On Demand Routing (ODR)

• Applicable in a hub-and-spoke topology only.
• Uses Cisco Discovery Protocol (CDP)
  • Sent as multicast
  • Sent every 60 seconds by default
    • cdp timer adjusts the timer.
  • Enabled by default.
  • Except ATM where CDP must be explicitly enabled.
• Configured on hub router
  • router odr global configuration command.
• Stub router can’t have an IP routing protocol. In fact, no IP routing protocol is considered a stub by ODR.
• WAN links such as dialer links and Frame Relay, use broadcast keyword in mapping statements.

Example:

autostart = False
ghostios = true
sparsemem = true

[localhost]

    [[7200]]
        image = C7200.BIN
        # On Linux / Unix use forward slashes:
        # image = /opt/7200-images/c7200-jk9o3s-mz.124-7a.image
        npe = npe-400
        ram = 160

    [[ROUTER A]]
        S1/0 = B s1/0
        model = 7200
        console = 2001
        idlepc = 0x6082d7a0

    [[router B]]
        s1/1 = C s1/0
        s1/2 = D s1/0
        model = 7200
        console = 2002
        idlepc = 0x607016a0

    [[router C]]
        model = 7200
        console = 2003
        idlepc = 0x607016a0

    [[router D]]
        model = 7200
        console = 2004
        idlepc = 0x607016a0

Here’s the configs:

Router B (Hub Router):

interface Loopback0
 ip address 10.4.1.1 255.255.255.255
!
interface Serial1/0
 ip address 10.1.1.1 255.255.255.252
 serial restart-delay 0
!
interface Serial1/1
 ip address 10.2.2.1 255.255.255.252
 serial restart-delay 0
!
interface Serial1/2
 ip address 10.3.3.1 255.255.255.252
 serial restart-delay 0

Router A:

interface Loopback0
 ip address 172.16.1.1 255.255.255.0
!
interface Serial1/0
 ip address 10.1.1.2 255.255.255.252
 serial restart-delay 0

Router C:

interface Loopback0
 ip address 172.16.2.1 255.255.255.0
!
interface Serial1/0
 ip address 10.2.2.2 255.255.255.252
 serial restart-delay 0
!

Router D:

interface Loopback0
 ip address 172.16.3.1 255.255.255.0
!
interface Serial1/0
 ip address 10.3.3.2 255.255.255.252
 serial restart-delay 0
!

• As soon as ODR is configured and running, routes from the stub routers are identified in the hub router’s routing table with an o character (shown below)
• Notice in the example that the metric is 1, and the administrative distance for ODR is 160.
• Also, do not confuse the o character of ODR routes with the O character of OSPF routes.

B#sh ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

     172.16.0.0/24 is subnetted, 3 subnets
o       172.16.1.0 [160/1] via 10.1.1.2, 00:00:56, Serial1/0
o       172.16.2.0 [160/1] via 10.2.2.2, 00:00:54, Serial1/1
o       172.16.3.0 [160/1] via 10.3.3.2, 00:00:55, Serial1/2
     10.0.0.0/8 is variably subnetted, 4 subnets, 2 masks
C       10.3.3.0/30 is directly connected, Serial1/2
C       10.2.2.0/30 is directly connected, Serial1/1
C       10.1.1.0/30 is directly connected, Serial1/0
C       10.4.1.1/32 is directly connected, Loopback0

I have just started going back at the beginning of the BSCI study guide to start the exam preparation. I plan on taking the exam by mid-March and hoping that I can get myself ready by then. I’ve been trying to find ways to stimulate my learning and help my memory retention for details that can only be done by rote memorization. I think I’ve pretty much improved my understanding of the concepts. It’s the minute details that I struggle with; for example, remembering the admin distance of all the routing protocols, or remembering all the OSPF LSA types. Hmmm… come to think of it, I do remember LSA types better than I thought after I wrote the last sentence .

After reading Greg Ferro’s tips on study methods yesterday, I was motivated to follow some of his suggestions. Last night I spent a good two and a half hours of solid studying – no TVs, no music, no IMs, no Internet (except when I had to look up things on the Doc pages). It worked for that time. Hopefully I can keep up this type of intensity for the next month.   In fact, in addition to the no-ADD-inducing-activites he mentioned, I even used a stopwatch to time my study sessions. I’ve done it before and even wrote about it in my previous posts. The challenge is to consistently improve on those study skills. I’m also considering picking up one of the iPod flahscard apps, similar to the one he mentioned on his post.

For the remaining of this week, I plan to get through the static routing and RIP portion of the materials and hopefully get started on EIGRP on the weekend. I’ve already finished my third time reading throught chapter 2 (with notes). I’ll hopefully be able to get through a couple of nights of labbing – or maybe one, since I have the impression that this part is not covered as deeply on the exam compared to the other protocols. I may also decide to create a high-level overview of my study schedule that I can follow – and also post on my BSCI study schedule page, which I regretfully neglected. Why? It turns my BSCI study schedule page is the most visited page on my site – 300 hits on that one page for the last 2 months. And regretfully it has been my most negelected. I’ve actually received many emails (ok, just two) asking me to update it. Sorry guys if I was such a disappointment.

Anyway, anybody have experience with Boson test engines vs Transcender for CCNP? I’m considering getting one of those.