Questions tagged [routing]
For questions about routing, the process of selecting to which network path traffic is sent. Consider using a more specific tag if your question is about a routing protocol like BGP or OSPF.
2,126
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What's the reasoning behind the "Longest prefix match" algorithm?
I understand the concept and how the longest prefix match rule works.
Let's say a router receives a packet destined for 192.168.100.5 and the router has the following matching routes in its routing ...
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When configuring NAT, it is important that the outside address and the inside address have what kind of subnet masks.? [closed]
Will the subnet mask be the same, different, or only on class A or C networks? Please explain.
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Should I be using point-to-point or broadcast if I plan on using SVI's in IS-IS on Juniper?
Apologies in advance if this is super-basic question, still learning ISIS.
I'm migrating from Cisco over to Juniper in an environment where all of the switches are running EIGRP, are on a 172.31.255.0/...
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How to connect single PC with multiple NICs to a another network using OSPF? [closed]
I've 2 networks connected together through CISCO L3 switches using OSPF for some reason Network B have one server only which can have multiple NICs. Can Network B PC configured to connect to Network A ...
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In router's config, why do I need to advertise the directly connected network?
I have learned that, in routing config, a router must advertise all of its networks.
For example, in this topo:
Router A need to network 192.168.1.1 0.0.0.255 and network 100.1.1.2 0.0.0.255
But why ...
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Static route is not saved - Why?
I have the following configuration. On R1 I do inter-vlan routing. The problem is when I ping the serial interface of ISP1 with PC MA11 the ping packet is not returned to R1. I wanted to add a static ...
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Trace Route RTO in two or more hop but next hop works [duplicate]
Today when I was doing tracert,
in the 2nd & 3rd and also 4th Hop I get RTO but my next hop seems to be reachable. How come it works?
Please answer asap.
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51
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Multiple GRE tunnels towards single host using anycast IP
I'm trying to build the following network architecture:
Where clients try to connect to a backend server (e.g. SSH) by using a Public Anycast IP adddress (1.2.3.4), that routes the client to the ...
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multi-site vpn with only one site reliably addressable from the web at large
i have a small network like so:
site-31:
wan public ip (dynamic) on isp fibre is reachable from the outside world. an automatically updated dns entry is maintained to keep the ip current whenever ...
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Routing vs Forwarding [duplicate]
What is the difference between routing and forwarding?When the network is a packet transfer network I dont see the reason for routing since forwarding a packet between nodes requires a routing ...
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Multiple hosts with same ip/subnet seperated by router possible?
Bit of a newb question but just curious if it can be done.
Is it possible to have multiple hosts with the same ip/subnet (eg 10.101.30.10/24) each seperated by a layer 3 switch/router, where one of ...
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Tracing a route, from 127.0.0.1 through my network to 20.43.161.105
Greetings in the name of network engineering!
BACKGROUND:
The IPV4 network consists of the following nodes:
Node 0:127.0.0.1
Node 1:10.1.1.1
Node 2:192.168.0.1
Node 3:192.168.1.1
Node 4:210.x.x.x
Node ...
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how do 2 different network communicate with each other
Suppose we have 2 networks with 3 PCs in each. As I understand, they can easily have the same IP addresses, but routers have different public IP addresses(e.g. here 158.127.10.3 and 158.127.10.4). So ...
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How Network layer routing actually works in the physical world
This is my first question here, It might be a vague or off topic, I apologise in advance, but I am happy to improve it
Basically I have a somewhat decent theoretical understanding of the OSI model. ...
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Are there any methods of differentiate between a single computer and a NAT router?
As far as I know, a traffic from a NAT router should appear similar to traffic from one computer with a single IP address. If you do not have any access to a network (let's say you are an ISP), can ...
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How should edge switches have their routing configured (when there is a mgmt vlan in the mix)
I'm having trouble with a new network topology we are trying to implement onto our environment. The issue seems to be with the switches. The problem is not relevant to this question but for ...
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If your ISP already has a gateway, why do you need another gateway with NAT to come before a layer 3 switch?
Please bear in mind that I am learning and have never set up a network with routers and switches myself. Also please bear this is sort of going to be loaded question because there are multiple layers ...
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Can you have multiple paths in BGP through different ASes?
In a course about networks in my university, we learnt about how in BGP routes, each AS chooses a single route to each IP prefix (though you may have multiple iBGP routes).
Meaning that in the ...
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For IPv6, How much processing delay difference between using /64 and /127 for Core network interconnection?
I've question about IPv6 routing processing delay.
Lets assume we've got big Core network with huge traffic and many hops.
All router's p2p interconnection addresses are used /127 network.
In my ...
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Sharing same IP address inside LAN? [duplicate]
Q: if 2 devices A and B share same ip address in LAN, can device A retrive all messages whose destination is device B?
I think this depends on how the LAN is configured.
If it's wireless then device A ...
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connect two private network using pfsense
I have two pfenses (say p1 and p2) in two separate networks. Each has a public IP. There is an internal network on each side (say n1 and n2). I want to connect these two networks through these two ...
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Exclude a certain vlan/subnet from layer3 inter-vlan routing
We have new gen aruba (hpe) switches in our environment.
There is a backbone (5412R zl2) which all edge switches are connected to. The edge switches are also layer 3 (2930F). The backbone delivers ...
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GNS3 subnetting and routing
I have a project assignment that consists of 3 routers, the ISP, and 2 company routers, the ISP can address a network /24 IPv4.
I delegated a /25 to DNS servers and a /26 to one company and 2*/30 to ...
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Possibility of transferring data over the same-level networks, rather than the higher-level network
This is a silly(maybe interesting) question.
Assume four ASes are connecting to the Tier 1 network(A, B, C and D). B is peering with C and D. A is close to B, but too far from C and D to make peering. ...
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141
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The relationship between AS upstreams, downstreams and peers
I find AS1221 is both the upstream and the peer of AS13445 from ipinfo.io/AS13445. However, as far as I know, there is no upstream or downstream relationship when talking about peering. Is anything ...
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How does a PIM router know which neighbour is the upstream router?
I understand that certain PIM messages such as Join/Prune and Graft have a field called 'Upstream Neighbour Address' used to indicate the recipient of the message, which is the upstream router for a ...
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Connecting L3 and L2 switches with VLAN settings
I have 1 L3 switch with
Static ip - 192.168.0.252
Two L2 switches
Switch A - 192.168.0.250
Switch B - 192.168.0.251
I have created VLANs in L3 switches with 192.168.1.1 and 192.168.2.2 ips abd set it ...
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In multicast, do shared trees exist solely to reduce router processing of (S,G) forwarding states?
I am asking this question strictly at a conceptual level. I am not asking from a specific protocol's standpoint.
Why do shared trees exist in multicast routing? What was the reasoning behind them?
...
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Make printer in different subnet accessible to other subnet
i am creating a network and i want the printer which is in a different subnet to be accessible by all other subnets. The router network is 192.168.10.0/24 further subdivided into /28 subnets.
The ...
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How does a new switch know how to reach the controller in an SDN?
Let's say we have an existing SDN network composed of several switches and a controller. Now say we connected a new switch to the network. Now how would the new switch know how to reach the controller?...
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Why Chassis MAC Address is used when advertising EVPN Type 5 routes
In case of EVPN Type 5 or IP Prefix routes advertisement why chassis MAC address or router MAC address is used in addition to VXLAN VNI?
I guess VXLAN VNI is working on same principle like MPLS VPN ...
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Why is congestion collapse from undelivered packets not possible when there's 1 congested link?
rfc 2914 says this:
The avoidance of congestion collapse from undelivered packets
requires that flows avoid a scenario of a high sending rate, multiple
congested links, and a persistent high packet ...
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Is it possible to assign a default gateway per routing interface on a layer 3 switch
Here is the scenario. Currently there is a flat layer 2 network with a single /24 subnet. The intent is to segment that /24 using a layer 3 switch. On the /24 network there exists clients with ...
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Is TCP used for data transfer after building the routing tables (using OSPF protocol)
I am trying to understand how Data (video, image, ...) is sent over the network, and what are the protocols and different processes involved. We know that OSPF (L3 protocol) does not use TCP or UDP, ...
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OSPFv3 Convergence Issue between OPNSense & Cisco Router
I have been digging around the internet and have been trying to get IPv6 up and running on my lab. Here is my current layout:
I have been trying to get OPNSense and the Cisco 1900 router to give each ...
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1
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SPAN/RSPAN monitoring VLAN vs Interface
I am a little lost with regards to the concept of capturing every traffic passing a core switch. If we set our monitor source to be all VLANs in a L3 switch, does that mean that traffic coming from a ...
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What are all the reasons for using a separate /31 subnet for a p2p link?
For example in this LAN, the 13.65 and 13.66 are a separate subnet between slip and bsdi, but what is the reason that they have a separate subnet?
The only reason i can think of is that bsdi cant have ...
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How can I clear all EIGRP routes?
Working through NetSim, I graded my work and found that at first I put the wrong IP address in the EIGRP routing table, so I then tried adding the write one.
I then tried to grade my work again, and ...
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Identify first six /49 blocks out of ABCD::/32 [duplicate]
The answer is given as
ABCD:0000:0000:0000:0000::/49
ABCD:0000:0000:0000:8000::/49
ABCD:0000:0000:0001:0000::/49
ABCD:0000:0000:0001:8000::/49
ABCD:0000:0000:0002:0000::/49
ABCD:0000:0000:0002:8000::/...
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How do devices on a network communicate when they are only connected through a router? [duplicate]
This is in my router's routing table:
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.1.0 0.0.0.0 255.255.255.0 U 0 ...
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Accept requests from Lan when Internet is down
I have a server with a Real IP serving a web application.
Sometimes the internet goes down and I need the local client machines to be still able to access that server from LAN.
What is the easiest ...
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Why does recursive routing happen?
According to:
https://study-ccnp.com/gre-tunnels-recursive-routing-problems/
Recursive routing occurs when the router learns the destination IP
address for the tunnel interface through the tunnel ...
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I am trying to wrap my head around NDP
I know before PC10 can ping PC11 it will use IPv6 Neighbor Discovery to resolve the Destination MAC address for layer 2 header.
But what would the DEST MAC ADDR be and what topics can I learn this
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Best way to configure for port forwarding
I am using a Peplink Balance 30 router. Right now I have only one public IP. I have set up the LAN for 192.168.8.1. I have five devices on the LAN side, including two Ubiquiti Rockets and three IP ...
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What does 'moving packets away from the source' in RPF means?
I recently started studying multicast and I am a bit confused by how reverse path forwarding is explained.
Most of the sources describe RPF as 'moving packets away from the source' but I understand ...
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Packet tracer is changing my addresses ipv4
Could someone help me with this?
I have a subnet with the ip: 172.16.193.0 in the fastethernet 0/0 of my router and when I go to put it in RIP the Packet tracer is changing it for another ip:172.16.0....
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Practically speaking, what is MPLS?
Theoretically speaking, Multi Protocol Label Switching is basically some sort of a routing technique that uses "labels" in contrast to normal routing using IP address.
But what is it ...
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ipsrc multicast group
I'm looking at some traces where a TTL exceeded in transit ICMP message with ipsrc as mcast is captured. The ICMP message is referencing the original ip header with a correct structure [ipsrc ucast, ...
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How to handle route conflict between two routers?
I am learning about route protocols and I would like to know what is the common approach to handle route conflict between two datacenter.
I have the scenario bellow:
So I want devices on DC1 to ...
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Is BGP always required when you have multiple ISPs?
I am trying to understand when is Border Gateway Protocol needed and I stumbled upon this question:
When is BGP needed?
The chosen best answer says:
You could peer with your service provider and ...
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