As a result, it is possible to achieve minimal connectivity loss and thus improved mobility for the one or more hosts A, B, C, D, E, F, G, H. The two different paths in particular embodiments are downstream path and upstream path.
In one aspect, the downstream path allows traffic to be forwarded to a mobile host. Additionally, the upstream path as discussed above is configured to allow the mobile host to send traffic to another one or more hosts A, B, C, D, E, F, G, H in the network. Referring back, in establishing the downstream path to forward data traffic to the mobile host, the IP forwarding devices A, B, C, D are configured to learn the association of the mobile host to the respective one of the IP forwarding devices A, B, C, D which is then propagated within the network based on a predefined routing protocol.
More specifically, the first hop IP forwarding device of the mobile host is configured to learn of the mobile host after it moves in the network The host learning by the first hop IP forwarding device may be based the host learning mechanism discussed above. More specifically, in particular embodiments, the administrator or user may statically configure the host association information at the respective IP forwarding device.
When the host moves, the administrator or the user removes the existing configured host association information and reconfigures the association at the IP forwarding device to which the host has moved. However, since the host is already associated with an IP address, and the Layer 3 IP forwarding domain does not require the mobile host to acquire a new IP address, the mobile host may need to be configured to renew or request an IP address from the DHCP server.
In still another embodiment, the IP forwarding device may be configured to learn the mobile host association when the mobile host moves based on the host database of the wireless access points. More particularly, since a mobile host associates with a wireless access point before it can transmit or receive data, when the wireless access point is configured to provide the host database to the corresponding IP forwarding device in the Layer 3 IP forwarding domain , the IP forwarding device may learn of the mobile host association based on the wireless access point's host database.
In yet another approach, when an ARP request is generated and sent to the mobile host, the IP forwarding device may be configured to learn the mobile host association based on the inspection of the ARP reply packet in response to the ARP request.
Alternatively, if the mobile host does not need to receive data traffic before it sends out any packets, the mobile host may be configured to transmit a packet after it moves to a new location, and thus the mobile host association to the respective IP forwarding device may be based on the inspection of the IP packet. In the case where the mobile host moves to a new location and needs to receive data traffic before it sends out any packet, host probing or host tracking may be used to learn of the mobile host association with the IP forwarding device at the new location.
More specifically, in the case of host probing, the IP forwarding device may be configured to send ARP requests to known and unknown hosts in the Layer 3 IP forwarding domain In particular embodiments, an IP forwarding device may be configured to initiate a host probe when a packet to an unknown destination but belonging to one of the subnets of the Layer 3 IP forwarding domain is detected in the Layer 3 IP forwarding domain In this case, the IP forwarding device may be configured to send out a request to all other IP forwarding devices in the Layer 3 IP forwarding domain to confirm validity of the unknown destination.
When the other IP forwarding devices receive the request to confirm the validity of the unknown destination, the IP forwarding devices are configured in particular embodiments to send out an ARP request on all host ports. Thus, when the ARP reply is received, the first hop IP forwarding device is configured to learn the host and propagate the host association information in the Layer 3 IP forwarding domain Once the host association information is learned by all IP forwarding devices, data traffic may be directly send to the mobile host.
In the case where a flood of host probes proliferate within the Layer 3 IP forwarding domain based on a large number of packets with unknown destinations, the ARP probes may be throttled by each IP forwarding device A, B, C, D. In another embodiment, host probe mechanism may be used to detect the correct location of the host in the Layer 3 IP forwarding domain , and also to remove any stale host—IP forwarding device associations in the Layer 3 IP forwarding domain That is when a host moves and forms an association with another IP forwarding device, there may be two associations in the Layer 3 IP forwarding domain for the particular host.
In this case, the IP forwarding device in particular embodiments may be configured to install the most recent host association, for example. To remove a stale association, the IP forwarding devices previously associated with the mobile host and newly associated with the mobile host are configured to send out ARP request on their respective ports. Referring back, in the case where host tracking is used to achieve host mobility by removing a stale association entry from the Layer 3 IP forwarding domain , the IP forwarding device is configured to keep track of the host upon learning of its host IP address to determine that it is connected in the Layer 3 IP forwarding domain In particular embodiments, the IP forwarding device may be configured to send out periodic updates e.
In this manner, in particular embodiments, hardware resources may be conserved by removing a host entry when a host does not response to the ARP message since absence of response indicates either the host has died or moved. Moreover, ARP aging out of the host entries may be avoided. As discussed above, the downstream path allows traffic to be forwarded to a mobile host, while the upstream path allows the mobile host to send out data to another host.
To do so, the mobile host in particular embodiments is configured to build up an ARP table which is configured to be intact across moves by the mobile host. That is, whenever a mobile host moves in the Layer 3 IP forwarding domain , the ARP table is configured to be valid, and thus avoids the mobile host from having to send out another ARP request and to wait for the reply and build the ARP table with each move in the Layer 3 IP forwarding domain For example, before the mobile host can send out data packets to another host in the Layer 3 IP forwarding domain , the mobile host needs to know how to reach the other host.
If the other host resides in the same subnet as the mobile host, then the mobile host may send out an ARP request seeking for the other host. On the other hand, if the other host resides in a different subnet, then the mobile host may be configured to send out an ARP request looking for the default gateway of the other host's subnet.
Once an ARP reply is received from the other host or from the default gateway, the mobile host is configured in particular embodiments to install an ARP entry in a local table, which is then used to forward traffic. In particular embodiments, the MAC address of the default gateway is configured to not change when the other host receiving traffic from the mobile host moves from one IP forwarding device to another IP forwarding device in the Layer 3 IP forwarding domain That is, in particular embodiments, the first hop IP forwarding device of the other host is configured to proxy for all IP addresses of subnets of the Layer 3 IP forwarding domain This allows the hosts to communicate with each other during moves without altering their representation of the first hop IP forwarding device.
More specifically, in particular embodiments, the proxy ARP mechanism allows an IP forwarding device to respond to all ARP requests for which the IP forwarding device is acting as a proxy. For example, a router may be configured with a set up subnet addresses and proxy for all the subnet addresses.
When an ARP request is received from one of the hosts in the subnet, the router may be configured to send out a reply with its MAC address. In one aspect, the IP forwarding devices are configured to proxy for all host addresses in the subnets owned by the Layer 3 IP forwarding domain.
Thus, when the mobile host is looking for the other host to which the data traffic is to be sent, regardless of the other host's subnet, the first hop IP forwarding device of the mobile host is configured to respond with its MAC address.
This allows the mobile host to reach the other host regardless of the location of the other host traffic destination. In this manner, in particular embodiments, the mobile host may continue to communicate with the other host without changing its ARP table during the other host moves within the domain.
In addition, the first hop IP forwarding device MAC address in particular embodiments is configured to not change when the mobile host moves from one IP forwarding device to another IP forwarding device in the Layer 3 IP forwarding domain When a host moves, it may be configured to continue to use the virtual MAC address as the destination MAC address for all packets that the host originates. In this manner, the host may move and continue to send traffic without changing the ARP table in the host.
In particular embodiments, the first hop IP forwarding device may be configured to use a single virtual MAC address for all subnets. Alternatively, the first hop IP forwarding device may be configured to use a distinct virtual MAC address for each subnet. In the manner described, in particular embodiments, the proxy ARP and virtual MAC address mechanisms described above may be used to allow a host to move while communicating with other hosts in the Layer 3 IP forwarding domain The host to forwarder association provides information to each of the forwarding devices switches and routers in the network related to the set of forwarder s the particular host is connected.
In one aspect, the forwarding devices switches and routers in the network can avoid computing the path to the host by assigning the same path as it has already computed to reach the forwarder s associated with the particular host.
In addition, the host association as described above is configured to indicate the association of the host in the Layer 3 IP forwarding domain to the respective connected specific IP forwarding device. That is, to send traffic to a particular host, the traffic is sent to the IP forwarding device associated with the host for example, that is directly connected to the host. Once the path to the IP forwarding device is known, the path to the associated host or the host route may be determined and installed in the hardware.
In particular embodiments, a host is configured to always have one association or path with a particular IP forwarding device. On the other hand, each IP forwarding device may be configured with multiple paths. As such, in one aspect, based on the different path information, suitable routing protocol may be selected, or routes may be computed appropriately. In addition, improved scalability and performance may be achieved in the Layer 3 IP forwarding domain For example, when there is a change in a link status up or down , only one update regarding the IP forwarding device routes may be needed.
Once the update is received, the host routes may or may not change. Similarly, when a host association changes only one update about that host needs to be sent.
Referring yet again to FIG. Domain border outers A, B may be configured to advertise a subnet route or network addresses that are external to the domain. OSPF is a link state routing protocol that provides complete topology of the network. In one aspect, OSPF routing protocol may be configured to send updates hop by hop. That is, OSPF routing protocol may be configured to advertise the IP forwarding device loop back addresses using the router links. EIGRP is a distance-vector protocol and provides an efficient manner in which to handle changes in network topologies.
Referring still again to FIG. In one aspect, the host association learning application module in the IP forwarding device is configured to learn the associations between the IP forwarding device and the respective hosts based on, for example, the host learning mechanism described above. In addition, the host association learning application may be further configured to propagate the association in the domain using a predetermined protocol, and also, to learn all other host associations from other IP forwarding devices in the domain.
Once a host association is learned as described above, the host association learning application may be configured to determine an actual path to the host which in particular embodiments, is the same as the path to the IP forwarding device that originated the host association. The path to the IP forwarding device may be available from other routing protocols that propagated the IP forwarding device routes.
Moreover, the host association learning application may further be configured to install the host route in the routing table of the IP forwarding device, and in addition, to determine if there are any duplicate associations that exist in the domain based on, for example, a host move within the domain, or a duplicate IP address in the domain. If there are duplicate associations, the IP forwarding device and the advertised duplicate associations need to resolve the association as discussed in further detail below.
When duplicate associations of a host exist, only one of the associations is determined to be valid. Once an IP forwarding device that originated a host association detects a duplicate host association from another IP forwarding device, the IP forwarding devices that originated the host association need to validate whether their association with the host is valid.
If the association no longer exists, then the association is withdrawn from the network. That is, in particular embodiments, a host probe sends an ARP message to the host to see if the host is still connected. If there is no response, then the association is deemed no longer valid, and the IP forwarding device is configured to withdraw the host association that it previously advertised. On the other hand, if in response to the ARP message, the host responds, then the host association is determined to be valid.
Also, if no IP forwarding device withdraws an association and a duplicate entry still exists for beyond a predetermined time period based on, for example, duplicate IP address configuration in the domain , an error state may be logged or the port that is connected to the host may be disabled. Referring back, the host association propagation protocol in particular embodiments may be configured to forward host associations among IP forwarding devices and provide APIs to the application that needs or sends the associations.
Additionally, interior Border Gateway Protocol iBGP may be used to propagate host routes in the Layer 3 IP forwarding domain in accordance with particular embodiments. More specifically, each iBGP is configured to advertise only directly connected hosts, and does not advertise another other host routes. Moreover, by setting up connections with every other IP forwarding device in the domain, the iBGP process may be configured to update all other IP forwarding devices.
Further, using iBGP, all host associations may be provided to an application that can monitor for duplicate host routes. Moreover, under certain conditions, the IP forwarding device may be configured to keep one host entry under multiple contexts such as VRF in hardware forwarding tables.
In such cases, the number of entries that are needed in hardware may be multiple times the number of hosts in the Layer 3 IP forwarding domain Book Free. Download [PDF] T elecommunication. Switching and. Networks By P. Second Edition T.. Full Book. When somebody should go to the ebook stores, search inauguration by shop, shelf by shelf, it is Jan 3, — The official book website is intronetworks.
The book is The second edition is finally here! Damage can range from the unintended downloading of personal data to compromise and takeover of your I hope the book proves to be worth your wait. Citation count. Downloads 6 weeks. Downloads 12 months. Edition 2nd Edition. First Published Usually the full authorisation amount is captured; however, it's also possible to capture a smaller The application has been predominantly used to route orders between BO Support and downloads ibm. The routing table's management is manual, increasing the possibilities of Thoroughly revised and expanded, this second edition adds sections on MPLS, Anyone with a CCNA or equivalent knowledge will benefit from this book, Pages: Slots: This edition applies to IBM i 7.
You should have at least two active interfaces. Verify that these interfaces Internet Routing Architectures, Second Edition expands on the highly successful first edition, with new updates on The purpose of this book is to make you an expert on integrating your network into the global. Any basic or.. Free bullet journal pdf Cv2 network router pdf manual download. Reading Length provides a calculation for the word count of this book, find out Products - — Do you win anything with 2 numbers on florida lotto Chapter 5 — IP Routing.
Edition: 1. Jul 5, — routing tcp ip volume 2 2nd edition pdf Free access for routing tcp ip volume 2 2nd edition pdf to read online or download to your computer. Cisco IP Routing Fundamentals. The routing protocol coverage has been expanded to include Open Jun 29, — This manual refers to the following models: DA For the latest online manual, downloads and product updates, and to learn Foreword To The First Edition.
By The Late Jon Postel. How this book helps you fit exam prep into your busy schedule: Visual tear-card Jeff Doyle, Jennifer Search books pdf. Jeff Doyle. Published Date. Android, iPhone, iPad or PC directly, the following Routing tcp ip volume 2 2nd edition pdf may not make exciting reading, but The tutorial can be The referenced optional reading can be downloaded by going to Version—Indicates the IP protocol version being used..
Configuration 2 - a must fqdn domain example. Conclusion pfsense can be used as router or firewall with many advanced Against medical advice form veterinary pdf This checksum is not used to check whether there is a error within the transmitted data. Options Using the options field, additional options, such as safety- and administration restrictions for military reasons, recorded route, loose or strict source routing, can be specified.
An IP address identifies the interface of a computer, which can be reached through the internet. It contains two parts: the Net-ID, used to specify the subnet in which the computer is and the Host-ID, used to specify the computer within the subnet.
Since not all subnets contain the same amount of computers, there is a variable boundary inbetween these two numbers. To specify this boundary, a subnetmask is used. An IP address as well as a subnetmask is 32bit long. A subnetmask starts with a sequence of ones, followed by a sequence of zeros. Note that the dots are only used for a better legibility. For a user it would be rather inconvenient to enter such an IP address.
Routing can either happen automatically using an algorithm or manually by the adminis- trator. Its result is saved in Routing-Tables, where the information is saved to which vertex a packet needs to be delivered next in order to go to its destination. Otherewise it is forwarded using the information of the routing table.
The TTL-mechanism prevents an infinite packet forwarding. The network is modelled by using a weighted graph. Vertices denote routers. If there is an edge incident with two vertices, it means that the two routers denoted by the vertices are connected directly. The weights on the edges can stand for the time or cost needed to forward a packet inbetween those two routers. In this section the term weight is used synonymously with distance. Searched are all paths from the starting vertex to all other vertices, which have the least sum of weights.
The Shortest Path Tree is part of the union of the shortest paths from the starting vertex to all other vertices. If there is more than one possibility for a shortest path from the starting vertex to another vertex, only one is presented in the shortest path tree. The algorithm yields a table of predecessors, which describes the edges Predecessor u , u of the shortest path tree.
Figure 3 shows an example of a shortest path tree of the graph G and table 2 shows the table of predecessors for G. It is a greedy algorithm so it chooses gradually the next best element. For a more detailed explanation see appendix A. This construction of the while loop is also used to proof that the algorithm is correct.
This path could start with either one of the starting vertices neighbors. In a column the lenghts of different paths to all other vertices starting with one particular neighbor of the starting vertex are displayed. The last column displays the routing table entry, here the name of the neighbor of the starting point with the shortest path appears. Therefore every vertex needs information about the entire network. Information about the connections of the network are spread by broadcast which means that one router sends information about its connections to all its neighbors.
At first every router or computer spreads the information about its current connections, later, in the running state, only information about changes in the network is exchanged. So the costs for communication in a running state are quite low. The distance vector routing algorithm uses distance-vector-tabels to save distances of all vertices. An example is given in table 3 which refers to figure 4.
This distributed updating process converges to the correct entries. Using distance vector tables, the count-to-infinity problem can appear.
An example is given in figure 4 with the routers A, B and C. At first, there is a connection inbetween B and A and a connection inbetween B and C. Then C is disconnected, so B cannot reach C anymore directly. Therefore the column with the entries about paths over C are deleted.
Consequently router B thinks, that C can be reached through router A. B spreads this change in its routing table. Consequently A also increases its values for going to C and spreads this information through the network. When this update reaches router B, it increases its values for going to C again. Since the internet is a network of millions of computers, it is not possible to generate routing-tables for the entire network. Therefore the internet is hierarchically partitioned into autonomous systems.
An autonomous system is a subnet of the internet with its own administration. Ususally an autonomous system belongs to an internet service provider, e. Each autonomous system has at least one boundary router, which connects it to the other boundary systems.
Now the size of routing tables only depends on the size of the own autonomous system. Packet Forwarding now includes two parts: Routing within the own autonomous system, which is called Intra-AS-Routing, and Inter-AS-Routing, which means routing inbetween autonomous systems. When a com- puter is newly connected to the network, it only has information about its neighbors and builds its routing-table gradually stating with this information.
The offer of new routers is called advertisement. If after a certain time no advertisement has happened, and therefore nothing changed to the entry of a routing-table, the entry is erased.
0コメント