Latest threads in Ethernet LANshow only best voted threads

Subject Author Posted Replies
 
BPSK
There is discussion in another newsgroup in whether Manchester coding is, or is not, a form of BPSK. I usually consider it as synchronous phase modulation (the wikipedia page seems to use the work...
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Where is generated the preamble?
Hi, I don't know if someone will see my message within spams. Is it the RS (reconciliation sublayer) that generates the preamble, or it comes higher, from the MAC sublayer. We can refer to the figure...
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EFM frames on tagged port
Hello, Reading the specs I didn't completely understand if EFM, CFM or LLDP frames can be tagged or not. Specifically, what is the behavior of a L2 switch when sending out such frames out a trunk...
 
for LACP, what is management key ,operation key and admin key?
How do these keys generated? and what is purpose for these key? management key=admin key? what I think is that it is important when connect to difference vendor. anyone can expain it? TIA. st
 
Cisco Wireless -N Home Router WRT120N
Greetings, Out of the box, I set up the WRT120N router per instructions from the manual. Problems: 1. I need to power-cyle the router every 24 hours for the devices to identify the hotspot, if I...
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MAC acl
Hello, some Cisco switches support MAC access lists on ingress traffic only. I'm trying to understand why it doesn't make sens (impossible?) to implement MAC ACLs on *egress* traffic. Is it because...
 
priority tagged frames
Hello I hear that priority-tagged frames, i.e. frames having 0x8100 ethertype AND valan id equal to 0, are considered untagged from the VLAN-aware bridge perspective. however I could find exact...
 
expected behavior of 802.1p mapping & schedulers
Hello, I'm trying to understand the expected behavior of a L2 switch with enabled QoS and 802.1p mapping, i.e. cos 0 is mapped to queue 0, cos 1 to queue 1 and so on. Consider example: 1G ports, pump...
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why we need 'bridge'
Hi, many layer2 ethernet equipment vendor, Cisco as example, have a concept (I don't really know if it is correct to call it concept?) of a 'bridge', i.e. on cisco CLI one needs to explicitly create...
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switch port types (access, trunk, hybrid ..)
Hello, usually ports on the L2 switches (I don't know agbout L3) can be configured in the following modes: access, hybrid or trunk (I think, terminology may vary among the different vendors). The IEEE...
 
MAC learning on switch
Hi All, I thought that MAC learning process is purely hardware, but wa recently told that in fact most decent hi-end L2 switches off-load part of this activity on the host CPU, specifically -- every...
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Layer 3 Bit Error Tester
I need a testing device to bit error test optical ethernet ports on a router. Can someone suggest a device that can be purchased cheaply, preferably used? To my understanding, a layer 3 IP based bit...
 
testing QoS with conventional PCs
Hello, what are the methods to test QoS functions (specifcally I'm interested in traffic shaping, scheduling) without packet generators Smartbits or Ixia, but having only a few PCs and a target board...
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Wanted - 3Com 3C505 Technical Reference Manual
Hi, I'm looking for the technical reference manual for 3Com's 3C505 Ethernet controller. This manual is mentioned in several drivers for that card (Linux, DOS packet drivers, etc.) - however, I could...
 
Used cisco PVDM voice modules in stock,for sale!
I have following used original cisco swithes for sale: PVDM-256K-4 PVDM-256K-8 PVDM2-8 PVDM2-16 PVDM2-32 PVDM2-48 PVDM2-64 PVDM2-24DM PVDM3-16 PVDM3-32 PVDM3-64 PVDM3-128 PVDM3-256 Please contact me...