We changed our privacy policy. Read more.
15

4 nines = 99.99 %. That means the probability that a link fail is 0.01 % or 0.0001 in terms of probability (scale 0 - 1). Assuming independence, The probability that both link fails is 0.0001 x 0.0001 = 10-8, which gives back 99.999999. Yup, that's 8 nines and not 5, but we usually don't consider more than 5 nines. Note that Assuming independence, is in ...


14

A link that is 99.99% reliable is down 0.01% or 0.0001 of the time. So if the downtime of the two links is independent then both lines will be simultaneously down 0.00000001 of the time. Your link is in-theory up 99.999999% of the time. In practice though you don't usually get the full benefits because of other factors. Do you know how independent the ...


12

Have you looked at using a separate external mux? I've run parts of our rings on pairings of ordinary (but colored) 10G optics and passive CWDM muxes with a single strand on each side. This let us also do multiple parallel links at the same time (we used 8 channel muxes).


11

Things you should be aware of: SRX HA links communicate using jumbo frames and multicast addresses. So to make this work you need at least the following changes on the EX switches: Configure a jumbo MTU on the HA links and the links between the EX switches. This will enable jumbo frames to go trough the switch infrastructure. set interface x mtu 9216 ...


10

I am looking for a technology to achieve TCP connection fault tolerance with the help of two links between hosts and without time delays for route failure detection. Something like this: link1 packet1copy1-> -------------------------- packet1-> / \ packet1copy1/...


9

There are two main options for controller redundancy in Cisco's current wireless offerings. You can either use Backup Controllers or High Availability; depending on the firmware level of your 5508's, your acceptable failover time, and your budget. Based on your question, we're working with the following topology: Traditionally, utilizing Backup ...


9

To add to Zac67's and JFL's answers: In case you decide to enable spanning-tree on the single switch, don't forget to configure the client's and server's switchports as Edge Ports (Cisco speak; spanning-tree portfast [trunk], spanning-tree portfast edge [trunk] or spanning-tree port type egde [trunk] , depending on platform and software generation). This ...


8

This will work but it would be a poor design choice (IMHO) unless you have a specific reason for doing so. See this discussion: Duplicate OSPF area IDs OSPF Best Practicies Recommended OSPF configuration best-practices (using the SSM example) OSPF area configuration best practices Update #1: For the sake of completeness, I mocked up this situation using ...


7

Regarding the question of splitting area 1 across the backbone (area 0): [area 1, subnet 1]---[ABR #1]---[area 0, subnet 2]---[ABR #2]---[area 1, subnet 3] [area 1, subnet 1]---[Router #1]---[area 0, subnet 2, end device #1]---[Router #2]---[area 0, subnet 2, end device #2]---[Router #3]---[area 1, subnet 3] Short answer: There is no problem with ...


7

This is the logical view of what you're trying to achieve: Configure the router priorities for both VRRP 'a' and VRRP 'b' as follows: Router 1: 110 (master) Router 2: 100 (backup) The configure interface tracking as follows: Router 1 VRRP a: track interface R1b with a track priority of 90 Router 1 VRRP b: track interface R1a with a track priority of 90 ...


7

Assuming a single context active/passive failover configuration with the ASAs connecting to the 2911s on unique subnets, you could trunk the links using two subinterfaces and vlan tagging. But the hack is to not have both subinterfaces active at the same time on a single ASA. On the ASA on the left assuming it's active, the first subint would be alive and ...


7

Even if you could still get PI IPv4 addresses in Asia: if your ISPs don't want to route your IP addresses then there is nothing you can do. Tunnels and LISP could solve some of your problems (I use LISP here), but you already stated that this is not available in your region. BGP is the protocol that is used to route your IP addresses from an AS. You need ...


7

If i remember, default spanning tree (802.1d) takes about 50 secs to reconverge. That is the duration for which you will be losing frames. A link is detected down by the loss of 10 hello pkts. These are usually 2 secs apart. So total=20 secs. This is called the max-age timer Next it has to transition another blocked port through listening and learning ...


6

A passive wavelength-division multiplexer, such as a CWDM or DWDM mux, would probably be your best bet; this is how Service providers supply fiber especially longer distances from their local Hub site. It is probably a larger investment upfront but it would also allow you to get more out of your existing leased fibers. This is also assuming that your lease ...


6

My question is if this is an OK design, what are the possible pitfalls (say if a sup blows, how long before the link fails over) This design seems fine if you don’t have any dedicated 10G uplink modules. You just need to remember that your supervisor cards will go down more than any other cards on your chassis for software upgrades. Those upgrades depend ...


6

It is possible, even likely, that at least one (probably more) frames will be lost on any failover. The speed of the failover is highly dependent on what type of redundancy you are using. Spanning Tree is the slowest, routing is an order of magnitude faster, and etherchannels are yet and order of magnitude faster than that. When frames are lost, there is ...


6

I don't understand how a bridge decides that it is not connected to another bridge performing STP. If it doesn't hear BPDUs, then there's no bridge connected. How long will it until it decides it is alone and probably the root bridge? It starts out assuming it's "alone." That is, the bridge sends BPDUs with its bridge ID as the root until it hears ...


6

Scenario A: Switch 1 has ports 1+2 trunked together via LACP. They are plugged into Switch 2 ports 1+2. Both links will be used, but a single flow will only use one link. There is a hashing algorithm that determines which flow uses which link. If one of the links goes down, then all the traffic will be switched to the other link. This happens very rapidly....


6

As explained by Zac67 answer STP is normally only useful when connecting several switches together. However there's other related features than can be useful on a standalone switch. BPDU Guard will protect your network in case 2 links are connected to the same device. The most common case in my experience is with IP phones. BPDU Guard will disable the ...


5

You are really looking for the Brocade Track Ports and Track Priority features. With these features configured, when the red connection fails, it will lower the priority of the green connection. This should then allow the blue connection to take over as master in the group. Personally, I would also add a direct link between the two L3 switches as well. ...


5

From a design standpoint, specifically referring to the route servers, the answer is no, they should not peer with each other via an iBGP session [disclaimer: I've never personally attempted to do this, but I might now for fun]. The reason why is because route servers behave similary to route reflectors, only it's eBGP rather than iBGP. The most important ...


5

If you have access to 10 layer 3 switches you can certainly make this work. Treat each trailer as if it is a campus building with local internet. choose the trailer with the NAS as the core of the network and wire up each trailer to that core switch. Wire each switch in the trailer to the LTE router and create a static default route to the specific LTE ...


5

I can see a few ways of doing this: Round robin DNS with multiple A records (as suggested in comments by JFL). This would require the clients to properly re-look up the addresses when required, and get rotated A records (small TTL would probably help) and/or properly try the different addresses themselves. VRRP/HSRP (per your original question) This looks ...


5

Generally, you should stick to one spanning-tree protocol or only use those that interact well (e.g. MSTP and RSTP). Given the 1810 can only run RSTP that would be your choice. The downside of RSTP is that you can't spread VLANs across redundant links. It's possible to mix RPVST and RSTP but it's not always easy and won't work when chaining mixed switches ...


5

STP protects your network in case two switch ports are connected together, so you should use it generally. With a single switch, you can have redundant links to an appropriately configured host. However, you must not connect multiple links between switches/bridges unless you're using STP, LAG or SPB.


4

A common solution is to run two separate route servers and mandate all peers to peer with both of them simultaneously, announcing the same set of prefixes. See the AMS-IX documentation for an example. They run two redundant route servers: When peering with the route servers we mandate that routers are set up to connect to both route servers and advertise ...


4

One option is to connect both switches together and create two vlans that span across both switches. Connect the routers and the WAN side of the FW to VLAN 1. Connect the LAN side and the servers to VLAN 2. If you run HSRP on the routers, that is your default gatewway for the firewall. Here is a logical diagram. Let me know if you need help configuring ...


4

OK, from the top; Down vote on your question from me; your question isn't clear enough based on your responses in comments to other peoples answer. You have assumed the solution is networking engineering related but you don't seem to know, and give the impression that you hope someone is going to give you the answer you need. You have the following problem ...


4

Could be: CSCub92666 ASA:Old connections tear down IPSEC vpn tunnel on switchover Symptom: In IPsec vpn tunnel fail over configuration on ASA,fail over from primary to backup link works. But after second fail over from backup to primary link vpn tunnel start flapping in few minutes and remains unstable. The behavior is observed because of old leftover ...


4

This is true of Cisco Catalyst and as far as I know all Cisco switches: If you already have made both switches stack members, the slave switch should be elected to master if the current master becomes unavailable. I believe the original master will be reelected upon a power cycle of the stack, or just the slave I suppose, assuming the original master is ...


Only top voted, non community-wiki answers of a minimum length are eligible