Hot answers tagged

12

Hi and welcome to Network Engineering. As for "delay" vs "latency": The terms are not always used consistently. Some hints may be found here. I think generally, the term latency is used when looking at end-to-end times for one direction, which essentially are composed of the sum of all propagation, serialization, buffering (and possibly processing) delays ...


11

Open vSwitch has a section on that in their FAQ: Q: Why would I use Open vSwitch instead of the Linux bridge? A: Open vSwitch is specially designed to make it easier to manage VM network configuration and monitor state spread across many physical hosts in dynamic virtualized environments. Refer to Why Open vSwitch? for a more detailed description of ...


9

I'd suggest to remove ports from bridge if it is possible to add them to switch group. When your ports are bridged - all packets going through these interface are processed using CPU while, if they would have been in the same switch group, special switch chip would process those packets, decreasing load on CPU. So, in your case, you can make ether1 to be a ...


9

The description of switches and bridges is "sort of" correct, "sort of" not. Bridges typically don't have the capability to filter frames. Switches may have the capability to filter, based on things like access control lists, but that's for a bit later in your networking course. For right now, consider the following: A bridge forwards ...


8

I would argue that repeaters hardly do exist today. A repeater amplifies the electric signal but is a completely analogue device and does not in any way interpret the signal. A repeater is the same thing as a 2-port hub although I've seen some companies starting to use the term repeater for equipment that resembles a switch more than a hub. Contrast this ...


8

Yes, a bridge / switch adds some delay to a frame - in the order of 1 to 20 ┬Ás. For switches you usually speak of latency - the delay between receiving a frame and forwarding it out another port. A switch requires some time to receive the destination address and make the forwarding decision. Store-and-forward switches (the common kind) need to receive the ...


7

A VLAN is a layer 2 construct which separates devices into separate broadcast domains. A VLAN is a group of devices on one or more LANs that are configured to communicate as if they were attached to the same wire, when in fact they are located on a number of different LAN segments. Because VLANs are based on logical instead of physical connections, they are ...


6

This sounds like broken broadcast to me. First, the fact that your laptop works is maybe due to how Windows tend to do strange things with DHCP, like trying a unicast DHCPREQUEST with its previous lease to try to renew it. I assume that it only works in your case because you always connect to the main site before connecting to the remote site, or your ...


5

The succinct answer is "S/W" = software and "H/W" = hardware. A bridge used to be a computer and controlled the layer 2 traffic flowing through it with a special program, hence "software." A switch is built for purpose and the layer 2 traffic flow is controlled by special hardware (ASICs as mentioned in other answers) as it flows through the switch.


5

You seem to be confusing layer-2 and layer-3. Bridging is not routing. Bridging has nothing to do with layer-3 addresses, and routing removes the layer-2 addresses. Routers route packets, and bridges switch frames. Routing happens at layer-3 with layer-3, e.g. IP, addresses. Routing routes layer-3 packets between networks. Bridging happens with layer-2, e....


5

IEEE definition are sometimes a bit historical - a wire connecting a node to a switch port is a layer-1 segment (historically, this could also be a shared coax cable with many nodes connected to it, or a collision domain held together with a repeater hub). A simple switch connects all ports together to a single layer-2 segment or broadcast domain. These ...


4

Matt, good question! Bridge and switch are almost same things. Bridge, now(in 2014 ;-), is a basic function of the ever modern OS, so this is software. Lets look on bridge architecture(bridge operations are described in ieee 802.1D), bridge must have: forwarding proccess, forwards frames. learning proccess, writes incoming frames source addresses to the ...


4

Please ignore the comment above, it was supposed to be an answer but I can't delete it. I have this evening spent some time in a remote session with Deliberant support, and between us we managed to nail down the issues so it now works. I'm posting this information in case it is of help to anyone else in the future. 1) The Deliberant APC web interface will ...


4

The three major differences between a managed switch and using Linux bridge interfaces are performance, port density, and features. Most managed switches will embed some of their programmed functionality into specialized hardware. This is not true in all cases, but this specialized hardware will tend to outperform devices that are purely software based (at ...


4

In general, repeaters are no longer needed or used in modern networking. This section of the article dedicated to repeaters is largely there to provide historical background, and a big hint that this is the case is that it also mentions thicknet (a long defunct network technology). Repeaters operate on L1 of the OSI model and simply "regenerate" the signal ...


4

The way switches (bridges) work is that a switch builds a MAC address table which relates MAC addresses to the port(s) where the MAC addresses are connected. When a frame comes into a switch port, the switch will update its MAC address table to show that the source MAC address in the frame is connected to that port. Each port can have multiple MAC addresses ...


4

By default, all switch ports are in VLAN 1. Since you've assigned VLAN 1 to your bridge group, they would all be a part of bridge group 1. You can assign a switch port to a different VLAN (for example, port 2 to VLAN 2) with the command interface fastethernet2 switchport access vlan 2 But... It's not at all clear what you're trying to do. Bridge ...


4

You might want to consider SFP modules/transceivers integrated into the switches instead of unmanaged converters - SFP modules in managed switches are much better to monitor and troubleshoot. In your diagram, you connect the converters to the switches using multi-mode fiber. If those switches have SFP slots, just use single-mode transceivers instead and ...


3

You need to provide a route, otherwise you have two networks with no reason to talk across the link, as they are different subnets, with different default gateways, and the nanostation at network 2 is on network 1. If you plug a single computer into the LAN port on that nanostation, does it connect to network 1? it should, if the link is working. But without ...


3

The big problem with this is out-of-order packets and statistically half your traffic flowing across a slower, more loss-prone link. If you can do L3 (ip) across both links, I would suggest "CEF per-packet" load balancing. But again, half the traffic would be crossing a slower link. (I'm not sure CEF uses link bandwidth.) What you have is an unequal cost ...


3

Yes, this should work since the channel is switch-to-switch ethernet from the perspective of the switches. If you don't actually need to negotiate the channel, why use a channel negotiation protocol? That's just one more unnecessary complication. With Cisco switches on each side of the channel, why not just use the channel-group <num> mode on ...


3

The linux bridge is a pure software switch -- the cpu is involved with every packet. With a "managed switched", there will be dedicated switching hardware.


3

Bridge and switches are the same things, marketing make the difference, so bridge was not fancy and switch was cool about 20 yeas ago. IMHO Daniel is right about interpretation of s/w & .h/w


3

So there's likely a whole lot of other things going on with this configuration so the amount of depth that can be provided is going to be limited. To answer your questions specifically- A1: (from CCO) The Bridge Group (BG) is a non-functional configuration hierarchy that ties several BDs together in part of the same functional group. If you remove it you'...


3

It seems to me that you mis-understand the TAP concept. It only means that you duplicate a link. Then you are able for example : to forward the first TAP output link to the destination (or next hop) and the second output TAP link to a monitoring device. But you also can forward the first output TAP link to a firewall which will filter and/or modify the ...


3

A bridge (a switch is a high-density bridge) can help reduce the number of devices in a collision domain by breaking a single collision domain into multiple, separate collision domains with fewer devices on each collision domain than were on the original collision domain. Each interface on a bridge is a separate collision domain. Assuming you were replacing ...


3

In most respects, yes. A bridge may be just a switch, but it may also be more: there are (were) bridges that could connect different MAC-oriented layer 2 protocols like Ethernet, Wi-Fi, Token Ring, ARCNET, ... These you wouldn't call switches since switches only support a single layer 2 protocol (but may support several layer 1 media like 1000BASE-T, ...


3

The trick is getting the router to appear on 10/24. DHCP and secondary addressing requires a bunch of VLAN Magic(tm). Assuming no one wants to get that messy... adding routes on the router and ap should get you where you want to be. The problem you have with the bridge is that the AP will not "see" the traffic it's bridging, as at layer-2 the traffic doesn'...


3

It will work. Keep in mind this to learn why: 1 - A LAN is a single broadcast domain and single collision domain. Collision Domain: It means that a collision will be sensed by all the devices in the network. Broadcast Domain: A broadcast frame will be heard by all the devices in the network. 2 - A layer 2 switch (also a bridge) is a single broadcast ...


3

Specifically answering about whether we implement VLANs without bridging. Without a bridge, this would refer to a subset of stations on a LAN (single segment), although in practice we never implement this (that I know of). Actually it's quite common in smaller networks to partition a single, larger switch; I've certainly seen many Layer-3 switches used ...


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