CCNA Teacher
If we create LOOPBACK address we are not giving no shutdown because we are creating logical interface, in switching if we create int vlan (for ex int van2,van3)this is also logically creating then why we need to give NOSHUTDOWN???????????
All IP interfaces are down by default. This is to allow you to add and move subnets without risk of propagating routes or creating an overlap. Loopbacks are a special case as they don't have an L2 component. It makes little sense for it to be up by default, but meh...
concept of loopback was mainly developed for testing purpose. hence they are up by default n order to save our time .but on vlans scenario is different intrface are logical but placed on physical
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In STP why priority is giving multiple of 4096??????????
It is because in the days of plain old vanilla STP we had 2 bytes for the bridge priority 0 - 65535 ( in math we inc the zero, so 65536 variations). But when RSTP came along we needed a vlan id field - that took 12 bits leaving only 4 bits for bridge priority.
4 bits have 16 possible variations, so 16 * 4096 = 65536
Very good question
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what is the difference between the root port and designated port ?
There can be ONLY one Root Port on a switch. There may be multiple Designated Ports on a switch
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Hi Community,
I am setting up a lab at the office to start studying by myself, I have SWs 2x3560 2x3550 3x2900, routers will be in GNS3, and to access the SWs I have a 2511 with 16 async interfaces.
I am trying to connect to any of the SWs with no joy.
---
Aux would go to a gateway to access the 2511 remotely. This particular 2511 doesn't have the interface to connect the octal cable, it has 16 Async interfaces, which go to every console ports of your devices
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An IP address can be divided in two parts, network bits 'x' and host bits 'y'. To obtain the number of usable IPs in a network do (2^y)-2. You remove 2 from the count since the IPs are in use for other reasons: one of them is the network boundary and the other is the broadcast.
In any network, there is a limited number of IP addresses that can be assigned to hosts on the network. This is the formula. Take for example the network 192.168.1.0/24. You have 32 bits total, or four octets of 8 bits, but 24 are network bits and can't be assigned to hosts. The last 8 bits are the host bits. You can't use the zero address, 192.168.1.0 because it belongs to the network itself. You can't use 192.168.1.255 because it is the broadcast address. Anything else from .1 to .254 can be assigned to a host on the network. So 2 raised to the 8th power minus 2 = 254 host addresses available
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Hey Rahul,
An un-managed switch is not an hub. I've a cyber-cafe.... earlier my LAN was built using Hubs, however i've replaced them with un-managed switches.
I see a lot of difference in the speed of my LAN. And i don't think the unmanaged switches maintain a MAC table. I believe the difference between those two is: Hub acts like a bus topology, whereas the un-managed switch acts like a star topology. And even hub operate at 10mbps whereas an un-managed switch can operate between 10-100 mbps. The unmanaged switch helped a lot for me to enhance my cafe..
While using hubs the video streaming was very slow it is used to stop for every few mins then again buffer like this... but now there is no latency at all using unmanageble switches.
Please don't forget to rate the helpful posts.
Regards,
Chandu
******************************
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As they are unmanaged , no you can't view the MAC table but if they flood everything you will see it by sniffing on another PC linked to the switch, if it doesn't flood unicast you'll only see unknown unicast frames but not known unicast frames.
Regards
Alain
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David :
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Joseph : An unmanaged switch is one you cannot configure (i.e. you cannot manage it, ergo its unmanaged). It is not a hub. BTW, there are (or were) manageable hubs.
If we create LOOPBACK address we are not giving no shutdown because we are creating logical interface, in switching if we create int vlan (for ex int van2,van3)this is also logically creating then why we need to give NOSHUTDOWN???????????
All IP interfaces are down by default. This is to allow you to add and move subnets without risk of propagating routes or creating an overlap. Loopbacks are a special case as they don't have an L2 component. It makes little sense for it to be up by default, but meh...
concept of loopback was mainly developed for testing purpose. hence they are up by default n order to save our time .but on vlans scenario is different intrface are logical but placed on physical
*************
In STP why priority is giving multiple of 4096??????????
It is because in the days of plain old vanilla STP we had 2 bytes for the bridge priority 0 - 65535 ( in math we inc the zero, so 65536 variations). But when RSTP came along we needed a vlan id field - that took 12 bits leaving only 4 bits for bridge priority.
4 bits have 16 possible variations, so 16 * 4096 = 65536
Very good question
*******************************
what is the difference between the root port and designated port ?
There can be ONLY one Root Port on a switch. There may be multiple Designated Ports on a switch
*********************
Hi Community,
I am setting up a lab at the office to start studying by myself, I have SWs 2x3560 2x3550 3x2900, routers will be in GNS3, and to access the SWs I have a 2511 with 16 async interfaces.
I am trying to connect to any of the SWs with no joy.
Here's what I am doing: I already have all my SWs configured with the
basic commands, they are all up and running. The 2511 is configured as
follows:
line con 0
line 1 16
transport input all
exec-timeout 0 0
no exec
session-timeout 20
int loopback0
ip add 1.1.1.1 255.255.255.255
ip host C13560 2001 1.1.1.1
.
.
.
.
ip host A32900 2007 1.1.1.1
When issuing in exec mode
#1
or
#telnet 1.1.1.1 2001
I get an unreachable host error message
Note: I am using the proper cable to connect from the async interface to the console port on the SW.
I wonder if any of you guys could help a little bit.
line con 0
line 1 16
transport input all
exec-timeout 0 0
no exec
session-timeout 20
int loopback0
ip add 1.1.1.1 255.255.255.255
ip host C13560 2001 1.1.1.1
.
.
.
.
ip host A32900 2007 1.1.1.1
When issuing in exec mode
#1
or
#telnet 1.1.1.1 2001
I get an unreachable host error message
Note: I am using the proper cable to connect from the async interface to the console port on the SW.
I wonder if any of you guys could help a little bit.
---
Aux would go to a gateway to access the 2511 remotely. This particular 2511 doesn't have the interface to connect the octal cable, it has 16 Async interfaces, which go to every console ports of your devices
*****************************************************
An IP address can be divided in two parts, network bits 'x' and host bits 'y'. To obtain the number of usable IPs in a network do (2^y)-2. You remove 2 from the count since the IPs are in use for other reasons: one of them is the network boundary and the other is the broadcast.
In any network, there is a limited number of IP addresses that can be assigned to hosts on the network. This is the formula. Take for example the network 192.168.1.0/24. You have 32 bits total, or four octets of 8 bits, but 24 are network bits and can't be assigned to hosts. The last 8 bits are the host bits. You can't use the zero address, 192.168.1.0 because it belongs to the network itself. You can't use 192.168.1.255 because it is the broadcast address. Anything else from .1 to .254 can be assigned to a host on the network. So 2 raised to the 8th power minus 2 = 254 host addresses available
********************
Hi Guys,
I want to know what is an Unmanaged Switch? Is it a Hub or not is what I want to know actually.
We know a Hub has one collision and one broadcast domain so let' say if I connect multiple devices to a Hub and if even two of them try to send at the same time there will be a collison causing data corruption etc. Now, if an Unmanaged switch is nothing but a Hub then wouldn't I face the same problem if two or more than two devices try to send or receice at the same time?
I want to know what is an Unmanaged Switch? Is it a Hub or not is what I want to know actually.
We know a Hub has one collision and one broadcast domain so let' say if I connect multiple devices to a Hub and if even two of them try to send at the same time there will be a collison causing data corruption etc. Now, if an Unmanaged switch is nothing but a Hub then wouldn't I face the same problem if two or more than two devices try to send or receice at the same time?
Reply : With a hub all workstations are essentially on the same wire and every port sees every packet.
A switch will build mac address tables and forward most traffic intelligently.
So a dumb switch isn't a hub.
I guess you could say the switch, even a toy one, operates more at layer 2 in the OSI model where the hub is purely layer 1.
A switch will build mac address tables and forward most traffic intelligently.
So a dumb switch isn't a hub.
I guess you could say the switch, even a toy one, operates more at layer 2 in the OSI model where the hub is purely layer 1.
***************
Hey Rahul,
An un-managed switch is not an hub. I've a cyber-cafe.... earlier my LAN was built using Hubs, however i've replaced them with un-managed switches.
I see a lot of difference in the speed of my LAN. And i don't think the unmanaged switches maintain a MAC table. I believe the difference between those two is: Hub acts like a bus topology, whereas the un-managed switch acts like a star topology. And even hub operate at 10mbps whereas an un-managed switch can operate between 10-100 mbps. The unmanaged switch helped a lot for me to enhance my cafe..
While using hubs the video streaming was very slow it is used to stop for every few mins then again buffer like this... but now there is no latency at all using unmanageble switches.
Please don't forget to rate the helpful posts.
Regards,
Chandu
******************************
Hi,
Regards
Alain
Don't forget to rate helpful posts.
And i don't think the unmanaged switches maintain a MAC tableThat would mean they would flood all the time so basically act like hubs and in this case I don't think you would have seen a performance increase in your network
Regards
Alain
Don't forget to rate helpful posts.
**************
As they are unmanaged , no you can't view the MAC table but if they flood everything you will see it by sniffing on another PC linked to the switch, if it doesn't flood unicast you'll only see unknown unicast frames but not known unicast frames.
Regards
Alain
***************
David :
An unmanaged switch is just that, unmanaged.
Its still a switch in that it maintains a MAC addresss table and forwards frames based on this.
A hub and an unmanaged switch are not the same thing.
Its still a switch in that it maintains a MAC addresss table and forwards frames based on this.
A hub and an unmanaged switch are not the same thing.
Joseph : An unmanaged switch is one you cannot configure (i.e. you cannot manage it, ergo its unmanaged). It is not a hub. BTW, there are (or were) manageable hubs.
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