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1500 questions
11
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2 answers

Trying to find out exact TCP overhead cost

Corresponding this topic: https://stackoverflow.com/questions/3613989/what-of-traffic-is-network-overhead-on-top-of-http-s-requests The maximum segment size (which does not include the TCP or IP headers) is typically negotiated between the layers…
agrrh
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1 answer

Can adding VLANs to a VPC be done hot?

In this scenario, we have a VPC '17', consisting of two single port port-channels 'po17'. There are 2 x N5K's (5548s) - so po17 from both sides combine to create the VPC. The downstream devices are blade switches (Cisco 3020s). We want to add a…
A L
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How can I make a PVST+ switch root towards MST network?

In a network where the majority of the 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: +--------+ +---------+ | …
Daniel Dib
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1 answer

How to understand "normal burst" and "maximum burst" in Cisco CAR?

As I understand, Cisco IOS CAR(Committed Access Rate) is based on leaky bucket algorithm(idea is exactly the same as token bucket algorithm) and the amount of bits I configure as average rate, is the amount of "water constantly leaking the bucket".…
Martin
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11
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2 answers

How do wifi clients detect SSIDs from APs?

How can my wifi board detect wireless networks that are in range? What protocol is used to communicate with the devices in the area to announce a wifi AP? Does every router transmit on its own frequency and my wifi board scans "every" frequency to…
zer0uno
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11
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7 answers

Only One Path in the Looking Glass

I understand that only the best path is advertised to eBGP neighbors, but is this true of iBGP? If I peer with two providers, I was under the impression that anyone else peering with both of my providers would have two paths to me. After inspecting…
Dennis Olvany
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11
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11 answers

Locate a host on Network

What is the best method of locating a particular workstation on a VLAN ? I sometimes need to do this, if a workstation IP address, shows up on an ACL Deny torrent use High bandwidth usage (Top Talkers) Snort alert The way I do it now, Logon to a…
hyussuf
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11
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1 answer

How can I check to see if I am receiving MED's?

I have a BGP session with a transit provider in two different cities. We are both using the same AS at both locations. I am expecting them to be sending me MED's for me to use for routing decisions of outbound traffic. (ie. so I can send traffic…
zevlag
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1 answer

Cisco IOS built-in SSH client default version

You issue the command ssh 192.168.97.97 from a IOS device and the destination IOS router/switch SSH server is accepting both SSH versions. Being that you did not specify a version to use on the SSH client, which version of SSH will be used to…
Adam Loveless
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11
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2 answers

RIP routing is broken between two routers

There are 2 routers connected something like this: Network1 ----- (172.16.1.1/24) Router 1 (172.16.3.1/30) ------ (172.16.3.2/30) Router 2 ------ (172.16.2.1/24) Network 2 I try to add addresses for dynamic routing using the RIP protocol, for…
Random42
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11
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3 answers

Circular BGP propagation

This one is a difficult to describe, it's hypothetical because I'm learning about routing and right now I'm focused on BGP. Let's say my ASN is 65000, and I announce 192.0.2.0/24. My peer, AS 65001 updates its routing table with its routes to the…
Libbux
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11
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2 answers

Preventing STP loops in etherchannels configurations

What is the best practice when configuring etherchannel on Cisco switches to prevent a STP loop/broadcast storm when etherchannel is mis-configured? I had an instance where 2 ports on a switch were configured with via trunk ports properly however…
knotseh
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11
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2 answers

In IPsec VPN, how is the pre-shared key encrypted?

I was doing IPsec VPN on ASA 8.0, and I understand a little about that. The initiator starts by sending its ISAKMP policy to the responder, and the responder sends back the matched policy. After that, the Diffie-Hellman key gets exchange, and then…
user3347934
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11
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2 answers

OSI model and physical location of the layers

Hi Cisco student/newbie here! I understand that data passes down through the OSI model and then at the physical layer is transported as bits across the networkcables. But I'm confused at exactly where the layers are happening (in the PC, in the…
Fibie
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11
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2 answers

Interpreting TTL in ping results

I work for a VoIP service provider and I am working an issue with a customer who has a cable internet connection that's throwing me for a loop. He has a single block, which we'll pretend is 70.141.15.0/29, with the gateway at .1 and routers at .2…
DTD
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