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Topic: Layer 3


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  Reinforced concrete containing coated steel reinforcing member - Patent 5100738
In a preferred embodiment, the thickness of the layer 3 is selected so that, after reaction with the free lime of the concrete and with oxygen to form calcium aluminate, at the region 5 concerned, only an extremely small residual thickness remains for the layer 3, the residual thickness ensuring tight fusion with the concrete.
During this bending cracks appear in the layer 4 so that in the region of such cracks the layer 3 is not covered by the material of the layer 4, but is exposed, as indicated in the figure, with the cracks or regions 5.
The layer 4 of synthetic material is likewise necessary to protect the layer 3 before imbedding of the reinforcing steel 1 in concrete, i.e.
www.freepatentsonline.com /5100738.html   (974 words)

  
 layer 3 switch Definition: TechEncyclopedia from TechWeb
Traditionally, routers, which inspect layer 3, were considerably slower than layer 2 switches.
In order to increase routing speeds, many "cut-through" techniques were used, which perform an "inspect the first packet at layer 3 and send the rest at layer 2" type of processing.
If a layer 3 switch supports packet-by-packet inspection and supports routing protocols, it is called a "routing switch" or "switch router," which simply means "fast router." For example, Cisco calls its high-end routers Gigabit Switch Routers.
www.techweb.com /encyclopedia/defineterm.jhtml?term=layer+3+switch   (536 words)

  
 Howstuffworks "How LAN Switches Work"
The fundamental difference between a router and a Layer 3 switch is that Layer 3 switches have optimized hardware to pass data as fast as Layer 2 switches, yet they make decisions on how to transmit traffic at Layer 3, just like a router.
Within the LAN environment, a Layer 3 switch is usually faster than a router because it is built on switching hardware.
The pattern matching and caching on Layer 3 switches is similar to the pattern matching and caching on a router.
computer.howstuffworks.com /lan-switch15.htm   (364 words)

  
 CCNP Practical Studies: Layer 3 Switching   (Site not responding. Last check: 2007-11-07)
In the previous chapter, you were introduced to the concept of Layer 3 switching on the Catalyst 3550; however, the focus of the chapter was more on the fundamental concept of inter-VLAN routing and routing protocols rather than focusing specifically on Layer 3 switching.
A Layer 3 switch on the other hand uses an ASIC to perform data plane operations because it is very easy to program the very simple operations required for the data plane into an ASIC.
Next-generation Cisco Catalyst Layer 3 switches use an optimized route lookup table, which organizes only the required routing information for data plane operations (e.g., destination prefix, next hop, egress interface) and also includes a pointer to another optimized adjacency table, which describes the MAC address associated with the various next hop devices in the network.
www.informit.com /articles/article.asp?p=102093&seqNum=1   (3255 words)

  
 Foundry Networks : Services : FAQs : What is the Difference between Layer 3 Switching and a Switching Router?   (Site not responding. Last check: 2007-11-07)
Once the source and destination IP addresses are cached in the Layer 3 switch, subsequent Layer 3 inter-subnet packet forwarding is off-loaded from the routers.
Layer 3 switching allows us to switch the IP packets from one IP subnet to another IP subnet, without sending the packet to an external router.
For Layer 3 switching, unknown Layer 3 IP frames are Layer 2 switched.
www.foundrynet.com /services/faqs/switchingRouter.html   (3356 words)

  
 Layer 3 switching - Computerworld   (Site not responding. Last check: 2007-11-07)
Layer 3 switches boost network performance and may eventually eliminate the need for expensive routers.
Layer 3 switches may cost less, but they shouldn't be used yet to replace routers.
Layer 3 switches were designed to provide greater performance at a lower price than traditional routers.
www.computerworld.com /printthis/1998/0,4814,43488,00.html   (842 words)

  
 IntelĀ® Express 10 Switch - IP Layer 3 Switching Concepts and Configuration
Layer 3 switching is only available for the Express 10 Switch+ and the Express 100FX Switch running software Version 1.5 or later.
Layer 3 switching is easier to implement if you know the theory.
In Layer 3 switching, it is not possible to set an Internet Address for your switch with all zeros or ones in the host part of the IP address.
www.intel.co.jp /support/express/switches/10/sb/cs-014372.htm   (3184 words)

  
 Layer 3 Switching   (Site not responding. Last check: 2007-11-07)
Layer 3 switches, sometimes referred to as IP switches, perform the routing functions of Layer 3, the Network layer.
Layer 3 switches address the limitations of current routers by offering a virtual-circuit service across a LAN.
Layer 3 switching provides higher performance for switched networks because the delays associated with routers are eliminated.
www.concord.com /help/files/reports/general/lyr3swch.html   (195 words)

  
 RFC 2149 (rfc2149) - Multicast Server Architectures for MARS-based ATM mul
Layer 3 packets received from cluster members, while no outgoing point-to-multipoint VC exists for that group, MUST be silently dropped after following the guidelines in the previous paragraphs.
If the MCS supports multiple layer 3 groups, it MUST follow the procedure outlined in the four previous subsections for each group that it is an active MCS.
A new VC for this layer 3 group will be established only on reception of new traffic for the group (as described in section 4.3).
www.faqs.org /rfcs/rfc2149.html   (5892 words)

  
 CSD - April 1998 - Layer 3 Switch Design   (Site not responding. Last check: 2007-11-07)
Layer 3 switches are becoming popular due to advances made in the design and development of ASICs for fast routing.
Such frames are identified by checking the Layer 3 destination IP address of the frame and verifying it to be one of the addresses of the Layer 3 switch.
Layer 3 switches cannot afford to do this, since the incrementing would have to be done in the main forwarding path and would cause a serious performance penalty.
www.commsdesign.com /main/9804fe2.htm   (3402 words)

  
 ATM and Layer 3 Troubleshooting Guide, 12.0(13)W5(19) - Troubleshooting Layer 3 Network Connections  [Cisco ...
Layer 3 switching refers to a class of high-performance switch routers optimized for the campus LAN or intranet, providing both wirespeed Ethernet routing and switching services.
The system route processor is the first element of the Layer 3 enabled ATM switch router architecture and resides at the core of the switch.
This "demand-caching" scheme used by other Layer 3 switches is optimized for networks where the majority of traffic flows are associated with a subset of destinations.
www.cisco.com /en/US/products/hw/switches/ps718/prod_troubleshooting_guide_chapter09186a00800f0250.html   (6596 words)

  
 EETimes.com - VPNs reopen switch/routing debate
The Layer 3 VPN MPLS implementation is an early leader.
In a Layer 2 MPLS VPN, the PE router is not a peer to the CE router and does not maintain separate routing tables.
The Layer 2 approach, on the other hand, is the preferred approach for service providers who want to extend and scale legacy Layer 2 VPN deployments, or any situation with few VPN sites and static routes.
www.eetimes.com /story/OEG20011018S0024   (1232 words)

  
 Network layer -- Facts, Info, and Encyclopedia article   (Site not responding. Last check: 2007-11-07)
The network layer is level three of the seven level (Click link for more info and facts about OSI model) OSI model.
It also determines the route from the source to the destination computer and manages traffic problems, such as (The act of changing one thing or position for another) switching, (Click link for more info and facts about routing) routing, and controlling the congestion of data packets.
The Network layer performs network (Click link for more info and facts about routing) routing, (Click link for more info and facts about flow control) flow control, ((embryology) the repeated division of a fertilised ovum) segmentation/desegmentation, and (Click link for more info and facts about error control) error control functions.
www.absoluteastronomy.com /encyclopedia/n/ne/network_layer.htm   (549 words)

  
 CCNP Practical Studies: Layer 3 Switching   (Site not responding. Last check: 2007-11-07)
Port density—Layer 3 switches are enhanced Layer 2 switches and, hence, have the same high port densities that Layer 2 switches have.
Layer 3 switching is cheap because Layer 3 switches are targeted specifically for inter-VLAN routing, where only Ethernet access technologies are used in high densities.
Layer 3 switching generally refers to data plane operations.
www.informit.com /articles/article.asp?p=102093&seqNum=1   (3255 words)

  
 Catalyst 6500 Series Software Configuration Guide, 7.4 - Configuring Layer 3 Protocol Filtering  [Cisco Catalyst ...   (Site not responding. Last check: 2007-11-07)
Layer 3 protocol filtering is supported only on nontrunking Ethernet, Fast Ethernet, and Gigabit Ethernet ports.
Layer 2 protocols, such as Spanning Tree Protocol (STP) and Cisco Discovery Protocol (CDP), are not affected by Layer 3 protocol filtering.
With Layer 3 protocol filtering enabled, ports are identified on a protocol basis.
www.cisco.com /en/US/products/hw/switches/ps708/products_configuration_guide_chapter09186a00800fb5a2.html   (819 words)

  
 Network Routers: Difference between router and layer 3 switch
I've been reading about layer 3 switching and understand that it is basically routing, done by hardware i.s.o.
The main difference is that a Layer 3 switch only routes the first packet in a flow.
As lrmoore pointed out, Layer 3 switches tend to leave out some of the more robust routing features that would be more suited to a dedicated routing device, although you can get those features on some L3 switches if you have the $$$$.
www.experts-exchange.com /Hardware/Q_20649414.html   (426 words)

  
 ePanorama.net :: View topic - brouter - bridging non routable (layer 3?!) addresses - term
MAC address are one in the same, IPX is still a Layer 3 protocol.
And IPX *IS* a *routable* layer 3 protocol.
Layer 3 means beyond the scope of the local Link Layer protocol.
www.epanorama.net /phpBB2/viewtopic.php?t=18837&start=0&postdays=0&postorder=asc&highlight=   (2354 words)

  
 CCNP Practical Studies: Layer 3 Switching   (Site not responding. Last check: 2007-11-07)
In this configuration, the switch is essentially a Layer 2 switch and possesses no Layer 3 switching or classification capabilities.
The PFC-1 enables Layer 3 and 4 classification for QoS classification and security ACL filtering; however, L3 switching is not supported unless an MSFC is added to provide route processor functions.
The Layer 3 switching performance in hardware is still 15 Mpps, regardless of the MSFC used.
www.ciscopress.com /articles/article.asp?p=102093&seqNum=2   (2774 words)

  
 Layer 3 switches (InfoWorld)
Layer 3 switching promises to circumvent many of the problems associated with routing.
Layer 3 switching is a surprisingly mature technology that not only lives up to but even surpasses the marketing hype.
Additionally, Layer 3 switches by their very nature incorporate Layer 2 switching capabilities -- the same kind of thing our trusty Ethernet switches have been doing for years.
www.infoworld.com /cgi-bin/displayArchive.pl?/98/22/layer3a.dat.htm   (6311 words)

  
 OSI: Securing the Stack, Layer 3 -- The role of ICMP
Layer 3 of the OSI model is the network layer.
While the data link layer provides node-to-node communication, the network layer provides routing and is the home of routable protocols; the best known is Internet protocol (IP).
There are other services at the network layer, such as Internet Control Message Protocol (ICMP), which is the focus of this article.
searchnetworking.techtarget.com /tip/0,289483,sid7_gci1227254,00.html   (1386 words)

  
 Configuring Layer 3 Interfaces   (Site not responding. Last check: 2007-11-07)
This chapter describes the Layer 3 interfaces on the Catalyst 4006 switch with Supervisor Engine III.
The Layer 2 function of filtering and forwarding data in frames between two segments on a LAN is known as bridging.
The logical Layer 3 VLAN interfaces integrate the functions of routing and bridging.
www.cisco.com /univercd/cc/td/doc/product/lan/cat4000/12_1_11/config/l3_int.htm   (648 words)

  
 tunneling protocol Definition: TechEncyclopedia from TechWeb
In a regular protocol, the lower layer protocol encapsulates packets from the higher level protocol.
For example, a network layer 3 packet encapsulates a transport layer 4 packet, and a data link layer 2 packet encapsulates a network layer 3 packet.
In contrast, a tunneling protocol encapsulates a packet of the same or lower layer.
www.techweb.com /encyclopedia/defineterm.jhtml?term=tunneling+protocol   (363 words)

  
 NewsFactor Network - - Security Considerations for Layer 3 Switches
Sometimes a firewall can be supplanted by a layer 3 switch, but at other times replacing a firewall with a switch would be foolish.
Layer 3 switches with security features or blades like the Catalyst 6500 are best used for internal security, not the edge, Ahlawat noted.
Layer 3 security definitely has its place, but it is not quite ready to blow down the firewall.
www.newsfactor.com /perl/story/22610.html   (1096 words)

  
 O'Reilly Network -- Layer 3 Switching -- Introducing the Router
Her background will be instrumental in helping them decide if they can continue to grow with a layer 2 switching architecture, of if they need to add routers to their topology.
A layer 2 switch communicates using frames on the wire at layer 1.
A router is a layer 3 device, which communicates with packets.
www.oreillynet.com /pub/a/network/2001/04/13/net_2nd_lang.html   (638 words)

  
 What is MP3? - A Word Definition From the Webopedia Computer Dictionary   (Site not responding. Last check: 2007-11-07)
Layer 3 is one of three coding schemes (layer 1, layer 2 and layer 3) for the compression of audio signals.
Layer 3 uses perceptual audio coding and psychoacoustic compression to remove all superfluous information (more specifically, the redundant and irrelevant parts of a sound signal.
The result in real terms is layer 3 shrinks the original sound data from a CD (with a bit rate of 1411.2 kilobits per one second of stereo music) by a factor of 12 (down to 112-128kbps) without sacrificing sound quality.
www.webopedia.com /TERM/M/MP3.html   (395 words)

  
 STD3   (Site not responding. Last check: 2007-11-07)
For incoming datagrams, the IP layer: (1) verifies that the datagram is correctly formatted; (2) verifies that it is destined to the local host; (3) processes options; (4) reassembles the datagram if necessary; and (5) passes the encapsulated message to the appropriate transport-layer protocol module.
For outgoing datagrams, the IP layer: (1) sets any fields not set by the transport layer; (2) selects the correct first hop on the connected network (a process called "routing"); (3) fragments the datagram if necessary and if intentional fragmentation is implemented (see Section 3.3.3); and (4) passes the packet(s) to the appropriate link-layer driver.
In those cases where the Internet layer is required to pass an ICMP error message to the transport layer, the IP protocol number MUST be extracted from the original header and used to select the appropriate transport protocol entity to handle the error.
rfc.net /std3.html   (14021 words)

  
 Specifying a layer-3 MLPA in the IRR
Section 3 provides a suggested method for construction of the as-macro.
Section 3 provides a suggested method for construction of the as-set.
To provide for simpler implementation of the control mechanism, it is suggested that only one aut-num be referenced in each members attribute.
www.ripe.net /ripe/maillists/archives/db-wg/1998/msg00005.html   (1915 words)

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