Questions tagged [gns3]

For questions about network simulations in the Graphical Network Simulator-3 (GNS3).

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6
votes
2answers
2k views

How to run a CAM Table Overflow attack in GNS3 using Cisco 3725 routers?

I am currently working on MiTM attacks and defenses in a virtual environment using GNS3 and an IOS c3725 (c3725-adventerprisek9-mz.124-15.T14) image to emulate some topology. The current experiment ...
5
votes
3answers
4k views

Configuring OSPF on two directly connected routers which are in different areas

I want to configure OSPF on the topology below. The problem is when I connect two routers to each other and when I config one router to area 0 and another one to area 1, they don't see each other as ...
5
votes
2answers
61k views

GNS3: Configuring/Emulating a Juniper Router on GNS3

I need to be able to emulate a Juniper Router (JunOS) on GNS3. I have seen that this is available as on option in the 'Node Types' list on GNS3. When I try to use this to add a Juniper Router to the ...
5
votes
2answers
208 views

Carrying remote VLAN via 2 routers to the local gateway

I have a serverA (192.168.15.1) from site A and VLAN is 15, however the VLAN 15 gateway is set at site B (192.168.15.254). There are two ISP routers as a metro role to connect each other by subnet ...
4
votes
3answers
9k views

How to configure PAgP or LACP on GNS3

In gns3, when i configure a router with a NM-16ESW module to use as a switch. And I can not configure PAgP or LACP on this router. It has only one mode ON, and there is no DESIRABLE or AUTO or ACTIVE ...
4
votes
3answers
3k views

GNS3: Local install vs Workbench

Does anyone have any experience running GNS3 locally (on Windows or Mac) vs the VM Workbench? I tend to have larger and larger topologies and my 4GB of RAM get pretty loaded... Anyway, can workbench ...
4
votes
1answer
132 views

GNS3 switches vs Real switches performance

I want to emulate the performance of switches in GNS3, and the focus is not the configuration of switches. My questions are: Do emulated switches perform worst than actual switches? Are emulated ...
4
votes
1answer
83 views

Why switch has records in mac-table when i just set ip address to the hosts which connected to the switch?

I created a new switch and connected to two hosts in GNS3.Like this: Host1--->LS<---Host2, i think the mac-table in the switch should be empty before i sent data between two hosts. But when i just ...
4
votes
1answer
2k views

Why do some interfaces not display unless I'm in config mode?

I'm using a Juniper vSRX image in GNS3. Here is my output before entering into config mode: And after entering into config mode: Why can I see my ge0/0/0 in config mode, but not outside of?
3
votes
1answer
5k views

GNS3: Map the console output of a router on GNS3 to a COM Port (Serial Port)

When a router is configured on GNS3 and started, it is possible to access the console output of the router by right clicking a router -> and then clicking Console I need to be able to map this output ...
3
votes
2answers
4k views

Virtual devices on GNS3 cannot ping the physical host

On GNS3 I have developed the following network: The enp2s0f2 is my own computer network interface. The router R1 configuration is shown below: R1#show running-config Building configuration... ...
3
votes
3answers
3k views

How to enable DHCP Cisco router

This is what I have done in my GNS3 R3 - Router R4 - Switch I have installed GNS3 and trying to enable on Router as mentioned above depict. How to enabled DHCP on Cisco router R3 ?
3
votes
1answer
332 views

Could launching a virtual router with less-than-recommened RAM cause interfaces to not initialize?

I'm trying to launch a few vSRX devices through GNS3 (and VirtualBox). The issue that I'm running into (I think) is that my interfaces seem to not properly initialize if I don't start the instances ...
3
votes
4answers
2k views

GNS3 console speed

Is there any way to change the console speed globally in GNS3. If you have seen GNS3VAULT videos the terminal speed is so fast but I could not find anywhere how to change the speed on GNS3 to get a ...
3
votes
1answer
180 views

Should I always use “no ip address” command?

I'm studying networking and GNS3. In every example I see that before configuring an IP (IPv4 or IPv6) address of an interface, there is always the command "no ip address". Why they write this command? ...
2
votes
2answers
2k views

Is “Host unreachable” the same as “Communication administratively prohibited” in Access List ping response?

Below is a portion of my topology. Faculty of Arts student subnet should not be able to ping Faculty of Arts staff subnet but the staff should be able to ping the student subnet. I know that this ...
2
votes
1answer
686 views

GNS3 Routers - what is the difference beteween line con 0, line aux 0, and line vty 0 4?

Totally new to this and am not sure what the difference between them are. Can anyone explain this to me in simple terms??
2
votes
2answers
3k views

How to assign multiple VLANS to a port?

I have a simple question about a network (I am new to this concept so please correct me if I am wrong). I have a simple network as shown (GNS3): The network have 3VLANS (VLAN10 = DesignTeam, VLAN30 ...
2
votes
1answer
2k views

Duplex mismatch between a Fast Ethernet router and Gigabit Ethernet switch with auto negotiation

i am connecting c3745 router on fast ethernet 0/0 interface with a IOSvL2 switch on gigabit ethernet 0/1 on GNS3. i have set the negotiation on the switch to auto for all interfaces on the switch. ...
2
votes
1answer
333 views

Juniper vMX Routers can't ping each other in GNS3

I have a couple of VMX Routers setup in GNS3 that are directly connected on their interface, ge-0/0/2 and they can't ping each other. PFB configuration. I can't seem to find the problem! UPDATE: Added ...
2
votes
1answer
7k views

If traceroute fails why does ping still work?

If I can ping a router successfully, why is it that when I do traceroute, it stops at a particular interface and says "ICMP type:3, code:3, Destination port unreachable". Doesn't that mean that it can'...
2
votes
1answer
114 views

Can adjacent AS in BGP run same protocol in IGP?

I am trying to create a BGP simulation in GNS3. I have the following topology Here's what I have understood: R1 will advertise 201.10.10.0 R2 will advertise 203.0.2.0 R3 will advertise 203.0.2.0 ...
2
votes
2answers
1k views

Learning Static Route: Is this correct?

In my network journey, I'm studying static routes now (I know that isn't used in large environments, but just studies). I made this topology in GNS3, and I'm wondering if some points are correct. PS:...
2
votes
1answer
65 views

Need help to replicate the results of a tutorial on Frame Relay Configuration on Router. What do I need to change/add?

I'm having trouble getting the output shown at 03:14 here: Frame Relay configuration by Kevin Wallace My Network is 3 routers, each connected to the frame relay switch via Serial2/0 interface, with ...
2
votes
1answer
110 views

How to make PCs in the same LAN but on different networks communicate

Is it possible to ping PCs in the same LAN but on different networks? I've done RIP version 2 on all the routers. They all can ping each other. However, the PCs cannot. For example, when I try to ping ...
2
votes
1answer
2k views

Is it possible to emulate ARUBA device in GNS3 environment?

Is it possible to emulate ARUBA device in GNS3 environment?
2
votes
1answer
976 views

GNS3 - Cisco router doesn't forward packets to different subnets

My network looks like this: For some reason there's no connectivity if I ping the machine named Server_TFTP from any of the Hosts. The router does however respond to pinging it. Apparently there's no ...
2
votes
1answer
475 views

GNS3 v2 router to host connection

I'm trying to make a router inside GNS3 to connect to the host device (a Debian 8) with no success. Am I missing something? DHCP works as expected: ! interface FastEthernet0/0 ip address dhcp ...
2
votes
1answer
2k views

How to connect two Juniper gns3 with fastethernet?

I need to connect two Juniper routers with fastethernet interface. When I am connected by em0, I can check the connection between them by ping. But when I tried to set fe-0/0/0 in two routers, I can't ...
2
votes
1answer
412 views

Is there no “mode on” for channel-group in GNS3?

I am using GNS3, and a 3700 as L3 switch (router with ethernet switch module); everything is OK, but when I want to configure two ports as an etherchannel connection, the command channel-group doesn't ...
2
votes
1answer
752 views

GNS3: No Response When Pinging Router Connected on Second Serial Interface

I'm attempting to set up a network with 3 Routers. A "West" and "East" router are each connected to a "Central" router via a PA-4T+ serial interface. The first interface (s1/0) on the Central is ...
2
votes
2answers
1k views

ASA cannot ping outside through NAT on border router

I have the following topology below, in GNS3. Basically, the cloud NAT-1 is the Internet, R1 is my border router with NAT and FWASAv-1 was supposed to be able to access the Internet, but can't. I ...
2
votes
1answer
337 views

GNS3 nat configuration issue

I'm studying for my CCENT exam, and I'm trying to practice configuration of the NAT. R1 configuration: Building configuration... Current configuration : 1211 bytes ! version 12.4 service timestamps ...
2
votes
1answer
189 views

Is it possible in a AS with full-mesh topology to use an iBGP route instead the directly connected route?

iBGP needs a full-mesh topology which means all the routers need to be directly connected each other. Does that mean the BGP attributes that we configure in iBGP, such as weight, will not have any ...
2
votes
1answer
3k views

Can't ping between 2 CE routers even though routes exist in vrf routing table

I checked the vrf routing tables and the CE's network is present but I cannot ping it from anywhere. I will provide the PEs' configuration files and the CEs'. Any ideas? PE1 configuration file(R2) ...
2
votes
1answer
1k views

Problem in routing the network in GNS3

Can someone please help me: Cloud 5 is configured with a loopback adapter on my PC with ip 10.84.104.254. R1 F0/1: 10.84.104.1 i am able to ping R1 F0/1 from outside, as well as I can ping and do ...
2
votes
0answers
7k views

Setup the BGP + ospf network

I've the next Lab with GNS3 I have two autonomous systems(100,200), when the AS 100 run a OSPF with two areas, 0 and 1. The AS 200 has only a router and computer, so easy. But I don't know how to ...
1
vote
2answers
57 views

Unable to add an abbreviated IPv6 to a Cisco router

I am very new to networking and playing around with GNS3. I am trying to configure a router to have 2 IPv6 addresses in a single interface (as far as I understood, this is possible with IPv6) I ...
1
vote
1answer
511 views

BGP (RIB-Failure - Higher admin distance)

I tried to make BGP routing on this topology .. After that I added 200.200.10.0 network and 200.200.20.0 network in R1, I had rib-failure (higher admin distance) on R2 and R3 .. but I was able to ping ...
1
vote
2answers
759 views

GNS3 ASA not pinging itself

I have been playing with network stuff so I installed GNS3 network simulator. I have deployed ASA 8.4 image and it has loaded fine. I connected it with basic Switch switch-----ASA I have ...
1
vote
1answer
40 views

ipv6: I can ping only 1 interface within same network even with static route

This is how I set up a static route. R1(conf): ipv6 route 2004:DB8:2233:23::/64 2001:DB8:1122:12::2 With this, I can ping to 2004:DB8:2233:23::2 (S2/2 on R2) but not to 2004:DB8:2233:23::3 (S2/2 on ...
1
vote
2answers
472 views

Difference between various network simulators

What are the main differences between GNS3, Cisco Packet tracer and EVE-NG? Detailed explanations would be appreciated.
1
vote
2answers
1k views

Simulate a real L3 WAN with VIRL or GNS3 (+/- VIRL images)

I would like to simulate or emulate the design of a replacement network which will be L3 routed (the easy part) but will have a lot of simultaneous L2 VLAN bridging (or tunnels) to accommodate the ...
1
vote
2answers
59 views

Can i use an actual network management application and connect it to a router inside GNS3?

I want to connect a NMS to a router on GNS if it's possible, so that i can practice the "actual thing".
1
vote
2answers
2k views

BGP problems, cannot ping

I'm beginner, and I have problems with BGP. I don't really understand why it doesn't work correctly. This is my topology: I need to ping from R8 to R10. This is the configuration of R8: ! ! ...
1
vote
1answer
29 views

ARP sending an ARP request on changing port IP address

Using the c7200 images on GNS3. I configured two routers as so: With arp debugging on, after assigning an ip address I see that each router sends a gratuitous ARP response packet (only debug output ...
1
vote
1answer
66 views

Connect routers in gns3

I have a topology of three routers connected with each other. The problem is that it has a different network address on two directly connected ports of router R1 and R2. So I am not able to ping R1 ...
1
vote
1answer
1k views

GNS3 wic vs slot

can any one explain the difference between WIC vs Slot? plus I want to have more L3 links in GNS3 but I cannot have more than 4 on 3725 router. there are two built in plus i can add two NM-1FE-TX in ...
1
vote
2answers
991 views

GNS3 - configure two DHCP servers within one VLAN

I have the following configuration: I would like to provide every host from VLAN_101 with DHCP-provided IP addresses. There are two DHCP servers running - one grants adresses for every host below ...
1
vote
1answer
3k views

Having 24 gigabit ethernet ports cisco switch in gns3

I need a 24 port gigabit ethernet cisco switch with 2 fiber ports in gns3. An example of this switch is the Cisco SGE2000 switch, i found out that the gns3 only provides only their default etherswitch ...