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1500 questions
14
votes
2 answers
Is daisy chaining switches increasing latency?
This is a general question not related to specific hardware. If we have the following configuration of daisy chained switches:
internet ---- core network ----- switch 1 ----- switch 2 ----- switch 3 ----- switch 4
Do you think the users connected…
vladiz
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14
votes
1 answer
Enterprise Network Equipment vulnerable to heartbleed
On 09/04/2014 the The Heartbleed vulerability was disclosed by the OpenSSL team.
The Heartbleed Bug is a serious vulnerability in the popular OpenSSL cryptographic software library. This weakness allows stealing the information protected, under…
radtrentasei
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14
votes
1 answer
Why BGP implements its own keepalive instead of using tcp keepalive?
BGP doesn't use TCP keepalive, it uses its own keepalive mechanism. My question is why can't bgp turn-on the SO_KEEPaLIVE of TCP and live happily? why does it not use tcp keepalive and implement its own keepalive ?
Hemanth
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14
votes
3 answers
Why isn't multicasting more popular?
Multicasting seems provide an efficient method of routing networking traffic from a source to multiple end users, especially at this moment in time with teleconferencing, streaming media, online collaboration tools in high use. Looking into it, it…
d1n037
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14
votes
2 answers
Shielded Twisted Pair (STP) termination and grounding
I have knowledge terminating CAT5 UTP.
But, for an installation in a remote office, the cable will be routed near a power source which we already know causes a substantial amount of 'noise' on standard telecom cables.
We have purchased some CAT5e…
HaydnWVN
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14
votes
2 answers
Why does "show interface" show "Last input never" when packets input is incrementing?
Why is it that when I perform a show interface command I see that Last input always shows never?
FastEthernet1/31 is up, line protocol is up (connected)
Hardware is C6k 100Mb 802.3, address is 000d.bd5a.e94e (bia 000d.bd5a.e94e)
Description:…
Mike Marotta
- 2,057
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14
votes
1 answer
Getting Cisco ISAKMP and IPSec SA lifetime confused
I always get confused about security association lifetime configuration on Cisco IOS.
On most web-managed hardware it is clear which SA lifetime is for Phase I and which is for Phase II.
On Cisco however you got this crypto isakmp policy …
Alex
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14
votes
2 answers
IPv6 link-local vs unique local
When do you use link-local or unique local in IPv6 networks? (Cisco doesn't manage to explain it properly in their online material.)
Axel Kennedal
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14
votes
2 answers
What is a non-portable IPv4 address block?
For example, a Whois query for 4.4.4.0 says:
ADDRESSES WITHIN THIS BLOCK ARE NON-PORTABLE
Does the owner simply declare the block or a subnet are not up for sale? Or does non-portable have a deeper, technical meaning?
Here is the relevant section…
user2964971
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14
votes
6 answers
Cisco BGP - see communities on advertised-routes?
We have an outbound route-map on an eBGP peer that adds some communities to certain prefixes. Is there any way to prove that this is actually happening from the sender side in classic IOS?
show ip bgp neighbor x.x.x.x advertised-routes does not show…
AnotherHowie
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14
votes
1 answer
How can a TCP window size be allowed to be larger than the maximum size of an ethernet packet?
I know that TCP window sizes can be scaled to over 64KB, but looking at an ethernet packet datagram, such as this one:
it looks like a layer 2 packet is limited in size to be much smaller than that. How does ACKing work at the TCP layer if a single…
Zach Smith
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14
votes
3 answers
What is the difference between routing table and forwarding table?
What is the difference between a routing table and a forwarding table?
Manjitha Teshara
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14
votes
3 answers
Is there such thing as a network bridge?
Is there such a thing as a network bridge or is it always meant as a switch implementing a bridging function?
Whilst bridges are described as devices that create separate collision domains in network specifications and tutorials, I have never been…
Marcos Gonzalez
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14
votes
3 answers
Where can I use the IPv6 documentation prefix
We are currently building a networking course with a practical part where students have to configure a small network in a virtual environment.
However, we are not sure what ipv6 prefixes we can use for the configuration. The IPv6 documentation…
sliebald
- 143
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14
votes
2 answers
What is SNR Margin and Line Attenuation?
I'm currently using an adsl connection and last week an engineer from my ISP came and told me that my SNR margin and line attenuation is not good, and they need to replace the main telephone cable to provide cable tv. I tried researching on SNR…
Dilum Jayawardhana
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