Cisco CCNP Certification / BCMSN Exam Tutorial: Writing QoS Policy
QoS – High quality of Service – is a big topic on both the BCMSN exam and real-world networks. QoS is so massive today that Cisco’s created separate specialist certifications that cowl nothing however QoS! It can be an overwhelming matter at first, but master the basics and also you’re on your approach to exam and job success.
If you happen to work with QoS at any degree – and in the end, you’ll – you’ve got to know how to write and apply QoS policies.
Creating and applying such a policy is a three-step process.
1. Create a QoS class to determine the traffic that might be affected by the policy.
2. Create a QoS policy containing the actions to be taken by visitors recognized by the class.
3. Apply the coverage to the appropriate interfaces.
If the phrase “establish the site visitors” feels like it is time to write an access-record, you are proper! Writing an ACL is one in all ways to categorise site visitors, and is the more frequent of the two. Earlier than we get to the less-frequent technique, let’s check out find out how to use an ACL to categorise traffic.
You need to use either a normal or extended ACL with QoS policies. The ACL will be written separately, and then referred to as from the category map.
SW1(config)entry-record 105 permit tcp any any eq 80
SW1(config)class-map WEBTRAFFIC
SW1(config-cmap)match entry-group a hundred and five
Now that we have recognized the visitors to be affected by the coverage, we higher get round to writing the policy! QoS insurance policies are configured with the policy-map command, and each clause of the coverage will comprise an action to be taken to site visitors matching that clause.
SW1(config)policy-map LIMIT_WEBTRAFFIC_BANDWIDTH
SW1(config-pmap)class WEBTRAFFIC
SW1(config-pmap-c)police 5000000 exceed-motion drop
SW1(config-pmap-c)exit
This is a simple coverage, however it illustrates the logic of QoS policies. The coverage map LIMIT_WEBTRAFFIC_BANDWIDTH calls the map-class WEBTRAFFIC. We already know that each one WWW site visitors will match that map class, so any WWW visitors that exceeds the stated bandwidth limitation can be dropped.
Lastly, apply the policy to the suitable interface.
SW1(config-if)service-policy LIMIT_WEBTRAFFIC_BANDWIDTH in
Getting your CCNP is a good way to spice up your profession, and studying QoS is a tremendous addition to your talent set. Like I stated, learn the fundamentals, do not get overwhelmed by taking a look at QoS as a whole, and you’re on your option to success!
To cross the BCMSN examination and earn your CCNP, you have to know HSRP inside and outside! A part of that’s realizing how the MAC address of the digital router is derived, and one other half is figuring out how one can change this address. We’ll take a look at both options in this tutorial.
We’ve got two routers on a phase running HSRP, so first we have to discover out what the MAC deal with of the HSRP virtual router is. The present command for HSRP is present standby, and it is the primary command you should run while configuring and troubleshooting HSRP. Let’s run it on both routers and compare results.
R2show standby
Ethernet0 – Group 5
Local state is Standby, precedence one hundred
Hellotime three sec, holdtime 10 sec
Next good day despatched in 0.776
Digital IP deal with is 172.12.23.10 configured
Energetic router is 172.12.23.3, priority 100 expires in 9.568
Standby router is local
1 state changes, final state change 00:00:22
R3show standby
Ethernet0 – Group 5
Native state is Energetic, priority 100
Hellotime 3 sec, holdtime 10 sec
Subsequent whats up sent in 2.592
Virtual IP address is 172.12.23.10 configured
Active router is native
Standby router is 172.12.23.2 expires in 8.020
Digital mac handle is 0000.0c07.ac05
2 state changes, last state change 00:02:08
R3 is in Active state, while R2 is in Standby. The hosts are using the 172.12.123.10 deal with as their gateway, however R3 is definitely handling the workload. R2 will take over if R3 turns into unavailable.
An IP handle was statically assigned to the digital router, but not a MAC address. However, there’s a MAC tackle below the present standby output on R3, the active router. How did the HSRP process arrive at a MAC of 00-00-0c-07-ac-05?
Effectively, a lot of the work is already carried out earlier than the configuration is even begun. The MAC address 00-00-0c-07-ac-xx is reserved for HSRP, and xx is the group number in hexadecimal. That’s a good ability to have for the examination, so make sure you’re snug with hex conversions. The group quantity is 5, which is expressed as 05 with a -bit hex character. If the group quantity had been 17, we’d see eleven on the end of the MAC address – one unit of 16, one unit of 1.
On uncommon occasions, you could have to alter the MAC address assigned to the digital router. That is executed with the standby mac-deal with command. Simply make sure you’re not duplicating a MAC handle that is already in your community!
R2(config-if)standby 5 mac-deal with 0000.1111.2222
1d12h: %STANDBY-6-STATECHANGE: Ethernet0 Group 5 state Lively -> Be taught
R2show standby
Ethernet0 – Group 5
Local state is Lively, precedence a hundred and fifty, might preempt
Hellotime 4 sec, holdtime 12 sec
Next hiya sent in 3.476
Virtual IP address is 172.12.23.10 configured
Active router is local
Standby router is 172.12.23.three expires in 10.204
Digital mac deal with is 0000.1111.2222 configured
4 state modifications, last state change 00:00:00
1d12h: %STANDBY-6-STATECHANGE: Ethernet0 Group 5 state Listen -> Energetic
The MAC address will take just a few seconds to vary, and the HSRP routers will go into Learn state for that time period.
An actual-world HSRP troubleshooting note: When you see fixed state adjustments with your HSRP configuration, do what you need to always do when troubleshooting – test the physical layer first. Better of luck in your BCMSN exam!
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