Monday, December 5, 2016

Updated Version of STP : RSTP ( Rapid Spanning Tree Protocol )

Networks Baseline
Updated Version of STP : RSTP ( Rapid Spanning Tree Protocol )

Well as per our earlier session on STP, we told that we will discuss the next version of STP and that is called as Rapid Spanning Tree Protocol. Now we have a question, If STP is provide us Loop free switched or Local Area Network then why there is a need of RSTP ( Rapid Spanning Tree Protocol ) comes in to picture. Is there any short comes in STP by which we are using RSTP or any specific reason to use RSTP in the switched network.

Any Idea ? Any clue ? Well lets discuss why we are using RSTP protocol in Switched network and now a days it is used in many of the enterprise networks.

Audience # Cisco Network Engineers, CCNA R&S Engineers, TAC/NOC Engineers and Systems Engineers


Fig 1.1- STP and RSTP Port States


Whats the issue with the STP : Well there is no issues with the STP but if you talking about the convergence time in STP, it takes 30 to 50 sec to converged the network and passes from the various Port states named as:

  • Blocking
  • Listening 
  • Learning
  • Forwarding
  • Disabled

So every port state takes 15 sec before they passed on to next state. All these states are the states of the port. So if a normal network needs to have the convergence it takes almost 
30 sec for forwarding the traffic from one port to another. Sometime the switch goes down or anyhow we have the port in the shut down state for avoiding the loop and we have the case where one path is down, then according to STP the shut down port needs to be up for traffic flow and takes 30 sec or 50 sec to be there in up state and it cause a huge loss to some of the banking and financial enterprise networks. so to skip the states of the port we uses the features like Backbone fast and uplink fast, we will makes the port convergence reduces from 30-50 sec to 3-5 sec and the shut down port will be up in 3-5 sec. 

Wow Great, so RSTP is excellent protocol by which one can increase the convergence time of the ports in the Switched network, Although It works on the same principle of the STP protocol but with some of the added features like " Backbone Fast " and " Uplink Fast "

We will discuss more on Backbone fast, uplink fast and one more feature that is Port Fast in the switched network.


Tuesday, November 1, 2016

How to check the Module/Interface Card Status and Backplane Switch Statistics in Cisco Router

ılılılı RouteXP ılılılı ılılılı
How to check the Module/Interface Card Status and Backplane Switch Statistics in Cisco Router

If you are looking which module and which cards are installed in the Cisco router, you need to check the below command on your router. It will populate all the details of the router with the interfaces and the modules installed in the router.

Fig 1.1- Cisco ISR 4451-X router

RouteXP_Router# show platform
Chassis type: ISR4451/K9

Slot      Type                State                 Insert time (ago)
--------- ------------------- --------------------- -----------------
0         ISR4451/K9          ok                    15:57:33
 0/0      ISR4451-4X1GE       ok                    15:55:24
 0/3      NIM-SSD             ok                    15:55:24
1         ISR4451/K9          ok                    15:57:33
 1/0      SM-1T3/E3           ok                    15:55:24
2         ISR4451/K9          ok                    15:57:33
 2/0      SM-1T3/E3           ok                    15:55:24
R0        ISR4451/K9          ok, active            15:57:33
F0        ISR4451-FP          ok, active            15:57:33
P0        Unknown             ps, fail              never
P1        XXX-XXXX-XX         ok                    15:56:58
P2        ACS-4450-ASSY       ok                    15:56:58

Slot      CPLD Version        Firmware Version
--------- ------------------- ---------------------------------------
0         12090323            15.3(01r)S            [ciscouser-ISRRO...
1         12090323            15.3(01r)S            [ciscouser-ISRRO...
2         12090323            15.3(01r)S            [ciscouser-ISRRO...
R0        12090323            15.3(01r)S            [ciscouser-ISRRO...
F0        12090323            15.3(01r)S            [ciscouser-ISRRO...

Fig 1.2- Cisco ISR 4451-X Modules

Viewing Backplane Switch Statistics
Statistics reports for each slot show incoming and outgoing packets or bytes. You can use the information to check traffic flow on the various ports of the backplane switch. The following example shows a sample output command:

RouteXP_Router# show platform hardware backplaneswitch-manager rp active summary
slot     bay       port         InBytes          InPkts         OutBytes         OutPkts 
----------------------------------------------------------------------------------------
   0       0         CP            6242         9361008             6241          403209 
   1       0        GE1               0               0                0               0 
   1       0        GE0            6306          407477             6241         9360934 
   2       0        GE1               0               0                0               0 
   2       0        GE0               0               0                0               0 
   0       1        GE1               0               0                0               0 
   0       1        GE0               0               0                0               0 
   0       2        GE1               0               0                0               0 
   0       2        GE0               0               0                0               0 
   0       3        GE1               0               0                0               0 
   0       3        GE0               0               0                0               0 
   0       4        GE1               0               0                0               0 
   0       4        GE0               0               0                0               0 
   0       0        FFP               0               0                0               0 

   0       0        FFP               0               0                0               0 


Deactivating a Module Configuration:
You can deactivate a module to perform OIR of that module. The following example shows how to deactivate a module (and its interfaces) and remove power to the module. In this example, the module is installed in subslot 0 of the router.
RouteXP_Router(config)# hw-module slot 1 subslot 1/0 shutdown unpowered

Activating a Module Configuration:
You can activate a module if you have previously deactivated it. If you have not deactivated a module and its interfaces during OIR, then the module is automatically reactivated upon reactivation of the router.

The following example shows how to activate a module. In this example, the module is installed in subslot 0, located in slot 1 of the router:

Router(config)# hw-module slot 1 subslot 1/0 start

Saturday, June 25, 2016

STP-Spanning Tree Protocol- Switching Techniques

Anonymous
STP- Spanning tree Protocol is one of the most important topic in the Routing and Switching domain. So now question is why STP is so much important, where we are using the STP.

Lets start with the basics, STP is generally used avoiding the loop in the Switched network, Switched network means the LAN- Local Area Network. So it is clear if STP is there in the Switched or LAN network then looping is not possible.

Audience # Cisco Network Engineers, CCNA R&S Engineers, TAC/NOC Engineers and Systems Engineers

Before you trying to understand the concept of STP, one must understand the selection criteria of the root bridge in the network. When i am saying the network make sure you understand it always be Local area network in this article.

Root Bridge Selection 

Case-1
Let us suppose we have 3 switches in the network which their different MAC address. So when you are talking about the selection procedure first of all check the priority set on the switches, If there is priority set on the switches then the high priority switch will be the Root Bridge and all east-west, North-south switched traffic will be passed from the root bridge.

Case-2
Now, if there is no Priority on the switches then ? so all switches will send the BPDU configuration message to each other and check the MAC address of all the switches in the database, then they recognise that which so ever switch is lower MAC address will be chosen as " Root Bridge "

So now by these two above cases, you may understand the criteria of the " Selection of the Root Bridge". Once Root Bridge selected the STP-Spanning tree Protocol comes in to picture.

Ports on the Root Bridge will always be " DP- Designated Port "and the other switch will be connected by this DP port will always have RP port.


Fig 1.1 - STP Topology

Above is the general STP topology and its for general understanding as i can explain you with the example which can not explain in the above picture.

So if you root bridge, lets suppose A is connected to other switch B then the port at switch A will be DP port and the port at Switch B will be RP port ( Root Port ). The reason why Switch B have the RP Port because it is the principle that which so ever switch have the lower MAC address and connected to the higher MAC address switch the port will be RP at High Mac address side and DP at Lower MAC side.

But we have another Switch C as well in the picture, so if we are connected Switch B and Switch C with each other then which one is DP and which one is RP port. The same condition applies, If the MAC address of the Switch B is less than the MAC of the Switch C then Port of Switch B will be DP ( that connected to Switch C) and the port of Switch C will be in Blocked state ( now thats the big Gochaa) , Why that port is in the block state. The reason is STP existence. Let me explain this one aswell

We have 3 Switches, Switch A, Switch B and Switch C, Switch A connected to Switch B and Switch C, so both these ports are DP Ports, Switch B is Connected to Switch A and Switch C, So the Port towards switch A will be RP port and towards Switch C will be DP ( due to lower MAC than Switch C), Switch C connected to Switch A and Switch B, so the port towards Switch A will be RP and Port towards switch B will be at blocked state. is it will not be in blocked state, then Switch B will get the same user traffic from Switch A as well as from Switch B and it will causes Loops in the network, similarly the same user traffic will be there at Switch B from Switch A and Switch C. so one port should be blocked to avoid looping and that is decided by STP protocol on the basis of MAC addresses.

So now you understand about STP, root bridge selection criteria and DP, RP Ports and traffic flow in the switched network. In our next session we will talk about the BPDU messages and where these messages generally used in the network and also talked about the advance versions of STP called RSTP and features in the RSTP protocol.

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