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1500 questions
18
votes
6 answers
IPv4 Segment 100.64.0.0/10
I recently got to know that IP segment 100.64.0.0/10 has been reserved by IANA for 'Shared Address Space'.
My question is: Can I use the IP Segment 100.64.0.0/10 as a private range in my network (like the way we are using 10.0.0.0/8)?
If yes, then…
Gaurav Kansal
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18
votes
5 answers
Why use PPPoE and not use IP directly?
As far as I understand, PPPoE operates over ethernet, so for PPPoE to be usable you should already be able to send Ethernet frames to your ISP.
At that point, why use PPPoE at all? Why not just run IP directly over that Ethernet-like link, assign an…
André Borie
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18
votes
3 answers
How does multihoming work with ipv6?
What are the differences between multihoming in IPv4 versus IPv6?
Can an enterprise request a provider-independent IPv6 address space from its RIR/LIR which can be advertised to multiple upstream providers via BGP just as in IPv4?
Are the rules…
User123456
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18
votes
3 answers
Can my MAC address be identified by a web site?
Can my MAC address be identified by a web site when I access the site?
Does it make a difference if the site requires me to upload files?
MRTgang
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18
votes
4 answers
Is GRE necessary for an IP-only tunnel?
I need to build a simple point-to-point tunnel to connect an office through an area of the network we trust but directly don't control. Does the tunnel need to be GRE-encapsulated or can I use direct IP-in-IP? (We won't be using IPsec for this…
Jeremy Stretch
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18
votes
7 answers
Cisco command to show which interfaces an ACL is applied to
For Cisco routers and switches, is there a show command, or something similar, that will display what physical and logical interfaces an ACL is implemented on and what direction it is applied in?
I am looking for something simpler than a show run |…
Adam Loveless
- 3,129
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18
votes
2 answers
In which OSI/TCP-IP model layers do BGP, RIP protocols belong?
We know that in the OSI or TCP-IP model, the higher layer utilizes the services offered by the lower layer. For example, the data link layer uses services offered by the physical layer, network layer uses services offered by the data link layer and…
Mahesha999
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18
votes
7 answers
Best practice for the combination of HSRP and ECMP
The combination of ECMP (or other causes of asymmetric paths) and HSRP is broken by default in Cisco IOS; the default behaviour with this design floods unicast traffic excessively.
What is the best-practice for using HSRP with ECMP to prevent…
Mike Pennington
- 29,876
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18
votes
4 answers
Cisco APs ignore DHCP Option 43 and use CAPWAP UDP broadcasts
Background
I am trying to redeploy Cisco 1242 LWAPs on new Cat4507R+E switches, which means the IP address of the WLC is changing for that LWAP. For some reason, I have to configure ip helper-addresses on my AP vlan to jumpstart communication…
Mike Pennington
- 29,876
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- 152
18
votes
4 answers
Bad Mask for IP Address Error
I'm not too clear on subnetting rules and experienced an error when I tried to assign 148.26.1.176/28 to an interface on my Cisco router. Can someone please explain why it was not allowing me to assign this address to the interface? I receive an…
THE DOCTOR
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18
votes
3 answers
Writing text to the log
Is it possible to write an arbitrary line of text to the log of a Cisco IOS 12.x device?
I should like to be able to put in markers when fetching configs via TFTP and I would like to be able to have log lines á la
May 30 14:14:00.000:…
Jan
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18
votes
4 answers
Why does WLAN use Collision Avoidance and not Collison detection?
I am searching for this answer for quite some time now. Why there is CSMA/CD in LAN but CSMA/CA in WLAN?
The best explanation I could find is "due to extreme ratio in transmitting and receiving power, it is very impractical to transmit data on the…
vish213
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17
votes
8 answers
When *not* to create a SVI for a L2 VLAN?
When creating VLANs for just L2 on a switch -- routing will be handled by a device within that VLAN such as a load-balancer -- it isn't necessary to create the vlan interface. As a matter of habit, I always create the interface anyway-- no IP…
generalnetworkerror
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17
votes
3 answers
Why does one say IP fragmentation is bad and to be avoided when in reality data always needs to be fragmented for MTU compatibility?
Why does one say fragmentation is bad and must be avoided due to performance issues when in reality fragmentation intrinsically occurs within the communication ?
Example:
User1 wants to send 100 000 bytes to User2
Maximum MTU size of the network…
Floji
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17
votes
3 answers
Is it possible to specify a route for a packet to take?
So, AFAIK, packets "hop" between routers. Packets are forwarded via a router's default path until it gets to destination IP. So is it possible to specify a specific set of routers this packet "hops" to?
lpydawa
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