RE: Designated Port/Switch and Root Port?? [7:39811]
> Hello,If every non-root bridge elects one root port to get to the > root-bridge, then why do we still need a designated switch/port per > segment? Do these two have different functions altogether?Thank you. I did a few searches on cisco.com and google and they appear to be different works for the same thing. I'll agree that the explanation I read in my Examcram wasn't that explicit. http://netcert.tripod.com/ccna/switches/2switch.html "Ports that have the lowest cost to the root bridge are called designated ports. The other ports on the bridge are considered non designated and will not send or receive traffic, (blocking mode)." Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=39833&t=39811 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Designated Port/Switch and Root Port?? [7:39811]
The designated port is not just the root ports. 1. Each root port is a designated port 2. Each designated port is not necessarily the root port. There are other ports as designated, on the other side of the root bridge to forward BPDUs downstream. Nadeem == Cisco Nuts wrote: > Hello,If every non-root bridge elects one root port to get to the > root-bridge, then why do we still need a designated switch/port per > segment? Do these two have different functions altogether?Thank you. > > > > Chat with friends online, try MSN Messenger: Click Here Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=39867&t=39811 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Designated Port/Switch and Root Port?? [7:39811]
I'll try to explain this: Think of a root port as the closest port to the root bridge on a given BRIDGE. Think of a designated port as the closest port to the root bridge on a given SEGMENT. This is the port used by all bridges on a given segment to get to the ROOT. Consider the following basic diagram to explain this further with 1 root bridge, 3 non-root bridges and 3 segments: |ROOT|--segment 1--|A|--segment 2--|B|--segment 3--|C| The root port on bridge A is the closet int to ROOT - the int on the left. The designated port on segment 1 is actually the int on ROOT that's in segment 1. The root port on Bridge B is the closest int to ROOT - the int on the left. The designated port on segment 2 is the closet interface to ROOT in segment 2 - the int on the right side of bridge A. The root port on bridge C is the the closest int to ROOT - the int on the left. The designated port on segment 3 is the port closest to ROOT - the int on the right side of bridge B. So, you wind up with something like a consistent and logical topology: ROOT(DP)--(RP)A(DP)--(RP)B(DP)--(RP)C The real distinction is knowing that a root port is a designation specific to a switch and a designated port is specific to a segment. To show this, we can make the following modification to the above topology: ROOT(DP)--(RP)A(DP)--(RP)B(DP)--(RP)C | |--(RP)D(DP)--(RP)E In this case, there are 2 root ports in segment 2 but there will always be ONLY 1 designated port per segment. This is one of the foundational concepts of STP. Also, the ROOT will never have a root port, all non-root bridges will have ONLY 1 root port (per VLAN) and there will ONLY be 1 designated port per segment (per VLAN). Root ports send BPDUs and designated ports receive BPDUs. Hope this helps, Rik -Original Message- From: Lomker, Michael [mailto:[EMAIL PROTECTED]] Sent: Thursday, March 28, 2002 2:44 PM To: [EMAIL PROTECTED] Subject: RE: Designated Port/Switch and Root Port?? [7:39811] > Hello,If every non-root bridge elects one root port to get to the > root-bridge, then why do we still need a designated switch/port per > segment? Do these two have different functions altogether?Thank you. I did a few searches on cisco.com and google and they appear to be different works for the same thing. I'll agree that the explanation I read in my Examcram wasn't that explicit. http://netcert.tripod.com/ccna/switches/2switch.html "Ports that have the lowest cost to the root bridge are called designated ports. The other ports on the bridge are considered non designated and will not send or receive traffic, (blocking mode)." Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=39870&t=39811 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Designated Port/Switch and Root Port?? [7:39811]
That was an excellent explanationThank you very much!! >From: "Rik Guyler" >Reply-To: "Rik Guyler" >To: [EMAIL PROTECTED] >Subject: RE: Designated Port/Switch and Root Port?? [7:39811] >Date: Thu, 28 Mar 2002 21:10:09 -0500 > >I'll try to explain this: > >Think of a root port as the closest port to the root bridge on a given >BRIDGE. Think of a designated port as the closest port to the root bridge >on a given SEGMENT. This is the port used by all bridges on a given >segment >to get to the ROOT. Consider the following basic diagram to explain this >further with 1 root bridge, 3 non-root bridges and 3 segments: > >|ROOT|--segment 1--|A|--segment 2--|B|--segment 3--|C| > >The root port on bridge A is the closet int to ROOT - the int on the left. >The designated port on segment 1 is actually the int on ROOT that's in >segment 1. The root port on Bridge B is the closest int to ROOT - the int >on the left. The designated port on segment 2 is the closet interface to >ROOT in segment 2 - the int on the right side of bridge A. The root port >on >bridge C is the the closest int to ROOT - the int on the left. The >designated port on segment 3 is the port closest to ROOT - the int on the >right side of bridge B. > >So, you wind up with something like a consistent and logical topology: > >ROOT(DP)--(RP)A(DP)--(RP)B(DP)--(RP)C > >The real distinction is knowing that a root port is a designation specific >to a switch and a designated port is specific to a segment. To show this, >we can make the following modification to the above topology: > >ROOT(DP)--(RP)A(DP)--(RP)B(DP)--(RP)C > | > |--(RP)D(DP)--(RP)E > >In this case, there are 2 root ports in segment 2 but there will always be >ONLY 1 designated port per segment. This is one of the foundational >concepts of STP. Also, the ROOT will never have a root port, all non-root >bridges will have ONLY 1 root port (per VLAN) and there will ONLY be 1 >designated port per segment (per VLAN). Root ports send BPDUs and >designated ports receive BPDUs. > >Hope this helps, > >Rik > >-----Original Message- >From: Lomker, Michael [mailto:[EMAIL PROTECTED]] >Sent: Thursday, March 28, 2002 2:44 PM >To: [EMAIL PROTECTED] >Subject: RE: Designated Port/Switch and Root Port?? [7:39811] > > > > Hello,If every non-root bridge elects one root port to get to the > > root-bridge, then why do we still need a designated switch/port per > > segment? Do these two have different functions altogether?Thank you. > >I did a few searches on cisco.com and google and they appear to be >different >works for the same thing. I'll agree that the explanation I read in my >Examcram wasn't that explicit. > >http://netcert.tripod.com/ccna/switches/2switch.html > >"Ports that have the lowest cost to the root bridge are called designated >ports. The other ports on the bridge are considered non designated and >will >not send or receive traffic, (blocking mode)." _ Join the worlds largest e-mail service with MSN Hotmail. http://www.hotmail.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=39908&t=39811 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
