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Questions tagged [ospf]

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

0
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1answer
14 views

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

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 ...
0
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1answer
19 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 ...
0
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1answer
25 views

High Availability for ISR 4431 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 ...
2
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1answer
29 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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1answer
38 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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2answers
53 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 ...
0
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0answers
20 views

OSPF and static route [closed]

What happens when we have a network where all routers are routing using OSPF and one of them has additional static default route. For example: Let's say all routers have OSPF protocol configured and ...
2
votes
2answers
52 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 ...
2
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1answer
60 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-...
2
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1answer
36 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 ...
1
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1answer
24 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 ...
1
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0answers
67 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 ...
2
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1answer
51 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 ...
1
vote
1answer
55 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 ...
2
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1answer
115 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 ...
1
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0answers
35 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 ...
1
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1answer
67 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 ...
1
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3answers
97 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 ...
2
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0answers
72 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 ...
1
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2answers
191 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 ...
1
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1answer
167 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 ...
7
votes
3answers
393 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
76 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 ...
2
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0answers
54 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-...
1
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1answer
62 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 ...
1
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1answer
33 views

Is the Backbone Area connected AS Area are through one router?

I am studying Networking, and I find the Area 0.0.0.1, Area 0.0.0.2 connect to the Backbone Area is through one path, is it means only through one router(or say not more)? we often hear that the ...
4
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2answers
72 views

Routing Table Eligibility

I have an architecture which is that each remote site has 2 Dialer interfaces dialling into a virtual-template core which authenticates the sessions and applies attributes from a RADIUS server. OSPF ...
1
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1answer
123 views

MultiLayer Switch to Ping different Switches and routers under different VLANs [closed]

Hey Guys, So this is basically a small design of a made up university which has 3 campuses( the 3 routers).Each connected to 1 College(Switch) and each college connected to 3 other Schools(switches) ...
1
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2answers
364 views

Prevent OSPF routes advertised by other routers from entering the routing table?

I have a fairly complicated scenario that I've managed to duplicate with GNS3. Please see the attached image. In this scenario I have four "Branch Offices" each with their own router connected to ...
0
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1answer
92 views

Prevent OSPF routes from one network from being redistributed to the rest of the network?

Synopsis: Network A needs to be able to use a static default route to Network B via a local connection (G0/0/3). Network A does NOT want to route ANY Network B addresses through the rest of its ...
1
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1answer
238 views

Cisco ASA context OSPF configuration issue

I've two cisco ASA configured in active/active HA. ASA is connected to switch with port-channel. Switch configuration: interface Port-channel47 description ASA2 switchport mode trunk switchport ...
-1
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2answers
194 views

the difference between RIP and OSPF [closed]

I was working with CISCO and to create a path between switches my teachers told me that I can use 2 types of protocols, but they did not explain to me what differences there are between the two: ...
3
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1answer
2k views

How to flush route cache in fortigate

Is there something like route cache on fortigate like in linux? How can i clear this cache? I have some problems with OSPF, after adding or changing redistributed network. Foritgate show routes ...
4
votes
1answer
74 views

Question about OSPF and Database Descriptions

After the adjacency as been formed between two routers, a master-slave-relationship between two routers is formed too, where the master begins to send Database Description (DBDs). My question is: ...
1
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1answer
77 views

Why does OSPF function on Network Layer whereas RIP functions on Transport Layer?

As far as I know, OSPF creates its messages directly at the network layer, whereas RIP function on UDP. Their function is pretty similar, so why is there such a difference in their messaging practice?
1
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1answer
452 views

Broadcast,multicast and unicast in OSPF

In OSPF, routers from down to full state,what's kind of networks(broadcast multicast unicast) used per state to exchange information? I always heard 224.0.0.5 and 224.0.0.6 these two address, and was ...
3
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1answer
178 views

OSPF Area Design

Have a hub and spoke design where each Branch has a single router with a WAN connection to DataCenter1 Hub and another WAN connection to DataCenter2 Hub. There is no OSPF running elsewhere in the ...
4
votes
3answers
1k 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 ...
3
votes
1answer
444 views

Why OSPF E1 and E2 exist?

I know the difference between E1 and E2 metric-types. I know the preference level given to those routes. I know difference between Metric and Forwarding Metric and how it works. What I don't ...
3
votes
2answers
402 views

OSPF on tunnel interfaces

Can I keep different tunnel interfaces in different OSPF areas. Keep in mind that the physical interface is going to be the same
4
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2answers
183 views

How does a route-map applied as outbound on a neighbor sees the redistributed ospf routes into bgp? Local or external?

Here's my scenario: Redistribute ospf routes into bgp Create a route-map that matches on route-type=local and modifies the nexthop (to 4.4.4.4 for example) Assign this route-map as outbound routemap (...
2
votes
3answers
196 views

Cisco Vlan block access

So I have 2 core switches and 1 access switch, I have the vlans 1, 10, 20, 30 and 100. Vlan 10 is voip and what I would like to do is stop anyone on the other vlans from being able to see that subnet, ...
4
votes
1answer
608 views

Why does EIGRP have lower Administrative distance than OSPF?

I have given the following network diagram and been told that, Since EIGRP has a better (lower) administrative distance than OSPF, the router on the far left will use the EIGRP path and publish ...
2
votes
1answer
261 views

BGP with OSPF configuration question

ISP - Sending default route to sw1/2 via eBGP sw1 - config router ospf 100 network 0.0.0.0 255.255.255.255 area 0 default-information originate always ! router bgp 100 bgp log-neighbor-...
1
vote
1answer
892 views

nexus ospf network statement missing

In old school IOS we used to do router ospf 1 network 0.0.0.0 255.255.255.255 area 0 But in Nexus switch i am not seeing any command or related doc, how do i announce my subnet in ospf in nx-os My ...
3
votes
2answers
307 views

OSPF - Default route doesn't get advertised to all areas

I am trying to find the reason why R1 doesn't have the default-route, propagated and generated by my Internet-PAT-Router, in his routing-table. The weird thing is, that R2 actually has an entry for ...
-1
votes
1answer
350 views

How to implement Layer 3 (OSPF, IS-IS) link redundancy?

I think this kind of topic may be a course basic, but I'm still have a lot of technical doubts on how to implement redundant links on Layer 3, for example: -In order to use dual homing for a remote ...
3
votes
2answers
456 views

vPC traffic flow question

This is going to be new network in my datacenter and i have question related vPC, as you can see i have A1/A2 switch (L3/L2 routing) in aggregation layer and C1/C2 switches for Core (L3 routing). I am ...
1
vote
1answer
182 views

Is it required for an ABR to be connected to area 0?

The question "why is it required for all the areas to be connected to area 0?" is answered many times on the internet. However, I could not find an answer to the above question. Please refer to the ...
1
vote
1answer
318 views

OSPF Area Multiple Subnets

Is it possible to have multiple subnets in one OSPF area? Everything I can find so far points to the answer being 'No', however I need to know for sure if it's possible or not. Our current setup is a ...