As i’ve been going though my mock CCIE labs, I’ve had to modify the initial configs before beginning each lab. The main problem i have is my routers are ISR’s and thus have the #/#/# format for modules vs the older #/# format. I was searching for an easy way to modify all of the initial configs prior to starting each lab. I ended up solving my problem with notepad++ and regex.

Notepad++ allows you to open multiple files at the same time in separate tabs. Notepad++ then allows you to do a find/replace across all OPEN documents using regex.

I first opened all my initial router configs in notepad++ and used the following settings below. Make sure regex is checked and you press replace all in all open documents.

The [0-9] = any number from 0-9. (E.G. Serial0/0 Serial0/1)

The Replace string uses a \1 which is replaced with the first Parentheses value from the find string above.

notepad++ can be found at http://notepad-plus.sourceforge.net/uk/site.htm

For stub areas, a default route is not propogated by default. You must explicetely tell the ABR to send the default route into the NSSA area.

router ospf 1
area nssa default-information-originate

The above output will generate NSSA Type-2 external default route (LSA type-7).
The metric type for the default route above can be changed to a Type 1 with the metric command.

router ospf 1 area
nssa default-information-originate metric-type 1

If the area is set to NSSA totally stuby area. An Inter-area default route will be created on the ABR and sent to the NSSA totally stubby area.

router ospf 1 area
nssa default-information-originate no-summary

I ran in to an issue where connectivity would drop randomly for around 1 minute. Sometimes this would happen multiple times a day. Other days would have no issues. To help facilitate troubleshooting of the issue, i created an ip sla session to span the path that tracks the last 25 failures.

ip sla 1
icmp-echo 10.1.1.1 source-ip 10.1.1.2
threshold 500
frequency 10
history filter failures
history buckets-kept 25
history lives-kept 1
ip sla schedule 1 life forever start-time now

I was using a tcl script with the IEWB to test connectivity. The extra data included with the pings made it difficult to check the connectivity. I found the below code that will ping multiple devices and output the results in a clean format with either (OK, FAILED)


tclsh
proc ping { IP } {
set PING [ exec "ping $IP repeat 3" ]
set PING [ regexp -inline -all {[\.!]{3}} $PING ]
if { [ string first "!" $PING ] == -1 } {
puts "[format "%-40s %s" "ping $IP" "\[FAILED\]" ]"
} else {
puts "[format "%-40s %s" "ping $IP" "\[ OK \]" ]"
}
}

foreach address {
155.1.146.1
155.1.146.4
155.1.146.6
155.1.67.6
155.1.67.7
155.1.79.7
155.1.79.9
155.1.9.9
155.1.37.7
155.1.37.3
155.1.13.1
155.1.13.3
155.1.23.3
155.1.23.2
155.1.10.10
155.1.108.10
155.1.108.8
155.1.8.8
155.1.58.8
155.1.58.5
155.1.5.5
155.1.45.5
155.45.1.4
155.1.0.1
155.1.0.2
155.1.0.3
155.1.0.4
155.1.0.5
} { ping $address}

And here are my results.

ping 155.1.146.1 [ OK ]
ping 155.1.146.4 [FAILED]
ping 155.1.146.6 [ OK ]
ping 155.1.67.6 [ OK ]
ping 155.1.67.7 [ OK ]
ping 155.1.79.7 [ OK ]
ping 155.1.79.9 [FAILED]
ping 155.1.9.9 [FAILED]
ping 155.1.37.7 [ OK ]
ping 155.1.37.3 [ OK ]
ping 155.1.13.1 [ OK ]
ping 155.1.13.3 [ OK ]
ping 155.1.23.3 [ OK ]
ping 155.1.23.2 [ OK ]
ping 155.1.10.10 [FAILED]
ping 155.1.108.10 [FAILED]
ping 155.1.108.8 [ OK ]
ping 155.1.8.8 [ OK ]
ping 155.1.58.8 [ OK ]
ping 155.1.58.5 [ OK ]
ping 155.1.5.5 [ OK ]
ping 155.1.45.5 [ OK ]
ping 155.45.1.4 [FAILED]
ping 155.1.0.1 [ OK ]
ping 155.1.0.2 [ OK ]
ping 155.1.0.3 [ OK ]
ping 155.1.0.4 [ OK ]
ping 155.1.0.5 [ OK ]

I’ve been working on my CCIE for a few months. I utilize a Cisco 2511 to connect to my lab remotely. I’ve found the following to be useful when going through mockup labs.

Exit a command (ping, traceroute, etc)
press “ctrl+shift+6″ twice consecutively

Remove all routing configuration
(config)# no ip routing
(config)# ip routing

Erase and reload all routers
You must have an active session from the 2511 (use # “show session” to verify )

send *
{enter}
wr erase
no
reload
{enter}

I’ll add more things as i think of them.

I spent a good amount of time troubleshooting a L2 link that is provided across two provider networks. The symptoms were packets above 1496bytes being dropped. I used ICMP echo packets to verify this.

# ping x.x.x.x size 1496
Sending 5, 1496-byte ICMP Echos to x.x.x.x, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms

# ping x.x.x.x size 1497
Type escape sequence to abort.
Sending 5, 1497-byte ICMP Echos to x.x.x.x, timeout is 2 seconds:
…..
Success rate is 0 percent (0/5)

Our switch on each side has an MTU of 1500 with the provider facing link set to DOT1Q. This means packets being sent on the provider link can be 1500bytes plus the 4byte header for the Q tag. If the provider dosen’t set the link interfaces with an MTU of at least 1504bytes, the traffic will fragment and be dropped.

An easy way to verify the MTU issue on the provider network is to pass traffic in the native VLAN. Since this traffic isn’t carrying the extra 4byte vlan header tag it should pass.

-Justin