Questions tagged [ospf]

For questions about OSPF. Open Shortest Path First (OSPF) is a link-state routing protocol for Internet Protocol (IP) networks.

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47 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 ...
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35 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 ...
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39 views

Struggling with Ospfv2 Single Area

My network looks like this: I do know how to configuration works. Enable config terminal Router ospf 10 Router-id (1.1.1.1 and 2.2.2.2 to each router) Network (ip) (subnett mask) area 0 I've used ...
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1answer
32 views

OSPF: What's the consequence of two nssa area translator router

If NSSA area has 2 ABR, then usually one of them will be elected to be translator by router id. But what if I have 2 translator routers and both translate the message simultaneously? How to route in ...
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2answers
65 views

How to ping from PC on EIGRP area to PC on OSPF area without middle router?

This is my topology. And I can send a package to every router and PC within the colored area, how can I ping from a PC on EIGRP area to a PC on the OSPF area? I heard about default route but I saw it ...
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72 views

Why backbone area can not be stub area in OSPF

If there is no ASBR used anywhere in topology. Is it safe to make a backbone area as a stub.
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17 views

In which real-life scenarios RIP is useful? [duplicate]

I'm working in a medium-size international network-components manufacturer. Almost for the past 1.5 years, no customer asked/used RIP. All our customers requests are for OSPF. So I asked my senior ...
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53 views

I need help in creating OSPF between MultiLayerSwitch and Routers in packet tracer

I know we cannot create OSPF with different subnets. What network addresses should I put in the MLS and R1 to make it adjacent? Here's the configuration for MLS: interface FastEthernet0/15 no ...
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34 views

OSPF Fast-Reroute Question

I'm running into a wall when doing some research on OSPF FRR. I came across this excerpt from the Cisco documentation: "Not all routes can have repair paths. Multipath primary routes might have ...
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1answer
64 views

Is OSPF router ID unique per area?

I found online that the router ID must be unique within the OSPF domain. But what exactly is an OSPF domain (an area?). Let's take the following topology: Can R1 and R5 have the same router ID, as ...
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574 views

Multi Area OSPF configuration in cisco packet tracer

I am a bit confuse in the concept of multi area ospf. I posted 2 days ago. And I was asked to leave the one interfaces of each router out of the circle. Now the center circle is area 0. The top circle ...
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42 views

Giving different OSPF areas to a router

In the topology shown above each circle represent an area. Now I want to configure multi area OSPF on each router. So for the first router can I do like this: router ospf 109 network 192.168.11.0 0.0....
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37 views

What does multi area OSPF mean?

Does this mean that all the routers in a given topology should have different values of area or just one i.e. area 0?
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122 views

Routes stopped redistributing through OSPF

I was entering a number of secondary addresses on some VLANs. In total there were 10 secondary addresses added. The subnets added were from three publically routable /24s (I will call them 25.0/24, ...
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2answers
659 views

OSPF increase bandwidth with load-balancing

This is my current setup where i have 40Gbps links between all 4 switches running OSPF using L3 links between them but now i want to double my bandwidth between switches so i am planning to add (...
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87 views

explanation on redistribution

I'm having trouble understanding redistribution in reference to this topology R1, R2, R3 and R4 have OSPF enabled on all IP interfaces, all in Area 0 R5 has a default route pointing to the VRRP ...
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1answer
97 views

Colocation rack setup (OSPF, VRRP)

I'm not a networking guy, so sorry if I mix some words up. We're moving in a new datacenter and want to setup the networking the right way. We have 2 uplinks coming into our rack and they assigned two ...
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22 views

How to force client side HSRP interface to go into standby when internet is not reachable [duplicate]

I have a VIRL setup in which the client router is connected to a client switch that connected to two provider switches that have HSRP configured for the client gateway. The two switches are in an OSPF ...
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187 views

What happens in Exstart state in OSPF neighbor state? Will DBDs be exchanged in that state?

According to my knowledge, DBD exchange happens in Exchange state.
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106 views

Why can the BGP protocol be implemented across routers, but the OSPF protocol can only be implemented direct connected routers?

Why can the BGP protocol be implemented across routers? But the OSPF protocol can only be implemented on directly connected routers? Is the OSPF protocol based on IP? we know the BGP is based on ...
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2answers
108 views

Do the Master/Slave Election happen in Broadcast Domain in OSPF? if not Why?

According to my knowledge, Mater-Slave election is needed to decide who will to start communication between two routers. In broadcast domains all the DR other routers communicate with DR. Is there a ...
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1answer
67 views

Understanding OSPF

In OSPF, what happens first, the SPF tree or the SPF algorithm? Once the LSDB is created does the SPF tree get created first and then the SPF algorithm runs or does the SPF algorithm run and the SPF ...
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49 views

OSPF and /30 for IPSEC VPN links on routes which support routing (as opposed to polices)

Traditionally i have always set IPSEC policies as /24 (/16 etc) on routers that had policies for encrypting IPSEC traffic (as opposed to routes). I have since started using a router (Fortinet) that ...
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1answer
453 views

What are the five flag bits in OSPF Hello packet that specify optional capabilities?

What are the five flag bits in OSPF Hello packet that specify optional capabilities? This may be a textbook question and probably less important.
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45 views

Basic connectivity won't work in Packet Tracer

I've been redoing this multiple times and I'm sure i configured it correctly, however there is nothing happening at all. It's just a basic network with 3 routers and OSPF configured. Here are the ...
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83 views

Is this a valid OSPF topology?

In the following topology: every Backbone router is an ABR. Router 2 belongs to three different areas, area 0, area 1, and area 4. is this a valid topology for OSPF ? it works as expected and it ...
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1answer
41 views

Why does my route-map blackhole some equally specific routes? [closed]

I have a challenging situation. I have two routers, in VIRL, sharing routes via BGP and OSPF I am attempting to remove the "network 0.0.0.0 255.255.255.255 area 0" from my OSPF process. I have tried ...
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133 views

Connecting eBGP and iBGP routers in Quagga

I am trying to run intra and inter-domain routing using Quagga. I like to announce a prefix from AS7 and I like AS6 receive it and send it to AS2(as shown in the attached topology). I know for intra ...
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1answer
119 views

High Availability for ISR 4431 IPSec VPNs

I have the following lab setup in GNS3. R1 & R2 are VPN endpoint at my datacenters and R3 is simulating a remote site. What i'm trying to accomplish is having one tunnel from R3 to the ...
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1answer
44 views

Which device initiates the data exchange in OSPF (is it the master device or slave)?

I want to know which device initiates the data exchange in OSPF protocol (master device or slave device).
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63 views

How to transition an unauthenticated OSPF area to an MD5 authenticated area on a Cisco?

I currently have an existing OSPF area that has neighborships and is exchanging routes, but has no authentication mechanism. Is there a way to transition it to an MD5 authenticated area without ...
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88 views

In OSPF, can I have an NSSA router act as the DR for the ABR router in area 0?

I have a router in an NSSA area attached, via an ABR, to area 0; this is done through a broadcast link with a point-to-point address (31 bit prefix), so there are basically only two routers on this ...
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2answers
70 views

In OSPF does a DR consume more resources than a BDR?

What is the best practice in conserving router resources? Should a single ABR router be the DR for all areas? Will that have a negative impact on the resources, or would it be better to let other ...
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1answer
161 views

Configuring BFD for OSPFv3 between IOS-XE and JunOS

i need to implement BFD on a IGP Link with dual-Stack OSPFv3 between an IOS-XE device (ASR903) and a Juniper MX480. i'm running BFD for Dual-Stack OSPFv3 members on many links between IOS-XE and IOS-...
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1answer
46 views

How does the OSPFv2 and OSPFv3 instance learn the neighbor IP address?

For example, when I view the output of show ospf neighbor detail or show ospf3 neighbor detail in Junos, then I can see the IP address of the neighbor device interface. This field indicates the IP ...
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1answer
30 views

Multiaccess link show two Designated Routers in area 0

I have 4 cumulus routers setup with a single ethernet connection from r3 -> r1 -> r2 - r4. From r1, show ip ospf neighbor displays the following: **Neighbor ID Pri State Dead Time ...
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171 views

OSPF over IPIP tunnel doesn't work for CSR 1000v in AWS

I literally have the following topology shown in the figure below. I have 4 VPCs, each VPC has 3 subnets (1 for the VM instance and the other 2 for interfaces). Each VPC hosts a Cisco CSR 1000v in ...
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1answer
70 views

My OSPF Multi Area Topology is not reliable

I made an ospf multi area topology, but it's inconsistent. At times, host from the A area could ping to hosts in other areas however, sometimes otherwise (failed to arrive). Whenever I tried to do a ...
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1answer
104 views

OSPF inter-area traffic - not so direct after all

a) Can I confirm inter-area traffic will be routed towards Area 0 / Area 0 will be the transit network for all inter-area traffic? b) Consider the diagram below q1) Does R1 receive Type 3 LSA for ...
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1answer
545 views

%OSPF-4-ERRRCV: Received invalid packet: mismatch area ID, from backbone area must be virtual-link

I have a topology like this: this Router0-1's Gig0/0/0 ip: 10.0.12.1/24, the Router0-2's Gig0/0/0 ip: 10.0.12.2/24, Gig0/0/1 ip: 10.0.23.2/24, this Router0-3's Gig0/0/0 ip: 10.0.23.3/24, at ...
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75 views

Whether the OSPF ABR Router's loopback network should announce to Backbone Area? [closed]

The OSPF ABR Router whether its loopback network should announce to Backbone Area? the upper snapshot shows the C,D,E are ABR Routers, if everyone has its own loopback networks, I want to know ...
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1answer
397 views

What's the definition of Router Link and Net Link?

When I show the ospf database: Router2#show ip ospf database OSPF Router with ID (2.2.2.2) (Process ID 1) Router Link States (Area 0) Link ID ADV Router ...
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3answers
448 views

Why the OSPF router do not have neighbor?

I have two Routers in the Cisco Packet Tracer: Router2-1, Router2-2, Router2-3 all have their own loopback 0 with IP address 1.1.1.1, 2.2.2.2, 3.3.3.3. I only launched the OSPF progress in the ...
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145 views

OSPF behavior for redistribute routes

I have 2 equal cost path links between PeerA and PeerB and all its interfaces are participating in the same OSPF area. When i redistribute a static route (172.16.2.0/24) from PeerB to A, does the ...
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2answers
769 views

How to assign all interfaces in one router to OSPF backbone area?

Is there any command to assign all interfaces in router (CISCO 2691) to OSPF backbone area? I was using this command for each interface. network address wildcard-mask area area-id Where wildcard ...
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1answer
391 views

Quagga - Configure 3 routers using OSPF

Hi I'm trying to use quagga to connect 3 routers but the middle one doen't complete the path that a trace route command would do even though it knows where the target address is. It seems that ...
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3answers
1k views

OSPF and its use of Multicast

When it comes to OSPF and its use of multicast, am I correct in believing that IGMP forwarding and an IGMP querier is still required within the local segment? My understanding would be without this, ...
4
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1answer
255 views

When do multiple routers connect to the same switch (ie for DR election process)

When studying for the CCNA we are presented with the 3 tier Cisco model below. Then when we discuss routing protocols there are many images where these routers are connected in a switch and thus need ...
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0answers
58 views

OSPF peering not forming when authentication is enabled

OSPF peering between two of my routers went down 2 days before. After troubleshooting, I removed the authentication commands from both devices GRE tunnel interfaces ip ospf authentication message-...
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1answer
173 views

OSPF DR and ABR relationship

I know the DR/BDR and ABR are of course separate concepts and serve different functions, but in many cases is the ABR router for a given area also made to be the DR? Or would the DR be more often an ...