Network Engineering Stack Exchange
Network Engineering Stack Exchange

Most Popular

more tags
1500 questions
15
votes
3 answers

What is the purpose of TIME WAIT in TCP connection tear down?

I found that the reason the active closer enters TIME WAIT is to make sure that the final ACK is not lost. But how does it know if the final ACK is lost? Will the passive closer resend the FIN and then the active closer knows the ACK was lost? Here…
czhao
  • 253
  • 1
  • 2
  • 4
15
votes
6 answers

Ethernet termination density per rack and space planning

I am in the process of designing the network for a new office space. To give a little bit of background... There will only be one network closet to start with potential for an IDF in the future. This closet will have approximately 600 termination…
thefiddler
  • 345
  • 1
  • 3
  • 6
15
votes
4 answers

/31 Point-to-point bitmasks

When is it appropriate to use a /31 network in production, and is using them considered good practice? On a point-to-point link, broadcasts shouldn't be required, so is there any compelling case for just using /31 over /30 as it seems /30s are…
knotseh
  • 2,535
  • 4
  • 24
  • 35
15
votes
2 answers

IPv4 Address Space Planning Best Practices

A recent question from Craig Constantine pertained to IPv6, but many people are not on the leading edge with IPv6 yet and are still responsible for new or improved IPv4 deployments. I would like to validate my own enterprise IPv4 address space…
generalnetworkerror
  • 7,094
  • 6
  • 32
  • 65
15
votes
7 answers

TCP acceleration over satellite or high latency networks

What viable companies, products or options are out there today for TCP Acceleration over satellite or high latency IP networks? The average satellite RTT is upwards from 600ms (depends on the location) TCP doesn't work too well as the window sizes…
knotseh
  • 2,535
  • 4
  • 24
  • 35
15
votes
2 answers

ASICs vs x86 general-purpose routing/switching

SysAdmins often try to convince me that x86 general-purpose OS's can perform just as well as routers with low MHz CPUs and dedicated silicon (i.e., ASICs) at 1Gbps line rates. This thinking is carrying over into the SDN realm such as virtual…
generalnetworkerror
  • 7,094
  • 6
  • 32
  • 65
15
votes
3 answers

Configure pfSense to not give 'potential DNS rebind attack detected' warning for local server

I am needing to access a local LEMP server through its domain name for a PHP package that uses domain names in every link, making IP address usage not possible for this application. I can access the domain just fine from devices elsewhere on the…
Paul
  • 251
  • 1
  • 2
  • 7
15
votes
3 answers

Why does BGP RR only reflect the best path?

Can anyone answer why does BGP RR only reflect the best path?
Bo Cao
  • 401
  • 4
  • 7
14
votes
4 answers

Enabling MLS QoS on a production 7600

I am looking at a 7609-S with a RSP720-3CXL running 12.2(33)SRE3. I have been asked to help with rate limiting some servers attached to a couple of ports running as L2 ports (switchport mode access), so this requires me to apply a policy-map to the…
jwbensley
  • 5,290
  • 7
  • 37
  • 79
14
votes
2 answers

Wireless Probe Request Forwarding Best Practices?

I'm working with a couple Cisco WLCs and I know that they use information about client signal strength in determining device locations but I was reading up on "probe requests" and found that, by default, access points will forward probe requests…
David
  • 315
  • 1
  • 4
14
votes
2 answers

What is the purpose of BGP TTL security?

What attack vectors does the BGP TTL security knob protect against?
Aaron
  • 1,637
  • 18
  • 34
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
  • 536
  • 1
  • 9
  • 23
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
  • 1,099
  • 13
  • 32
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
  • 1,114
  • 11
  • 22
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
  • 1
  • 14
  • 26
1 2 3
…
99 100