Interior Gateway Routing – 27 Points
4.1 Bridging
“Disable ip routing on r6″
r6(config)#no ip routing
“Bridge IP between the Frame Relay and Ethernet segments on r6″
That explains why fa0/0 does not have an IP address configured. 
After this task, I can finally ping bb1:
r6#p 54.1.10.254
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 54.1.10.254, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 100/286/1032 ms
4.2 Bridging
This task confused the crap out of me. My bridging skills are pretty poor.
“Configure the IP address of 54.1.10.6/24 on r6.”
Ummmm….that’s already configured as the IP address of the Frame connection to bb1. I guess that we’re going to use the same IP address for fa0/0 as well.
“r6 should have reachability to any address of the 54.1.10.0/24 subnet.”
“Don’t use IRB for this task.”
No IRB. CRB? Actually, the IE solution doesn’t use IRB or CRB. The last two subtasks are basically red herrings. I will need to review bridging.
r6#sh bridge 1 group
Bridge Group 1 is running the IEEE compatible Spanning Tree protocol
Port 4 (FastEthernet0/0) of bridge group 1 is forwarding
Port 11 (Serial0/0.1 Frame Relay) of bridge group 1 is forwarding
r6#sh ip int br | i 54.1.10.6
FastEthernet0/0 54.1.10.6 YES manual up up
Serial0/0.1 54.1.10.6 YES manual up up
r6#p 54.1.10.254
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 54.1.10.254, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 48/89/100 ms
r6#p 54.1.10.100
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 54.1.10.100, timeout is 2 seconds:
…..
Success rate is 0 percent (0/5)
I can’t ping r4 but I can ping bb1. This poster has the opposite problem:
Task 4.2 can not ping 54.1.10.254
r6#sh cdp neigh
Capability Codes: R – Router, T – Trans Bridge, B – Source Route Bridge
S – Switch, H – Host, I – IGMP, r – Repeater
Device ID Local Intrfce Holdtme Capability Platform Port ID
BB1 Ser 0/0.1 147 R T S I 2821 Ser 0/0/0:0.401
sw2 Fas 0/0 174 S I WS-C3560- Fas 0/6
r6#
sw2#sh run int fa0/6
interface FastEthernet0/6 <-that’s a minimal configuration
end
How did I miss this????? Because the port on r6 was initially shut down so I didn’t see it with “show cdp neighbor” on sw2. Arrgh!!! I need vlan 46 assigned to this port.
sw2(config)#int fa0/6
sw2(config-if)#swit acc vl 46
r6#p 54.1.10.100
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 54.1.10.100, timeout is 2 seconds:
!!!!!
I guess that I can take solace in the fact that I was able to find my mistake. I just barely missed going down a deep rabbit hole chasing bridging options.
4.3 RIPv2
I initially thought that there was an error in the IE lab because although r6 was shown as running RIP on the protocol diagram, there was no mention of r6 in the task. That’s because r6 is bridging the 54.1.10.0/24 network. I turned off ip routing in task 4.1 so I wouldn’t be able to configure RIP on r6:
r6(config)#router rip
IP routing not enabled
This means that we should be able to see the routes from bb1(54.1.10.254) on r4:
r4#sh ip route rip | i 54.1.10.254
R 212.18.1.0/24 [120/1] via 54.1.10.254, 00:00:12, FastEthernet0/0
R 212.18.0.0/24 [120/1] via 54.1.10.254, 00:00:12, FastEthernet0/0
R 212.18.3.0/24 [120/1] via 54.1.10.254, 00:00:12, FastEthernet0/0
R 212.18.2.0/24 [120/1] via 54.1.10.254, 00:00:12, FastEthernet0/0
4.4 Network Redundancy
backup interface
Hmmmm….this is the reason for the point-to-point subinterface on r4 back in task 3.2
r4#sh ip int br | i Serial
Serial0/0 unassigned YES NVRAM up up
Serial0/0.1 unassigned YES unset up up
Serial0/1 152.1.54.4 YES NVRAM standby mode down
r4#sh backup
Primary Interface Secondary Interface Status
—————– ——————- ——
Serial0/0.1 Serial0/1 normal operation
4.5 EIGRP
Basic.
4.6 OSPF
“Use the OSPF network type that was specifically designed to handle issues with routers on the same logical IP subnet not having direct communication with each other.”
Remember that we have a multipoint subinterface on the hub (r3) and point-to-point subinterfaces on the hubs (r1 and r2). The task calls for the point-to-multipoint OSPF network type.
r3#sh ip os nei
Neighbor ID Pri State Dead Time Address Interface
150.1.2.2 0 FULL/ - 00:01:49 152.1.123.2 Serial0/0:0.1
150.1.1.1 0 FULL/ - 00:01:54 152.1.123.1 Serial0/0:0.1
r3#sh ip route os
152.1.0.0/16 is variably subnetted, 5 subnets, 2 masks
O 152.1.123.2/32 [110/65] via 152.1.123.2, 00:00:07, Serial0/0:0.1
O 152.1.123.1/32 [110/65] via 152.1.123.1, 00:00:07, Serial0/0:0.1
4.7 OSPF
Basic
4.8 OSPF
In this task you need to advertise the loopbacks on r1 and r2 into area 0. But r1 and r2 are not in area 0. Time for a couple of virtual circuits.
4.9 OSPF Loopback Advertisement
“Advertise the Loopback0 networks of r3 and sw1 into OSPF.”
“These networks should appear in each other routing tables as intra-area routes.”
Since I’m not told which area to advertise the loopbacks into, can’t I just make this simple by advertising both loopbacks into area 37? Answer: YES!
sw1#sh ip route | i 150.1.3.
O 150.1.3.3/32 [110/2] via 152.1.37.3, 00:00:37, Vlan37
r3#sh ip route | i 150.1.7.
O 150.1.7.7/32 [110/2] via 152.1.37.7, 00:00:00, FastEthernet0/0
4.10 IGP Redistribution
Four points of mutual redistribution. Ugh. The first two points are no worry (discontiguous RIP). The other two are dangerous though. I’ll work on those in task 4.11
4.11 Redistribution Loop Prevention
“Ensure that EIGRP extenal routes that are redistributed into OSPF on r1 and r2 do not get redistributed back into EIGRP.”
“Use AD to accomplish this.”
Here is a (simplified) view of the the two network redistribution points on r1 and r2:
————(D)r1(O)———–
r4(R<->D)—r5(D) (O)r3—(O<->R)sw1
————(D)r2(O)———–
If we do mutual redistribution between EIGRP and OSPF on r1 and r2 we’re going to have problems with D EX routes (AD of 170) being reflected back into the EIGRP domain. We’re given the method for preventing this.
I missed an issue on sw1 though:
Task 4.11 Redist Loop Prevention
You need to change the RIP distance or SW1 sees the routes learnt from BB3 as OSPF external routes which it uses over the correct RIP routes. if you check the routing table on SW1, the next hop for all the BB3 subnets is R3. This is resolved by changing the AD [router rip - distance 109].
