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1500 questions
12
votes
4 answers

How to know whether a protocol uses TCP or UDP

Well I know that might sound a stupid question and I believe that the most proper answer will be like I will be able to tell as my experience builds up and I learn more and more about the protocols. However I am a student and I am not having much…
Mahesha999
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12
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2 answers

Syslog message for CDP interface down

I have been searching for this for a while and haven't found one yet. I need a Cisco IOS command to send a syslog message or snmp trap whenever an interface that has a CDP neighbor goes down. Some people have told me just rely on routing protocol…
radio-free-europe
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12
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2 answers

What are EUI-48 and EUI-64?

What are EUI-48 and EUI-64 addresses formed and used? Give me examples. What are MA-L, MA-S and MA-M assignments? I have read https://standards.ieee.org/develop/regauth/tut/eui48.pdf and https://standards.ieee.org/develop/regauth/tut/eui64.pdf And,…
user15062
12
votes
3 answers

Identifying a Cisco access point post-install

We have about 50 Cisco 1242 access-points and we're managing them with a Cisco 4404 Wireless Lan controller. The guy who installed the APs did not assign a location to the access points in the controller. We are seeing some malicious behavior from…
Michael Teeman
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12
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2 answers

Tracing TCN Messages in STP

We have about 20 vlans on a L2 network running Rapid PVST+ where the root bridge is a stack of Cisco's 3750 switches. I am a bit puzzled by the number of TCN notifications I receive on the switch.. The 3750 stack is the root for all VLANs and it…
user209
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12
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1 answer

Site-to-Site VPN Tunnel Up Not Passing Traffic

I have a site-to-site VPN that seems to be dropping traffic from a particular subnet when a lot of data is being pushed through the tunnel. I have to run clear ipsec sa to get it going again. I notice the following when running show crypto ipsec sa.…
Rowell
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12
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2 answers

Do unused Cisco IOS features take up RAM/CPU resources?

For example, let's compare IP Base vs. Advanced Enterprise Services. Let's say you have advent installed, but you're only actually using the features relevant to ipbase. Other than flash memory space, would running advent when you only need ipbase…
WaxTrax
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12
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2 answers

What's the difference between TPID of 0x88a8 or 0x8100

I was reading over some JNCIS-SP documentation on provider bridging and it had this to say regarding the TPID field for QinQ: IEEE 802.1ad has reserved a TPID of 0x88a8 for the S-TAG however the JUNOS operating system default behavior is to set…
Luke Klimasauskas
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12
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5 answers

What does the notation F0/0 and F0/1 mean in this diagram?

I've recently been taking over an OpenStack environment that makes use of neutron networking with the use of GRE tunneling. We had a problem with network performance and I determined it to be an issue with the MTU setting in certain VM instances…
slm
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12
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1 answer

NX-OS peer-switch issues with 6500 VSS

I'm bringing up a new pair of Nexus 5500s running NX-OS 5.2 and I'd like to make use of the new vPC Peer Switch feature: The Virtual Port Channel (vPC) peer switch feature addresses performance concerns around STP convergence. This feature allows a…
scottm32768
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12
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2 answers

Does SCTP work over the Internet?

I am working on an application that would be able to take advantage of the multi-streaming features of SCTP. Does SCTP work across the Internet? Is it supported by ISP's routers and consumer routers such as in homes and small businesses? I worry…
jamesbtate
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12
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5 answers

Do faster segments of a network mean faster flow rate or lower latency?

This is another one of those hypothetical questions. I've been trying to figure out whether or not having a faster 'segment' of a network in between host A and host B will translate into a faster flow rate or lower latency between them. Let me show…
Libbux
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12
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1 answer

How is BGP "AS_SET" used?

RFC 1771 defines a path attribute type of AS_PATH as follows: AS_PATH (Type Code 2): AS_PATH is a well-known mandatory attribute that is composed of a sequence of AS path segments. Each AS path segment is represented by a triple
Eddie
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12
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3 answers

POE, POE+, UPOE

I see that Cisco now has a 60 watt POE option. What was the limitation that caused POE to have to be developed in stages of 15, 30, and then 60 watts? Why could they not just do 60 watts from the inception of POE?
Adam Loveless
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12
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3 answers

1 router, 1 internet connection/IP - multiple VRFs using the same ISP gateway

My knowledge of inter-VRF routing isn't the best. I have one public IP. The public Internet and its quad 0 is on the default VRF.... Then I have a Guest_VRF and a corporate_VRF which would both need to access the Internet and point to the default…
knotseh
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