Most Popular
1500 questions
20
votes
3 answers
What do TCP/UDP add to "raw ip"?
I know that both TCP and UDP are built on top of IP, and I know the differences between TCP & UDP, but I'm confused about what exactly "raw ip" is. Would it be fair to say that TCP & UDP both implement IP, but that IP in and of itself isn't capable…
John Dorian
- 303
- 2
- 5
19
votes
5 answers
Should portfast be used on a port potentially connecting to an unmanaged switch?
I understand the basics of how spanning tree works and why you would want to use portfast on user access ports.
When dealing with a topology with a large number of dumb switches under desks and other undocumented locations do you really want to…
Tim Brigham
- 688
- 1
- 4
- 15
19
votes
6 answers
Why use IP if we already have a MAC address?
I am preparing for ICND1 exams and recently started to learn about different Cisco devices.
I have just come to know how the packet is generated to be transmitted over a network, or outside the network.
For example,
When the packet is generated, it…
Sufiyan Ghori
- 449
- 3
- 6
- 12
19
votes
4 answers
Routing traffic out different links from the same BGP AS
I have two sites, A and B, in BGP AS 65000, and a third site, C, in AS 65001. All three sites have connectivity via carrier MPLS and there is internal connectivity between sites A and B. I am trying to influence BGP so that traffic from site A to…
Jeremy Stretch
- 4,718
- 1
- 31
- 42
19
votes
6 answers
Network latencies between opposite ends of the Earth
This is just out of curiosity.
when I pinged domains such as bbc.co.uk and google.com (in California), I get latencies of around 5ms as below:
64 bytes from xx: icmp_seq=0 ttl=55 time=2.940 ms
64 bytes from xx: icmp_seq=1 ttl=55 time=3.785 ms
64…
user58476
19
votes
5 answers
How is 8 bits sufficient for the TTL in an IP header?
The TTL (Time to Live) is an 8-bit field in the IPv4 header. It can take any value from 0 to 255. If this means that the packet can take a maximum of 255 hops (routers) on its way to its destination, then the packet will be discarded.
How is it…
reddi hari
- 199
- 1
- 3
19
votes
2 answers
How do you get an ASA to announce NAT'd 'outside' addresses in to an OSPF zone?
Device arrangement is as follows:
BGP Peers
+
|
|
+------+-------+
| |
| Juniper MX5 |
| |
+------+-------+
|.254
OSPF | 10.0.1.0/24
|.1
+------+-------+
| |
| Cisco…
SimonJGreen
- 1,675
- 12
- 29
19
votes
4 answers
Can DHCP Server determine client's OS?
Is it possible for the DHCP Server to determine the client operating system?
I'm working on a monitoring tool for gateways on local networks that is web-based and would like to be able to somehow determine what OS a device on the network is running…
Michael Lang
- 291
- 3
- 4
19
votes
2 answers
Ethernet autonegotiation differences between (10M | 100M | 1G) Ethernet
I am studying for CCNA and on Wendell Odom's book is said that(regarding autonegotiation):
When autonegotiation fails on one node, to choose (half/full-duplex) we must use the rule:
If you have a 10/100 Mb/s interface -> use half-duplex
If you have…
BrunoMCBraga
- 811
- 3
- 9
- 13
19
votes
1 answer
Finding transparent firewall packet loss
We use the Cisco ASA 5585 in a layer2 transparent mode. The configuration is just two 10GE links between our business partner dmz and our inside network. A simple map looks like this.
10.4.2.9/30 …
user2096
- 285
- 2
- 7
19
votes
2 answers
Can a probe request be answered on a different channel?
I am monitoring the 802.11 traffic in my network, and especially the active probing from my smartphone. I am sending Probe Requests for certain hidden SSIDs, but also an Undirected Probe Request, supposed to reveal networks matching the capabilities…
olamotte
- 293
- 2
- 6
19
votes
2 answers
Cause of high CPU load on Juniper peering router's routing engine
Recently the routing engine CPU utilization on two of our Juniper peering routers increased from ~10-20% average load to 80+%. I'm trying to figure out what's causing this (and how to get this high load back down).
Some info on the routers: both run…
Teun Vink
- 16,953
- 6
- 44
- 70
19
votes
8 answers
What is real difference between host and node in network
According to wikipedia host is
A network host is a computer or other device connected to a computer network. A network host may offer information resources, services, and applications to users or other nodes on the network. A network host is a…
apm
- 423
- 2
- 4
- 12
19
votes
3 answers
Is the "default VLAN" simply the default native (untagged) VLAN on all interfaces that have no configuration?
... or does the "default VLAN" have some wider meaning?
Also, can it / should it be changed? For instance, if a switch is going into part of a network that is only one VLAN and it's not VLAN 1, is it possible to make the "default" / native VLAN on…
Matty Brown
- 353
- 1
- 2
- 8
19
votes
2 answers
How does the router know how to route the packets to my terminal?
Suppose I have a network of 2 computers, each having a private network address of 192.168.1.101 and 192.106.1.102.
For my public ip address, it is 10.2.10.172.
When I make a http request to google.com, my computer will send out a packet with source…
Mc Kevin
- 301
- 2
- 6