Top posts
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Help to understand L3 SW
Question: I hope you can help me as usuall , i designed a layer 3 lab contains 4 L3 WS-C3560X-48T-S switches + Vlans , the issue is as the following : i can ping any pc from sw0 to sw1 but i can't which is weird ping any thing else like from sw0 to sw2...
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Open a range of TCP ports in Cisco IOS NAT
Question: ip nat inside source static 192.168.1.10 10.10.10.9 route-map RANGE ! route-map RANGE permit 100 match ip address 102 ! access-list 102 permit tcp host 192.168.1.10 range 3000 3389 any The configuration does not seem to work.. just creates a...
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Native VLAN explanation
Question: Can someone explain to me what a native vlan is? How it compares to other types, i.e. management, default, etc. I am having a hard time with the terms. Answer: I am looking at a network with different native vlans across multiple switches. While...
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How to configuring default gateway on switch
Question: I took some very good advice & signed up for the Cisco Learning Lab. The wording on the intial switch setup instructions & the default gateway is a little confusing. For a switch the ip default-gateway command should be run in the global config...
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How to get interface traffic snmp information for routers
Question: I have cisco 2921, zte, huawei routers..How can i get the traffic information of every interfaces of these routers. I donot have mib file of zte and huawei. So, i want a generic mib file which can monitor every interfaces of these routers Answer:...
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How VLAN Tagging, Untagging Works
Question: This seems like a simple concept but I'm having a hard time grasping which traffic is tagged vs that which is not tagged. We have a network of primarily WS-C3750X-24T-S switches with several VLANs, and dot1q trunks setup between the switch stacks....
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How does IPv4 Subnetting Work
Your ISP gives you the range the network ID 192.168.40.0/24 (11000000.10101000.00101000.00000000). You know that you'd like to use a firewall / router device to limit communication between different parts of your network (servers, client computers, network...
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How do you configure vlan routing through 871 router
Question: We have a WS-C2960-48TC-L switch with three vlans connected to an 871 router. Vlan10 for servers, Vlan20 for workstations and Vlan30 for testing purpose. How can we get all three Vlans to go out the internet and have Vlan's 10 and 20 to talk...
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Cisco Routers Password Reset
Learn how to reset and/or clear the console and enable passwords from a Cisco 2900 Series Router(s) and other routers including the 1700, 3600, 3700, 1800, 2800, 3800 and the New ISR G2′s Series routers. The Cisco 2900 Series routers are by far the most...
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How can I make a PVST+ switch root towards MST network?
Question: In a network where the majority of the Cisco WS-C3750X-48P-S switches are running MST but a select few are still running PVST+, how can the PVST+ switch be configured to be the root of the spanning tree? Topology below: +--------+ +---------+...
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Portfast to non managable switch
Question: Recently i have found that in one of the Cisco WS-C2960S-48FPS-L switches in our environment, portfast enabled to a interface whichis connected to a non-managable switch. But 3 servers are conencted to that non-managable switch. Since this switch...
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Cisco active/standby FWSM pair went active/active after switch upgrade
Question: PROBLEM: Both FWSM in our core switches went active/active and protected subnets have partial accessibility. SETUP: We have 2 x Cisco Catalyst 6509 switches running IOS version 12.2(18). Each switch has a FWSM internal firewall module. Both...
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Details about C6509-E with the modules VS-S720-10G-C,WS-X6708-10G-3C, and WS-X6548-GE-45AF.
Question: We are building C6509-E chassis that will have dual supes with the following modules VS-S720-10G-C Does this already come with the MFSC3/PFC3C WS-X6548-GE-45AF Does this already come with the WS-F6K-AF card What is the difference between this...
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Cisco 3750X channel-misconfig
Question: I have two WS-C3750X-24T-S for stack, and i want connect a 2960 switch on this stack with port-channel. I connect 2960 G0/1 to 3750X G1/0/24, and 2960 G0/2 to 3750X G2/0/24. the config is that: 3750X: interface Port-channel1 switchport trunk...
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Is EIGRP a Hybrid Routing Protocol or Advanced Distance Vector Routing Protocol?
This question was discussed recently on the Cisco CCIE Routing and Switching Study Group website. It took me years to work out that the problem with this question is the question itself, not the answer. The question gives the impression that “Hybrid“...
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Private VLAN (PVLAN) on Cisco switch
The definition of Private VLAN is: Virtual LAN (VLAN) is a mechanism to divide a broadcast domain into several logical broadcast domains. Private VLAN is an extension to the VLAN standard, already available in several (most recent) physical switches....
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Subnetting question
Question: What valid host range is the IP address 172.29.217.11/22 a part of? Answer: Network= 172.29.216.0 Range= 172.29.216.1 to 172.29.219.254 Broadcast= 172.29.219.255 Next Network= 172.29.220.0 Just want to share with you how would I do to calculate...
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VLAN Communication Problem
Question: So the problem is we have a device or host that needs to communicate on a specific VLAN. This VLAN is not new, it is running all throughout our environment and works fine. But the VLAN was recently configured on the switch in question, a Cisco...
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IP Route Problem
Question: If a Cisco WS-C3750X-24S-S wants to forward a packet to X destination when it looks in its routing table what does it compare for? a.Mask b. Next-hop router c. Subnet ID (I know this is one but what is another option in this) d. Outgoing interface...
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ACL blocks ping or telnet both ways
Question: When I tried some textbook ACL to block pings or telnet from a certain source, the ACL not only blocked pings or telnet from that IP address, but also blocked itself from ping or telnet into that IP address. It's out of my expectation that ACL...
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Eigrp -- Stuck in Active
Question: I was asked about SIA (EIGRP) in an interview, I explained the SIA but when interviewer asked me how can SIA situation be avoid, I could not answer. Could someone help me about this please.....?? Answer: There are actually lots of methods to...
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Cisco ospf router-id
Question: The rules for assigning the OSPF router-id to a router or a 3-layer switch like WS-C3560X-24T-L (if no router-id is configured manually, the highest ip of the loopback interfaces is used. If no loopback interfaces then the highest ip of physical...
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SNMP -- String Read only
Question: I would like to know is the Read only SNMP string is able to retrieve/read the full config? I got vendor request for SNMP read-only string, i wonder if they can read running-config of my WS-C3560X-24T-L by pulling with read-only right, they...
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Passive interface question
Question: Just a small query on the use of passive-interface. Say I have a router with 2 interfaces, 1 fast ethernet (LAN) and 1 serial. I configure the serial interface for RIP using network 192.168.1.0. Now if I DONT use the network command to configure...
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VRRP feature
Often one of the least redundant parts of a network is the first hop between a host and the rest of the network. This is because they are typically configured with a default gateway IP address that links to a single device. Should this device fail, then...