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1500 questions
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2 answers

Cisco 2960 Portfast ports generate Spanning Tree TCN

We are operating several Cisco 2960S stacks here and, for some time, are experiencing regular Spanning Tree TCNs (Topology Change Notifications). When using show spanning-tree detail to get to the source of the TCN, they originate from different…
xpac
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Determining optimal bandwidth needs for the office

We're currently using the Cisco 1921/K9 router along with SG300 L3 switch and other L2 switches in the office environment. We're hooked up to a 10M fiber line for internet but not sure if we need that much bandwidth yet. What's a good way to test…
lamp_scaler
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8
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4 answers

How to divide an IPv4 network into subnets of different sizes as efficiently as possible?

I need to divide a network 172.16.0.0/12 into 3 different subnets for different purposes. One of them needs 6 host addresses, another 85 host addresses and the last 100 host addresses. It should be done so that as few addresses as possible goes…
markus
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8
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3 answers

Traffic Policing

I know traffic policing isn't something that you normally find in a LAN environment, and I wish I wouldn't be finding it in mine. That being said... I have no choice. The device is a 3750X. The requirement is to POLICE (not shape) all traffic coming…
BrianK
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8
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7 answers

Signaling vs encoding

Here are Cisco's definitions. Signaling The physical layer must generate the electrical, optical, or wireless signals that represent the "1" and "0" on the media. The method of representing the bits is called the signaling…
user1534664
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8
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5 answers

Cisco Static NAT with route-maps

Update: Seems that route maps only match on IP addresses, not on the ports. Had another situation this week on a different device, model and software version. Ended up changing the NAT statements to: ip nat inside source static tcp 192.168.1.20 3389…
Firebirdnz
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1 answer

Why have all my lab routers set their OSPF priority to 0?

I have 4 routers in my lab. FR1 is the frame relay switch (2621), R1(2621), R2(2651) & R3(2651) are all connected in a mesh using sub interfaces - R1 has pvc to R2&R3 and so on. Without OSPF I can ping all points successfully. With OSPF I can also…
A J Rossington
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8
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2 answers

Does 2504 WLC support LAG?

I am finding some contradictions in Cisco documentation about the LAG support in 2504 WLC. On one hand, the Cisco 2500 Series Wireless Controller Deployment Guide clearly states: Note: Link Aggregation (LAG) is not supported on the Cisco 2500…
Daniel Yuste Aroca
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8
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3 answers

OSPF Backbone Area and the WAN

I am working on a new network deployment, and have run into an interesting question... Should the OSPF area 0 be extended across a WAN's point to point links (thereby creating more border routers), or should one's WAN Aggregation router serve as…
Justin Jahn
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8
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4 answers

Is multicast possible in tcp?

I got an assignment to implement unicast, multicast and broadcast in UDP or TCP in java, so I searched for it and I only got UDP implementation of multicast. My question is following: Is there multicast possible in TCP?
lazarus
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1 answer

Unusual wildcard mask in Cisco ACL configuration

I inherited some configs on a network I manage from a previous administrator. In some of the ACLs there are some very strange wildcard masks that i've not seen before, for example: 10 permit ip any 10.160.1.0 0.31.0.255 I cannot find anywhere…
BenSBB
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8
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7 answers

Why would a VPN require a T1?

Forgive me as I have very little domain knowledge in this area, I'm helping out at my parent's office and was asked to look into speeding up the internet. They've been using this IT guy that I think is ripping them off... They have a T1 line which…
user2755334
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8
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3 answers

cheaper 40gb optics/uplinks?

I'm pricing out a decent size 10gb network (6-8 ToR switchs) and the uplink costs are a major factor. I figure each ToR switch needs 4x40gb uplinks and you have a cost for the uplink optics that is approximately the cost of the ToR switch itself,…
Kelly McDowell
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8
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2 answers

Stopping Cisco Prime/NCS from resizing maps

I've been having problems with Cisco Prime 1.3 (and other versions) re-sizing maps once you've put them into the map view. This happens for buildings and floors alike. On the cisco documentation it says this: Step 1 Save the map in .PNG, .JPG,…
user275
8
votes
5 answers

Why is the IP layer aware of higher layers in the network stack?

In the IP packet header there is an 8-bit Protocol field (at offset 9) that holds the "next level protocol", with assigned numbers given in RFC 790. For example, TCP is 6. My question is, why is the IP layer aware of higher layers in the network…
I. J. Kennedy
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