Cisco :: Does OSPF Cause Loops
Dec 6, 2012What if i run ospf in all of the routers in network diagram ? does it caus loops ? if so how to prevent it ?
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Cisco WAN :: AGFR01RTR03 / AGFR02RTR03 - Missing Route In OSPF To OSPF Redistribution?
Sep 22, 2011I have 2 ASBR routers, AGFR01RTR03 and AGFR02RTR03, performing OSPF to OSPF redistribution in both ways for the same ***. They also do summarization for our private addressing scheme. It is all working just fine for that part (neighbors, summarization, redistribution).
AGDC01RTR01 --- AGDC02RTR01 (OSPF 1000 ABRs)
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AGFR01RTR03 --- AGFR02RTR03 (OSPF 1000 / 53 ASBRs)
Let's focus on AGDC01RTR01 with a specific entry here (IP subnet is fake) :
Routing entry for 1.1.1.0/25
Known via "ospf 1000", distance 110, metric 300, type inter area
Last update from 10.2.244.76 on GigabitEthernet5/1, 1d03h ago
Routing Descriptor Blocks:
* 10.2.244.76, from 10.2.1.249, 1d03h ago, via GigabitEthernet5/1
Route metric is 300, traffic share count is 1
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Cisco WAN :: VLAN 160 / 162 - Different OSPF Process ID For Interconnect Between 2 OSPF Domain
Mar 14, 2011Currently the OSPF network consist of 2 segment route via static route.One is AREA 0 and another AREA 10.Both network are seperate entity, only static route to route between 2 networks.But the static route do not provide the dynamically and flexibility, I plan to run routing between 2 networks via VLAN160 and VLAN162.
I still want to manitnace it was 2 different OSPFrouting domain.Can I run OSPF with differrent OSPF porcess ID?
Cisco :: How To Avoid Loops In The Network
Jul 20, 2012A friend of mine faced an interview, the question is what if there is no STP feature in the switches over the network and what would be the alternate method to avoid any sort of loops?
I guess we can think beyond till layer 3 devices by using some split horizon commands?
Cisco :: ASA 5505 Introducing Networking Loops
Jun 19, 2012Have a number of organisations that I work with who are currently all changing their ISP to a different one. The company who are supporting this are introducing a new router and firewall to the network and removing the old layer 3 switch. Firewalling and filtering was previously done off site but will now be handled by the ASA 5505. I personally do not have permission to configure the ASA (nor would I know how to) So these places are set up with 2 ip ranges, so int 0 on the ASA is 10.0.0.1, int 1 is 10.0.1.1. The Cisco ASA has been configured with the same settings on it's required ports as the old layer 3 switch had, so nothing much has to change on the internal network. Problem is that the old layer 3 switch must have only been passing data through at layer 3, so basically not switching and not creating networking loops. It seems that due to certain required network topologies, switch A is connected to switch B, which is connected to switch C, which is connected to the ASA, but switch A will also be plugged into one of the interfaces on the ASA (creating a loop). As I've said, this was not a problem with the layer 3 switch but now the ASA must be switching at layer 2 (I guess...?) as well as routing to the internet (which is required for both ports, which are vlans) and so is messing up the lan with a switching loop.
can the ASA 5505 be configured so as to allow access to the internet for both vlans/ip ranges while also preventing switching loops being created? It seems definite that this is being caused by the introduction of the 5505 as the old setup was exactly the same, it's just that the 2 cables have been plugged into the 5505. We do not have the option of using STP here as the rest of the switches on the network are unmanaged.
Cisco :: How Spanning Tree Protocol Detects Loops
Sep 6, 2012For last few days I've been reading about Spanning Tree Protocol ,L2 protocol and understood how it prevents loop in network ,various steps in STP but one thing i wanted to know how STP actually detects the loops in network so that it can prevent it.Somewhere I read STP uses BPDU as probe and detects loops I mean how it happen is when switch send a BPDU with Destination Address as multicast and receive same BPDU again mean there is loop in network .But is it how STP detects loops in network?
View 5 Replies View RelatedCisco LAN :: 6500 / 3550 - Method For Detecting Loops
Sep 23, 2012I am a network tech at a local school district (easily enterprise network). I am just a worker bee, so have no say in the design of the networks. Our topo at a site goes WAN rtr---LAN rtr (6500 of 3550)----distro switches----access switches.
Now at most of our sites we use Extreme, which has a handy feature called ELRP Extreme Loop Recovery Protocol, despite the name, this mechanism just detects loops, in the logs we can see, ok...off the LAN rtr, port 2, then on port 2 we see whats hanging off it...ok, loop off port 5 of that switch.....and work your way down the room.
We do not have STP on our network (dont ask) and yes, logging is not set to standards also......what is the best way to detect loops? Commonly these loops come from classrooms that have mini-sw's that are looped onto themselves or a wall jack connected to mini sw and that mini sw then connected to another wall drop going back to same sw. Sometimes I disable all ports minus the WAN uplink on the LAN router, then enabled ports one by one while having a LR hooked up to a user facing rj45 port on the 6500 and when the LR (link runner) shows 100% util, I know that port is now suspect.
Cisco Switching/Routing :: Nexus 5000 - What Cause Loops On Ports
Dec 14, 2011Any opinion on what could cause loops on nexus 5000 ports that are connected to esx hosts ?
View 3 Replies View RelatedCisco Switching/Routing :: 2950 - Bridging Loops / STP Protection
Jan 20, 2012I have a network where if an end user attaches an hub to the network, or rather one of those cheap unmanaged 8-port mini-switches and then plugs the two ends of the same cable into two ports of that mini-switch, all the network goes down. Loops are generated and many uplinks are shut down in err-disable state due to the loopback reason.
I know I could discourage the use of those mini-switches using port security. I even have NAC (cisco) deployed on the network, but there are cases where that mini-switches are allowed by the managment.In those cases, is not possible to exactly know wich hosts (mac addresses), and even how many of them will attach the network concurrently.As I know, they could even chain many mini-switch one to another. Of course, when even a single mini-switch is allowed on the network, it raises as a security hole.
Is there a way to allow the use of those devices without the risk of network outages? Some STP protection method? The best would be to have the Cisco access switch to get aware of the loop on its affected switchport (where the mini-switch is attached), immediately shutting down that port (to avoid loops on the network) and maybe sending an SNMP trap or a syslog message.
We are using Cisco Catalyst 2950 and 2960 for our access layer.
Cisco Routers :: RV042 QuickVPN Loops While Verifying Network?
Nov 15, 2012I used to have the problem where QuickVPN keeps on trying to verify the network because the RV042 cannot get the final ping to the client.I then bought a RV042 HW version 3 on the VPN side and I installed RV042's at the clients as well.This may look like overkill but believe me, it gives peace of mind, it made things a whole lot better, everybody happy.I am going to set up tunnels but for the time being the clients use QuickVPN. The above setup is all good if people access the vpn from the same source.
I now have a problem where one of our people is in Vietnam and she cannot access the vpn due to the "verifying network" loop.Looking at the log everything looks great, I compared a successful connect with an unsuccessful one and the logs are identical.The only difference is that the final ping is blocked (recorded in the QuickVPN log on the client side).The client uses W7 with firewall on.No need to repeat suggestions, such as turing printer sharing off, I have been through all that. isn't this simply caused by the ISP in Vietnam blocking pings ?
Cisco Switching/Routing :: 3750 BPDU Guard And Bridge Loops
May 22, 2013We have an environment where users create a lot of bridge loops. We have tried to send E-mails about it and educate the users but it is almost a lost cause at this point. The loops are created when users don’t pay attention and they plug a patch cable coming off of an access port up to ANOTHER access port by mistake.
All of our access ports are from 3750 stacked switches. The way we tried to deal with this in the beginning was with BPDUGuard and ERRDiable (BPDUGuard) auto recovery. We turned BPDUGuard on globally and left BPDUGuard auto recovery at the default value (I believe it was 30 seconds). so a loop would be detected and after 30 seconds, the switch would try to enable the port and if the loop still existed, close the port for 30 more seconds. Then we started having problems with printers getting "fried". Their NICs would die out and the control board would need to be replaced. After a lot of troubleshooting and testing, it was determined that allowing the ports to come out of ERRDisabled state would flood the network and the packets would generate in the millions per second range and fry the NIC of these printer.
The fix for this and saving the printers was terrible. We removed ERRDisable auto recovery and just let the ports that are looped stay in an ERRRDisabled state. We wait for the user to figure out the loop and try to use the port and then put in a work order. Then we physically visit the site and verify the port was shut (ERRDisabled) from a loop and we bounce the port (shut/no shut) and everything is resolved. I did lab tests with a switch looped and a printer on the switch and watched it fry. We have had no printers fry after we removed the auto recovery protocol at every location. Only the locations where loops existed and auto recovery protocol running were printers going bad. What I found during my lab tests was that each time the port was auto-recovered (yes, for that millisecond while it checks if a loop still exists), more packets were re-generated and eventually enough was re-broadcastthat printers would go down. We never had a problem with computer NICs. I guess the cheaper printer NICs couldn’t handle the broadcast storms created by this. I tried playing with the auto recovery timers and even the highest setting would eventually re-create these storms.
So my question is what best practices are others using? Should we get rid of BPDUGuard and just try to let spanning-tree handle these bridge loops? Is there something else I can try? I’m not CCNA by any means, just trying to do what I can in my environment. Manually visiting sites when loops occur is becoming more and more my job, though and I have plenty of other things to be doing.
Cisco Switching/Routing :: STP Stops Loops But R-PVST Goes Flapping 2960
Feb 22, 2012Stange problem which I encountered today, I have a Cisco 2960 which is connected to a netgear. The switch started showing itself in CDP and was running STP. I checked the cables physically today and noted 3 uplinks to the netgear, all port on the Cisco active and forwarding and green lights.
The Cisco was running STP, I changed it to R-PVST and the lights on the Cisco went crazy and I got the message port flapping on the switch but the switch did not block any ports (all ports on same vlan).
There after I changed it back to stp and the switch blocked the other up links apart from one.
Sure R-PVST is far superior than STP?
Windows 7 Laptop - Errors And Login Loops When Cookies Enabled
Mar 19, 2011My mum is running Windows 7 Home Premium on her laptop, with AVG Free Anti-Virus. She uses Chrome, Firefox, and Safari. Cookies are enabled on all browsers.I'm running Ubuntu "Lucid Lynx" 10.04. I use Chromium and Firefox, occasionally Opera. Cookies are enabled on all browsers.I also have an iPad, which is running the latest software. Never had a problem with cookies before.My brothers use Facebook through Xbox. They can't log in either.My router settings are set to allow cookies, and according to my ISP, my internet is up and doing fine.Now, the issue ...My mum noticed a login loop when she tried to get into Facebook. Every time she tried to log in, it would just redirect her to the login screen. I tried the same thing to no avail. I can't log in to some other sites as well, such as Photobucket. I can't upload to tinypic either. However, as you may have noticed, I can log in to forums just fine - however, it only keeps me logged in for one session, even if I ask it to remember me.My neighbours don't seem to be having this issue - except for the neighbour that shares our internet. She can't log in to Facebook either. I thought it might have something to do with our IP, so I tried using the Tor/Vidalia proxy assistant to log in to Photobucket from a different server/location. It worked. So, we can log in to various websites via proxy, but not from our home IP.
View 5 Replies View RelatedTP-Link TD-W8960N / Connecting To Wireless Network Loops But No Error Message?
May 7, 2011My roommate has just gotten a second hand laptop and he's trying to connect it to the Wireless network so that he can browse the internet from his room.However, although all the settings are correct, attempting to connect to the network loops.It comes up showing the Wireless Networks available, I select the network and click connect, it then asks for the encryption key. I enter the key and hit connect again, it comes up with the 'Connecting' pop-up and then loops back to the Available Networks screen again.There are no error messages, it just goes back to the starting screen and it hasnt connected.The Laptop in question is a Lenovo T60 with a Intel PRO/Wireless 3945ABG card.The router is a TP-Link TD-W8960N.
View 5 Replies View RelatedLinksys Wireless Router :: EA4500 - Connection Getting Loops And Power Outage?
May 12, 2013I have a Cisco EA4500 wireless router. The only issue I have had with this router is when power gets disconnected or if I have a power outage, I have to go through some loops to get it to work again usually taking upwards of 45 minutes to fix.
View 1 Replies View RelatedCan OSPF V2 And OSPF V3 Run In The Same Time
May 15, 2011I am running IPv4 with OSPFv2 currently. However, I planed to deploy IPv6 in my network. Is it possible to deploy V6 with OSPFv3 without affecting current network traffic in V4?
View 7 Replies View RelatedCisco :: OSPF On ASA Not Getting A Route?
Aug 29, 2012why a subnet wouldn't be passed on to just one participating OSPF device?
I have two routers and an ASA, all of which are in area 0, it's a pretty simple config. The two routers are connected to some other devices (also in area 0) that pass of an external route to a particular subnet, let's call it 192.168.4.0. The routers are getting it just fine, but the ASA is not:
Cisco :: Increase The TTL Of An OSPF Hello Packet?
Jul 12, 2012Isn't there a way to increase the TTL of an OSPF Hello packet or am I thinking of a different protocol? Or is it only with virtual links? I can't seem to find it in my ROUTE cert book or on the Intarwebz outside of setting TTL security, but I could have sworn I remembered configuring something like this in my ROUTE lab book that I unfortunately do not have at work.
View 8 Replies View RelatedCisco :: Presenting Public IP To ASA Over OSPF?
Oct 29, 2012I will be provided with /29 public IP address from my ISP. The idea is to run OSPF between ISP and my ASAs over private IPs so /29 is presented to ASA. This is because I will be using 5 out 6 available IPs on my ASA so I cannot use them on the routers.I need to run HA in Active/Standby mode on ASA, terminate site-to-site and remote access VPNs on ASA, and use static NAT for kit in DMZ network I am trying to figure out how to present this public IP range on ASA. Should I create two subinterfaces on physical interface towards OSPF area and assigned private IP address on one of them for OSPF and public IP on another and then setup a failover on each subinterface.
View 4 Replies View RelatedCisco :: Run An OSPF Protocol Over An ATM Connection?
Apr 25, 2013I'm trying to run an OSPF protocol over an ATM connection:
192.168.80.0 |----10.0.0.1-----------10.0.0.2----| 192.168.50.0
Cisco :: Link Between Different Ospf Process ID
Dec 22, 2012how would u link(or in other word route) different OSPF process ID? i have OSPF 1 and OSPF 2 and i want them to see each others networks...how can i accomplish this ?
View 7 Replies View RelatedCisco :: Backup WAN Connections With OSPF?
Feb 11, 2013implement backup WAN links to complement the metro Ethernet links we currently use so we have some redundancy. These will most likely be a VPN over an Internet service but might be another Ethernet type service, the medium shouldn't really matter I wouldn't think. What I am looking for input on is what is the best way to implement this? Would I just set costs so that the backup is only used when the primary goes down, or should I create new OSPF area for the backup links?
Currently the core switches that are also our routers are 3750G stacks running ip services. We are getting ready to install new firewalls at each location that will become the gateways for the vlans currently on the core switches to give us much more control over segmentation, and because of this I am thinking that it may make sense to then move the OSPF instance from the core to the firewalls. In the drawing I did not show the access layer switches off of the core, and the MOE circuits actually terminate into a 3550-12T switch before the core. I think I will actually eliminate those 3550-12T switches and go straight into the core. This is a current state drawing, so does not include the backup links I am planning.
Cisco Firewall :: Run OSPF In ASA 5520?
Aug 12, 2011I have 10 different segments in ASA 5520, so i created 10 VLAN in ASA & made the inside interface as Trunk that connects with core switch. Now i need to run OSPF in the ASA.
View 1 Replies View RelatedCisco WAN :: Support For OSPF For 3560C
May 13, 2013I am in the datasheets page for Cisco 3560C Compact switch and states that it ships with IP Base image that "includes the support for routed access, MACsec, and Open Shortest Path First (OSPF)"
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Does this image come with the full fledged OSPF feature or is it a cut-down version of it?
Cisco WAN :: 2821 OSPF WAN Routing
Dec 19, 2010I will be getting a WAN connection to a few offices and I have a need to control routes recieved and advertised to/from them. The service provider will be placing a CPE device on-site and will support OSPF with my edge router; in this case a Cisco 2821. That 2821 router will ideally be configured with OSPF routing toward my two core switches.
-> C2821 to NOT have the full routing table from the Core switches
-> Only needs knowledge of two routes from the Core switches and routes from remote offices.
-> Controlled routing advertisements. I do not control the remote offices and would like to ensure they do not accidentally advertise routes into my enviroment that could create a conflict.
I'm assuming the Service Provider will be running BGP on their CPE router, which will mean that the OSPF routes recieved by my Cisco 2821 edge router will be OSPF E2 routes. So if thats the case the 2821 would need to advertise E2 routes.I'm not sure if I should be configuring the 2821 in Area 0...because its meant to be a WAN edge router; but if I configure it in another area...say 200...the Service Provider may configure his CPE router in Area 0...which I'm guessing would pose a problem as the 2821 would be lodged in between two area 0s?
From the reading I've done it sounds like I could use NSSA...but I'm not sure if this is the best design.
Cisco :: OSPF NSSA Default Route?
Jan 19, 2013Looking through the SPROUTE course material they state on several occasions that an ABR will announce a default route in to a standard NSSA area, same as a stub area, because LSA5 external routes are not allowed.
View 8 Replies View RelatedCisco :: OSPF Within Tunnels In ASA5505 - ASA5510
Jun 27, 2011I have 3 tunnels established (full mesh) with 3 CISCO ASA (all security+), through Internet : - Site A : ASA5510 - Site B&C : ASA5505, There is no main site or client site, each site has more than one network behind it. So I'd like to setup OSPF between all the ASA for them to exchange their route within the tunnel. I thought this was automatic when establishing the tunnel, but it isn't.
View 1 Replies View RelatedCisco :: Inter-Area OSPF Summary?
Feb 26, 2013When you configure an ABR to inject a summary route into an area, what are the circumstances under which the ABR will inject the summary? I.e., since it's not a set of specific subnets learned directly from other OSPF routers, does the summary get injected regardless of what's in the routing table of the ABR?
I would imagine this could cause problems in a situation where there is an ABR injecting a large summary into an NSSA that also has a backup path over the Internet (IPsec tunnel or something). For example, if the area 0 routers from which the ABR receives routes went down, the ABR would continue to inject the summary route into the NSSA thus tricking those routers into sending traffic to the ABR rather than over the backup link.
I can't imagine any other way an ABR would decide when it's suitable to inject the summary though.
Cisco :: NAT For Ospf Networks Or Any Inside Network
Jul 1, 2012I have a simple isp topology built in GNS3, for testing (pppoe) dialers:cisco router(R1) connected to my pc network card, doing NAT translations for all the devices in the topology.I know how to configure NAT for spesific ip range, but i can't find out how to configure NAT for networks which are learned through ospf (or any other dynamic way).
View 2 Replies View RelatedCisco :: OSPF Link ID As Broadcast Address?
Sep 24, 2012I have an AS-external route being redistributed into OSPF from a static route on one of my routers. I recently changed the static route from a /24 to a /26 and all of a sudden the link ID of the segment in the OSPF database went from the network address to the broadcast address: Code:
View 5 Replies View RelatedCisco :: NAT Overload Breaks OSPF Adjacency
Aug 30, 2012I have 3 routers all running OSPF. each of the three routers have 2 networks they are advertising..NAT Overload breaks OSPF Adjacency
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Cisco :: OSPF Multi Access Network
Feb 10, 2013OK. I think Im going crazy here. Im studying OSPF and I'm working on the DR/BDR election process. I have a topology where three devices (RIDs 1.1.1.1, 2.2.2.2, and 9.9.9.9) are on the same ethernet segment so they need to elect a DR. 9.9.9.9 is a switch and Im using a SVI for the OSPF interface. Van't get the darn thing to show up in the post but here is the topology.URl After OSPF came up, I noticed that router2 was selected as the DR and that switch1 was selected as the BDR. I thought initially that it was a matter of timing and that perhaps router2 just came up first and the slower SVI interface came up second. Shutdown the interfaces, cleared the OSPF process, and set the OSPF router priority on the VLAN interface to 10.
View 11 Replies View RelatedCisco :: OSPF Route Propagation Over GRE Tunnel
Oct 16, 2012Cisco device is neighbored up with a Brocade device via OSPF, and the desired routes are present.This Brocade device is neighbored up with another Brocade device via OSPF over a GRE tunnel. I am not seeing the desired routes present.What kinds of things can I look at to determine the issue? I think I've viewed the OSPF topology database (I'm not that familiar with Brocade) with the show ip ospf routes command and I'm not seeing the desired routes there either.There is no form of route filtering in place. I'll double check, but I do not believe there is any stub routing going on either.
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