a1. How are MAC addresses used on a switch: The MAC address of the switch,
depending on the interface being used, handle this in different ways. Some
Catalyst switches assign a global MAC address, some switches use a pool of
addresses assigning one to each interface(You can assign one manually), and
sometimes the MAC address can be a virtual MAC address when using HSRP on
mulitiple internal route processors such as the MSM, RSM, RSFC, NFFC, NFFCII
or the MSFC. The switch is assigned an IP address and default gateway which
allows you to telnet to the switch. On most switches you can also use the
your webrowser to access the switches configuration and make changes simply
by typing in the switches IP address.
a2. If two nodes on the same switch want to communicate on the same switch:
(This question requires a long answer!)
If: A. They are connected to the same port on the switch the switch does
nothing since the two nodes are in the same collision domain they will see
each others traffic.
If B. They are in the same VLAN and reside on the same switch, the switch
learns the location of each node attached by reading the first frame
received and logging the source address and port of arrival in it's Content
Addressable Memory(CAM) table. When the switch receives another frame it
checks the CAM table and if it knows the port the destination node resides
on it forwards the frame directly to that port. If it does not know the
port, it broadcasts the frame to every port which are members of the same
VLAN with the exception to the port of arrival.
If C. If the destination and source node reside on ports assigned to
different VLANs on the switch, the switch requires an external router to
resolve the address and send the packet back to the switch. If the switch
contains an internal route processor, the external router needs to only
resolve the first packet and then the internal route processor can finish
the job from there. (An external router needs to be used so that a routing
protocol can be used to map the network topology to base it's routes.)
Hope this answers your questions.
Sean Odom, CCNP, MCSE, CNX-EtherII, Author, Instructor
GlobalNet Training Solutions
[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
www.TheQuestForCertication.Com <http://www.TheQuestForCertication.Com>
-----Original Message-----
From: Raees Ahmed Shaikh [mailto:[EMAIL PROTECTED]]
Sent: August 08, 2000 11:50 PM
To: '[EMAIL PROTECTED]'
Subject: Switches !!!
If all the ports of the switches have mac addresses than
q.1 If somebody telnets to swithes the actual physical communication occurs
through which mac address.
q.2 If two pcs are connected to the same swithc, and they want to
communicate the real communication should go like this ( pc mac- switch
port mac - destination switch port mac - destination pc).
Totally confused arp arp arp.
Please Help.
Shaikh Raees Ahmed,
Microsoft Certified Systems Engineer,
Systems & Network,
IT Division.
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