Questions tagged [switching]

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

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46 views

Fiber link loss on Cisco Catalyst 3750x series switch

I have cisco catalyst 3750x 24 port switch series switch, and the switch has C3KX-NM-10G module. Problem : I have connected fibre optic in SFP+ transceiver on G2/TE1 (Uplink).  After 7 to 8 hours, the ...
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1answer
108 views

GNS3 switches vs Real switches performance

I want to emulate the performance of switches in GNS3, and the focus is not the configuration of switches. My questions are: Do emulated switches perform worst than actual switches? Are emulated ...
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1answer
28 views

Is it possible to assign an IP to a tagged dual-mode port (Brocade)

I have a router (ubiquity USG) and a Brocade FCX648 Layer 3 switch. (I have a second one in a stack, but that's unrelated). The end goal is to be able to connect the switch to my router, provide IPs ...
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2answers
27 views

In RSTP, where all switches generate their own BPDUs, are they limited to forwarding them only on designated ports? (like in classic STP)

I recently learnt a rule in STP: only Designated ports forward BPDUs. However, I'm not sure about this in RSTP since ALL switches generate their own BPDUs every few seconds. So, in a certain LAN ...
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2answers
37 views

Need explanation on vlan tag/ip mismatch

What happens if I have a switch configured with an accessport on vlan 20 and someone uses a static ip in a different subnet. vlan 20 has the subnet 192.168.20.0/24 in the router. Suppose the ip used ...
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1answer
23 views

Virtual Chassis Setup in Juniper EX4200 Using Mixed Interface Types

We want to setup Virtual Chassis using 2 x Juniper EX4200 switches. In case of Virtual Chassis for EX4200 , we have to use 2 x VC cables (connected back to back) between 2 x Ex4200 switches along with ...
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3answers
58 views

What are the Major Differences between Juniper EX4200 vs Juniper EX4300?

Can someone please explain that what are the major differences between Juniper EX4200 and Juniper EX4300 switches? Both are standard Juniper Ethernet switches but is there any situation where EX4300 ...
1
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1answer
27 views

VLAN not working in Comtrend switch

I'm trying to configure VLANs with 3 switches Comtrend (2- CNGE2FE8MSPOE + 1- CWGE26FX2TX24MSPOE) and it's not working as I expect. It's the first time that I work with VLAN and I don't know If I ...
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3answers
61 views

What kinds of organizations use routing protocols (aside from ISPs)?

I don't understand why would an organization aside from an ISP even use routing protocols. Let's say there is a big company with 5000 employees, and they want to have a network throughout their ...
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1answer
23 views

Is SONET a physical layer or a data link layer?

According to some sources, SONET is physical layer. But some sources say that SONET can carry IP directly. Also, SONET defines its own frame -- it has a header and a payload. That must make SONET a ...
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2answers
33 views

Query regarding LACP System Priority

This is regarding LACP System Priority. From my research I could find the following info pertaining to system priority. LACP combines the System Priority value with the MAC address of the switch to ...
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2answers
68 views

Do X.25/Frame Relay/ATM/MPLS have their own switches?

In the context of networking when we say "switch" we always think of Ethernet switch. But do we have X.25 switch, Frame Relay switch, ATM switch, and MPLS switch? If yes, how are they ...
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1answer
24 views

Query regarding LACP timeout flag

Say we have two swicthes. Switch A and Switch B. Switch A sends LACPDU's with timeput flag set to 1 (fast). Switch B sends LACPDU's with timeout flag set to 0 (slow). By researching came to know that ...
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0answers
20 views

Queries regarding LACP

I have following queries regarding LACP. Query 1 In LACP flag we have a field called as Aggregation, where 1 represents Aggregatable and 0 represents Individual. In all the PCAP's I have seen so far ...
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2answers
56 views

Criteria to match for lacp status to come up

I did research and found that below are the minimum requirements for LACP to be Up. One of the side should be active. All the port speed should be same. Duplex settings need to be same. Also I have ...
2
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1answer
25 views

Wants to understand traffic flow of Catalyst layer3 Switch 3850 . what are sequence this switch will check to delivery packet to destination

i wants to know clear understanding about how Cisco layer3 switch checks in sequence order when traffic arrive to its L3 Interface . i want to know traffic flow in Cisco layer 3 switch ,because switch ...
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0answers
29 views

Issue with PIM-SSM Multicast Configuration ISR4431s

I have an issue with my PIM-SSM multicast configuration using ISR4431s.    I am wanting to forward broadcast data from an application from one VLAN in on the multicast source to another VLAN on a ...
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1answer
114 views

Sending a gratuitous ARP on an interval - Cisco

In response to my question Propagating Static MAC Addresses , I realize I can not avoid the unknown unicast problem. Essentially I have hosts that forward their traffic via an L2 frame to a ...
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3answers
51 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 ...
2
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1answer
57 views

Do switches allow parallel connections?

I am new to networking and not from Engineering domain. Sorry If I sound silly. I came across an article on Network Switches and How they work. Diving deep into it, I found some interesting topics ...
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1answer
34 views

How a wifi AP handle packets

Computers are connected to a wifi AP. The wifi AP is connected to a L2 switch. A server is also conected to this switch. When computers sends packets to the server, how the wifi AP manages the paquets?...
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2answers
66 views

Connecting switches together

I have L2 switches which will be daisy chained together (yes I know, daisy chaining isn't great, but anyway..) The L2 switches will then link to a L3 switch. Both the L2 and L3 switches have x4 10GbE ...
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1answer
57 views

Why does the Layer 3 switch drop the ping packet?

I am trying to ping from PC2 (not PC1, there's typo in the picture) to the router's int g0/0, but the packet is dropped at the L3 switch which is along the path. I have tried setting a default static ...
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0answers
23 views

Tracing a host in a network [duplicate]

If I have a host connected to a say patch panel port number 39 which is connected to the switch. There's a cable manager in-between and there's no easy way to find out which switch port the cable is ...
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1answer
35 views

Can use virtual port as the port mirroring's destination port?

Port mirroring can mirror several source port to a destination port(mirroring port). I have several questions about port mirroring. in the dest port, how to differentiate the different source port? ...
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0answers
11 views

Why would OpenFlow require N^2 entries for MAC address learning in single table?

I'm reading this whitepaper and trying to wrap my head around why it would require O(N^2) entries for MAC address learning in OpenFlow with single table. See paragraph 2.2.1. In my naive mind, I think ...
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2answers
117 views

Vlan vs. Subnet Broadcast Domain

It is my understanding that Vlans separate broadcast domains, but I often see people say, "subnets define a broadcast domain" as well. Is it correct to say, "Vlans define a L2 broadcast domain, and ...
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2answers
73 views

ping in the same VLAN with multiple switches in between

Refreshing VLAN knowledge with PT7.3, I came across some unexpected behavior. Why does a chain of switches having proper trunk configuration between them DROP packets? Trying to ping hosts from the ...
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0answers
8 views

Dynamic Link Aggregation Speeds [duplicate]

This might be a stupid and easy to answer question, but I can't seem to get a straight answer from anywhere. I have the following setup. Modem --> Router --> 8 port switch --> server I have ...
2
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1answer
184 views

What is the effect of having too many bridges / routers between 2 devices?

I am building a network, with each node connected to each other using fiber media converters. They are actually a bridge with 2 ports: one Ethernet and one optical (or one single-mode and one multi-...
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2answers
78 views

How would a bridge loop occur?

As I understand it, STP is used to prevent bridge (/switch) loops, which will typically occur in the case of redundant links on a switch. But how can a loop occur and cause a broadcast storm? If a ...
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1answer
36 views

Unknown device mac address listed in switch table on start out

After playing a little bit with a topology randomly created in packet tracer, I figured out that the switch (Switch0) stores a unknown device mac address on start out, wich I think that it belongs to ...
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1answer
52 views

Fastest way to switch between redundant wireless links

I have a system using 2 redundant point-to-point wireless links to access the internet, and I'm trying to find the fastest way to switch between them if one goes down. We need to switch within 1 ...
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1answer
51 views

How do (LANCOM) Tag-Based vlan groups work and on which vlan does the device respond?

I just started a new job and part of it is to manage and maintain the ICT. As the previous network/system engineer left the company i'm on my own to figure out how everything works. I have ...
1
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1answer
141 views

How do computers send switches packets, if switches don't have IP or MAC addresses?

I am new to networking, so please excuse me if I am saying stupid stuff. From my understanding, PCs are sending packets to switches, which then decide which physical port to forward that packet to. ...
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1answer
34 views

I Cannot Ping Switch to Device, but can ping Device to Device

I'm currently troubleshooting a network i built and I'm having an issue with ping connectivity, i have set up DHCP and DNS and my end devices can get IP's from DHCP as well as i have intervlan ...
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1answer
132 views

Switch doesn't learn MAC of a connected device

I am new to networks. What does it mean when a switch doesn't learn the MAC address of the connected device? And how can VLANs can impact that?
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2answers
51 views

How could the line rate of T1 be 1.544 Mbps?

T1 signal is the output of a 24-to-1 digital multiplexer whose inputs are 64 kbps each (plus one framing bit). But a multiplexer is simply an electronic device that selects between several inputs and ...
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2answers
47 views

Switch Operation Beyond VLAN Segmentation

What are the other operations performed by a switch which are outside the VLAN's boundaries. Is Logical (VLAN) Segregation is exactly same as breaking a switching network physically via a Router?
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3answers
52 views

Can a switch be used for either circuit- or packet- switching?

If my understanding is correct, circuit- or packet- switching does not happen inside the switch -- it happens on the network. It is a characteristic of a network and not of a switch. The difference on ...
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0answers
16 views

Since packets holds next hop MAC address, how does a switch knows to which port to send a packet to a destination? [duplicate]

Lets say a switch has 4 ports : P1, P2, P3, P4 Host A is connected to P1 Host B is connected to P4 If Host A wants to send a packet to Host B, the packet will have as destination address the MAC ...
2
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4answers
969 views

Will IP cameras increase the traffic in our local network?

We need to place 16 IP cameras (4MP) to monitor a warehouse, where all these cameras will be handled by a CCTV. We have 2 options: Connect these cameras through the same cables under the same switch ...
0
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1answer
58 views

Why does HPE disable STP by default? [closed]

It this certainly true that switches needs STP to avoid loops or broadcasts storms, but recently I saw the configuration of my Hewlett Packard switch and I noticed that it has STP feature disabled by ...
0
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2answers
69 views

VLAN based subnets, where should I untag a VLAN?

I have attempted to search this problem but I don't really know how to explain it properly (possibly a sign I've taken on more project than I can handle). Anyway I am currently working on chopping ...
5
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2answers
664 views

Whats the difference between VOICE VLAN and ACCESS VLAN

Can someone please tell me the difference in Layman's termsfor these 2 configurations? interface FastEthernet0/1 description PHONES switchport mode access **switchport voice vlan 51** spanning-...
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1answer
76 views

OSPF neighbor not working

I'm currently designing a spine leaf network, 2 Spine switches and 4 leaf switches. btw this in packet tracer. So in order its Spine1# and Spine2#, then Leaf1#, Leaf2#, Leaf3#, Leaf4#, and addresses ...
3
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1answer
89 views

Why can't get host's mac address on l2 switch through snmp? But can get it on l3 router

I am trying to get computer's mac address through snmp. I have an envirmont in GNS3: l3 R1's image is vios-adventerprisek9-m.SPA.157-3.M3 l2 SW1's image is viosl2-adventerprisek9-m.SSA....
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0answers
162 views

when to disable CEF on an interface

i am currently learning about CEF and i came across the command "no ip route-cache cef", which i do understand what it does, essentially, it enables Fast-switching/process switching on an interface. ...
1
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1answer
44 views

How does the swtich know if a packet needs layer 2 switching or layer 3 routing?

I have a network topoloty as follows A --------- B --------- C /|\ /|\ /|\ / | \ / | \ / | \ A1 A2 A3 B1 B2 B3 C1 C2 C3 A, B, C are ...
2
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2answers
567 views

Can a single subnet work across several switches?

New to networking and studying hard but limited access to a kit to try things at the moment... My question is - if I had, for example, two Layer-2 switches cable connected, could I have devices on ...

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