Unanswered Question
Jan 30th, 2010
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Dear Netpros,

i ned help from community to know about below point...

1) How many tables does EIGRP maintain ?

As i know it is two --> Routing Table & Topology Table..please confirm.

2) How ARP is exactly working ?

3) In OSPF Virtual link.

If we want to connect the area 1 with area 3 and area 1 to area 4 on via virtual link. then what will ne the config at both end areas router. If possible kindly give example.


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Mohamed Sobair Sat, 01/30/2010 - 01:16
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1) Eigrp maintains 3 tables:  a) Routing table. b) topology table.  c) neighbor table.

2) The concept of ARP or Address resolution protocol is to send broadcast request for destination unkown to the sender.

    when a Host send an ARP request, it needs the destination MAC address inorder to send the frams to when the IP address of the destination already exist and known to the sender.

3) OSPF Virtual link needs to connect partitioned AREAs ,  including AREA 0.

   Virtual link is not used to connect AREA 1 to AREA 3, The concept is to connect partitioned Areas (AREA 0) or Areas that are not connected directly to AREA 0. as required by OSPF design structrue. as According to OSPF, each AREA must be connected to AREA 0.

There are examples where you need to connect Area 0 incase if its partitioned or in some cases for failover scenarios.



netbeginner Sat, 01/30/2010 - 02:33
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Hii Mohamed,


One more question i was skipped to asked.  which is about Collision & BroadCast Domain.

Lets say i have 24 port SWITCH, Then how many collision domain and broadcast domain will be there.

As i understand, There will be one Broadcast domain and 24 different collsion domain...right..?

Second, If we have a ROUTER with four port fastethernet then how many collision domain and broadcast domain will be there.


Mohamed Sobair Sat, 01/30/2010 - 02:56
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Switch with 24 ports has the following:

a) 24 collision domains

b) 1 Broadcast domain.

Keep in mind if the Switch configured with Vlans, each vlan is a single broadcast domain.

Router with 4 ports , depends, If its 4ESW switch module, then each port is a collision domain and all ports are part of one broadcast domain.

If any of the four ports is layer-3 port, then each port is a single broadcast domain.




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