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1500 questions
14
votes
7 answers
Is a DHCP offer packet a broadcast or unicast?
DHCP OFFER is a layer3 broadcast because the server doesn't know the client's IP, but the server knows the client's MAC address. So why does it send the OFFER as L2 broadcast?
If anyone ask me about this - how should I answer? Can I say its layer3…
ashok
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14
votes
3 answers
What is the meaning of RSSI?
When using mobile 3G routers, you see in the output of the "show cellullar 0 all" command. What is the significance of this value? Is this interpretation the same when talking about 2G or 3G?
Ex:
2G connection, RSSI -75
3G connection, RSSI…
Bulki
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14
votes
3 answers
Why we get high fluctuation on bandwidth measurement Cacti graph?
We were on redundancy test of Etherchannel and Routing on our network. During this intervention we made some measurement. Our monitoring tool is Cacti for graph.
The equipment monitored is a 4500-X on VSS. Each link is on a different physical…
cgasp
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14
votes
1 answer
BGP "no synchronization" command not showing up in running-config
I noticed in the running config I don't see the no synchronization command under the BGP section. Is this a default command so I won't see it unless I change it?
Hardware / software
Cisco 1921
c1900-universalk9-mz.SPA.151-4.M5
evolvd
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14
votes
0 answers
PIM-SM with BSR over SSG5 VPN tunnel
I've created a lab to troubleshoot an issue I'm having with PIM-SM and BSR. There are two sites connected via two Juniper SSG5s (6.3.0r17) with just enough configuration to focus on the problem at hand (configs below). The sending site has an…
user1038451
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14
votes
1 answer
Troubleshooting low Metro Ethernet TCP throughput
Background
We rented a few layer 2 leased lines, i.e. you have one big pipe at the datacenter and the remote sites have smaller pipes. Inside the layer 2 network you can do whatever you like. Probably they use 802.1ad to give each customer their…
Marki
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14
votes
3 answers
How broadcasting works on different networks?
I was reading DHCP ( RFC 2131 ), I have basic knowledge about Relay Agent and Broadcasting. But for Understanding DHCP in depth, I felt like I have to know Broadcasting and Relay Agent ( RFC 1542 ) in details. But could not find any RFC (RFC919,922…
dillip_beta
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13
votes
3 answers
Management network. Best practises: big VLAN or routed interfaces
We are going to deploy a campus network with approximately 50 switches (Core, Agg, Access). Some of them will be L2 (20), and others will be L3 (30). We are thinking about how to manage these devices:
A big VLAN across all switches. Easy to deploy,…
Эдуард Буремный
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13
votes
6 answers
Finding Non-Cisco End Device IP Addresses Connected to Cisco Switch
I have Cisco catalyst switch, with many VLANs and address ranges.
How do I find IP addresses connected to the switch that are not Cisco devices?
John
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13
votes
3 answers
Mac-flap due to roaming clients on wireless
We are running an Aerohove wireless network (controller-less).. I occasionally get mac-flaps within the VLAN tied to a SSID. I know this is coming from a roaming client.. The problem is that the company I work for has end to end vlans (no money to…
user209
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13
votes
1 answer
Why in TCP the first data packet is sent with "sequence number = initial sequence number + 1" instead of "sequence number = initial sequence number"?
In the 3-way handshake, the initial sequence number of both endpoints of the TCP connection is synchronized.
Here is an example:
Endpoint A randomly generates an initial sequence number: 123.
Endpoint B randomly generates an initial sequence…
ilBarra
- 241
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13
votes
4 answers
What is the use of wild card masks vs normal masks
I've always wondered what the use of wild card masks was. When I learned about them in college I wondered what the use was, we saw that you could separate subnets by for instance even and uneven IPs. What is the practical use of wild card masks vs…
Lucas Kauffman
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13
votes
2 answers
Who has control over allocating MAC address to device manufacturers?
As of my knowledge each MAC address is unique for each device like servers, computers, firewalls, switches and routers, proxies, etc. So my question is: who is responsible for allocating these MAC addresses to the device manufacturers?
user73764
13
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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13
votes
5 answers
ASA 5550 - Reboot Worthwhile?
I've got an ASA 5550 that is performing loads and loads of operations (AnyConnect, NAT, ACL, RADIUS, etc, etc). It isn't particularly overloaded in terms of CPU & Memory, but it has an uptime of over 3.5 years.
Lately I have been attempting to…
BrianK
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