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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9
votes
3answers
3k views

Using latency to calculate OSPF metrics

Is it possible to configure OSPF to use latency in its link cost/metric calculations. The idea being to enable performance based routing whereby the fastest and least congested links in the network ...
4
votes
2answers
870 views

OSPF LSA checksum error

I have a Centos 5 box running quagga 0.98.2 which is flooding ospfd.log with: OSPF: Link State Update: LSA checksum error 2a32, 58d5. OSPF: Link State Update: LSA checksum error 2a32, 63bf. OSPF: ...
12
votes
3answers
12k views

OSPF Stuck in Exstart Adjacency State

According to this article two routers will get stuck in the exstart adjacency state when their configured MTU sizes do not match. Does a VLAN tag affect this as well even if the routers involved are ...
2
votes
2answers
2k views

loopback ip issue

So I have a weird issue. If I configure a /30 ip on an ethernet interface, for example 10.10.10.1/30 on Router1 and 10.10.10.2/30 on an ethernet interface on Router2, I can ping each other fine...no ...
8
votes
1answer
2k views

Wireshark Filter - OSPF Database Description Link State ID

Within Wireshark, how would one write a display filter for the IP address of the Link State ID within an OSPF Database Description packet? The Link State ID addresses are found within the LSA Header ...
4
votes
1answer
119 views

NBMA neighbor-ship process

Could someone explain what is NBMA neighbor-ship process in OSPF? I have gone through several books but did't get satisfactory explanation.
5
votes
2answers
2k views

HSRP + OSPF over tunnel interface

We have 3 sites over an MPLS. Each site has 2 x Cisco 2911's running HSRP. Each site has a tunnel interface from it's local site to the remote site over the MPLS. The tunnel interfaces are mirrored on ...
6
votes
2answers
463 views

Metro Ethernet settings on Customer devices

I am about to connect three remote sites to the main office by means of an metro ethernet provided by a service provider. The sites are connected by means of l3 and running OSPF on the connecting ...
5
votes
1answer
131 views

ip-fwd-entry allocation fail OSPF

Any idea what this error means? I can't find much on googling. Device is a Brocade SX. Output is from: show ip ospf error **** Warning! ip-fwd-entry allocation fail 3629337 times --- The ...
6
votes
1answer
2k views

How to find a duplicate router-id ospf in the network?

Hi I've got a problem in the network with a duplicate OSPF router-id. We tipically use the loopback ip address as the router-id, but I'm afraid that someone in the network don't care about that. I ...
8
votes
1answer
684 views

Why have all my lab routers set their OSPF priority to 0?

I have 4 routers in my lab. FR1 is the frame relay switch (2621), R1(2621), R2(2651) & R3(2651) are all connected in a mesh using sub interfaces - R1 has pvc to R2&R3 and so on. Without OSPF I ...
4
votes
2answers
3k views

OSPF LSA Refresh Time

Is there a Cisco command that would allow one to modify the default value of 1800 seconds (30 min) for the OSPF LSA refresh rate?
4
votes
4answers
979 views

OSPF LSA Performance Tuning

Does it make more sense to modify the 1800 second refresh rate, pacing timers, or all of the above in terms of network stability/best practices/etc to achieve quicker LSA maintenance? I am dealing ...
4
votes
7answers
10k views

Dynamic Routing Protocol (IGP) over IPSec VPN tunnels to branch offices?

What are the best practices for running an IGP to learn networks at HQ from branch offices when those offices connect via IPSec LAN-to-LAN VPN tunnels over the Internet? The branch offices terminate ...
-2
votes
1answer
2k views

Routes disappearing from OSPF routing table

For some reason I am seeing OSPF routes being removed from its routing table every 3-4 hours, yet they are still in the database. When this happens, there is still a neighbor relationship between the ...
9
votes
1answer
316 views

Remote Campus Routing Design

A third party provider supplies connectivity my remote satellite campus over metro ethernet. Due to red tape the provider is required to supply a routed point-to-point connection (R2 and R3) to the ...
4
votes
3answers
340 views

Subnet not being seen by OSPF

I have 2 routers running OSPF. Each router has a vlan configured with an ip from a /29. The routers are directly connected. I also have a loopback configured on each router with a /30. Example: ...
7
votes
4answers
9k views

Distributing static routes across an OSPF area

If you have a router which does not support OSPF, but your routing topology makes use of OSPF as all other devices do support it, what is the best way to get this routers networks in to the OSPF area? ...
10
votes
3answers
1k views

OSPF link cost design

What kind of processes and/or tools do you use to design OSPF cost on links in your environments?
16
votes
4answers
5k views

Why does this router fail to use multiple, equal-cost routes from OSPF?

A Brocade router running NetIron 5.2, and a Dynamips emulation running IOS 12.4 both fail to dependably use equal cost paths in what seems to be a very simple configuration. I say "dependably" because ...
22
votes
3answers
61k views

Protocols: EIGRP vs OSPF [closed]

EIGRP and OSPF are both IGP protocols, the former is a mostly Cisco protocol and the latter is a well established open standard. What are the benefits of one over the other? Put another way, when ...
11
votes
3answers
4k views

OSPF over vPC on Nexus7k

I'm trying to help a friend with some Nexus issues. The topology is like this: Cat 3750 stack -> vPC -> 2x N7k -> LACP -> Fortigate firewall cluster The 3750 stack is running OSPF to both the ...
26
votes
7answers
7k views

Does it make sense to deploy OSPF across Metro Ethernet?

When I need to connect a number of branch sites to one another for a customer, I typically recommend an MPLS VPN through a trusted carrier. The CE at each site speaks BGP with its upstream PE and each ...
19
votes
2answers
2k views

How do you get an ASA to announce NAT'd 'outside' addresses in to an OSPF zone?

Device arrangement is as follows: BGP Peers + | | +------+-------+ | | | Juniper MX5 | | | +------+-------+ |.254 OSPF | 10.0.1.0/24 ...
15
votes
6answers
2k views

Securing OSPF with only passive interfaces

I know that to secure OSPF you should 1) use OSPF authentication, 2) use passive interface command on interfaces that do not have ospf neighbors. If I only use the passive interface command and not ...

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