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.

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policy based routing to send one host to a different internet gateweay

I have a Cisco C3560X with multiple internal networks (10.0.0.0/24, 10.0.1.0/24, et.) and two internet connections (10.0.0.3 and 10.0.0.4). The default gateway for the internal subnets is the switch (...
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Hot potato routing topology

Im trying understand hot-potato routing better using this diagram that I have made. It shows R1 and R2 in automous system 1 (AS1) are receiving full routes from their parent providers P1 and P2 ...
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Routing question

Let’s say I have router A and B and a subnet 192.168.10.0/24. Can I use part of that subnet as a connector between router A and router B (ie. 192.168.10.0/30, .1 on A and .2 on B) and have a route 192....
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Does the order of Link State Advertisement packets in OSPF matter?

Does it matter in what order an OSPF router receives LSA packets while reliable flooding is being performed in its area?
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How to NAT a unicast address to a broadcast address?

I have a 800-Series router connected in the following configuration: Port GigabitEthernet7 is connected to an external server (192.0.2.251) that sends unicast UDP to destinations 192.0.2.42:45100 and ...
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Understanding output of "ip route get" [closed]

My routing table looks as below: [root@master ~]# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 172.31.16.1 0.0.0.0 ...
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Link utilisation

Studying Packet Switching. Encountered a question - What i know? Packets are transmitted over each communication link at the rate equal to full transmission rate of the link. Router is using Store-...
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Cisco router access list not working as expected

I'm trying to set up a network in packet tracer with inter-VLAN routing. I need to restrict one of the VLANs to only accept traffic from the 172.25.30.0/24 network. To do this I am using an access ...
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How do I make it take the floating route and not the main static route in this case?

In this topology I have configured the devices in this way: R1: Building configuration... Current configuration : 916 bytes ! version 15.1 no service timestamps log datetime msec no service ...
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What Specifically Happens When You Add a Static IP to a Computer in a Subnet?

This question may be too naive to be Google-able, but I haven't found anything. I'm curious what happens when I go in to a Client device like my personal Laptop and add a Static IP (as opposed to ...
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How does a router find the next hop when the receiver is in a distant IP network?

Say I want to send a frame to a web server, and let's say this web server is in a very distant IP outside my local network e.g. a Google server. I initially send the frame to my router. My router ...
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Flex-algos vs Forwarding Equivalence Classes (FEC)

I am learning about flex-algos on segment routing networks. I understand that flex-algos are an attempt to apply traffic engineering practices to packet switched networks, where a given flex-algo is ...
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Why we need MAC address when transferring if we have static IP? [duplicate]

I just wanted to know if h1 and h2 have static ip and we want to transfer some file, so why we need to use mac address? Are not static ip addresses enough for this ?
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OSPF area or ABR impact on CPU and RAM consumption

I have two statments on OSPF, are they correct? 1- If I split a single area OSPF to an OSPF domain with area 0 and area 1, and there is just one ABR between area 0 and area 1, The load on CPU will ...
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1 answer
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How CIDR helped to slow down routing table growth?

Besides allowing for a greater number of ip addressed, Classless Interdomain Routing (CIDR) was also intended to slowdown routing table growth in core routers.[1] I may understand how it expands the ...
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Trying to get data from a server outside my LAN to a client within my LAN [closed]

Could I clarify the data flow when a device within a network requests data from a device outside a network? So say I have a LAN, and I want to get data from a server outside my LAN. The server gets ...
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1 answer
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eBGP load balancing - why is it not use

I used to think that eBGP does not support load balancing but in Cisco there is the maximum-path parameter that enable ECMP / Fortigate has ebgp-multipath as well so that is obviously not the case ...
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Why can multiple ASNs have ROAs for the same prefix in RPKI?

I am trying to understand RPKI better and I am looking at some raw data dumps. My initial understanding of RPKI was that it would help identify and authenticate "the one" ASN that is ...
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OSPF routes are not advertised

routers with ASBR2 connecting to AREA 0 and 10 and ASBR1 connecting to area 0 and 20, there's no entry of routes in R1's routing table, help me out R1#sh run Building configuration... Current ...
2 votes
1 answer
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RIP routes are not being advertised

I have 2 routers(R3 and R4 connected with serial links). I have advertised my loopbacks with RIP ver 2. with 192.168.1.1/32 and 192.168.2.1/32 on R3 and 192.168.3.1/32 and 192.168.4.1/32 on R4. My ...
2 votes
3 answers
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When would we use more than 1 dynamic routing protocol?

I am learning about different dynamic routing protocols and I've learned that each dynamic routing protocol has an AD assigned to it which indicates the trustworthiness of the learned route from that ...
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OSPF - How does slave know what to send LSR to when DBD is not shared by the master

Consider a topology where R1 and R2 are connected. R1 has following networks. 192.168.1.0/24 192.168.2.0/24 192.168.100.1/32 R2 has following networks. 192.168.2.0/24 192.168.30.0/24 192.168.2.1 and ...
1 vote
4 answers
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Can a router provide DHCP to multiple subnets that are connected via switches?

I'm trying to understand if it is possible to have a router (as shown in the below diagram) provide DHCP leases to more than one subnet if the subnets are not directly attached. If both the printers ...
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1 vote
1 answer
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Basic question on 'network history based routing tables'

I have encountered the following sequence of words: 'routing table formed on the basis of network history information'. I know that initially, routers discover neighbor nodes and therby the possible ...
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Understanding mtr output [duplicate]

Here is my mtr output to googe.com. mehost (me_IP) -> google.com (142.251.40.142) 2022-06-09T09:55:16-0400 Keys: Help Display mode Restart ...
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Routing VLANs to Firewall Ports

My network has 3 VLANs: 10, 11, 12, and their address spaces are 10.0.X.0/24 where X is the VLAN ID. Their default gateway is a virtualized pfSense (even though it's virtual, I will use terminology as ...
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VLAN and firewall interconnection

I'm encountering some difficulties to connect some VLANs to a physical firewall. In details I have a core network with a L3 switch as a router and some L2 switches as access network. The network is ...
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2 answers
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IPv6 subnets without delegated prefix

I have received an IPv6 network from my provider, say it's 2001:db8:1::/48. I did not get delegated prefix from them. I would like to use the IPv6 addresses on different networks behind a firewall (...
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How do we discover hosts on another subnet without knowing their IP or MAC address

If I have a client who wishes to send a UDP packet to another client, how would I scan for his IP address if Client 2 is located in another subnet? If I'm trying to discover clients on my own subnet I ...
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Setting an OSPF router in one area that doesn't see other areas

Could an OSPF router be configured so that it can only see its own area LSAs and does not accept LSAs from other areas? (For example, if it is in area 2, its routing table just shows routes in area 2, ...
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Routing correctly mesh + gatewaty [closed]

I have a router modem DSL I have 2 Aimesh Asus AX XT8 For a reason the node can not talk with the router base over WIFI (long range). I than connected the lan on the modem(DSL ROUTER) to the NODE - ...
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Connecting 9 Remote Sites with VPN Tunnels

I am working in a Cisco ecosystem and need to be able to test a 9 tunnel IPSec network over the internet using 10 x Cisco 1941 routers. This is a "hub and spoke" type configuration; where ...
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bgp and routing

I need a bit of help understanding what is going on in my topology. I really want to understand why i can ping 1.1.1.1 from r4 but not from r5 or r6. Please help and advise me. Many thanks guys r1 ...
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What are the IP/MAC addresses of requests between 2 different subnets? [closed]

Assume that networks 172.15.10.0/24 and 172.15.11.0/24 are connected through a router with interfaces 172.15.10.254 (MAC3) and 172.15.11.253 (MAC4). If host A sends a packet through its network ...
2 votes
2 answers
108 views

Why iBGP speaker should not modify next hop address?

I understand the concept of "Split Horizon" that an iBGP router A learns an external route from an iBGP router B, thereafter, iBGP router B will not advertise the same route to other iBGP ...
7 votes
3 answers
704 views

Can I announce the same block of /24 given to me by ARIN at two different locations?

The setting: Two locations I'm trying to connect. I have a /24 address block from ARIN Both location have the Same ISP. The Question: Can I announce the same /24 address block at the HQ location to ...
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2 answers
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How to configure a layer-3 switch for routing between VLANs?

I have set up the router as a dhcp server and I would like to use the layer 3 switch to route each PC in seperate vlans. How do I configure the router and L3 switch for inter vlan routing ? the router ...
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Cisco EFP point-to-point -- How to see MAC addresses

I see on cisco ME3600x and I read in documentation as below, that "the MAC learning is not supported in point–to–point bridge domains" Table 1 MAC Learning Actions Scenario Action A bridge ...
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VLAN routing on the same subnet

Consider following situation: You have 10.3.0.0/16 network without any VLANs. Now You want to divide it... You want Your IT department be able to reach the entire network, but sales department only ...
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2 answers
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How does a host (HOST_A) on LAN1 send a packet to a a network more than 1 hop away and how does a router (ROUTERX) handle that packet?

Suppose there is a host, HOST_A, on LAN1 and is sending a packet. The destination address of that packet is: 10.10.11.77 HOST_A will refer to it's routing table and see that that there is no entry for ...
1 vote
1 answer
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Ospf multicasting with two different group

Suppose I have one ospf network where two multicast group exists. And some routers is ospf which belongs to one group or multiple group (Like: routers E, H) and router is layer3 router (Like: ...
4 votes
1 answer
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How Can a VPC ping the Router through an Etherswitch that behaves in one port as router and in the other as switch

In the following topology my main purpose is to: 1)PC11 ping Router(R) 2)PC11 ping PC13 ESW10: In gig0/3 has the no switchport command and a given IP address. In gig0/2 it has the switchport access ...
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2 votes
3 answers
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CCNA | OSPF | What differences can exist between two processes of a single routing protocol?

It is my understanding that a process is a specific-instance of a routing protocol. The process-id is a symbolic representation of a unique instance of that RP within a router. If that's the case, ...
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2 answers
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Can Loopback IP be Public

I have a Usecase where an Access Device need to reach a Core Device over the Internet. Access Device is configured with the Public IP of the Core device as of now so that it can reach the Core over ...
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Can an application on two separate devices share a packet to similar resource?

Can packets requested for an image by an app on a phone be sent to same app on another phone by another user?
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Connecting geographically distinct sites using a WAN

I am studying for my CCNA and my current topic is related to WANs, and I need some clarity on certain things. Here is a topology I've quickly built. (Don't mind the IP addressing, I've have purposely ...
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Why can't I ping from a pc in one OSPF area to a pc in another OSPF area after configuring each neighbouring network?

So I have an exercise with this topology: I have configured all the OSPF networks on each router and I made every g0/0 interface (except for the ABR in the middle) a passive interface. However, I ...
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How to reset a Default username and password of Allied Telesis AT9000/28 switch using CLI? [duplicate]

How to reset a Default username and password of Allied Telesis AT9000/28 switch using CLI?
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1 answer
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Actually ICMP message makes layer3 reliable?

We know that ICMP is connectionless because it does not require hosts to handshake before establishing a connection. But when packets gets dropped in between route then respective router informs the ...
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Routing for same subnets in remote sites

Is it possible to have interVLAN routing with router on a stick topology, but with remote sites communicating via OSPF? In the diagram below, I can ping PC1 from PC0. What I want is to ping PC2 and ...
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