Cisco Switches :: SG-300 Series - Network Loop Broadcast Storm
Sep 12, 2012
So the SG300's have STP on them and prevent network loops when other switches on the network also support STP too. However, if someone plugs in a non-managed switch that doesn't support STP with a network loop, is there anything within the SG300 switches to isolate and/or prevent that from happening?
(I currently have port mirroring turned on for one port and a network sniffer attached awaiting the incident to happen again).
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Jun 7, 2012
I have a bunch of 3750x switches that each have a 10 gig routed link back to a central 4507 (loopback = 172.30.255.255).We carved up a /24 (of course, the /24 doesn't really exist except in our address tracking spreadsheet) into a bunch of /30's for routed WAN links and /32's for loopback addresses.We started on the low end for /30 subnets (ie 172.30.255.0/30, 172.30.255.4/30, etc.).We started at the high end for the /32 loopbacks (ie 172.30.255.255/32, 172.30.255.254/32, etc.)
Well, when I try pinging 172.30.255.255 from the access layer 3750x switches, the 3750x seems to be treating it as a broadcast ping where it lists each member that responds instead of the regular !!!!! response (this makes think something is odd with the 3750x). Of course, only one member responds (the core). But even the core seems to respond with the other end of the /30 instead of the actual /32 loopback (which makes me think something is odd in the core). I could have sworn that I've setup similar topologies without problems (ie, using 10.0.0.0/32, 10.255.255.255/32, etc as loopbacks) and as long as the mask is a /32, it should work.Also, I can ping/ssh to that loopback if my laptop is on a directly connected subnet. But I can't do it from any of the 3750x switches (which are also directly connected).I've double checked for overlapping subnets, but nope. I don't see any. Routing looks fine. The actual /32 is being propagated everywhere properly.
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Jun 23, 2011
I have 30 branch all over the country.There we have Cisco 3825 Series router at HO, and 892/k9m 1841 and 1811 routers in BO.My branches are being connected to HO via dual link which has been linked with two ISPs,both are Layer 2 link provided by the service provider,
-ISP1 subnet: 172.19.0.0/24
-ISP2 subnet: 172.20.0.0/24
usually i have the route pointing to HO ip from each branch routers. [code] Where, there are four branches acting as the gateway for the branch router 172.20.0.13. What cause the problem,and how can I solve this issue permanently?
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Oct 27, 2011
To prevent virus to spread throughout the network ports or switches, can i used broadcast storm to control? sometime, network may encountered loop, or some virus spread?
interface gi0/1-24
storm-control broadcast level ?
storm-control multicast level ?
storm-control unicast level ?
storm-control action shutdown
What will be recommended level? or the threshold / pps ?I read through cisco website, and understand, however, just never apply before, what is the recommended level for ?in my network, we do have network ports connected to media server, just sharing video, song, etc for testing purpose, however not using PIM, but it work.
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Jul 17, 2011
We have 3750 and 4510 switches and in both we run Q-n-Q but we observed looping/Broadcast Storm we already run TSP on 3750 end and this is corporate branch but 4510 its difference branch where we run q-n-q technology.
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Dec 20, 2012
Which command in the Cisco AP1200 series will you use to broadcast the SSID using VLANs?
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May 29, 2012
Yesterday there was huge storm, and lightning smashed into nearby house. My computer was running and I turned it off just after that. Result of nearby lightning was that internet no longer worked afterwards.
Soon after I was able to connect on my laptop, (laptop was connected and turned on during storm too) but desktop was still unable to do so.
I noticed that in device manager there is missing network adapter in list. EVerything is connected as it should be, but ethernet port doesnt have any lights on. I believe there should be some small light on port as is on my laptop, but Im unsure.
how I could check whether my network card is ok? Or what could the problem be? I really hope its just software issue.
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Feb 19, 2012
I have to use 9 Cisco 300 series switches to build a new network. I will use one of them (core switch) in L3 for routing between Vlans (3 Vlans) and the others in L2. Is there a software to centralized all switches configuration, operation and monitoring?
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Apr 26, 2011
how to check and trouble shot broadcast issues on network
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Dec 27, 2012
All my switches were connected together as ring topology. We use REP to block redundancy link.One of my colleagure was setting up a new link(VLAN) for one customer which was then caused a L2 loop. The CPU was hitting 100% and REP started to lost neighbors then we had a big outage.I am thinking to deploy QoS on all REP switch (on trunk links from switch to switch) to give priority to control traffic like REP and some importance data VLAN. Of course,Storm-Control already implemented on all access-port.
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Aug 9, 2011
My SG300-52 is struck in reboot loop after i set tcp congestion avoidance in webui.
********************************************
Boot1 Checksum Test...............................PASS
Boot2 Checksum Test...............................PASS
Flash Image Validation Test.......................PASS
[code]....
i've tried flashing new firmware via xmodem but still have problem.
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Nov 24, 2012
We have a couple of cisco SGE switches connected to a single DELL, between the cisco switches we have a trunk interface. I'm not sure which setting should be configured on the switches to get it working because a loop is occuring.
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Jun 22, 2012
After performing a firmware upgrade on an SG300-20 switch from ver 1.1.0.73 to 1.2.5.70 the switch now boots up with the following error and resets:
30-Aug-2011 10:47:33 %L1Mngr-F-PARAMTOOLONG: csco-sb parameter %s is too long.
The attached file contains a full output of the console boot process. I have tried loading different versions from the console, but all produce the same error.
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Sep 5, 2011
I've got an SG300-10P switch and am trying to use it to create a testing environment for a Fiber Test set. What I would like to do is get two hosts, A & B, plugged into ports 1 and 3 on the switch, to talk to each other, but forcing the traffic to be routed through the two Combo ports 9 & 10. Please see the attached diagram.I've attempted to configure two VLAN's, 10 and 20. Vlan 10 is used for traffic between Ports 1 and 9, Vlan 20 is used for traffic between Ports 3 and 10.I don't really care whether the traffic is tagged or untagged as it passes between ports 9 and 10.
I've tried various combinations of tagged/untagged ports, PVID's, etc. As a first test I've bypassed the Fiber Test set and simply created a direct connection between ports 9 and 10. I am unable to get the traffic from Host A to Host B to get routed through ports 9 and 10 (I ping each host from the other and get no response).
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Sep 25, 2012
I need to apply DHCP snooping on 4500 series switches working as L2 in my Network. We have external DHCL Server in another location connected with 6500 series switch.
Running EIGRP Configured Voice & Data Vlan both
DHCP Server -------- 6509 switch<----------------------------------->6509 Switch -------- 4500 switch ----------------------------------------------------------Ip Phones.
(ving Redundant) (ving Redundant)
I need to know whether the configuration which I mentioned in scenario is enough for apply DHCP snooping in my network.
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May 2, 2012
i have recently tried to change the catos on a Catalyst 2948G-L3 and since then i have the following message in a loop : [code] I know that the solution would be to download a new valid image from tftp via the common prompt but what i don't undertand is why i cant access the rommon prompt.
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Nov 7, 2012
I have a couple of 3560 switches running c3560-advipservicesk9-mz.122-44 and they are randomly experiencing the following:
- The switch locks up with no preceding error message in the log (I am forwarding syslog to Splunk).
- Upon reboot, the switch goes through the normal startup sequence with no error messages, then for some reason reloads the flash and starts all over again. (refer to doc)
This could happen after days or weeks. Sometimes they will go through two of these reloads on boot and be fine for awhile, and other times they will be stuck in the loop infinitely. I am using this same image with all of our 3560s, but am only having this issue with two of them.
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Feb 5, 2013
We have a Cisco 3750G Core switch which has physical connections, each configured as trunks to two HP Access switches. The client who uses these access switches would like to put a link between the two, but this would create a loop.
------- Core Switch -------
| |
| |
[Code]....
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Mar 27, 2013
I have a stack of 6 switches and I want to add another over the gbit connector using fiber. I already connected but I can acces the network from the new switch. I don't have any issues on my Stack all resources are available Do I need to do some special setup or connection to enable this? Can be stacked like the others? I already usen the 2 stacking port can i Add another switch?
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Mar 16, 2011
RSTP port role in the switches are flapping if broadcast data is flowing through the ring. Also I've tried applying broadcast suppression to all the port to 64kbps for ports of 100Mbps/1Gbps, All the devices I'm using are L2 switches.
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Aug 1, 2011
model: SG300-52
version: 1.1.0.73
Switch is running in layer 3 mode.How can I turn off mDNS broadcast coming from the vlan interface on the switch.Getting mDNS broadcast from switch every 5 seconds.
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Aug 21, 2011
How to erase or remove configuration file from ESW 500 Series Switches?
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Apr 21, 2013
I don't do a lot of networking however during a cisco lesson the other day my lecturer briefly touched upon loop-back tests, would it be okay for somebody to very imply sum up exactly what loop-back tests do in a couple of lines and how they are carried out? (not in detail, so literally for example - a wire is put in from one end of the network to the other etc.) I don't really understand all the different wiring types etc.
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May 19, 2011
How can I identify loop or virus in the network? is there any command to find out these ?
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Jun 7, 2013
when this error occurs
we can't see the cdp neighbor and the wireless crash.
we login onto the ap with console , we can see the error log : “Network interrupt loop detected” . last forever
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Dec 22, 2011
I`m connecting a client directly to a 3750, and giving them a public IP.
On the port I have set spanning-tree bodyguard enable
But I guess I should also set some storm control etc. What settings should I use for storm control?
The client has a 100Mbps internet connection running trough this port....
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Apr 30, 2012
We're using ME-3600 and ME-3800 switches to create VPLS domains. Now to avoid L2 loop issues with 3rd parties connected to the multiple ME-3X00 switches and configured in the same VPLS domain, we would like to configure storm-control.
When checking the configuration manual about storm-control on ME-3X00 switches it mentiones: storm-control is configured on the physical interfaces and when it's triggered it will not only impact the physical interface buy also the EFP configured on it.
According to me this could mean two things:
When there's a storm on the physical port, the port wil be shutdown (it if this the action configured) and of course the EFP on that physical interface will be impacted too (logical consequence).When there's a storm on an EVC (EFP) configured on a physical interface, it will shutdown the entire physical port (if this is the action configure) and as a consequence all other EFP will be impacted too. Briefly: is the configured storm-control on an interface also triggered by storm-controls on an EFP? I suppose it would but like to have some confirmation.
configuration example
interface GigabitEthernet0/2
description TEST storm-control
switchport trunk allowed vlan none
[Code].....
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Jul 26, 2011
I have three eigrp configured routers A, B , C in a single broad cast LAN.I want to deny router A eigrp peering with router B, need to retain A peering with C. A router:no neighbor <B router lan ip> under router eigrp will work ?or how can i deny using the multicase ip address 224.0.0.10 usinng access lis an din which direction i need to apply.
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Dec 8, 2010
There is a port on 3560E, facing POP, this port is in the dedicated vlan, that is terminated on 7606 on SVI (peering point).There is configuration made on the 3560E port, that prevents storm of ucast or bcast kind. This is: switchport block multicast switchport port-security maximum 1000 switchport port-security switchport port-security violation restrict storm-control broadcast level bps 1m storm-control multicast level bps 1m storm-control action shutdown storm-control action trap no cdp enable no lldp transmit no lldp receive spanning-tree portfast spanning-tree bpdufilter enable spanning-tree bpduguard enable. [code]
I want to get info not only about the fact of storm attack but also about at least source and destination of it (i.e. source and/or destination MAC). Perhaps this could be some logging messages.Are there any means for this on C3560E-UNIVERSAL-M (IOS ver 12.2(53)SE2) and 7606-S.
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Aug 10, 2011
how do i broadcast a message on my network using command prompt?
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Nov 5, 2011
im using microsoft network monitor to monitor all traffic in and out (public) and mirrored ports for local traffic, except wireless traffic as its connecting to the router. I want to use a wifi NIC on the server to broadcast, so wireless clients can connect via the server and obtain DNS and DHCP etc from there, therefor, monitoring all traffic.
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Oct 4, 2012
I am using 1841 LAN router. Recently some broadcast is happening in our network when some users are connected. I need to block them automatically by detecting who are they.
I can block them manually but i want router to detect them and block.
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Mar 3, 2010
I recently had trouble connection to my Linksys WRT54G router. However, in this process I had to create a couple of new profiles/networks/SSID or whatever they are called. I now have one functioning network, but my router is still broadcasting the other two networks. How can I get my router to only broadcast the one network, I am currently using? I erased them from Vista, so that my own computer does not automatically log on to the, but that is clearly not enough. Since one of the networks is not secured with a password (dont ask why), my concern is that my neighbours can access it. BTW, I am using Windows Vista on a Toshiba Satelite A200.
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