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1500 questions
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1 answer

Network not participating in OSPF. Does not appear in the routing table

I am running OSPF on 2 router in GNS simulation for practice. Adjacencies are ok. Router R2 has in the routing table all networks of R3 . But R3 fails to add R2 network in its routing table . The network that is not participating in ospf is the…
blended
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2 answers

What does no shutdown command do? Cisco

Newbie here. I'm studying networking and struggling to understand the no shutdown command. I don't understand what no shutdown command actually does. I've read that it enables the interface but I don't even understand what that means. What does…
The_Bear
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6
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2 answers

How does a TCP segment fit into a smaller IP packet?

The IP protocol can handle fragmentation and it includes the fragmentation offset and identifier. I know this comes into play when your IP packet is too big for some specific network or link where the MTU is lower then the previous one. For example,…
Lucas
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6
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2 answers

Cisco show log number of messages

When I run the "show log" command, it displays the latest 360 messages. Why 360? Can this value by changed? If yes, what is the command for that? Thanks.
Léa Massiot
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2 answers

How does a router know the MTU of a network?

I've done several exercises where you're given the MTU of a net or subnet, but I wonder how routers know the MTU of the nets they're connected. I've learnt that in OSPF protocol this information is excanged among routers. However, is there another…
Josemi
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6
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1 answer

Two boot system images in cisco router

on my router I have two boot lines: boot-start-marker boot system flash c1900-universalk9-mz.SPA.157-3.M3.bin boot system usbflash0:c1900-universalk9-mz.SPA.157-3.M3.bin boot-end-marker I have a feeling that there should be only one line, and it…
TelePuzik
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4 answers

OSI layer of Neighbor Discovery Protocol

NDP operates using ICMPv6 and, even though ICMPv6 messages are encapsulated in payload field of IPv6 datagram, ICMPv6 and ICMP are usually considered as network layer protocols. At least, on Wikipedia they are network layer protocols. So I thought…
JenyaKh
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2 answers

RJ45 Cable only has 4 wires

The cable that connects to my rj45 only has 4 cables, blue, orange, blue stripe, orange stripe. When I connect them to their corresponding ports, there is no internet connection.(Blue = 4, Orange = 6, Blue stripe = 5, Orange stripe = 3) How can I…
Kevin Zhang
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6
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2 answers

Policy Based Routing for VPN connections with VPN Client configuration

We have a Cisco 2800 router in our company that also serves as a VPN server. We use the VPN Client to connect to our corporate network (pls don't laugh, I know that it is very obsolete but I haven't had the time lately to switch to SSL VPN). The…
Spirit
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6
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2 answers

How to connect a special device in a network

I have a question which is puzzling me. I have a couple of custom electronic devices (are identical, one is a master and the other is a slave) which implement only up to level 2 of the ISO/OSI layer, so they have only a (different) MAC address If I…
Lukariello
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6
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1 answer

TX-ring-limit Values

So, I am getting deep into my CCIE study and I just read about the TX-ring-limit interface command. I have used QoS a bit to oversubscribe software buffers to prevent frame loss on switches and whatnot, can you use the "TX-ring-limit" in a similar…
John Kennedy
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6
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3 answers

What's the difference between Serial DCE and Serial DTE link?

In the Cisco Packet Tracer we also see the Serial DCE and Serial DTE: but I don't know what's the difference between them.
26334_zeal
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6
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3 answers

Why is the BGP base on TCP 1027 rather than 179?

Why is the BGP foreign address port 1027? I use BGP to connect Router1 and Router2, but when I show the TCP progress: Router1>show tcp brief TCB Local Address Foreign Address (state) 4E976890 10.0.0.1.179 …
three-blocks
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6
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0 answers

HSRP IPv6 configuration

Looking at the Cisco documentation for HSRP IPv6 configuration I noticed the use of 'standby 1 ipv6 autoconfig'. interface FastEthernet0/0 no ip address duplex auto speed auto ipv6 address 2020:AB8:2001::1011/64 ipv6 enable standby version 2 …
dcrearer
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6
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2 answers

Internet structure and ISP networks in detail

I am studying about internet structure, ISPs and their interconnection. However, I have trouble connecting some terms and understanding the greater infrastructure of internet in more detail. I will explain my view below so let me know if I am…
konstantinosAR
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