...(intermediate system to immediate system and open shortest path first). • The OSPF routes (open shortest path first) in Cisco has no hop count limitations. The external for Cisco (EBGP) is 20 compares to Junos (BGP) with 170. Cisco is lower because it goes out as a AS instead of staying as a AS. The IBGP is 200 because of its internal route should be a IGP. The BGP prefers the paths learned by using the EBGP over paths learned using IBGP to eliminate loops. • distance Bgp 200 • default-metric 4 This table lists the administrative distance default values of the protocols Route Source Default Distance Values Connected interface 0 Static route 1 Enhanced Interior Gateway Routing Protocol (EIGRP) summary route 5 External Border Gateway Protocol (BGP) 20 Internal EIGRP 90 IGRP 100 OSPF 110 Intermediate System-to-Intermediate System (IS-IS) 115 Routing Information Protocol (RIP) 120 Exterior Gateway Protocol (EGP) 140 On Demand Routing (ODR) 160 External EIGRP 170 Internal BGP 200 Unknown* 255 Default Route Preference Values How Route Is Learned Default Preference Statement to Modify Default Preference Directly connected network 0 - System routes 4 - Static 5 Static MPLS 7 MPLS preference in the JUNOS MPLS Applications Configuration Guide LDF 8 LDF preference in the JUNOS MPLS Applications Configuration Guide OSPF internal route 10 OSPF export IS-IS Level 1 internal route 15 IS-IS external-preference, preference IS-IS Level 2 internal route 18 IS-IS external-preference...
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...A REPORT ON CURRENT BGP PROBLEMS AND SUGGESTED SOLUTIONS CS526- Assignment# 4 Amit Jhamb & Bhavani Prasad University of Missouri- Kansas City BGP Overview The Border Gateway Protocol (BGP) is an exterior gateway protocol (EGP) also known as inter-Autonomous System routing protocol. The primary function of a BGP speaking system is to exchange network reachability information with other BGP systems. This network reachability information includes information on the list of Autonomous Systems (ASs) that reachability information traverses. This information is sufficient to construct a graph of AS connectivity from which routing loops may be pruned and some policy decisions at the AS level may be enforced. BGP-4 provides a new set of mechanisms for supporting classless interdomain routing. These mechanisms include support for advertising an IP prefix and eliminate the concept of network "class" within BGP. BGP-4 also introduces mechanisms, which allow aggregation of routes, including aggregation of AS paths. BGP also performs interdomain routing in TCP/IP networks. Problems in BGP I-BGP Scaling Problem: All BGP speakers within a single AS must be fully meshed so that any external routing information must be re-distributed to all other routers within that AS. This "full mesh" requirement clearly does not scale when there are a large number of IBGP speakers as is common in many of todays internet networks. For n BGP speakers within an...
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...Fall 2006, Syracuse University Lecture Notes for CIS/CSE 758: Internet Security Routing Protocols (1) Introduction Static routing versus dynamic routing Static routing Fixes routes at boot time Useful only for simplest cases Dynamic routing Table initialized at boot time Values inserted/updated by protocols that propagate route information Necessary in large internets Routing with partial information The routing table in a given router contains partial information about possible destinations For the unknown destinations, forward them to the default router. Potential problem: some destinations might be unreachable. Original Internet and the problem if the core routers are allowed to have default routes. Core routing architecture with single backbone. Assumes a centralized set of routers that know all possible destinations in an internet. Non-core routers use the core routers as their default routers. Work best for internets that have a single, centrally managed backbone. Inappropriate for multiple backbones. Disadvantage Central bottleneck for all traffic Not every site could have a core router connected to the backbone: how do they get routing information? No shortcut route possible: non-core routers always forward their traffic to the default routers even though another core router provides a better route. This is because the noncore routers do not know which one is better without full knowledge of all possible destinations...
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...Switches and Router Christina Bennett IT242 Switches and Router One of the main reasons that Cisco is number one in the enterprise networking market place is their Internetwork Operating System (IOS).The IOS provides a similar function to Microsoft Windows or Linux: it controls and manages the hardware it is running on. Basically, the IOS provides the interface between you and the hardware, enabling you to execute commands to configure and manage your Cisco device. “Originally, the IOS was developed for Cisco routers, but over the last few years, Cisco has been porting the IOS to it so there platforms, including the Catalyst switches”. (Cisco.com) There are actually many ways of accessing a Cisco device, including the following: console, auxiliary (only certain Cisco routers), telnet, web browser, and an SNMP management station .A console interface provides serial connection access to a router— with console access, you can enter commands in a text-based mode. In order to access your Cisco device from a remote station, however, you first need to create a basic configuration, including IP addressing. Therefore, to perform your initial configurations, you need access to the console port of your Cisco device. Before you can actually begin configuring your Cisco device, you first have to connect it to your network and set up a terminal connection to its console interface. No two routers are setup in the same manner; however, the command modes they use are pretty much alike...
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...The Evolving Network Model EIGRP OSPF IS-IS Optimizing Routing CCNP BSCI Quick Reference Sheets Exam 642-901 BGP IP Multicast IPv6 Introduction Brent Stewart Denise Donohue ciscopress.com [2] ABOUT THE AUTHORS CCNP BSCI Quick Reference Sheets About the Authors Brent Stewart, CCNP, CCDP, MCSE, Certified Cisco Systems Instructor, is a network administrator for CommScope. He participated in the development of BSCI, and has seperately developed training material for ICND, BSCI, BCMSN, BCRAN, and CIT. Brent lives in Hickory, NC, with his wife, Karen and children, Benjamin, Kaitlyn, Madelyn, and William. Denise Donohue, CCIE No. 9566, is a Design Engineer with AT&T. She is responsible for designing and implementing data and VoIP networks for SBC and AT&T customers. Prior to that, she was a Cisco instructor and course director for Global Knowledge. Her CCIE is in Routing and Switching. © 2007 Cisco Systems Inc. All rights reserved. This publication is protected by copyright. Please see page 73 for more details. [3] ICONS USED IN THIS BOOK CCNP BSCI Quick Reference Sheets Icons Used in This Book Si Router 7507 Router Multilayer Switch with Text Multilayer Switch Communication Server Switch I DC Internal Firewall IDS Web Browser Database App Server © 2007 Cisco Systems Inc. All rights reserved. This publication is protected by copyright. Please see page 73 for more details. [4] CHAPTER 1 CCNP...
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...Impact of BGP Dynamics on Router CPU Utilization Sharad Agarwal1 , Chen-Nee Chuah2 , Supratik Bhattacharyya3 , and Christophe Diot4 1 University of California, Berkeley, USA, sagarwal@cs.berkeley.edu 2 University of California, Davis, USA, chuah@ece.ucdavis.edu 3 Sprint ATL, Burlingame, USA, supratik@sprintlabs.com 4 Intel Research, Cambridge, UK, christophe.diot@intel.com 1 Introduction The Internet is an interconnection of separately administered networks called Autonomous Systems or ASes. To reach entities outside the AS, the inter-domain routing protocol used today is the Border Gateway Protocol or BGP [1]. It has been approximately 15 years since BGP was deployed on the Internet. The number of ASes participating in BGP has grown to over 16, 000 today. However, this growth has been super-linear during the past few years [2]. With this sudden growth there has been concern in the research community about how well BGP is scaling. In particular, it has been noted that there is significant growth in the volume of BGP route announcements (or route flapping) [3] and in the number of BGP route entries in the routers of various ASes [2]. For every BGP routing update that is received by a router, several tasks need to be performed [4]. First, the appropriate RIB-in (routing information base) needs to be updated. Ingress filtering, as defined in the router’s configuration, has to be applied to the route announcement. If it is not filtered out, the route undergoes the BGP route selection...
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...Discretionary · Must be supported; propagation optional 5 Local Preference Metric for internal neighbors to reach external destinations (default 100) 6 Atomic Aggregate Includes ASes which have been dropped due to route aggregation Optional Transitive · Marked as partial if unsupported by neighbor 7 Aggregator ID and AS of summarizing router 8 Community Route tag Optional Nontransitive · Deleted if unsupported by neighbor 4 Multiple Exit Metric for external neighbors to reach the Discriminator (MED) local AS (default 0) 9 Originator ID The originator of a reflected route 10 Cluster List List of cluster IDs 13 Cluster ID Originating cluster -- Weight iBGP AD 200 Standard RFC 4271 Protocols IP Transport TCP/179 Authentication MD5 Terminology Autonomous System (AS) A logical domain under the control of a single entity External BGP (eBGP) BGP adjacencies which span autonomous system boundaries Internal BGP (iBGP) BGP adjacencies formed within a single AS Synchronization Requirement A route must be known by an IGP before it may be advertised to BGP peers Packet Types Cisco proprietary, not communicated to peers (default 0) Path Selection Attribute eBGP AD 20 Open Update Keepalive Notification Neighbor States Description Preference 1 Weight Administrative preference Highest Active · Attempting to connect 2 Local Preference Communicated between peers within...
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...Instructions: Research all of the concepts below, answer the following questions, and then respond to the questions about the configurations on pages 2 and 3. Research the following concepts: • Area border router (ABR) • Autonomous system boundary router (ASBR) • Designated router (DR ) • Backup designated router (BDR) Answer the following questions: 1. When would you use an ABR as opposed to an ASBR? The time I would use ABR as opposed to ASBR is when I want to connect one or more OSPF areas to the backbone of the Network 2. What are the effects of using two OSPF processes? The effects of using two OSPF process would be you having absolute control over what prefixes are advertised between the two OSPF processes 3. What is the difference between a DR as opposed to BDR? DR and Bdr concept work in broadcast multi access network. It reduces Lsa flooding within broadcast domain by electing one DR and Bdr to which other routers in broadcast domain Form adjacency. So that only Dr and BDR have full adjacency That means full link state database. 4. How does the election process work? a network with 3 OSPF routers on a Fast Ethernet network. They are connected to the same switch (multi-access network) so there will be a DR/BDR election. OSPF has been configure so all routers have become OSPF neighbors, Instructions: a is ABSR B is ABR...
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...Category | Points | Description | Section 1Configuring OSPF Single Area: 40 Points * Task 1: Step 5 * Related Explanation or Response * Task 1: Step 6 * Related Explanation or Response * Task 1: Step 10 * Related Explanation or Response * Task 2: Step 4 * Related Explanation or Response * Summary Paragraph | 2323232320 | Paste the requested screenshot.Provide the requested answer.Paste the requested screenshot.Provide the requested answer.Paste the requested screenshot.Provide the requested answer.Paste the requested screenshot.Provide the requested answer.In your own words, summarize what you have learned about IP subnetting and configuration. | Total | 40 | | ------------------------------------------------- Name: Date: Professor: ------------------------------------------------- Configuring OSPF Single Area vLab (30 points) Write a paragraph (minimum five college-level sentences) below that summarizes what was accomplished in this lab, what you learned by performing it, how it relates to this week’s TCOs and other course material, and (just as important) how you feel it will benefit you in your academic and professional career. (10 points) ------------------------------------------------- Copy and paste the following screenshots from your Configuring OSPF Single Area lab below. Task 1, Step 5: Paste a screenshot showing the route table of the Indianapolis router. (2 points) Question: Based on the information...
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...NETW204: Assignment 4, Link-state Routing and OSPF (50 points) Fill in the blanks below with either the term defined or the definition for the terms listed. Each answer is worth 2 points each, 25 questions X 2 = 50 total points. Type answers in the appropriate cell; text will automatically wrap. Post your completed assignment to the dropbox. NAME | Chad White | | Term | Definition | 1 | ABR | Attaches to multiple areas, maintains separatelink-state databases for each area it is connectedto, and routes traffic destined for or arriving fromother areas | 2 | Autonomous System Boundary Router (ASBR) | Routers that have at least one interface attached to an external internetwork (another autonomous system [AS]), such as a non-OSPF network. ASBRs can import non- OSPF network information to the OSPF network and vice versa; this process is called route redistribution. | 3 | Backup Designated Router (BDR) | Used to provide redundancy in broadcast networks which are utilizing the OSPF | 4 | DBD | Contains an abbreviated list of the sendingrouter’s link-state database and is used by receiving routers to check against the local link-state database | 5 | Designated Router (DR) | A router that informs end nodes of the existence and identity of other routers. | 6 | DRothers | Routers that are not a dr or bdr. they are the routers in the ospf network. | 7 | Flapping link | A link which cycles between up and down. | 8 | Highest active IP | Router ID for an OSPF...
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...BGP PART 1 Attribute Types Must be supported and propagated Must be supported; propagation optional packetlife.net About BGP Type Path Vector eBGP AD 20 iBGP AD 200 Standard RFC 4271 Protocols IP Transport TCP/179 Authentication MD5 Terminology Autonomous System (AS) A logical domain under the control of a single entity Well-known Mandatory Well-known Discretionary Optional Transitive Marked as partial if unsupported by neighbor Deleted if unsupported by neighbor Attributes Optional Nontransitive Name Type Description Aggregator OT AS Path WM Atomic Aggregate WD Cluster ID ON Community OT Local Preference WD Multiple Exit ON Discriminator (MED) Next Hop WM Origin WM Originator ID ON Weight O ID and AS of router which performed summarization List of autonomous systems which the advertisement has traversed Includes ASes which have been dropped due to route aggregation Originating cluster Route tag Metric for internal neighbors to reach external destinations (default 100) Metric for external neighbors to reach the local AS (default 0) External peer in neighboring AS Origin type (IGP, EGP, or unknown) Identifies a route reflector Cisco proprietary, not communicated to peers (default 0) Path Selection External BGP (eBGP) BGP adjacencies which span autonomous system boundaries Internal BGP (iBGP) BGP adjacencies formed within a single autonomous system Synchronization Requirement A route must be known by an IGP before it may be advertised...
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...minimal downtime during the transition. Example.com is running EIGRP while Example.net is running a multi-area OSPF. Because it is imperative that the two booksellers continuously deliver Internet services, you should bridge these two routing domains without interfering with each router’s path through its own routing domain to the Internet. The CIO determines that it is preferable to keep the two protocol domains shown in the diagram during the transition period, because the network engineers on each side need to understand the other’s network before deploying a long-term solution. Redistribution will be a short-term solution. In this scenario, R1 and R2 are running EIGRP while R2 is the OSPF autonomous system border router (ASBR) consisting of areas 0, 10, and 20. You need to configure R2 to enable these two routing protocols to interact to allow full connectivity between all networks. In this lab, R1 is running EIGRP and R3 is running multi-area OSPF. Your task is to configure redistribution on R2 to enable these two routing protocols to interact, allowing full connectivity between all networks. In Appendix A of this lab, you explore the black hole operation. Note: This lab uses Cisco 1941 routers with Cisco IOS Release 15.2 with IP Base. Depending on the router or switch...
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...one is not necessarily better, but rather just different. Both are tools you can use to solve a problem they’re well suited to solve. Unfortunately, nothing on either protocol goes into too much detail on why we would use one or the other. EIGRP is known widely as a proprietary protocol. So is it just a matter of using EIGRP with Cisco equipment and OSPF without? OSPF is pretty cool because it allows us to decide the path through the network by being aware of all links in a given logical topology. OSPF gives us a bit more control, seeing as each router knows about every other link in an OSPF area, allowing us to get really granular path selection. OSPF does require more resources on the device than most other protocols, such as the relatively light DUAL algorithm that sits behind EIGRP. So use OSPF when you have beefy equipment and EIGRP when you don’t. From what I’ve read Cisco will be allowing EIGRP to be used on non-Cisco equipment. That will make it more available to use. So now EIGRP may be kind of open and newer equipment is less affected by the power of OSPF. So back and forth we go. One thing where OSPF holds an advantage is the ability to see your route. With EIGRP it’s considered routing by rumor. EIGRP is able to summarize on any interface running EIGRP, and OSPF is only able to do this at Area Border Routers, or routers at that join multiple areas together. There are a couple ways of looking at this, but I’d like to make one very clear point. Any large network that...
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...to provide physical security for a router are shown below. The room that contains the router should be free of electrostatic or magnetic interference. It should have controls for temperature and humidity. If continuous operation of the router is critical, an uninterruptible power supply (UPS) should be installed and spare components kept on hand. 4. List three services you should block at a border router. Answer: The below table shows the services that should be completely blocked by a typical border router. Services to Block Completely at a Border Router Port (Transport) Servie 1 (TCP & UDP) tcpmux 7 (TCP & UDP) echo 9 (TCP & UDP) discard 11 (TCP) systat 13 (TCP & UDP) daytime 5. List two strategies that could be applied to mitigate Denial of Service (DoS) attacks on a router? Answer: There are three primary strategies for combatting DoS attacks, Mention below. 1. Prevent malicious traffic from entering the common network from the enterprise network. 2. Configure and deploy local protective measures, at both border and interior routers. 3. Coordinate protective measures against distributed DoS attacks with network access providers and/or backbone administrators. 6. If I allow remote administrative access to my router, what is the main advantage of ensuring access ifs via SSH rather than Telnet? Answer: Most important benefit of ensuring access via SSH is that the server authenticates itself to the...
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...Routing protocols: Routing protocols are broken up into few different categories Distance Vector: DVRP use a distance to a remote network to find the best path. It is called hop when each time a packet of data goes through a router. The best is considered to be with the least number of hopes. The vector is the determination of direction to the remote network. Examples for distance vector routing protocols are RIP and IGRP. RIP (Routing information protocol): RIP is a true distance vector routing protocol. Every 30 seconds, RIP sends the entire routing table out to all active interfaces. It only uses hop count to find the best way to a remote network, but it has a only maximum allowable hop count of 15, which means one more hop count of 16 is deemed unreachable. They...
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