Use this tag for questions about OSPF. Open Shortest Path First (OSPF) is a link-state routing protocol for Internet Protocol (IP) networks.
-1
votes
1answer
67 views
Can anyone differentiate the convergence speeds in different protocols (RIP , OSPF , BGP) [closed]
I am new to networking, I searched different books and tutorials and i did not find the convergence speeds of RIP, OSPF, or BGP protocols in a single statement.
Can anyone please explain the ...
5
votes
2answers
213 views
What is the advantage of an “area” in OSPF configuration?
As we know, during OSPF configuration we use the area. Each area has its different number, while there is only one area (area 0) which creates communications between all other attached areas.
I am ...
1
vote
3answers
188 views
Can't we use ospf between 2 routers that are in different Autonomous system?
Based on the same statements in all the books and articles , OSPF is IGP (Interior Gateway Protocol) , i.e, we can use it between 2 routers that are in the same Autonomous system .
Can we use OSPF ...
8
votes
4answers
260 views
What is the need of IBGP inside an Autonomous system as IGP protocols fulfill the need for internal communication
Can anyone explain me what is the need of IBGP communication for the routes, when we have the IGP protocols (OSPF, RIP) for internal communication?
I have read a lot of articles and books did not ...
3
votes
1answer
142 views
Routing of 2 Gateways via a Layer 2 Switch
Please refer to the network diagram below, it is a very simplified version of an actual network installation.
The Router has 3 Vlans, OSPF has been configured and all the 3 vlans have been added to ...
7
votes
1answer
202 views
Why does OSPF need Type2 LSAs?
Learning more about OSPF for CCNP studies. I'm looking at how OSPF builds its links, and have just covered Type1 LSAs. Looking at Type1 LSAs, I'm wondering why these are even necessary?
The book ...
1
vote
1answer
130 views
OSPF between ASA and IOS: Subnet and area design
Network: 100.10.0.0/21
R1, 100.10.0.9/29 (loopback 100.10.0.1/32)
R2, 100.10.0.10/29 (loopback 100.10.0.2/32)
ASA (active), 100.10.0.11/29
ASA (passive), 100.10.0.12/29
R1 has two bgp transit ...
4
votes
1answer
102 views
Can we do redistribution of ipv4 routes onto v6 address families?
Iam just curious to know whether ipv4 routes can be redistributed to ipv6 address-families.
Eg: I have a router for BGP configuration with ipv6 address-family and OSPF in ipv4 with other neighbor. Can ...
2
votes
3answers
195 views
OSPF and routing table
I have several questions on OSPF.
1 OSPF is a link-state prototol, so routers inside an AS only broadcast their link states to all the other routers.
I'm wondering if a router doesn't tell other ...
6
votes
1answer
191 views
JUNIPER: Why is OSPF adjacency breaking when I enable FBF on an OSPF interface?
I've built a test lab where I am testing Filter Based Forwarding (FBF), aka Policy Based Routing. Question will follow below, but first, the details:
Below is the topology diagram:
OBJECTIVE: Any ...
8
votes
3answers
504 views
3 subnets, 2 OSPF areas - Will This Work?
Will any issues occur if I have a topology involving 3 subnets and two OSPF areas where one subnet is in AREA 0 and the other two subnets are both in AREA 1?
For example:
[area 1, subnet 1]---[ABR ...
8
votes
3answers
243 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 ...
3
votes
2answers
121 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: ...
6
votes
2answers
322 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 ...
1
vote
2answers
181 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 ...
5
votes
1answer
222 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 ...
3
votes
1answer
53 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.
0
votes
1answer
84 views
Which protocol is used in the network and how do I find out [closed]
I understand that there are 2 main protocols exist such as OSPF and RIP.
How do I find which protocol is used in the network? Seems like RIP would be sufficient since I am running one router, but I ...
3
votes
2answers
221 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 ...
5
votes
2answers
152 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 ...
4
votes
1answer
77 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 ...
4
votes
1answer
149 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 ...
6
votes
1answer
137 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
1answer
148 views
Passive Network Monitoring Software [closed]
What are some good passive network monitors aside from Wireshark that can be used for analyzing OSPF traffic? In particular, I would like to be able to inspect the routing table and link-state ...
3
votes
2answers
235 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?
2
votes
4answers
178 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 ...
2
votes
7answers
1k 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
166 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 ...
6
votes
1answer
152 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 ...
2
votes
3answers
160 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:
...
6
votes
4answers
863 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?
...
4
votes
1answer
116 views
OSPF default route on a Brocade (Foundry) FESX 424
I have what I think is a weird behavior on a Brocade (Foundry) FESX 424.
This router receives a default route (0.0.0.0/0) in iBGP from one router, and route for
0.0.0.0/8 in OSPF from another ...
8
votes
3answers
249 views
OSPF link cost design
What kind of processes and/or tools do you use to design OSPF cost on links in your environments?
12
votes
4answers
608 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 ...
12
votes
2answers
2k views
Protocols: EIGRP vs OSPF
EIGRP and OSPF are both IGP protocols, the former is proprietary of Cisco and the latter is an open standard. What are the benefits of EIGRP over OSPF and vice versa?
What protocol should one choose ...
6
votes
3answers
389 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 ...
17
votes
7answers
984 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 ...
13
votes
2answers
259 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
...
11
votes
5answers
298 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 ...
