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1answer
76 views

Why do Designated Ports in STP still send BPDUs if the otherside of the link is blocking?

Is there a particular reason for a Designated Port to continue sending out BPDUs after convergence has occurred on a link where the other side is in a STP blocking state? I get the idea of a ...
1
vote
1answer
64 views

Difference between 802.1X vs 802.11 standards

What does the x means in 802.1x and which are the differences between the 802.1X and 802.11 standards ? Can you explain to me ?
1
vote
1answer
55 views

TCP handshake immediately RST [closed]

I'm trying to set up a modbus TCP connection on port 502 but get a RST packet immediatly. So the TCP connection handshake doesn't even succeed. This is done on a windows machine on an ESX server. The ...
1
vote
3answers
81 views

What is the purpose of a VPN?

A VPN connects a PC, smartphone, or tablet to another computer (called a server) somewhere on the internet. But, i could comunicate to another pc even without a VPN, so what is the purpose of using it ...
0
votes
1answer
35 views

Realistic Benchmarks for Comparing VPN Performance

I'm looking to quantify the performance of different VPN technologies as part of my PhD thesis and want to know if there are any standard metrics for end-to-end performance that are used to compare ...
15
votes
2answers
1k views

Router won't hold configuration

I have reset the password on a Cisco 1700 router, now when I copy run start or write mem then reload or reboot, it defaults to factory settings, i.e. it is not holding the configuration I have just ...
0
votes
1answer
38 views

MAC vs Local IP [duplicate]

As far as i've understood the datalink layer (level 2) of the ISO/OSI stack is responsible for local networks and it uses MAC addresses to establish connections between nodes. Also, local ip allow ...
0
votes
3answers
40 views

Ip phone problem cannot get an ip address from dhcp using other vlans except from vlan 1

i am trying to understand native vlans. when i use vlan 1 it worked and it provides an ip address to my ip phone. When using vlan 100 it does not work even i tried using native trunking on it. please ...
0
votes
2answers
48 views

Do all computers on a wifi network have the same Network ID in their IP address?

I'm trying to clear something up that I haven't been able to get a simple answer to. If I have multiple computers on the same wifi network, is it correct that they will have the same network ID, but ...
2
votes
2answers
62 views

SFP-10G-LRM compatible with Single Mode Fiber?

I just started working with new company and found they are using SFP-10G-LRM with single mode fiber. How could this be? I thought since the SFP-10G-LRM is Multimode, it can't work with single mode ...
1
vote
1answer
35 views

ex4200 bootup warning

we have some old juniper ex4200 in our stock and it shows following warning in console : --- JUNOS 12.3R3.4 built 2013-06-14 00:08:02 UTC *************************************************************...
3
votes
3answers
210 views

BGP and NAT Not working

I have an odd issue with BGP+NAT. I have 2 separate routers and 2 different ISP's. Topology looks like this: ISP1--BGP--> RTR1 \ \--OSPF-- Palo Alto Firewall-- Internal ...
0
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0answers
19 views

giving a network 192 addresses from an internet pool [duplicate]

I am answering a question in my networking course. It says, given an internet with a 9-bit address space (/23 subnet mask). The addresses are to be divided between 3 networks N0, N1 and N2; with 64, ...
-5
votes
1answer
44 views

What are Cisco Devices? [closed]

I am doing CCNA online and not for a minute have I not failed to come acroos the statement 'Cisco Device' What exactly are cisco devices ? Please don't tell me 'Devices that use Cisco iOS' Can you ...
2
votes
1answer
62 views

Confusion about IANA “Protocol Numbers” registery

In the IANA registery for "Protocol Numbers", there listed 2 IP protocol versions: IPv4 at #4 and IPv6 at #41. Their "protocol" column says IPv[46] Encapsulation, and "reference" column points to 2 ...
1
vote
1answer
50 views

Filter tagged route to downstream routers

I'd like to filter a redistributed route from EIGRP into OSPF to all routers in AREA2 and AREA34. I have tagged the route 10.90.100.0/24 with tag 90 at the Tampa router where its redistributed into ...
0
votes
1answer
26 views

PPTP encapsulation process

i am learning networking and vpn technologies now and i have some problems with understanding the whole PPTP encapsulation process. So i will write steps of PPTP encapsulation process (as i understand ...
0
votes
1answer
28 views

GRE Encapsulation

i am learning networks and tunneling and i have problems with understanding some things about GRE. The structure of tunneling below: [Transport Protocol][ensapsulationg protocol(GRE)][encapsulateed ...
0
votes
0answers
11 views

Simulating link error in Cisco Packet Tracer?

I have to design a highly redundant network as a homework and wonder if it is possible to simulate a link error (during an active Simulation) in Cisco Packet Tracer.
0
votes
1answer
24 views

Does network layer provide connection oriented service

I know that in TCP/IP model the data link layer provides connection less service. While reading IPv6 Header. 'The flow label is used for connection oriented servie'. How does TCP/IP model provide ...
0
votes
1answer
25 views

What is the time of the first RTO in the TCP protocol without knowing the RTT?

I know that 3 way handshake is used. But, the first time a connection is established and there is no RTT data, what is the expected time before sending another packet? How does the client know how ...
0
votes
1answer
43 views

Why computers can communicate on different networks and routers won't?

I have a problem that I can not understand it myself and I need some help. I'm doing a kind of challenge, well network challenge in cisco packet tracer. I have a .pka file that stands for Cisco Packet ...
1
vote
1answer
40 views

tcpdump filter for ERSPAN session ID value

I am using rcdcap to decapsulate ERSPAN on a Linux host. I would like to be able to split ERSPAN session IDs out to different logical capture interfaces. My current ERSPAN session IDs are 10 and 20. ...
0
votes
0answers
17 views

is crypto ikev2 supported on 1921 router?

is the "crypto ikev2" command supported on Cisco's 1921 ISR g2 router. I'm trying to deploy a site-to-site FlexVPN but the command wouldn't show. I updated the image to c1900-universalk9-mz.SPA.157-3....
-2
votes
1answer
42 views

How is IP tramsmitted from client to server? I checked HTTP requests but its not there [closed]

how do websites know our IP? I checked in HTTP requests, headers and everything is there but no IP why so?
3
votes
1answer
52 views

No packets showing up in Wireshark despite Client-Server communication

I am somewhat new to computer networking and I created a little project where I have two computers connected to an Ethernet switch, forming a small network. Computer server (192.168.1.1) has a mail-...
2
votes
1answer
36 views

Cisco configure RADIUS with local account same time

In LAB i am working on Cisco authentication with freeradius and everything works but i want my cisco switch first lookup in radius and if user didn't find then it go to local database. currently i ...
2
votes
1answer
48 views

Why do wifi devices slow down as other devices start doing work?

I've been doing some testing lately on 802.11g and I'm very confused by the results. I'll go into the details below. First please understand I'm a software developer, but not a network engineer. I ...
0
votes
2answers
87 views

How to differentiate if a Cisco device is a L3 switch or a Router?

I need to check all the L3 switches if they are configured with same ospf ID, As i am doing it in the Cisco prime, there are routers in the inventory too. Is there a show command where i can clearly ...
0
votes
1answer
31 views

Border links vs backbone links

While reading an article about a traffic classification I came across these two terms, which were unfortunately not explained. It was just said that border links are more suitable for the host ...
2
votes
1answer
44 views

How to check the route table on a neighboring router?

I have a router in a network, which use to show list of routes in the route table. Using the command- show ip eigrp topology I see some of the routes are removed after sometime, which were advertised ...
0
votes
1answer
36 views

Macsec and Optics

Do Macsec have any bearing with respect to optics? Wanted to understand, if Macsec is enabled, will the optics perform any additional task or they are transparent and it doesn’t bother if Macsec is ...
0
votes
2answers
36 views

OSPFv2 through firewall

My network. https://imgur.com/a/5QI1NNq So my question is, on the 3 yellow above. Sub networks, I've used static routing, but on the other side of the internet (blue field) I've used Ospfv2. on the ...
0
votes
1answer
38 views

Logical Link Control (LLC) vs Medium Access Control (MAC)

What differs the LLC sublayer from the MAC sublayer? From what I've understood - The MAC sublayer does what the PHY layer should be doing: detection (error, collision), channel listening, analog-to-...
1
vote
2answers
77 views

Which port determines the protocol?

If we have a common protocol port on both ends.. say source point is 443 and destination port is 80 (hypothetical situation, I know this combination of ports probably makes no sense).. how do we ...
0
votes
0answers
9 views

How to subnet correctly? [duplicate]

For an organization having 5 departments with less than 256 devices per department and IP address pool 172.16.0.0/16. what is the correct approach for subnetting? 1. should 4 bit be borrowed to ...
1
vote
1answer
31 views

Ubiquiti APs on manged or unmanaged switch?

I have three APs, one UAP-AC-IW and two UAP-AC-LITE. I have a Netgear Smart Managed Plus Switch, mainly for VLANs with plenty of open ports. I need to either add an unmanaged POE switch or a POE ...
2
votes
3answers
101 views

Will pinging the multicast “all hosts” IP 224.0.0.1 fill my ARP cache with all hosts on my current subnet?

Just wondering in case I ever have a want / need to see all the hosts on my subnet.
3
votes
1answer
64 views

Cisco MIB for physical memory

router#show ver 4194304K bytes of physical memory. Does anyone know the mib for physical memory of a cisco router? Lots of examples of memory used etc. Edit: Nothing is easy in cisco land -sh-4....
0
votes
1answer
49 views

BGP local-as command clarification

On my network infrastructure, an Arista switch is the core switch and a pfsense server the gateway. BGP is used to advertise routes for all the internal networks. On Arista switch, I see the BGP ...
0
votes
1answer
36 views

How to extract destination MAC from PCAP? [closed]

I have PCAPs collected at the Raspberry Pi (from this paper). I want to extract the following headers: Ether header (3) IP header (12) TCP header (10) UDP header (4) Then convert the PCAP into csv....
0
votes
1answer
27 views

Uses of Rollover Cable

Whilst looking into rollover cabling, I stumbled across this page - https://www.computercablestore.com/straight-through-crossover-and-rollover-wiring - which claims that: Rollover cables are not ...
4
votes
1answer
38 views

Function of the P-bit flag in an IPv6 multicast

Currently I'm trying to learn (common) things about IPv6 and started with the address format and the address scopes. Finally I reached the multicast part where my problem with the definiton of the ...
1
vote
1answer
37 views

ARPs in WIFI Interface Monitor Mode

I set my WIFI interface to monitor mode. I did not expect to see any ARP requests. Can someone explain why there is ARP traffic?
0
votes
1answer
24 views

Crossover Cabling - Reversing TX and RX Signals [duplicate]

It is often said that crossover cables 'reverse the transmit and receive signals' compared to straight through cables. However I am yet to see an actual explanation of why the reversal of signals is ...
3
votes
2answers
70 views

Is the first address in an IPv6 subnet assignable?

I am working in a lab and have configured a series of /125 subnets between routers. Lets ignore the best practice for this discussion of using /64 for everything. When I assign fd00:f9a8:ffff::257 to ...
0
votes
1answer
22 views

How does a transmitter re-modules a wave radio to get more distant devices?

I was told that a WiFi AP re-modulates its radio signal in order to enable it to better go through obstacles and noisy places, reaching more distant client's transceivers this way. Basically, the ...
2
votes
2answers
315 views

Why are session states synchronized with high availability?

Like my title says, why are session states synchronized between peers in most HA protocols? I assume TCP states like Esablished, Invalid, New and Related are synchronized, but I don't get why you want ...
0
votes
1answer
25 views

How to analyze packet monitor export from Dell SonicWall?

I have four export options: -Libcap -Html -Text -App Data I can obviously read the Html and Text data, but they are formatted horribly for being able to slice and dice in Excel or, preferably, for ...
0
votes
0answers
16 views

Networking and IP address [duplicate]

If an Isp is allocated to equal ranges for 64 companies with address 130.192.0.0 what is the subnet mask, and host of the first and last company? If not being able to solve it..I’ve little knowledge ...

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