I also tend to go the route-tag route.
I've also starting drawing out redistribution diagrams that show the routing
domains and AD for each router, it helps identify problem areas.

Cheers,
Donald Robb

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Di Bias, Steve
Sent: November-29-11 2:01 PM
To: Jay McMickle; IPExpert Online
Cc: Chris Moore (CCIE Vegas)
Subject: Re: [OSL | CCIE_RS] Redistribution tagging?

I use a combination of tags as well as modification of AD values myself.
Typically I use the AD value of the routing plrotocol as the tag itself. In
other words RIP is tagged as 120, EIGRP as 90, etc. There are times when
tagging alone may not be enough or could lead to suboptimal routing. In
these cases manipulating the AD values is the way to go.

Happy labbing lads!

Sent from G2

Jay McMickle <[email protected]> wrote:



Does anyone else use tags when redistributing from one protocol to the next
(for the Lab only)?

For instance, I'm learing routes from R4 that get redistributed from RIP
into OSPF on R5.  There are 2 Frame-Relay peers: R2 and R6.  R2 is
redistributing from OSPF to RIP, and R6 is redistributing from OSPF to
EIGRP.  Each redistribution is done mutually.

This is IPX V3 Lab1, in case it looks familiar.

       R2
       /\
      /  \
    R5  R6
   /      ||
 R4     R9

Summary-
When redistributing on a router, say R5 (RIP to OSPF), I use a route-map on
the redistribution point and set a tag.  This way, I know what protocol and
router it originated from. (I remove the non-essential commands here to make
this as clear as possible)


R5
---
router ospf 1
 redistribute rip subnets route-map RtoO  network 5.5.5.5 0.0.0.0 area 0
network 141.41.26.5 0.0.0.0 area 256 !
router rip
 version 2
 redistribute ospf 1 metric 1 route-map OtoR  network 141.141.0.0  no
auto-summary !
route-map RtoO permit 10
 set tag 5120
!
route-map OtoR permit 10
 set tag 5110
!
My result is this;  I can see that it was redistributed on R5, and was
originally RIP.  Even if this was 6 routers and 4 protocols later, I could
trace them out to eventually see that it was R5 and RIP.  Reverse
Engineering the routes on R9, the route shows in EIGRP as coming from R6
(redist via OSPF), then from R5 (redist via RIP), and originating from R4
(RIP).

R9#sh ip route 172.20.42.2
Routing entry for 172.20.42.2/32
  Known via "eigrp 679", distance 170, metric 2560512256
  Tag 6110, type external
  Redistributing via eigrp 679
  Last update from 141.41.69.6 on Serial0/0/0, 00:18:47 ago
  Routing Descriptor Blocks:
  * 141.41.69.6, from 141.41.69.6, 00:18:47 ago, via Serial0/0/0
      Route metric is 2560512256, traffic share count is 1
      Total delay is 20010 microseconds, minimum bandwidth is 1 Kbit
      Reliability 1/255, minimum MTU 1 bytes
      Loading 1/255, Hops 1
      Route tag 6110

R6#sh ip route 172.20.42.2
Routing entry for 172.20.42.2/32
  Known via "ospf 1", distance 110, metric 20
  Tag 5120, type extern 2, forward metric 65
  Redistributing via eigrp 679
  Advertised by eigrp 679 metric 1 1 1 1 1 route-map OtoE
  Last update from 141.41.26.5 on Serial0/0/0, 00:22:24 ago
  Routing Descriptor Blocks:
  * 141.41.26.5, from 5.5.5.5, 00:22:24 ago, via Serial0/0/0
      Route metric is 20, traffic share count is 1
      Route tag 5120

R5(config)#do sh ip route 172.20.42.2
Routing entry for 172.20.42.2/32
  Known via "rip", distance 105, metric 2
  Redistributing via ospf 1, rip
  Advertised by ospf 1 subnets route-map RtoO
  Last update from 141.141.45.4 on Virtual-Access1, 00:00:12 ago
  Routing Descriptor Blocks:
  * 141.141.45.4, from 141.141.45.4, 00:00:12 ago, via Virtual-Access1
      Route metric is 2, traffic share count is 1 (no tag)

Regards,
Jay McMickle- CCNP, CCSP, CCDP, MCSE
http://mycciepursuit.wordpress.com/

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