Lab 4 - switches and snmp,  v2.0

Use deedee and lixia, but pay attention to the ports
you use for the vlan/trunk exercise.

General:

1. 
If you learn something from a Cisco, show how it is done in terms
of commands/config setup.

2. 
Note: hahaha has two interfaces, you can move and use them both.
Use ifconfig to assign ip addresses:

Interfaces are named xl1, xl0:

	#ifconfig xl1 1.1.1.1 netmask 255.255.0.0 
	#ifconfig xl0 2.2.2.2 netmask 255.255.0.0 

Be sure and put the main hahaha.cs.pdx.edu interface back when done
and reinit it (make sure the default route is there too).
(the cheap way to reinit is to 
# reboot
)

OR

# nslookup hahaha.cs.pdx.edu
Name:    hahaha.cs.pdx.edu
Address:  131.252.215.15

# ifconfig xl0 131.252.215.15 netmask 255.255.255.192
# route delete default
# route add default 131.252.215.1

when done
# ping www.cs.pdx.edu   

3. 
Resources:
	1. Cisco 2900 manuals are findable in the netlab/documentation
	directory on the netlab web page.

	2900commands.ps.gz
	2900vlan.ps.gz

	2. you may move and use both of the hahaha network cables.

	3. use the two Cisco 2900 series switches, deedee, and lixia.
	or whichever switches are provided.  This may change in the future.
	These two switches are the bottom two *CISCO* switches in the switch rack,
	that are NOT resting on the floor.

4.
hardware to use.  Use the lixia and deedee switches (the bottom 2 cisco
switches).  lixia is a 2924.  deedee is a 2916.  Use mandark for a router
if you need one.  It is ok to move mandark's "wires".  (try not to lose them, ok?).
Note that if you are using the 2916 and trying to do trunking you must use the
gigabit interface.  If you are using a 3524 any port should work.

part 1: Switch part

1.1. why does the forwarding/mac table have a per entry aging timer?

What is the value of that timer in our switches? 

Also what are the max number of mac addresses the mac table can hold?

What command/s show the forwarding table?

2..2 create a shared vlan that goes between the two Cisco switches.
Make this vlan 666.  You need to use the gigabit port for this
exercise.  This is because the 2914 does NOT support trunking
on its 10/100 ports.

You should have 3 ports total used between the two switches.
One port should be a trunk port.  First set it up on one switch, then
set it up on the other switch, then setup a trunk port between them.

Use one port of the host (xl0) to ping another port on the host (xl1) (ping -n).
Both ports should be on both switches.  Prove to yourself that the
following two cases hold:

	1. you cannot see packets from vlan 666 in vlan 1
	2. you can see packets from vlan 666 on another port both
	on the same switch and a different switch.

Something like this:

                         | 666 broadcast domain port
        lixia:          port N,  N+1,  N+2  all in 666
                                       |    trunk 666
        deedee:       	port N,  N+1,  N+2
                                 | 666 broadcast domain port

part 2: spanning tree exercises.

2.1. using hahaha and tcpdump -vvv -n -s 1500, capture a spanning tree packet.
Show it here ...  what is the MAC destination address?
What is the default timer for the generation of STP packets?
What is the root MAC address?   
Which switch does it belong to?

2.2. Use vlan 1 for this exercise. You have one spanning tree.  Now take one
of the additional "switch" (cross-connect) ethernet cables
and hook it up between the two switches.  How can you figure out
which one of the two cables is being used for the now
redundant vlan 1 connection?

	What happens when you take out the connection
	that is green/up/in use?

	What happens when you put it back?

It can be very instructive to do this exercise and have one person
run tcpdump -n on a connected vlan port.   What does that person see?

2.3. Using the two switches, and vlan 1 again, with two redundant
connections between the two switches, find out how to 
disable the spanning tree.  Do that, and hook up hahaha and 
send one broadcast packet.  What happens?
(one ping will do it, as it will cause an arp).
# ping -n -c 1 etc on BSD will send one ping packet.

IMPORTANT NOTE OF CAUTION: make sure that lixia and deedee are NOT
hooked up to any other lab switch.

2.4. does an ordinary host (or router) cause a spanning tree recalculation, or only
a switch?  Try and find different ways to tell that a spanning tree recalculation is going on?

*************************************************************************************

part 3: snmp exercises

3.1. what is the basic snmp config setup for a Cisco switch?

3.2. using snmpwalk on hahaha.cs.pdx.edu, do an snmpwalk
of dexter, for the following MIBS: system, interfaces, ifmib.

3.3. Using SNMP, show the arp table from dexter.

3.4. identity the following two Cisco enterprise MIB variables.
Find the appropriate mib and cite it for the meaning of
the variable.

Can you find these variables on dexter?

1.3.6.1.4.1.9.2.1.57.0

1.3.6.1.4.1.9.9.13.1.3.1.3.1

optional:

o.1. you have vlan 666.  now make 667 on the same switch.
How can you get packets routed between the two vlans?
(You may use mandark or dexter as a router here).

o.2. who is the root STP switch for vlan 1 (the default vlan)
in the lab?

o.3 download nagios from the web and install it.  try to manage 1 switch, 1 router,
and 1 host with it.  You may have to do an ubuntu/linux install before you
try this.  manageable target systems could include minshall, dexter, and a host
of your choice.