QoS - High quality of Service - is a huge subject on each the BCMSN exam and real-world networks. QoS is so large right this moment that Cisco's created separate specialist certifications that cowl nothing but QoS! It may be an awesome matter at first, however grasp the basics and also you're in your method to examination and job success.
If you happen to work with QoS at any stage - and sooner or later, you will - you've got to know learn how to write and apply QoS policies.
Creating and applying such a coverage is a three-step process.
1. Create a QoS class to determine the site visitors that will likely 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 suitable interfaces.
If the phrase "identify the visitors" appears like it's time to write an entry-record, you're proper! Writing an ACL is one of ways to classify site visitors, and is the extra frequent of the two. Earlier than we get to the much less-frequent method, let's take a look at tips on how to use an ACL to classify traffic.
You need to use both an ordinary or extended ACL with QoS policies. The ACL will be written separately, and then called from the class map.
SW1(config)access-record one zero five permit tcp any any eq eighty
SW1(config)class-map WEBTRAFFIC
SW1(config-cmap)match entry-group 105
Now that we have recognized the traffic to be affected by the coverage, we better get round to writing the coverage! QoS policies are configured with the coverage-map command, and each clause of the policy will include 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 can be a simple coverage, but it illustrates the logic of QoS policies. The policy map LIMIT_WEBTRAFFIC_BANDWIDTH calls the map-class WEBTRAFFIC. We already know that every one WWW visitors will match that map class, so any WWW site visitors that exceeds the stated bandwidth limitation will be dropped.
Lastly, apply the coverage to the appropriate interface.
SW1(config-if)service-coverage LIMIT_WEBTRAFFIC_BANDWIDTH in
Getting your CCNP is an effective way to spice up your profession, and learning QoS is an incredible addition to your talent set. Like I stated, study the basics, don't get overwhelmed by looking at QoS as a complete, and you're on your approach to success!
To move the BCMSN examination and earn your CCNP, you've got to know HSRP inside and outside! Part of that's figuring out how the MAC tackle of the virtual router is derived, and one other part is understanding find out how to change this address. We'll take a look at both options in this tutorial.
We've got two routers on a section working HSRP, so first we have to discover out what the MAC tackle of the HSRP digital router is. The show command for HSRP is present standby, and it's the primary command you must run whereas configuring and troubleshooting HSRP. Let's run it on both routers and evaluate results.
R2show standby
Ethernet0 - Group 5
Native state is Standby, precedence a hundred
Hellotime three sec, holdtime 10 sec
Next hiya despatched in 0.776
Digital IP deal with is 172.12.23.10 configured
Energetic router is 172.12.23.3, priority a hundred expires in 9.568
Standby router is native
1 state modifications, final state change 00:00:22
R3show standby
Ethernet0 - Group 5
Local state is Active, priority one hundred
Hellotime three sec, holdtime 10 sec
Subsequent hey despatched in 2.592
Virtual IP tackle is 172.12.23.10 configured
Lively router is native
Standby router is 172.12.23.2 expires in 8.020
Virtual mac tackle is 0000.0c07.ac05
2 state adjustments, final state change 00:02:08
R3 is in Lively state, while R2 is in Standby. The hosts are utilizing the 172.12.123.10 tackle as their gateway, but R3 is actually dealing with the workload. R2 will take over if R3 becomes unavailable.
An IP deal with was statically assigned to the digital router, but not a MAC address. Nonetheless, there's a MAC handle underneath the show standby output on R3, the lively router. How did the HSRP course of arrive at a MAC of 00-00-0c-07-ac-05?
Well, most of the work is already achieved before the configuration is even begun. The MAC deal with 00-00-0c-07-ac-xx is reserved for HSRP, and xx is the group number in hexadecimal. That is a very good talent to have for the examination, so ensure you're comfy 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 11 at the end of the MAC handle - one unit of sixteen, one unit of 1.
On rare occasions, you could have to alter the MAC tackle assigned to the digital router. This is performed with the standby mac-address command. Just be sure to're not duplicating a MAC tackle 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 Energetic -> Study
R2show standby
Ethernet0 - Group 5
Local state is Lively, priority a hundred and fifty, might preempt
Hellotime four sec, holdtime 12 sec
Subsequent hi there despatched in 3.476
Virtual IP deal with is 172.12.23.10 configured
Lively router is local
Standby router is 172.12.23.three expires in 10.204
Digital mac address is 0000.1111.2222 configured
four state adjustments, last state change 00:00:00
1d12h: %STANDBY-6-STATECHANGE: Ethernet0 Group 5 state Listen -> Energetic
The MAC deal with will take a number of seconds to vary, and the HSRP routers will go into Be taught state for that time period.
An actual-world HSRP troubleshooting be aware: In the event you see fixed state modifications together with your HSRP configuration, do what you should at all times do when troubleshooting - test the bodily layer first. Best of luck on your BCMSN exam!
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