Redistribution with route tags are KILLING ME!!!` >> >> I have been trying to grasp the use of redistribution using only route >> tags, >> but I just keep getting killed by it. I can redistribute using >> prefix-lists >> and ACL's all day long, but I know I am going to see something where I >> need >> to "make sure all IP's are fully reachable without the use of >> ACL's/Prefix-lists" and I am going go down in flames..Is there someone out >> there that has a solution that can help me??????? I have used NMC and >> IPEXPERT (BOTH VERY GOOD TOOLS, NOT KNOCKING ANY OTHERS) but my brain is >> just not grasping the concept. >> >> >> >> HELP!!!!!!! >> >> >> >> Thanks >> JB >> >> _______________________________________________________________________ >> Subscription information may be found at: >> http://www.groupstudy.com/list/CCIELab.html >> >> _______________________________________________________________________ >> Subscription information may be found at: >> http://www.groupstudy.com/list/CCIELab.html > > _______________________________________________________________________ > Subscription information may be found at: > http://www.groupstudy.com/list/CCIELab.html > > _______________________________________________________________________ > Subscription information may be found at: > http://www.groupstudy.com/list/CCIELab.html
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