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ROUTING TCP/IP PDF

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understanding of the interior routing protocols of TCP/IP. Routing TCP/IP, Volume I, Jeff Doyle does a fantastic job of building the TCP/IP concepts, from IP. Although many books describe the TCP/IP protocols, Stevens provides a level of “W. Richard CCIE Professional Development - Routing TCP-IP, Volume resourceone.info This book is designed to provide information about routing TCP/IP. Jeff is the author of CCIE Professional Development: Routing TCP/IP, Volumes I and.


Routing Tcp/ip Pdf

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resourceone.info Volumepdf - Ebook download as PDF File .pdf) or read book online. Register Free To Download Files | File Name: Routing Tcp Ip Volume 1 2nd Edition PDF. ROUTING TCP IP VOLUME 1 2ND EDITION. Download: Routing Tcp. Addit ional exercise and solut ions are also included. CCIE Professional Development Routing TCP/IP, Volume I, Second Edition By Jeff Doyle - CCIE No.

Some fields specifically related to OSI operation may be included by dual routers, and will be ignored by IP-only routers. Only IP traffic will be routed in an pure IP domain. OSI- only routers may be freely mixed with dual routers. Some fields specifically related to IP operation may be included by dual routers, and will be ignored by OSI-only routers. Any IP traffic may be discarded. In a pure IP area within a dual domain, IP-only and dual routers may be freely mixed.

Only IP traffic can be routed by level 1 routing within a pure-IP area. In a dual area within a dual routing domain only dual routers may be used. Within a dual domain, if both IP and OSI traffic are to be routed between areas then all level 2 routers must be dual.

An alternative approach is known as "Ships In the Night" S. With the S.

Cisco.Press.Routing.TCP.IP. Volume.2.pdf

With S. However, dual routers will need to implement both routing protocols, and therefore there will be some degree of competition for resources. Note that S. In particular, if the integrated IS-IS is used within a routing domain for routing of IP and OSI traffic, it is still possible to use other independent routing protocols for routing other protocol suites.

In the future, optional extensions to IS-IS may be defined for routing other common protocol suites.

However, such future options are outside of the scope of this document. A primary advantage of the integrated IS-IS relates to the network management effort required. Since the integrated IS-IS provides a single routing protocol, within a single coordinated routing domain using a single backbone, this implies that there is less information to configure.

This combined with a single coordinated MIB simplifies network management. Note that the operation of two routing protocols with the S. Since the interactions are explicit, again it may be easier to manage and debug dual routers. Another advantage of the integrated IS-IS is that, since it requires only one routing protocol, it uses fewer resources. In particular, less implementation resources are needed since only one protocol needs to be implemented , less CPU and memory resources are used in the router since only one protocol needs to be run , and less network resources are used since only one set of routing packets need to be transmitted.

Primarily this translates into a financial savings, since each of these three types of resources cost money. This implies that dual routers based on the integrated IS-IS should be less expensive to purchase and operate than dual routers based on S. For example, if one routing protocol becomes unstable and starts to use excessive resources, the other protocol is likely to suffer.

A bug in one protocol could crash the other.

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However, with the integrated IS-IS, the interactions are explicit and are defined into the protocol and software interactions. The use of a single integrated routing protocol similarly reduces the likely frequency of software upgrades.

Specifically, if you have two different routing protocols in your router, then you have to upgrade the software any time EITHER of the protocols change. If you make use of a single integrated routing protocol, then software changes are still likely to be needed, but less frequently. Finally, routing protocols have significant real time requirements.

In IS-IS, these real time requirements have been explicitly specified. In other routing protocols, these requirements are implicit. However, in all routing protocols, there are real time guarantees which must be met in order to ensure correct operation. In general, it is difficult enough to ensure compliance with real time requirements in the implementation of a single real time system.

These fields are encoded using a "Code, Length, Value" triplet, where the code and length are encoded in one octet each, and the value has the length specified from 0 to octets.

This allows IP-specific information to be encoded in a manner which OSI-only routers will ignore, and also allows OSI-specific information to be encoded in a manner which IP-only routers will ignore. IP-capable i. IP-capable routers need to know the IP address of the adjacent interface of neighboring routers. In some cases, it will be useful for IP-capable routers to be able to determine an IP address es of all other routers at their level i.

This is useful whenever an IP packet is to be sent to a router, such as for encapsulation or for transmission of network management packets. Where a single router operates as both a level 1 and a level 2 router, it is required to include the same IP address es in its level 1 and level 2 LSPs. IP-capable routers need to know, for any given IP destination address, the correct route to that destination. Specifically, level 1 routers need to know what IP addresses are reachable from each level 1 router in their area.

In addition, level 1 routers need to find level 2 routers for traffic to IP addresses outside of their area. Level 2 routers need to know what IP addresses are reachable internally either directly, or via level 1 routing from other level 2 routers, and what addresses are reachable externally from other level 2 routers. All of this information is made available by inclusion of IP reachable address information in the Link State Packets.

Internal within the routing domain and external outside the domain reachability information is announced separately in level 2 LSPs. In general, for external routes, metrics may be of type "internal" i. A route using internal metrics i. In general, this information may be determined from the level 1 LSPs from all routers in the area. If we ignore resource constraints, then it would be permissible for a level 2 router to simply duplicate all [IP address, subnet mask, metric] entries from all level 1 routers in its area with appropriate metric adjustment , for inclusion in its level 2 LSP.

However, in order for hierarchical routing to scale to large routing domain sizes, it is highly desired to abbreviate the reachable address information. This is accomplished by manual configuration of summary addresses. Each level 2 router may be configured with one or more [IP address, subnet mask, metric] entries for announcement in their level 2 LSPs. The set of reachable addresses obtained from level 1 LSPs is compared with the configured reachable addresses.

Generally it is expected that the level 2 configured information will specify more inclusive addresses corresponding to a subnet mask with fewer bits set to 1. The manually configured addresses are included in level 2 LSPs only if they correspond to at least one address which is reachable in the area.

For manually configured level 2 addresses, the associated metric values to announce in level 2 LSPs are also manually configured. The configured addresses will supercede reachable address entries from level 1 LSPs based only on the IP address and subnet mask -- metric values are not considered when determining if a given configured address supercedes an address obtained from a level 1 LSP.

Any address obtained from a level 1 LSP which is not superceded by the manually configured information is included in the level 2 LSPs. In this case, the metric value announced in the level 2 LSPs is calculated from the sum of the metric value announced in the corresponding level 1 LSP, plus the distance from the level 2 router to the appropriate level 1 router.

Note: If this sum results in a metric value greater than 63 the maximum value that can be reported in level 2 LSPs , then the value 63 must be used. Delay, expense, and error metrics i.

In general, the same [IP address, subnet mask] pair may be announced in level 1 LSPs sent by multiple level 1 routers in the same area. In this case assuming the entry is not superceded by a manually configured entry , then only one such entry shall be included in the level 2 LSP.

The metric value s announced in level 2 LSPs correspond to the minimum of the metric value s that would be calculated for each of the level 1 LSP entries. A level 2 router will have IP addresses which are directly reachable via its own interfaces. For purposes of inclusion of IP reachable address information in level 2 LSPs, these "directly reachable" addresses are treated exactly the same as addresses received in level 1 LSPs. Manually configured addresses may hierarchically supercede multiple level 1 reachable address entries.

However, there may be some IP addresses which match the manually configured addresses, but which are not reachable via level 1 routing.

If a level 2 router receives an IP packet whose IP address matches a manually configured address which it is including in its level 2 LSP, but which is not reachable via level 1 routing in the area, then the packet must be discarded.

In this case, an error report may be returned as specified in RFC , with the reason for discard specifying destination unreachable. Suppose that the network number for the entire routing domain is 17 a class A network.

Suppose each area is assigned a subnet number consisting of the next 8 bits. The area may be further subdivided by assigning the next eight bits to each LAN in the area, giving each a 24 bit subnet mask counting the network and subnet fields.

Finally 8 bits are left for the host field. Suppose that for a particular area given subnet number Only this one address needs to be announced in level 2 LSPs. Thus if an IP packet comes along for an address in subnet The inclusion of If any traffic comes along that is for an unreachable address such as Suppose that subnet number In this case, the level 2 router in the left area would be announcing in its level 2 LSPs according to manually configured information reachability to subnet However, the level 2 router in the lower right area would be announcing in its level 2 LSPs according to information taken from its received level 1 LSPs , reachability to subnet Due to the use of best match routing, this works correctly.

All traffic from other areas destined to subnet For example, these addresses are used to determine area membership of routers. This approach is recommended even for pure IP routing domains, as it will simplify future migration from IP-only to dual operation.

Instead, an alternate mechanim is provided below for algorithmically generating a valid OSI style address from existing IP address and autonomous system number assignments. The AS number in this context is used only for definition of unique NSAP addresses, and does not imply any coupling with exterior routing protocols. The Area field must be assigned by the authority responsible for the routing domain, such that each area in the routing domain must have a unique Area value.

The ID must be assigned by the authority responsible for the routing domain.

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The ID must be assigned such that every router in the routing domain has a unique value. It is recommended that one of the following methods is used: 1 use a unique IEEE 48 bit station ID 2 use the value hex "02 00" prepended to an IP address of the router.

Since the IEEE station IDs are assigned to be globally unique, use of these values clearly assures uniqueness in the area. Prepending the indicated pattern to the front of the IP address therefore assures that format 2 illustrated above cannot produce addresses which collide with format 1.

Finally, to the extent that IP addresses are also globally unique, format 2 will produce unique IDs for routers. The indicated hex value is specified in IEEE canonical form [ 10 ]. This is useful whenever an IP packet is to be sent to a router, such as for encapsulation or for transmission of network management packets. Where a single router operates as both a level 1 and a level 2 router, it is required to include the same IP address es in its level 1 and level 2 LSPs.

IP-capable routers need to know, for any given IP destination address, the correct route to that destination.

Routing TCP/IP, Volume II: CCIE Professional Development, Second Edition

Specifically, level 1 routers need to know what IP addresses are reachable from each level 1 router in their area. In addition, level 1 routers need to find level 2 routers for traffic to IP addresses outside of their area.

Level 2 routers need to know what IP addresses are reachable internally either directly, or via level 1 routing from other level 2 routers, and what addresses are reachable externally from other level 2 routers. All of this information is made available by inclusion of IP reachable address information in the Link State Packets. Internal within the routing domain and external outside the domain reachability information is announced separately in level 2 LSPs.

In general, for external routes, metrics may be of type "internal" i. A route using internal metrics i. In general, this information may be determined from the level 1 LSPs from all routers in the area. If we ignore resource constraints, then it would be permissible for a level 2 router to simply duplicate all [IP address, subnet mask, metric] entries from all level 1 routers in its area with appropriate metric adjustment , for inclusion in its level 2 LSP.

However, in order for hierarchical routing to scale to large routing domain sizes, it is highly desired to abbreviate the reachable address information. This is accomplished by manual configuration of summary addresses. Each level 2 router may be configured with one or more [IP address, subnet mask, metric] entries for announcement in their level 2 LSPs. The set of reachable addresses obtained from level 1 LSPs is compared with the configured reachable addresses.

Generally it is expected that the level 2 configured information will specify more inclusive addresses corresponding to a subnet mask with fewer bits set to 1.

Cisco.Press.Routing.TCP.IP. Volume.2.pdf

The manually configured addresses are included in level 2 LSPs only if they correspond to at least one address which is reachable in the area. For manually configured level 2 addresses, the associated metric values to announce in level 2 LSPs are also manually configured.

The configured addresses will supercede reachable address entries from level 1 LSPs based only on the IP address and subnet mask -- metric values are not considered when determining if a given configured address supercedes an address obtained from a level 1 LSP. Any address obtained from a level 1 LSP which is not superceded by the manually configured information is included in the level 2 LSPs.

In this case, the metric value announced in the level 2 LSPs is calculated from the sum of the metric value announced in the corresponding level 1 LSP, plus the distance from the level 2 router to the appropriate level 1 router. Note: If this sum results in a metric value greater than 63 the maximum value that can be reported in level 2 LSPs , then the value 63 must be used. Delay, expense, and error metrics i. In general, the same [IP address, subnet mask] pair may be announced in level 1 LSPs sent by multiple level 1 routers in the same area.

In this case assuming the entry is not superceded by a manually configured entry , then only one such entry shall be included in the level 2 LSP. The metric value s announced in level 2 LSPs correspond to the minimum of the metric value s that would be calculated for each of the level 1 LSP entries. A level 2 router will have IP addresses which are directly reachable via its own interfaces. For purposes of inclusion of IP reachable address information in level 2 LSPs, these "directly reachable" addresses are treated exactly the same as addresses received in level 1 LSPs.

Manually configured addresses may hierarchically supercede multiple level 1 reachable address entries. However, there may be some IP addresses which match the manually configured addresses, but which are not reachable via level 1 routing. If a level 2 router receives an IP packet whose IP address matches a manually configured address which it is including in its level 2 LSP, but which is not reachable via level 1 routing in the area, then the packet must be discarded. In this case, an error report may be returned as specified in RFC , with the reason for discard specifying destination unreachable.

Suppose that the network number for the entire routing domain is 17 a class A network. Suppose each area is assigned a subnet number consisting of the next 8 bits. The area may be further subdivided by assigning the next eight bits to each LAN in the area, giving each a 24 bit subnet mask counting the network and subnet fields.

Finally 8 bits are left for the host field. Suppose that for a particular area given subnet number Only this one address needs to be announced in level 2 LSPs. Thus if an IP packet comes along for an address in subnet The inclusion of If any traffic comes along that is for an unreachable address such as Suppose that subnet number In this case, the level 2 router in the left area would be announcing in its level 2 LSPs according to manually configured information reachability to subnet However, the level 2 router in the lower right area would be announcing in its level 2 LSPs according to information taken from its received level 1 LSPs , reachability to subnet Due to the use of best match routing, this works correctly.

All traffic from other areas destined to subnet For example, these addresses are used to determine area membership of routers. This approach is recommended even for pure IP routing domains, as it will simplify future migration from IP-only to dual operation.

Instead, an alternate mechanim is provided below for algorithmically generating a valid OSI style address from existing IP address and autonomous system number assignments. The AS number in this context is used only for definition of unique NSAP addresses, and does not imply any coupling with exterior routing protocols. The Area field must be assigned by the authority responsible for the routing domain, such that each area in the routing domain must have a unique Area value.

The ID must be assigned by the authority responsible for the routing domain. The ID must be assigned such that every router in the routing domain has a unique value. It is recommended that one of the following methods is used: 1 use a unique IEEE 48 bit station ID 2 use the value hex "02 00" prepended to an IP address of the router.

Since the IEEE station IDs are assigned to be globally unique, use of these values clearly assures uniqueness in the area. Prepending the indicated pattern to the front of the IP address therefore assures that format 2 illustrated above cannot produce addresses which collide with format 1.

Finally, to the extent that IP addresses are also globally unique, format 2 will produce unique IDs for routers. The indicated hex value is specified in IEEE canonical form [ 10 ]. In IEEE addresses, the multicast bit is the least significant bit of the first byte. The routes announced in IP external reachability information entries include all routes to outside of the routing domain. External routes may make use of "internal" or "external" metrics.

Internal metrics are comparable with the metrics used for internal routes. Thus in choosing between an internal route, and an external route using internal metrics, the metric values may be directly compared. In contrast, external metrics cannot be directly compared with internal metrics. Any route defined solely using internal metrics is always preferred to any route defined using external metrics.

When an external route using external metrics must be used, the lowest value of the external metric is preferred regardless of the internal cost to reach the appropriate exit point.

It is useful, in the operation of external routing protocols, to provide a mechanism for border routers i. This is made possible by inclusion of "inter-domain routing protocol information" fields in level 2 LSPs. The inter- domain routing protocol information field is not included in pseudonode LSPs. In general there may be multiple types of external inter-domain routing protocol information exchanged between border routers.

The IS-IS therefore specifies that each occurance of the inter-domain routing protocol information field include a "type" field, which indicates the type of inter-domain routing protocol information enclosed. Values to be used in the type field will be specified in future versions of the "Assigned Numbers" RFC. Initial values for this field are specified in Annex A of this specification.

Information contained in the inter-domain routing protocol information field will be carried in level 2 LSPs, and will therefore need to be stored by all level 2 routers in the domain. In designing the use of this field, it is important to carefully consider the implications that this may have on storage requirements in level 2 routers including those level 2 routers which are not directly involved in external routing. This allows for routing on the basis of throughput the default metric , delay, expense, or residual error probability.

Note than any particular packet may be routed on the basis of any one of these four metrics. Routing on the basis of general combinations of metrics is not supported. If a particular packet calls for a specific TOS, and the correct path from the source to destination is made up of routers all of which support that particular TOS, then the packet will be routed on the optimal path.

However, if there is no path from the source to destination made up of routers which support that particular type of service, then the packet will be forwarded using the default metric instead. This allows for TOS service in those environments where it is needed, while still providing acceptable service in the case where an unsupported TOS is requested.

The IP TOS field is mapped onto the four available metrics as follows: Bits Precedence : This field does not affect the route, but rather may affect other aspects of packet forwarding. Use of independent multiple packets has the advantages with respect to segmentation or fragmentation that: i when information in the IS-IS changes, only those packets effected need to be re-issued; ii when a single packet is received, it can be processed without the need to receive all other packets of the same type from the same router before beginning processing.

As specified in section 5 "Structure and Encoding of PDUs" , some of the IP-specific fields those which may be fairly long may be split into several occurences of the same field, thereby allowing splitting of the fields across different packets. Some specific variable length fields may be required to occur in LSP number 0. Complete Sequence Number Packets may be split into multiple packets, with the range to which each packet applies explicitly reported in the packet.

Partial Sequence Number Packets are inherently partial, and so can easily be split into multiple packets if this is necessary. However, there are some variable length fields from the IS-IS packets that can be omitted. The details of encapsulation and decapsulation are for further study. Routers complying with the Integrated IS-IS are not required to implement encapsulation nor decapsulation. The authentication information contained in each packet is used to authenticate the entire packet, including OSI and IP parts.

If a packet is received which contains invalid authentication information, then the entire packet is discarded. Use of the authentication field is optional.

Routers are not required to be able to interpret authentication information. As with other fields in the integrated IS-IS, if a router does not implement authentication then it will ignore any authentication field that may be present in an IS-IS packet. Annex D specifies a proposed use of the authentication field.

The Dijkstra calculation must calculate routes to each distinct IP reachability entry. Naturally, each IP reachability entry is treated as distinct from any OSI end systems which may also be reachable in the same area or routing domain. For any particular IP reachability entry, this is the same as another entry if and only if: i the subnet masks are identical; and ii for each bit in the subnet mask which has the value "1", the IP address is identical.

This can easily be tested by zeroing those bits in the IP address which correspond to a zero bit in the mask, and then treating the entry as a 64 bit quantity, and testing for equality between different 64 bit quantities.

Best-selling author Jeff Doyle offers crucial knowledge for every network professional who must manage routers to support growth and change. Its expert content and CCIE structured review makes it invaluable for anyone pursuing this elite credential. While its examples focus on Cisco IOS, the book illuminates concepts that are fundamental to virtually all modern networks and routing platforms. Therefore, it serves as an exceptionally practical reference for network designers, administrators, and engineers in any environment.

Dense Mode, Sparse Mode, and Bidirectional. This book is part of the CCIE Professional Development series, which offers expert-level instruction on network design, deployment, and support methodologies to help networking professionals manage complex networks and prepare for the CCIE exams.The detailed encoding and interpretation of this in formation is specified in sections 3 , 4 , and 5 of this RFC.

Each router on the LAN reports that it has a link to the pseudonode rather than reporting a link to every other router on the LAN. A level 2 router will accept another level 2 router as a neighbor, regardless of area address. SlideShare Explore Search You. For destinations which are not reachable via level 1 routing, or for level 2 only routers routers which do not take part in level 1 routing , then level 2 routes are selected as follows: 1 Routes using internal metrics only are always preferred to routes using external metrics.

The area may be further subdivided by assigning the next eight bits to each LAN in the area, giving each a 24 bit subnet mask counting the network and subnet fields. Some fields specifically related to IP operation may be included by dual routers, and will be ignored by OSI-only routers.