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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12
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2answers
6k views

Are there any global network other than the Internet?

I found this definition of Global Networks: Currently does any Global Network exists (apart from Internet)? Can someone Quote some examples? Or non-global but on a country-wide scale(ATM network ...
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1answer
1k views

Label Distribution Protocol(LDP) in MPLS

I have been going through the MPLS technology recently.I have this doubt in my mind after reading some of the features of the MPLS. A---B---c | | D----E Lets say routers A,E are LER and B,...
8
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3answers
5k views

MTU vs MSS? When to change MTU and when to change MSS?

Here is the question. When and Why do we decrease MSS instead of MTU. In the router that we can configure can configure both of them separately. Suppose I have kept MSS as 1260.I have not made any ...
8
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1answer
282 views

Upgrading our Network to Managed Switch with Internet Routing

I am a business owner with multiple BT Buisness Broadband lines. We have two sets of VOIP lines and two sets of PC's, each with there own switch board. The problem that we have is that our lines go ...
7
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2answers
6k 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 ...
6
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2answers
2k views

In MPLS VPN, Which one become first? MPLS Label tag or VPN encapsulation?

In MPLS VPN network, which one is the first thing to do? I mean label tagging is first or VPN encapsulation is first? If you can, please explain about this case.
5
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1answer
419 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?
5
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3answers
3k 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 ...
5
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1answer
204 views

LTE EPC Synchronization between redundant components

I am investigating resiliency in LTE Evolved Packet Core. Each EPC components has information storage as defined for each user in 3GPP TS 23.40 (Ch 5.7). In case of failure this info needs to be ...
4
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2answers
197 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 ...
4
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2answers
477 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 ...
4
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2answers
193 views

Help with BGP configuration

Consider this network diagram Routers A and B belong to the same AS Networks 10.0.10.0/24 and 10.0.20.0/24 are routable via AS200 and AS300 Network 10.0.10.0/24 is accessible via Router A and pass ...
4
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1answer
950 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 ...
4
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3answers
10k 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?
4
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3answers
967 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 ...
4
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1answer
486 views

Is this the core layer?

I am new to networking and currently I have been learning about three layer model from Cisco. All sources say that Core layer is the one providing high speed switching and it is at the top of the ...
4
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1answer
547 views

Need information on MPLS-TP, BHH & BFD

I am not able to find information on BHH; I got this link to draft-bhh-04 but was not able to understand the operation/function of BHH. If you guys have any info on above topics please let me know.
4
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1answer
871 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 ...
4
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2answers
176 views

Circuit-Switched Network

What happens to data being sent into a circuit-switched network when the incoming data rate exceeds the bandwidth of the network?
4
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1answer
119 views

NBMA neighbor-ship process

Could someone explain what is NBMA neighbor-ship process in OSPF? I have gone through several books but did't get satisfactory explanation.
4
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2answers
30k views

How to calculate sample RTT? [closed]

I am new to networking and figuring out that how to calculate sample RTT which will be used later to calculate estimated RTT, Here's my assigned problem: Suppose that TCP's current estimated values ...
3
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7answers
9k 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 ...
3
votes
3answers
2k 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?
3
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1answer
174 views

Network Transport Connection

I am working with some colleges in another geographical location on connecting two satellite locations to a co-location facility. We are going to be moving all our server infrastructure to the co-...
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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 ...
3
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2answers
147 views

Why don't we send fragmented packets over multiple cables simultaneously?

I came up with this idea of using more than LAN cable for transmitting data. Suppose we have 6 wires running between two clients, we can divide the each packet into 4 equal parts (2 for error ...
3
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1answer
931 views

Distributed Trunking With core and Access Swtiches?

Is it possible to set up a Distributed Trunk with 2 Core an 1 Acces Switch on HP 5406zl? I know that you can connect two switches with an interswitchconnect port. That would be the 2 core switches. ...
3
votes
1answer
343 views

H323 Gateway configuration

I configured a Cisco H323 Gateway between 2 CUCMs connected via Intercluster trunk(non-gatekeeper controlled) Dial peer configuration is : dial-peer voice 10001 voip destination-pattern 3971... ...
2
votes
2answers
704 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 ...
2
votes
2answers
143 views

BGP Question please

Would like to ask a BGP question; in the first link picture there is no direct link on the two bottom layer3 switches but they form a ibgp neighbor with each other. In the second link picture, the ...
2
votes
3answers
753 views

Does TCP improve the ability of IP to send really really large files? [closed]

How does TCP improve the ability of IP to send really large files? Show me the math. (Calculate the max packet that IP can send and multiply by the maximum fragments. Compare that to what TCP can do.)
2
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3answers
11k views

Difference between CBR and FTP

I am new to networking. I have some confusions regarding CBR and FTP? Are they any protocols like TCP or UDP or something else? When do we use them?
2
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4answers
65 views

P2P Connections

Hey there I am a noob in the field of networking and I have a confusion: What is the difference between point-to-point and end-to-end connection ?
2
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2answers
55 views

DHCP does every host know of ongoing requests?

When a new hosts joins a network and broadcasts to find a DHCP server every host on the netowkr knows of the new hosts and its' request. Does every host also know of the final ACK packet, that ...
2
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2answers
228 views

Measure the distance between hosts

In graph theory, the length of an edge is mostly represented by a numerical value to indicate the distance between the two end nodes. Thus, in the field of networking, is it acceptable if someone uses ...
2
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2answers
88 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 ...
2
votes
1answer
954 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 ...
2
votes
1answer
1k views

Duration of TCP connection last in idle state(no data exchange)?

What happens when we create the TCP connection and we wait while(1) i.e. infinite loop, Does it get terminated automatically? or It will last forever if my connection is very good
2
votes
1answer
4k views

Understanding bisection bandwidth

I have trouble understanding the concept of bisection bandwidth in high performance computing clusters. Wikipedia article on bisection bandwidth, and online materials say that bisection bandwidth is ...
2
votes
1answer
2k views

What is RTAG7 hash

I am trying to read about RTAG7 hashing in ASICs. I am unable to find good literature on it. Can someone please explain what is the RTAG7 hash?
2
votes
1answer
265 views

Understanding the effect of transmission rate change in network

Suppose there are 4 switches connected using a normal ethernet cables of speed 100mbps as follows: (S1)---100mbps---->(S2)----100mbps--->(S3)----100mbps--->(S4) Now suppose the link between ...
2
votes
2answers
9k views

Connecting clients to two networks using Mikrotik router [closed]

I have two networks Network 1 and Network 2 shown in the picture, and one client machine that must access resources on both networks. Due to security reasons the two networks must be isolated from ...
2
votes
1answer
26 views

Wants to understand traffic flow of Catalyst layer3 Switch 3850 . what are sequence this switch will check to delivery packet to destination

i wants to know clear understanding about how Cisco layer3 switch checks in sequence order when traffic arrive to its L3 Interface . i want to know traffic flow in Cisco layer 3 switch ,because switch ...
2
votes
1answer
142 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 ...
2
votes
1answer
988 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 ...
2
votes
1answer
474 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 ...
2
votes
2answers
59 views

What NIC card should do before transmission

When a computer X is about to send a set of frames over the network to computer Y, should the NIC card of the computer X notify the other computers' NIC cards on the same communication link before ...
2
votes
2answers
525 views

Is publishing iBGP default routes a good idea in a multi-router multi-homed environment?

I'm looking at a network with two independent core routers, each with a different sized uplink, one 50mbps and the other 100mbps to a different ISP. I'm trying to get redundancy as well as load ...
2
votes
1answer
87 views

Routing between several nets

I have 4 IDFs(cisco 3560) and one MDF(cisco 3560). IDFs are connected via fa0/24 to MDF. Every fa0/24 is in mode trunk. Look at the picture Fa0/1-4 on MDF is in mode trunk. Problem : I cannot ...
2
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4answers
348 views

What is purpose of router?

According to OSI reference model layers communicate with lower layer to transmit information on to other network. So they add header and tail for data and pass it on to lower layer and finally passed ...