Hey Alef,
It's best to see this in action; in fact you should do some testing to help
solidify the information. The topology is simple:
R1---R2---R4
R1 and R2 are connected via there FA0/0 interfaces on the 150.100.12.0/24
subnet. R2 and R4 are connected over point-to-point frame relay serial
interfaces on the 150.100.24.0/24 network.
We will run EIGRP on all three routers using specific, less specific, and exact
network commands on R1 and R4, and then verify what get's advertised.
R1(config-if)#router eigrp 100
R1(config-router)#no auto-summary
R1(config-router)#network 150.100.12.0 0.0.0.255
R2(config-if)#router eigrp 100
R2(config-router)#no auto-summary
R2(config-router)#network 150.100.12.0 0.0.0.255
R2(config-router)#network 150.100.24.0 0.0.0.255
R4(config)#router eigrp 100
R4(config-router)#no auto-summary
R4(config-router)#network 150.100.24.0 0.0.0.255
At this point R4 should see the 150.100.12.0/24 network in it's routing table
R4(config-fr-dlci)#do sh ip ro ei
150.100.0.0/24 is subnetted, 2 subnets
D 150.100.12.0 [90/2172416] via 150.100.24.2, 00:00:09, Serial0/0.24
Now let's advertise this out from R1 using a /32 wildcard mask
R1(config-router)#router eigrp 100
R1(config-router)#no network 150.100.12.0 0.0.0.255
R1(config-router)#network 150.100.12.1 0.0.0.0
R2(config-fr-dlci)#router eigrp 100
R2(config-router)#no network 150.100.12.0 0.0.0.255
R2(config-router)#network 150.100.12.2 0.0.0.0
R4(config-fr-dlci)#do clear ip route *
R4(config-fr-dlci)#do sh ip route ei
150.100.0.0/24 is subnetted, 2 subnets
D 150.100.12.0 [90/2172416] via 150.100.24.2, 00:00:01, Serial0/0.24
Still the same with most specific... Now let's match "everything" and we will
check out what interfaces are participating!!
On R1 I have a bunch of networks and interfaces as you can see here
R1(config-router)#do sh ip int br
Interface IP-Address OK? Method Status
Protocol
FastEthernet0/0 150.100.12.1 YES manual up up
FastEthernet0/0.100 192.168.100.1 YES manual up up
FastEthernet0/0.200 192.168.200.1 YES manual up up
FastEthernet0/0.300 192.168.255.1 YES manual up up
FastEthernet0/1 unassigned YES manual up up
FastEthernet0/1.146 10.0.146.11 YES manual up up
FastEthernet0/1.1256 9.9.156.11 YES manual up up
Loopback0 1.1.1.1 YES manual up up
Let's advertise them all with on command
R1(config)#router eigrp 100
R1(config-router)#no network 150.100.12.1 0.0.0.0
R1(config-router)#network 0.0.0.0 0.0.0.0
All of these interfaces should be participating now and R4 should see of these
routes:
R1(config-router)#do sh ip ei inter
IP-EIGRP interfaces for process 100
Xmit Queue Mean Pacing Time Multicast Pending
Interface Peers Un/Reliable SRTT Un/Reliable Flow Timer Routes
Fa0/0 1 0/0 2 0/1 50 0
Fa0/0.100 0 0/0 0 0/1 0 0
Fa0/0.200 0 0/0 0 0/1 0 0
Fa0/0.300 0 0/0 0 0/1 0 0
Fa0/1.146 0 0/0 0 0/1 0 0
Fa0/1.1256 0 0/0 0 0/1 0 0
Lo0 0 0/0 0 0/1 0 0
R4(config-router)#do clear ip route *
R4(config-router)#do sh ip route ei
D 1.0.0.0/8 [90/2300416] via 150.100.24.2, 00:00:03, Serial0/0.24
D 192.168.200.0/24 [90/2174976] via 150.100.24.2, 00:00:03, Serial0/0.24
10.0.0.0/24 is subnetted, 2 subnets
D 10.0.146.0 [90/2174976] via 150.100.24.2, 00:00:03, Serial0/0.24
D 192.168.255.0/24 [90/2174976] via 150.100.24.2, 00:00:03, Serial0/0.24
D 192.168.100.0/24 [90/2174976] via 150.100.24.2, 00:00:03, Serial0/0.24
150.100.0.0/24 is subnetted, 2 subnets
D 150.100.12.0 [90/2172416] via 150.100.24.2, 00:00:03, Serial0/0.24
Test this in your lab when you have time! Remember we are just "matching"
interfaces here!
Thank you,
Steve Di Bias
Network Engineer - Information Systems
Valley Health System - Las Vegas
Office - 702- 369-7594
Cell - 702-241-1801
[email protected]
-----Original Message-----
From: Alef [mailto:[email protected]]
Sent: Friday, June 24, 2011 7:21 AM
To: Di Bias, Steve
Cc: [email protected] IE
Subject: Re: [OSL | CCIE_RS] vol1 27.2 why are the links in OSPF not advertised
as in EIGRP
Hey Steve,
I have to admit i never thought of it that way (that it matches the interface).
When i advertise a network for a link i always advertise the correct mask.
It's good to know but i will find it hard getting used to, i don't think i will
change that unless specifically told either.
But it's good to hear the explanation behind it though.
On Jun 24, 2011, at 2:51 PM, Di Bias, Steve wrote:
> Hey Alef,
>
> Your subject confuses me, however the message body seems to make more sense.
>
> The thing to remember about routing protocols like EIGRP and OSPF is that
> when using your network statements you can be as vague, or as specific as you
> want to be. Remember, you're using the network command to "match" the
> interfaces you want to participate in the routing protocols which are smart
> enough to see the "actual" IP address and mask and that's what gets
> advertised out.
>
> In the real world do what you're told to do, however in the real world I use
> "exact" wildcard masks when advertising, but it's up to you.
>
>
>
> Thank you,
>
> Steve E. Di Bias
> Network Engineer - Information Systems
> Valley Health System - Las Vegas
> Office - 702- 369-7594
> Cell - 702-241-1801
> [email protected]
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of Alef
> Sent: Friday, June 24, 2011 3:37 AM
> To: [email protected] IE
> Subject: [OSL | CCIE_RS] vol1 27.2 why are the links in OSPF not advertised
> as in EIGRP
>
> In this task, the the assignment seems the same (apart from the configure the
> network statements to include the network mask) but the link is advertised as:
>
> network 150.50.25.2
>
> and not as 150.50.25.0 0.0.0.3 or 0.0.0.1
>
> in 27.1 eigrp does advertise as a /30, 0.0.0.3
>
> is it not best practice to always advertise the networks into any routing
> protocol properly ?
>
> Alef
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