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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34 views

OSPF and RIPv2 behaviour with route through switch

I have 2 questions, both relates to routing protocols. How route/path looks like when there is L2 switch inside path. I mean with turned on either RIPv2 or OSPF. To clarify I must say there are 2 ...
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26 views

OSPF peering is not forming and is looping through the states [closed]

Any ideas or hints on what could cause an OSPF peering to break and start looping through states indefinitely? The adjacency is formed with no issues after a reboot (of the other peer) and remains ...
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1answer
31 views

OSPFv3 Authentication IPSEC SPI/Logging issues - Can you filter out logs?

I'm running into a problem with our Cisco ASR-1002HX and ASR-1006X. I have a mix of Juniper and Cisco routers all configured exclusively with IPv6. All of our routers are in the same ospfv3 area 0. We ...
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3answers
142 views

How does OSPF work on point-to-point Ethernet interface (i.e, 2 routers connected by a cable)

OSPF RFC describes two different modes of operation of OSPF for (1) point-to-point and (2) broadcast networks (and others). The operation on (2) involves selecting designated router and backup ...
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3answers
229 views

Why does OSPF use flooding despite using multicast?

We know that flooding is only possible in layer2 switch. But in OSPF router in layer3 uses flooding with multicasting. Suppose we have one router in OSPF uses multicast address 225.0.0.9. If router ...
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2answers
84 views

How in Distance vector routing one router communicates adjacent router through broadcast address and OSPF uses unicast with another?

In distance vector routing algorithm one router can communicates(shared the routing table) with adjacent router by broadcasting message which are in same subnet. OSPF uses flooding to unicast message ...
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1answer
30 views

osfp route filtering directly connected route

I am using Cisco 2960XR switch 192.168.1.0/24 is directly connected on gi1/0/1 192.168.97.0/24 is directly connected on gi1/0/7 router ospf 10 network 192.168.1.0 network 192.168.97.0 q1) how do i ...
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5answers
301 views

BGP <-> OSPF Route Redistribution Loops

In the following topology I have a multi-point redistribution from BGP <-> OSPF and I have recently encountered a routing loop. After further reading I have understood the problematic routers ...
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1answer
136 views

Traffic sent to GRE Tunnel fails, but GRE Tunnel is up and OSPF adjacencies are formed

NEW INFO_7-12-21 R1#sho ipv6 rout 2001:db8:B2:200::2:2 Routing entry for 2001:db8:B2:200::2:2/128 Known via "static", distance 1, metric 0 Route count is 1/1, share count 0 Routing ...
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85 views

I cant Ping from lan 192.168.44.0 and 192.168.45.0 , pc 3 pc 4

R0 and R1 are linked with ospf , and R1 with static route with MLSw. If i change R1 conn with MlSw to #ip route 0.0.0.0 0.0.0.0 g0/1 or g0/2 i can ping , but need help with static route conf ...
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43 views

PIM-SM over OSPF for mDNS traffic

I have connected 2 Routers via OSPF (using N links, N == 1 but it should be scalable to N > 2) and I am trying to have mDNS traffic go from LAN to LAN across the OSPF link, but I can't seem to make ...
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24 views

Huawei USG OSPF P2MP Network Limits

Good day! Configured an L2TP over IPSec tunnel on Huawei USG6500E. On the tunnel interface prescribed ospf type p2mp. I connect clients to this tunnel. When 32 clients are connected, the OSPF ...
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3answers
63 views

BGP-OSPF route injection doesn't work

Background: BGP is fully functional and works as expected so nothing need to worry about, the problem is the route injection between HK_Office <> HK2 and LON1 <> LON_Office, as you could ...
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2answers
152 views

OSPF with 2 Routers, N redundant links

I'm having a hard time trying to find a solution, and I can't seem to find anywhere on the web exactly what I need. We need to configure 2 Routers (MOXA EDR 810) to have N redundant links between one ...
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1answer
108 views

Can't ping neighboring router OSPF

I have set up an OSPF network and I cannot ping from the Edge router to Main Branch.
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0answers
41 views

Router on one side of a GRE tunnel not adding OSPF route through the tunnel whilst the router on the other side is

I have configured GRE tunnel between the Dublin and Carlow routers with the following commands: //Carlow int tunnel 0 ip address 172.16.12.1 255.255.255.252 tunnel source s0/0/0 tunnel destination 87....
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24 views

OSPF in DMVPN phase 1,2 and 3

What difference in DMVPN Phase 1, 2 and Phase 3 if we use OSPF?
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4answers
496 views

What are some real world applications of OSPF?

When I search for OSPF real world application or implementation, I always get the explanation of how OSPF works or how to calculate the cost. My question is, is there any real life scenarios of how ...
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1answer
169 views

Is it possible to have a second ASBR in my OSPF area 0?

I have three routers in area 0, two of which are connected to separate WAN circuits. I have one router that is sending the default route but when I try to add a second router with the configuration ...
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1answer
47 views

Why is OSPF more popular than IS-IS in enterprise networks? [closed]

I've read that IS-IS is more popular than OSPF in Internet Service Providers due to historical reasons (mainly that initially IS-IS had better hardware support and wasn't for IP only). But why did ...
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2answers
143 views

What is exact meaning of broadcast network in OSPF?

According to rfc2328(OSPFv2), broadcast network is "Networks supporting many (more than two) attached routers, together with the capability to address a single physical message to all of the ...
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2answers
101 views

Understanding the OSPFv2 MD5 authentication when packets contain LLS data block

When an OSPFv2 packet does not contain the LLS data block, then the calculated MD5 hash should be on the "Auth Crypt Data" field. For example, here is a LS Update message which does not ...
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2answers
99 views

Routing Protocols and sharing information

I am running multiple Protocols on different Routers as so: R1-RIPv2 EIGRP OSPF R2-OSPF and RIPv2 R3-RIPv2 and EIGRP R4-EIGRP and OSPF This is not a practical exercise, it is just to explore how ...
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1answer
197 views

Junos not automatically advertising an address configured on loopback interface to OSPF

According to JNCIP study guide(page 156) from 2003, the Junos should advertise a prefix on lo0.0 interface to OSPF if the RID is not manually configured: JUNOS software automatically advertises a ...
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15 views

OSPF Router ID election query [duplicate]

I have a query regarding ospf router id election. Suppose I have a router with 3 connected interfaces. 10.1.1.0/24 11.1.1.0/24 12.1.1.0/24 I have enabled ospf area 0 on network 10.1.1.0 and 11.1.1....
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1answer
43 views

Brocade OSPFv3 Routes are not installed

I am trying to deploy OSPFv3 across our network. However a few routers do not install the OSPFv3 route's to their routing tables. For example, this router is able to ping a certain host on the network....
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1answer
388 views

How an OSPF network react when an attacker deactivate one of the network interfaces on the router?

I am a bit stuck with OSPF. Want to know how an OSPF network react when an attacker deactivate one of the network interfaces on the router? What are possible impacts on the network if this ...
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1answer
408 views

OSPF route advertising same subnet in same area 0?

Now: SW02 currently running OSPF area 0 with redistribute connected subnets which includes VLAN10 with another router/switches which isn't in the picture and not in the scope of this question; VLAN10 ...
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0answers
110 views

How should OSPF work over WiFi? [closed]

I've had problems running OSPF over my WiFi network, and it seems to be related to multicast. The routers can't maintain a neighbor relationship, and when I watch the packet traffic I see one router ...
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1answer
340 views

Layer 2 redundant network and OSPF

What is a recommended way (in terms of maintenance, simplicity and failsafe-ness) to essentially run a "ring" of switches, but allowing OSPF to run properly (so equal-cost-path routing can work - in ...
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47 views

Are OSPF standard areas consisting of only one router any use?

I am currently reviewing the OSPF configuration of an existing network in an attempt to streamline it. From a Layer 3 standpoint, this network consists of two core routers in Area 0 (CORE1 and CORE2) ...
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75 views

Connecting layer 3 switches together without trunking

I currently have 2x Juniper EX4200 and I'm looking into changing it into Ubiquiti EdgeSwitchs. The diagram: SW01 and SW02 are connected to each other using OSPF P2P. Both of the switches have their ...
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1answer
136 views

why does the show ip protocols command at each router for ospf router output not showing any Routing Information Source for all loopback 0?

NarS-R1(config)#router ospf 1 NarS-R1(config-router)#network 192.168.12.0 0.0.0.255 area 0 NarS-R1(config-router)#network 192.168.17.0 0.0.0.255 area 0 NarS-R1(config-router)#network 1.1.1.1 0.0.0.0 ...
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1answer
34 views

"ospfNbrIpAddr" parameter in RFC 4750 page 53

in RFC 4750 page 53, there is a parameter called "ospfNbrIpAddr", I am not sure exactly what it means. Suppose I have two router, they are connected through physical ethernet port1, router A port1: ...
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1answer
38 views

Do DR-Other router forwards Type 2 LSA received by DR?

In the Diagram below when R1 is newly added to Network Topology R1 and R2 become neighbors and exchange Type 1 LSA from R2, R3, R4. But how R1 knows Network LSA created by the DR in LAN(subnet 1). ...
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1answer
124 views

OSPF neighbor not working

I'm currently designing a spine leaf network, 2 Spine switches and 4 leaf switches. btw this in packet tracer. So in order its Spine1# and Spine2#, then Leaf1#, Leaf2#, Leaf3#, Leaf4#, and addresses ...
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1answer
470 views

Layer 2/3 Ring with VRRP/OSPF

I have a few questions about my understanding if this is possible and how to achieve the following. As per the example diagram (simplified from potential network) I have a ring network as shown below. ...
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1answer
415 views

Transient looping problems in Link State Routing versus Persistent looping problem in Distance Vector routing

Can someone please explain how looping problem is transient in case of link state routing, but is persistent in distance vector routing.(maybe with a nice example) Thanks in advance! :)
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1answer
359 views

How important is it for time to be synchronized between adjacent OSPF neighbors?

I have two routers that; when first powered up, will initially form full OSPF neighborship with each other and exchange their respective advertised routes with each other. After approximately 2 hours ...
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1answer
77 views

How can I get OSPF to see the VLANS that are trunked through the gigabit port

I am relatively new to this and I have been trying various configs but nothing is catching. I have three routers, with various vlans. The vlans are working. The routers are seeing each other using ...
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1answer
83 views

PacketTracer: Why can I not ping from one to another router?

I'm trying to ping from Router DC_GE to BE: I uploaded the Packet Tracer File (v. 7.2.1): https://www.4shared.com/file/aEsd_0Piiq/Topologie_Ausgangspunkt_MH.html CD_GE: CD_GE#show running-config ...
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1answer
48 views

What is the need of LSA refresh after every 30 minutes?

What is the exact need of LSA being refreshed every 30 minutes.
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1answer
54 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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2answers
48 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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1answer
45 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
308 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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1answer
212 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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1answer
147 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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1answer
173 views

OSPF Fast-Reroute Question

I came across this excerpt from the Cisco documentation: "Not all routes can have repair paths. Multipath primary routes might have repair paths for all, some, or no primary paths, depending on ...
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1answer
321 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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