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Questions tagged [network-core]

One of the three layers of network design. The main characteristics of the network core are that is should be highly redundant and high performance. As such, it is often one of the simpler layers in that it should not implement any services that impact performance. No user/server connections should be made to a pure network core.

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1answer
64 views

Deploying Virtual Stackwise Catalyst 9400

I am looking into deploying Virtual Stackwise on the Catalyst 9400 series switches. I wanted to know based on best practices where should the VSL links be deployed on the Sups or the modules? Is there ...
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3answers
62 views

How to explain the data flow of OSI model layers in a single picture [duplicate]

Take an example of searching www.example.com in a web browser. I have some confusions at each layer and they are We have opened a web browser and searched for www.example.com. Now, As far as I know, ...
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1answer
46 views

What is the use of Phy and MAC chip?

Is it mandatory to have a MAC and PHY chip? Are these two chips within a NIC CARD? As I understand, these two chips are connected using RGMII or SGMII or xaui.
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2answers
88 views

IP Domain-name on aggregation layer switch

Hi I was trying to generate ssh key for a switch I read that , ssh key is generated as a combination of hostname and domain-name I created a domain name like test But doubt is , why isn't the ...
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1answer
50 views

Network ( routing and switching) , security

In my company network i am installing new cisco2811 router but i have problem, my LAN network can not ping and access network. i get point to point internet from ISP. PTP IP is 192.186.86.200/24 and ...
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1answer
55 views

Are There Link Layer Switches in the Network Core? [closed]

Do we use link layer switches only in LANs, or are they deployed in the network core as well? I cannot picture the network core in my mind, is it just all routers starting from the edge router?
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1answer
843 views

value EstimatedRTT at first time?

What is the value of EstimatedRTT at first time? EstimatedRTT = (1-α) EstimatedRTT + α*SampleRTT Is it the average of all sampleRTT ? For example i have following SampleRTTs: 120 ms, 140 ms, 160 ms ...
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1answer
128 views

What are the significance of different types of routers?

Initially when I started learning networking, I understand the 'Switches' and 'Routers' are the core components of networking. As I started getting more into networking, I started hearing different ...
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1answer
732 views

Should a Metropolitan Area Network (MAN) be setup with a router at each site?

Should a Metropolitan Area Network (MAN) be setup with a router at each site? Or, because the connections between sites are usually at layer two, should each site operate on one "master" switch which ...
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1answer
116 views

HSRP - 2 separate Virtual Router for Distribution and WAN?

I've got 2 Core-Multilayer-Switches connected with each other with two cables (trunks). They are also connected with the distribution-switches (and each switch is connected with both core-switches). ...
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2answers
85 views

Separate a network within the enterprise environment

What will be the best solution, to securely separate a network and have internet connectivity. In an existing enterprise environment (Firewall, Dhcp, routers and switches) i will like to separate ...
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0answers
318 views

Cisco Nexus 7k Mac move

I have been troubleshooting a mac move behaviour on my core network, which is made of 2 Nexus 7K with F3 series modules. They are inter-connected with a fabricpath mode port-channel. All the remote ...
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2answers
456 views

Unbundling local loop

When we are dealing with local loop, we indicate the last mile of connection from the CABINET (or whatever else) to the subscriber. Now, I'm asking to you, the local loop is the medium of the access ...
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2answers
53 views

Given a network switch, can we identify the devices (IP not assigned yet) connected to it? [closed]

If IP is not assigned to the server yet and suppose it is connected to a switch, then can we still get the details of the server from the switch?
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2answers
3k views

Cisco 3064 switch upgrade from 6.0.x to 7.0.x issue

I am trying to upgrade from 6.0.2.U6.5c to nxos.7.0.3.I4.7, before upgrade i want to make sure it pass all checks but i got this error. This switch isn't in production yet but want to make sure it ...
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4answers
2k views

L3 Core to Firewall question

I'm in need of some advice regarding the implementation of the network core layer of a network I need to design. I've found some similar questions asked (and answered) already, but none have really ...
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1answer
47 views

How to use MCLAG for In Service Software Upgrade (ISSU)

In following video, the CTO of Arista claims that they use Multi Chassis Link Aggregation (MCLAG) setup for In Service Software Upgrade (ISSU) with zero down time on their switches https://www....
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7answers
4k views

Cant ping & access HP switch on network connected on trunking mode

I have been facing this problem for a very long time. Here is a diagram of the switch situation: The problem is that I have been trying to access the switch on the RIGHT(A3100) through the network ...
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2answers
281 views

Physical interface as switch port and VLAN interface as layer 3 [closed]

In most of large ISP networks, physical interfaces are used as switch ports (layer 2 port) and VLAN interfaces are used as layer 3. Could you please explain what is the main purpose to use like this?
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0answers
166 views

How does a Switch Fabric Module work internally?

I am interested how does a switch fabric module work internally. What interfaces does it use to physically connect the I/O modules on switches? Where are the CAM / MAC tables of the switch? Are ...
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1answer
240 views

ASA 5585 licensing question

We have purchased Security Plus and output showing following, in Failover it's showing Active/Active does that means i can't configure Active/Standby ?? Licensed features for this platform: Maximum ...
2
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1answer
520 views

Cisco ACL for NTP

We have Cisco ACL configured for all inbound traffic and today i have add NTP to allow few remote NTP server to sync tim. I have created object-group NTP group and multiple remote NTP server in that ...
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2answers
74 views

VPN in single host vs VPN on GATEWAY

I was looking at some lightweight VPN solution like wireguard etc. If am correct, VPN provide two functionalities. 1. Tunneling which helps in anonymity 2. Encrypted channel which helps in ...
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3answers
901 views

subnetworks in the following diagram

I know that routers are used to divide the networks but i am confused to check the number of networks in the following diagram. Does the switches that are in the green color is a seperate subnetwork? ...
2
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1answer
111 views

How do routers pass packets back down to switches?

I just had a very fundamental question about the transition between the router and the switch: I want to know about what happens when a router receives a packet, how does it go about passing it down ...
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2answers
172 views

Working of Application Protocol and TCP/IP Protocol

I was reading Steven's book on Unix Network Programming.There was a paragraph in chapter 1 which said: Even though the client and server communicate using an application protocol, the transport ...
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1answer
317 views

Vrf-lite limitations on Cisco 6800

I wish to segment a network consisting on 150 tenant using vrf lite on Cisco 6800. The vrf configuration will be standalone as only the 6800 will be configured with vrf. Tenant's CPE will be connected ...
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1answer
171 views

What problem does Dynamic NAT solve?

I have been reading the below link, and got few question. http://www.omnisecu.com/cisco-certified-network-associate-ccna/static-nat-dynamic-nat-and-pat.php What I understand? Static Nat -> Just a ...
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3answers
321 views

About Tiers in the internet

If I'm connected to a Tier 3 ISP then does that mean whenever I access anything over the internet, the traffic has to go through a Tier 1 ISP because I've read that Tier 3 ISPs purchase their ...
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1answer
81 views

Relationship between DNS records of routers, whois information and geolocation? [closed]

Let's assume I have a connection between a machine at a datacenter in France and a datacenter in Singapore and the RTT between the two is around 270 ms according to ping. If I do a traceroute from ...
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2answers
697 views

Spanning Tree cost calculation

We have following network diagram, but SW3 isn't in place, and I have a question before I plug SW3 into the network. Sorry, I put in the wrong diagram before. The following diagram is the correct ...
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1answer
78 views

High Speed data Transmission [closed]

How does NVIDIA GeForce NOW manage such high and massive data transmission between PC and servers? PS: Please attach relevant articles or journal papers to support your claim.
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1answer
217 views

Is bandwidth a sum of network speed each computer in sub network?

I'm not good at English But I really confused about this. I used the word computer but it can be mobiles or any of devices which can have networking. Let just the Internet bandwidth is 100Mbps, ...
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2answers
447 views

F5 as a backbone router

We've been using the LTM and ZebOS for some time now. Time and again we've run into OSPF bugs, and an upgrade usually resolved them. ZebOS's BGP has been relatively stable in that regard. We're ...
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2answers
404 views

Why Label switching is faster than table lookups

I learned that Label Switching (LS) technique, such as MPLS, is really faster than the classical routing method where each router takes a bit time to look up its IP table for routing to the next hop. ...
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1answer
43 views

Finding the TCP throughput for intermediate switches along a transmission path

I am working on network simulation where my network should be as close from real-world conditions as possible. I am coding a function that calculates the latency and bandwidth of between switch A and ...
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1answer
427 views

How to refer packets that belong to specific TCP session?

How can I know which packet belongs to a specific TCP session? In my experiment, a client establishes a TCP session with the web server every 5 seconds using wget command (I also noticed it uses ...
4
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3answers
2k views

The Difference between session and flow in networks

What is the difference between session and flow in networks? In fact, I always visualize flow as a set of packets having the same source and destination. What confuses me is session. So I'd like to ...
3
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3answers
1k views

Can OSPF v2 and v3 coexist in the same router?

Can we run OSPFv2 on few interfaces and OSPFv3 on few interfaces within the same system? Can we run both OSPF v2 and v3 as different processes?
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2answers
41 views

Understanding the ways of communication in IP networks

I am trying to check my understanding about the ways of communication in IP networks. I would classify the ways of communication in IP networks into three generic types: The source requests name ...
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1answer
138 views

The meaning of end-to-end QoS in network

When saying (end-to-end QoS) in network, what do we really mean by that?
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3answers
5k views

What is a headend device?

I see the term headend thrown around a lot at work? What sort of device in what role gets considered a headend?
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1answer
339 views

What do packets look like?

I have heard a lot about packets in networking. What do they look like? How are they transmitted through a medium like air?
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2answers
178 views

WSN vs Ad hoc in real practice

Wireless Sensor Network (WSN) and Ad hoc Network differ in one important factor: Infrastructure-based vs Infrastructure-less. In WSN, network is managed by a base station such as these antenna around ...
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1answer
856 views

Difference of data transmission between wired and wireless networks

Is data transmission different between Wired and Wireless network? In other word, when talking about TCP/IP, does it mean that TCP/IP stack is not suited for wireless networks?
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1answer
635 views

How to capture GTP-C Traffic using mininet? [closed]

I am trying to capture the GTP-C packet, I am using Scapy to generate GTP-C Packet. But I could not find any good tutorial related to "How to use Scapy?"
4
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3answers
385 views

Cisco 3750 switch to Cisco 1841 router to Cable Modem?

I was rushing to help a friend out today who was trying to get a 3750 attached to a 1841 behind a cable modem. He called me at the last minute and figured it would be simple considering his needs were ...
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1answer
261 views

Change MTU without infrastructure change

It's very strange issue, on openstack cluster we have VxLAN between network and compute node and its using 1450 MTU (1500-50) because of encap header. Because of it some of my application not working ...
2
votes
1answer
328 views

Layer 2 Failover

How can I setup a layer2 failover configuration? My Network setup: The distance between Site A and Site B is 2 km. Both sites are connected via a wireless link. As a backup line, we also have a ...
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2answers
630 views

Subnet and routing on IPv6

I would like to know: 1) What is the smallest routable subnet size in IPv6 ? 2) Can a /128 address be routed in a IPv6 network?