24 votes

Why are rings not a favorite option in IT networks?

Historically, there were several competing technologies using ring structures like Token Ring or FDDI, but due to higher cost, lower performance, or simply slower development they've all vanished. ...
Zac67's user avatar
  • 83.9k
21 votes

Why are rings not a favorite option in IT networks?

The downside with ring networks as opposed to for example star networks, is that in a ring topology, any link in the ring needs to have enough capacity for all nodes on that ring, in order to be able ...
Teun Vink's user avatar
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15 votes
Accepted

5 nines, how is it built from 4 nines links

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....
JFL's user avatar
  • 19.6k
14 votes

5 nines, how is it built from 4 nines links

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 ...
Peter Green's user avatar
  • 13.3k
10 votes

Why are rings not a favorite option in IT networks?

Historically, we did use ring topologies - e.g. token ring. It didn't have redundancy. Whenever the ring broke, the whole network went down. Bus topologies (Ethernet over coaxial) were a bit better in ...
fraxinus's user avatar
  • 269
9 votes

I have a single ethernet switch. Should I use spanning tree?

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; ...
Marc 'netztier' Luethi's user avatar
7 votes

Why are rings not a favorite option in IT networks?

I mean it's a great way of providing redundancy with low cost. That is true if and only if multiple faults don't happen at the same time and one fault is fixed before the next fault happens. ...
Peter Green's user avatar
  • 13.3k
6 votes
Accepted

How does STP convergence work?

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 ...
Ron Trunk's user avatar
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6 votes
Accepted

Network Redundancy with LACP Trunking

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 ...
Ron Maupin's user avatar
  • 99.4k
6 votes

I have a single ethernet switch. Should I use spanning tree?

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 ...
JFL's user avatar
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5 votes
Accepted

Network Ten LTE Hubs Into One Network

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 ...
Trevor Butler's user avatar
5 votes
Accepted

Is it bad practice to use a Virtual Router for NTP-Clustering?

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 ...
jonathanjo's user avatar
  • 16.2k
5 votes

PVST + MST + RSTP network. Possible to make it work?

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 ...
Zac67's user avatar
  • 83.9k
5 votes

I have a single ethernet switch. Should I use spanning tree?

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. ...
Zac67's user avatar
  • 83.9k
5 votes
Accepted

Can LACP connect to 2 different firewalls?

Can LACP be set up to connect to two different firewalls? If LSW-1 and LSW-2 are indeed multi chassis LACP capable (Stack, Stackwise, M-LAG, multichassis LACP, VPC, VSS ... feature names vary by ...
Marc 'netztier' Luethi's user avatar
4 votes

Network redundancy design question with BGP

How should i perform failover link using BGP with same ISP? Form the BGP neighborship loopback interface. As per this thread: The use of a loopback interface ensures that the neighbor stays up ...
OzNetNerd's user avatar
  • 2,337
4 votes
Accepted

Network redundancy with low cost switches in a ring

As long as your "expensive" switch runs Spanning Tree Protocol, you can connect your switches in a ring. STP will prevent packet storms by only allowing packets out one of its (ring) ports. But if ...
Ron Trunk's user avatar
  • 67.3k
4 votes

Reduce ARP cache time-out?

I have personally done that ARP timeout set to 60 sec for a single VLAN caused 0.05% ARP usage on cisco 29XX series. It is running like that for over a month. No problems at all. Still I'd not ...
Viktor Borisov's user avatar
4 votes

Connect two routers to a single uplink for full redundancy

I have a single uplink with my ISP at a data center. I have 2 routers (CISCO 3850). How do I connect these routers to that uplink WITHOUT a network switch? That switch will be a single point of ...
Ron Maupin's user avatar
  • 99.4k
4 votes

Network Ten LTE Hubs Into One Network

Two ideas... I think the typical way to handle it would be a router in every trailer with three subnets: one goes to a switch for a trailer LAN, one goes to a campus backbone LAN for access to ...
batsplatsterson's user avatar
4 votes
Accepted

4507r Supervisor engines aren't operating redundantly

Redundancy on these Catalyst platforms operates in two modes: RPR (Route Processor Redundancy) and SSO (Stateful Switchover). In RPR mode, the Standby boots up "partially". When the Active dies for ...
mere3ortal's user avatar
  • 2,416
4 votes

Network Redundancy with LACP Trunking

From a functional point of view, there's no difference between LACP trunks and static trunks. All links are aggregated (with the limitations Ron has already pointed out) and the aggregation group is ...
Zac67's user avatar
  • 83.9k
4 votes

Can LACP connect to 2 different firewalls?

Generally, LACP does not support grouping links from multiple chassis. LACP works between two entities, not more. However, there are proprietary stacking solutions that combine multiple physical ...
Zac67's user avatar
  • 83.9k
3 votes
Accepted

ASA Redendent Failover and stateful link issue

"Everything working good but when i remove g0/6 cable..." --> Does this mean failover is working for you when g0/6 cable is plugged? Please plug back the cable and run the commands show failover and ...
Hung Tran's user avatar
  • 3,754
3 votes
Accepted

Load balancing between multiple layer 3 switches

Actually if your access switches connected to the so called "core switches" have just one uplink, either to the HP or to the Juniper, full redundancy is not an option given your constraints of no ...
matteo's user avatar
  • 266
3 votes
Accepted

BGP VPN created, how do I give access to internet

There are a few different ways to achieve what you are after. In my experience the easiest way to do this is to use vlans between the Service Provider "PE" router and the Customer "CE" router. One ...
Firebirdnz's user avatar
3 votes
Accepted

Adding a switch to provide redundancy

Do you have enough router ports available to do this ? You would still have your five trunks between the two buildings, but an outage on SW1 wouldn't bring down the whole LAN anymore. You would need ...
tonton gerrit's user avatar
3 votes

Fault tolerance with 3 routers in Packet Tracer

The simplest solution would be to add a dynamic routing protocol such as RIP, EIGRP or OSPF. Then raise the Administrative Distance of the static routes so the dynamically learned routes are ...
TDurden's user avatar
  • 1,241
3 votes

How to connect high-availability routers to high-availability firewalls

High availability is a big and sometimes tricky topic, depending on what you actually want to achieve. If you want to maintain running TCP connections, for example, with sub 100 ms retransmission, ...
jonathanjo's user avatar
  • 16.2k

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