Top posts
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Cisco IOS File System
Every Catalyst switch requires an operating system to ensure the ongoing operation of the switch, as well as ensure the configuration applied to the switch is implemented by the various hardware components. Cisco Catalyst switches include a main operating...
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VLANs, Trunk and Access ports
Let’s talk about VLANs today. Some time ago a friend of mine made me a question. If two PCs are connected to two different switches and they are in two different VLANs, however, the switches are connected to each other with access ports (each belonging...
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Cisco ospf lsa types
Type-1 LSA – It’s is the Router LSA; this is defined in order to send the link state information about the attributes of the directly connected routes, besides of that you have just ONE type-1 LSA per every router inside your area. Type-2 LSA – It’s the...
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Blocking and listening state in STP
Question: In blocking state switch ports will only listen BPDUs but not forward BPDUs. If yes then how this switch is receiving BPDUs from other switches since other switch ports will also be in "disable" state so they can not send BPDUs. I heard that...
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How to find the actual boot image on cisco catalyst 6503 E
Question: I would like to verify what is the actual boot image running on my catalyst 6503 E SUP 2T. My IOS is s2t54-adventerprisek9-mz.spa.151-2.sy.bin and my Rommon is ok with the version 12.2(50r)sys3. I tried many command without any success. Here’s...
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Cisco CEF
Cisco Express Forwarding (CEF) is an advanced layer 3 switching technology used mainly in large core networks or the Internet to enhance the overall network performance. Although CEF is a Cisco proprietary protocol other vendors of multi-layer switches...
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The basic ospf configure
OSPF is an interior gateway routing protocol that uses link states rather than distance vectors for path selection. OSPF propagates link-state advertisements rather than routing table updates. Because only LSAs are exchanged instead of the entire routing...
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How to calculation OSPF metric
Question: Hello,I have some questions reagrding OSPF metric calculation. Within network configuration I have uploaded, I have shown two routing tables, with lines indicating which router they are from. I understand that the OSPF metric calcualtion uses...
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The question about 2960 vlan implementation
Question: A company with a flat network has an estate of 2960 switches. They also have Sophos UTM 425 devices with 4 spare ports. They need to implement VLANs with ACLs to segment the network. Is it possible to implement the ACLs on the switches? Or would...
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The problem between layer 3 and layer 2 device
Question: I have a WS-C2960S-24PS-L switch and its set only as an Access layer switch. uplinks arent even trunked. im using the native VLAN for mgmt and a different vlan for the users. the switch is being able to work as layer 2,switching packets. but...
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Cisco 3560X vlan acl
Question: I am having some issues getting ACL to function they way I would like. I have many clients on differnet vlans (vlan 6-10) and my ASA (10.1.99.254) on vlan 99 for internet access. I need vlans 6-10 to have access to the ASA for internet, but...
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Cisco rip configure
IP RIP comes in two different versions: 1 and 2. Version 1 is a distance vector protocol and is defined in RFC 1058. Version 2 is a hybrid protocol and is defined in RFCs 1721 and 1722. The CCNA exam now primarily focuses on version 2. There are no major...
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Cisco ip sla and track
Question: Today I have configured IP SLA tracking for Internet link and used PBR to route my LAN traffic as per my choice. Everything went fine and working very good without any problem, just have a question how it is working. below is my topology and...
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Cisco 3560 advanced ip services image
Question: Bought a WS-C3560X-24P-L poe and its currently running base ip services. c3560-ipbasek9-mz.122-44 Decided to download the latest version of Advanced ip services since its needed for Ccnp switch which ill be starting soon. Problem is i cant find...
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Storm controll and unicast flooding
Question: What is the difference between storm controll and unicast flooding? Also, why is unicast flooding called "unicast" if it refers to multicast as well? I know the second questions is picky but just wanted to hear opinoons on it. Answer: Storm...
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The way to control MAC flooding attack?
Question: Port security is the only control method for MAC flooding attack? Answer: To prevent MAC flooding attacks, network operators usually rely on the presence of one or more features in their network equipment: With a feature often called "port security"...
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How to choose a DR & BDR
Question: In a topology i implemented OSPF having 4 3-layer switch(like WS-C3750X-24T-L) connected. A, B, C and D named router. can u help me determining the Designated Router and BDR.? list Router ID of A, B, C & D ? and describe types of LSA's being...
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Startup config file on cisco 3560x
Question: I have a WS-C3560X-24T-L switch in my CCNP that I have configured already and its working as I wanted. The issue that I am facing is that I have got an another swith,I want this one to be exact replica of what I have in place right now. I have...
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Multicast and Unicast in Ospf
Question: I am currently studying OSPF and I got confused by reading the book (Foundation Guide) and then aplying what learned to my 3-layer switch WS-C3560X-48T-L. The book refers that Update and ACK packets are sent to multicast address alongside with...
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Cisco default router ID
Question: I guess first of all, are Cisco routers configured with a default router ID? I was thinking router IDs are used only (for CCNA exam purposes anyway) in configuring OSPF DR and BDR, and there is no default ID, just what you assign, and is used...
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Root bridge ID and root port
Question: On the list of tie breakers to determine a root port or DP the first item is root bridge ID then root path cost in cisco switch,for example Cisco WS-C2960S-24TS-L. Whenever working it out we always start by looking at path cost and never consider...
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OSPF DR/BDR election
Question: I am unable to understand the ospf DR/BDR election process on which is elected first. I got a fair idea from some of the previous discussions in this forum that elections is done for BDR first, i need to know in depth about the process of this...
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Benefits of single ospf area
The original question was about advantages of single area OSPF. It seems to me that is really more advantages of multi area OSPF. I offer the suggestion that an advantage of single area OSPF is that every router or just a 3 layer switch like WS-C3560X-48T-L...
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VTP vlan updates
Question: I am getting following issue after configuring SW1(WS-C3560X-48T-L) as aTRANSPARENT MODE and SW3 & SW4 as a CLIENT MODE. - SW3 does not update or delete VLAN definition. -SW4 does update and delete vlan definition. -SW2 is configured as a SERVER...
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Some questions about vtp
Question: I need some guidance in VTP Configuration in cisco WS-C3560X-48T-L, 1. How I can delete VTP Domain name without removing vlan.dat . 2. What is the path for vtp configuration fil and can we save it separetely 3. Can VTP 3 and VTP 2 are compatible...