Questions tagged [switching]

For questions related to traffic switching and troubleshooting the traffic switching process.

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19
votes
4answers
13k views

Why is the CAM table in a switch called CAM table and not MAC table even though it holds MAC addresses?

I know the CAM table in a switch holds MAC addresses and the ports that are associated with the respective MAC addresses. There are no such thing as CAM addresses from my knowledge, so why is it ...
4
votes
3answers
12k views

Inter-switch IGMP on a VLAN with two switches, and a multicast source per switch

I have a network consisting of two HP 2810 switched. Attached to each switch is, on one port, a multicast video coder, and on a different port, a decoder. There are two VLANs - a control VLAN (...
8
votes
3answers
5k views

Does a switch understand packets? If yes, what is the frame terminology for?

I was a little confused between packet and frame. The confusion was based on, if a switch is a layer 2 device, how does it reads a packet from a layer 3 device, and where is the 'frame' thing which is ...
2
votes
1answer
3k views

What is the purpose of native VLAN on a trunk link?

Most VLAN articles I've read recommend avoid using VLAN1 for ports with untagged traffic (aka access ports). I've heard enough of this nonsense. Except for the reserved values of 0x000 and 0xFFF, a ...
5
votes
2answers
4k views

Does a switch MAC address table sync across all switches in the same VLAN?

Ok, I have read up about this 16K limit for the MAC address table, or better known as the CAM table, on certain switches. Lets say I have 14 different edge switches with that 16K limit, and I have ...
6
votes
3answers
3k views

Is there any reason to use a hub over a switch?

Given that hubs are essentially the same as switches, as far as I know, except they share bandwidth between all connected devices, while switches do not, resulting in faster connections. I am simply ...
3
votes
1answer
357 views

question about switches and frame and forwarding table

hey guys was wondering if someone can potentially explain this to me but lets say switch-A just learned a Ethernet address on port 4 (00:0f:4b:02:63:ae) based on the forwarding table now a station ...
1
vote
1answer
335 views

Packet forwarding in Circuit switching

Does circuit switching make sure that all packets follow the same route?I understand that there will be a dedicated path between two end systems before data transfer and all packets are received in ...
1
vote
1answer
1k views

Layer 2 Switch Mac Address

I know a layer 2 switch floods the frame out asking who has a certain mac address. My question is how does it know what mac address to ask for in the first place? Scenario: A brand new switch is ...
5
votes
1answer
333 views

Optimizing Network Topology

Recently I wish to split the network by VLANs. Mainly for two reasons Exclude management interfaces from the commonly accessible lan Separate WiFi traffic (security and broadcasts) The current idea ...
13
votes
4answers
18k views

MTU and Fragmentation

Consider the following: NAS with 10G interface connected to 10G interface on switch. Client computers connected to switch via gigabit Ethernet. Will there be any gain in performance if MTU size is ...
12
votes
1answer
25k views

RIB vs FIB differences?

Can someone explain the differences between a RIB and FIB a little further? I didn't see any similar questions on the site so I thought this would be a good addition. The RIB routes and the FIB ...
11
votes
2answers
2k views

How did I break (half of) my network?

I'm looking for some post-event advice so this event doesn't happen again. We have a network core of two Cisco 4500x switches, configured for VSS redundancy. From those, we have iSCSI devices, our ...
10
votes
2answers
1k views

Can a switch that does NOT support VLAN capability be considered a managed switch if it has other features?

So the question is in the title. If a switch does not support Virtual Local Area Network capabilities can it still be considered a managed switch? What other features should it have to be considered ...
8
votes
2answers
12k views

Why each and every single port on Layer 2 switches need to have it's own MAC address?

A switch doesn't alter the frame, and source/destination mac addresses remain how sending host specified them,so let me say it again Layer 2 Switching never changes the frames means no changes in MAC ...
6
votes
4answers
65k views

How can hosts on two different VLANs communicate?

It is clear that hosts on two different VLANs can't directly communicate on a single switch, but how do they communicate to each other at all? Do they use a router? How does it work?
4
votes
1answer
130 views

[L4, F/W]How can I deal with SPEED?

I have a problem about Speed when accessing web servers.. [Circumstances] Everything is OK, every packet flows well. However, now I have focused on the speed... That is, connection is ok [Issues] ...
4
votes
1answer
5k views

What happens if two hosts with the same MAC address are in the same broadcast domain?

I am aware that situation, where duplicate MAC addresses appear in the same broadcast domain, should never happen. However, if such situation happens, then how will the network work? I think one ...
3
votes
3answers
6k views

Default static route per vlan

I would like to know if it is possible to configure inter-vlan routing on a level 3 switch with a default route per vlan. Actualy, I have one switch with 3 VLAN (VLAN1, VLAN2, VLAN3) and a router ...
2
votes
2answers
1k views

Designing OSPF mesh network

We have bought two new switches that will be used as the core in our network. They will be directly connect with some LACP link. The aggregation layer consists of 5 L3 switches that will have one ...
2
votes
2answers
1k views

Exiting to a Router from Layer 3 Switch with SVI enabled routing

I am trying to simulate a network, I am having problem directing traffic to exit the L3 Switch and to go to router for routing to outside network. (I don't want to use routing capability of switch, ...
2
votes
1answer
96 views

What does a LAN switch do if hosts are/are not in the same LAN?

If some host sends a frame to another one that is not in the same LAN, a the frame arrives to a LAN switch, what does it do? I believe it would broadcast it, but I'm not sure about it. And what if ...
1
vote
1answer
74 views

DHCP Help 3560-CX + Aruba AP515

The problem VLAN 100 is not assigning IP address to the SSID Guest from the AP, but Aruba is Tagging the SSID to be VLAN 100. How do I get the Switch to assign the DHCP? On the switch, it seems to ...
1
vote
1answer
652 views

Help this problem with Dhcp Server with two switches

I will try to explain my problem. I am trying that Switch 1 can give dhcp for pcs but i cannot, in Switch 0 I can give dhcp server in the pcs. sorry for my bad english ROUTER ! version 15.1 no ...
1
vote
2answers
416 views

How does a switchport learn a MAC address

I have a very basic question. How does a switch port learn a MAC address? In this scenario say a host is not trying to communicate with any one. It is just plugged in the switch port. Does the host ...
0
votes
3answers
122 views

Regarding Cisco's hierarchical network design

why routed ports usually implemented between the distribution layer and the core layer ? why not just extend the layer 2 domain to the core layer ? is the other design model more practical than this ...
0
votes
3answers
105 views

Propagating Static MAC Addresses

I have a situation where I need to place a static MAC on a switch as the server in question does not generate any outbound traffic. This static MAC seems as if it will work for hosts on the same ...