CCIE R&S Advanced Technologies Class v4.5 - EIGRP Path Selection, EIGRP Metric Weights, EIGRP Traffic Engineering

Transcript

1	Introduction	0h 43m
2	Using the Cisco Documentation	0h 52m
3	Ethernet Overview, Layer 2 Switchports, Trunking, ISL, 802.1q, DTP	0h 47m
4	VTP, VTP Authentication, VTP Pruning	1h 02m
5	VTP Prune Eligible List, VTP Transparent, VTP Troubleshooting, Trunk Allowed List, Extended VLANs	0h 48m
6	VLAN and VTP Review	0h 19m
7	SVIs, Native Routed Interfaces, Router-on-a-Stick	0h 46m
8	Layer 2 EtherChannel, EtherChannel Load Balancing, Layer 3 EtherChannel	0h 57m
9	802.1q Tunneling, Layer 2 Protocol Tunneling, EtherChannel over 802.1q Tunneling	1h 03m
10	STP Root Bridge Election, STP Root Port Election, STP Designated Port Election, STP Priority, STP Cost, STP Port-Priority	1h 46m
11	STP Review	0h 12m
12	STP Timers, STP PortFast	0h 34m
13	STP UplinkFast	0h 11m
14	STP BackboneFast	0h 12m
15	STP BPDU Filter	0h 13m
16	STP BPDU Guard	0h 11m
17	STP Root Guard	0h 11m
18	STP Loop Guard, Unidirectional Link Detection (UDLD)	0h 11m
19	Multiple Spanning-Tree Protocol (MST)	0h 40m
20	Rapid Spanning-Tree Protocol (RSTP), Rapid-PVST	0h 18m
21	MST with Multiple Regions	0h 33m
22	Flex Links	0h 16m
23	Frame Relay	0h 39m
24	Frame Relay Configuration Part 1	0h 34m
25	Frame Relay Configuration Part 2	0h 41m
26	Frame Relay Switching	0h 27m
27	Back-to-Back Frame Relay	0h 08m
28	Frame-Relay End-to-End Keepalives	0h 18m
29	PPP, PPP PAP Authentication, PPP CHAP Authentication	0h 59m
30	PPPoFR, PPPoE	0h 40m
31	Transparent Bridging, IRB	0h 32m
32	Fallback Bridging	0h 14m
33	IP Routing Overview, Switching Paths, Static Routing	0h 42m
34	Static Routing Examples	0h 25m
35	IP Default-Gateway, IP Default-Network	0h 14m
36	On-Demand Routing (ODR)	0h 07m
37	Floating Static Routes	0h 10m
38	Backup Interface	0h 29m
39	Enhanced Object Tracking, IP SLA, Reliable Static Routing	0h 21m
40	Policy Routing	0h 43m
41	GRE Tunneling, GRE Recursive Routing Errors	0h 27m
42	Reliable Backup Interface with GRE	0h 25m
43	RIP Overview, RIP Versions, RIP Auto-Summary	0h 48m
44	RIP Split-Horizon, RIP Timers	0h 22m
45	RIP Broadcast Updates, IP Directed Broadcast, IP Broadcast-Address, Smurf Attacks, Fraggle Attacks	0h 16m
46	RIP Unicast Updates	0h 03m
47	RIP Offset-List	0h 18m
48	RIP Authentication	0h 11m
49	RIP Summarization	0h 10m
50	Prefix-Lists, RIP Distribute-List Filtering, RIP Administrative Distance Filtering	0h 48m
51	RIP Default Routing, RIP Conditional Default Routing	0h 18m
52	RIP Triggered, RIP Validate Update Source,	0h 12m
53	EIGRP Overview	0h 29m
54	EIGRP Auto-Summary	0h 07m
55	EIGRP Split-Horizon	0h 11m
56	EIGRP Update Types, EIGRP Neighbor, EIGRP Passive-Interface	0h 24m
57	EIGRP Hello-Interval, EIGRP Hold-Time	0h 05m
58	EIGRP Authentication	0h 11m
59	EIGRP Time Based Authentication	0h 25m
60	EIGRP Path Selection, EIGRP Metric Weights, EIGRP Traffic Engineering	0h 47m
61	EIGRP Unequal Cost Load Balancing, EIGRP Variance	0h 19m
62	EIGRP QUERY, EIGRP Summarization, EIGRP Leak-Map	0h 28m
63	EIGRP Stub Router Advertisement	0h 22m
64	EIGRP Default Routing	0h 13m
65	EIGRP Route Filtering	0h 11m
66	EIGRP Router-ID	0h 07m
67	Miscellaneous EIGRP Features	0h 02m
68	OSPF Overview	0h 27m
69	Establishing OSPF Adjacencies, Understanding the OSPF Database	0h 43m
70	OSPF Network Type Broadcast, OSPF DR/BDR Election, OSPF over NBMA, OSPF Network Type Non-Broadcast and Point-to-Multipoint	0h 56m
71	OSPF Network Type Point-to-Point, OSPF Network Type Mismatch	0h 13m
72	OSPF Network Type Point-to-Multipoint Non-Broadcast, OSPF Per Neighbor Cost	0h 17m
73	OSPF Network Type Loopback	0h 02m
74	OSPF Path Selection	0h 27m
75	OSPF Convergence Timers	0h 09m
76	OSPF Authentication	0h 12m
77	OSPF Summarization	0h 32m
78	OSPF Stub Areas, OSPF Totally Stubby Areas, OSPF NSSAs, OSPF Totally NSSAs	0h 40m
79	Controlling OSPF NSSA Redistribution	0h 02m
80	OSPF Type 7 to 5 Translator Election, OSPF LSA Type 3 Filter, OSPF Forwarding Address Suppression	0h 24m
81	Route Redistribution Overview	0h 36m
82	Route Redistribution Configuration & Verification, Connected Redistribution	0h 22m
83	OSPF External Path Selection, TCL PING Scripting	0h 33m
84	Routing Loops Overview, EIGRP Route Loop Prevention	0h 55m
85	Metric Based Routing Loops, Route Tagging	0h 46m
86	Administrative Distance Based Routing Loops, Debug IP Routing, IP Route Profile	0h 58m
87	BGP Overview, BGP Peering Types	0h 51m
88	Establishing BGP Peerings, EBGP Multihop, BGP Neighbor Disable Connected Check, BGP TTL Security	0h 49m
89	BGP 4-Byte ASNs	0h 20m
90	BGP Local AS, BGP Peer Groups	0h 30m
91	BGP Next-Hop Self, BGP Next-Hop Processing	0h 30m
92	BGP Route Reflectors	0h 37m
93	Large Scale BGP Route Reflectors with Clusters	0h 34m
94	BGP Confederation	0h 37m
95	BGP NLRI Advertisements, BGP Network Statement, BGP Redistribution	0h 43m
96	BGP Aggregation, BGP Aggregation & Summary-Only, BGP Aggregation & Unsuppress-Map	0h 46m
97	BGP Origin, BGP Aggregation & AS-Set, BGP Aggregation & Advertise-Map	0h 22m
98	BGP Conditional Route Injection	0h 21m
99	BGP Bestpath Selection, BGP Multipath, BGP Weight	0h 53m
100	BGP Local Preference, BGP Local Preference and Communities, BGP AS-Path Prepending,	0h 30m
101	BGP MED, BGP MED Missing As Worst, BGP Deterministic MED	0h 17m
102	BGP Communites, BGP Regular Expressions	0h 43m
103	BGP Filtering, BGP Convergence Timers, BGP Default Routing, Miscellaneous BGP Features	0h 24m
104	MPLS Overview, MPLS Label Distribution Protocol (LDP)	1h 05m
105	MPLS Tunnels, MPLS Penultimate Hop Popping (PHP)	0h 40m
106	MPLS Layer 3 VPNs Overview, VRF Lite	0h 36m
107	MPLS Layer 3 VPNs and VPNv4 BGP	1h 08m
108	MPLS Layer 3 VPN Verification & Troubleshooting	0h 49m
109	MPLS Layer 3 VPN OSPF PE-CE Routing Overview	0h 06m
110	MPLS Layer 3 VPN OSPF PE-CE Routing Path Selection & Sham-Links	2h 01m
111	MPLS Layer 3 VPN OSPF PE-CE Routing Loop Prevention & Down-Bit, OSPF Capability VRF-Lite	0h 40m
112	IPv6 Overview, IPv6 ICMPv6 ND, IPv6 over NBMA	0h 44m
113	IPv6 Routing Overview, IPv6 Static Routing	0h 28m
114	IPv6 RIPng	0h 20m
115	IPv6 EIGRPv6	0h 09m
116	IPv6 OSPFv3	0h 31m
117	MP-BGP for IPv6	0h 26m
118	IPv6 Tunneling	1h 13m
119	Multicast Overview, IGMP	0h 34m
120	PIM Overview	0h 18m
121	PIM Dense Mode	1h 03m
122	PIM Sparse Mode	0h 30m
123	PIM Sparse Mode Configuration	0h 36m
124	PIM Sparse Mode RPF & RP Troubleshooting	0h 27m
125	Auto-RP, Multicast over GRE Tunnels	0h 53m
126	Bootstrap Router (BSR), Bidirectional PIM, Source Specific Multicast (SSM)	0h 40m
127	MSDP, Anycast RP	0h 27m
128	IPv6 Multicast Routing	0h 24m
129	QoS Overview, IntServ QoS, DiffServ QoS, IP Precedence, DSCP, MQC, HQF	0h 41m
130	MQC Classification	0h 44m
131	FIFO, FQ, WFQ, CBWFQ, HQF	0h 50m
132	LLQ	0h 23m
133	WRED	0h 31m
134	Traffic Shaping, Traffic Policing	0h 40m
135	Frame Relay Traffic Shaping (FRTS)	0h 33m
136	RSVP	0h 07m
137	Catalyst 3560 QoS	1h 00m
138	IOS Security Overview, Access Lists (ACLs)	0h 58m
139	Time Based ACLs, Dynamic ACLs	0h 33m
140	Reflexive ACLs	0h 21m
141	TCP Intercept, Content Based Access Control (CBAC)	0h 34m
142	Zone Based Policy Firewall (ZBPF)	1h 09m
143	AAA, Local Authentication, Local Authorization, Role Based CLI Access	0h 43m
144	Port Security, Static CAM Entries, Storm Control, 802.1X Authentication, PACLs, RACLs, VLAN Access Maps (VACLs)	0h 48m
145	DHCP Snooping, Dynamic ARP Inspection (DAI), IP Source Guard	0h 12m
146	Protected Ports, Private VLANs	0h 25m
147	IP Services Overview, HSRP	1h 10m
148	VRRP, GLBP	0h 28m
149	NAT	0h 42m
150	DHCP, DNS	0h 30m
151	NetFlow	0h 09m
152	WCCP, Miscellaneous IP Services	0h 06m
153	System Management Overview, NTP, NTP Authentication	0h 24m
154	SNMP, RMON	0h 38m
155	Syslog, Telnet, SSH, Banners	0h 21m
156	EEM Scripting, Miscellaneous System Management	0h 26m
Total Duration		81h 42m

Slides - Diagrams

Slides - Introduction

Slides - Ethernet Switching

Slides - Advanced Ethernet Switching

Slides - Frame Relay

Slides - PPP

Slides - Transport Bridging

Slides - Redistribution

Slides - IOS Security

Slides - Layer 2 Security

Slides - IP Services

Slides - System Management

0:00:12	In our next section here, we're gonna talk
0:00:17	and how we can modify the different
0:00:21	the bandwidth, delay load, and reliability
0:00:24	in order to get different traffic
0:00:29	Now, we talked a little bit about
0:00:33	which path it's gonna use,
0:00:37	I'm gonna look at basically all
0:00:40	and then choose whatever one has
0:00:46	The actual metric value
0:00:49	is a composite value that could
0:00:53	which are bandwidth,
0:00:57	Now, the bandwidth is the inverse
0:01:04	scaled by 10 to the 7th times 256.
0:01:08	So, when we look at the actual
0:01:12	it's not gonna relate 1 to 1 with
0:01:18	Essentially, what this means is
0:01:22	is going to be the bandwidth
0:01:26	because if we have 10 gigabit
0:01:31	and then, we have one
0:01:35	it doesn't matter that we can send up to 10
0:01:40	Really end-to-end or effective bandwidth
0:01:44	So, whatever the bandwidth
0:01:47	that's what EIGRP is using for the
0:01:54	Now, the delay value...
0:01:56	is cumulative on a hop-by-hop basis,
0:01:59	because everytime the router needs
0:02:04	whether this is a T1 serial link or
0:02:08	there is going to be some
0:02:12	that it takes for us to switch the
0:02:16	and then actually encapsulate
0:02:19	The delay value EIGRP uses...
0:02:23	is then the cumulative delay
0:02:29	So, this means that if we have an interface
0:02:35	then, EIGRP is using 10 tens of
0:02:43	The last two, the load and reliability,
0:02:46	the load is gonna be the
0:02:48	where the reliability would
0:02:52	but by default, we'll see that these values are
0:02:58	Now, the metric calculation itself
0:03:01	uses this formula where we have the bandwidth
0:03:04	plus the bandwidth over 256
0:03:11	which is then offset by what we call these K values,
0:03:15	or the administrative weights for the formula.
0:03:20	Then, if the last K value, K5 is not equal to zero,
0:03:24	we take the result of the first calculation,
0:03:27	multiply it by K5 over the reliability plus K4.
0:03:32	Now, the result of this...
0:03:35	is gonna give us our composite metric that we
0:03:41	Whichever paths has the
0:03:44	this route is considered the successor.
0:03:47	The successor is the one that would
0:03:52	Now, actual metric of the successor
0:03:58	So, EIGRP uses the separate terms
0:04:02	routing protocols that sometimes makes
0:04:07	exactly how the calculation works.
0:04:10	Now, these k values,
0:04:12	by default, k1 and k3 are the
0:04:17	that have any non-zero value to them.
0:04:20	So, it effectively means that the
0:04:25	is just gonna be the bandwidth plus the delay.
0:04:29	Now, we can add...
0:04:32	either the load or the reliability in there
0:04:36	by changing the metric weights of the device,
0:04:41	but if we change it on one router, effectively,
0:04:44	Because it is required that everyone in
0:04:50	to make sure that the feasibility
0:04:56	So, if I change it on one routers, it means
0:05:01	Now, we'll see, when we actually
0:05:06	we can make it a little bit easier
0:05:09	if we wait only the delay,
0:05:12	because the delay again, is
0:05:16	So, we can use it kind of just like a hop count
0:05:19	as opposed to the bandwidth,
0:05:22	which is the inverse of the minimum
0:05:25	then scaled by 10 to the 7th times 256.
0:05:30	So, you can do the calculation and eventually
0:05:35	You'll see in the volume 1 workbook, I do have some
0:05:41	but we're not gonna go through
0:05:43	So, when we do the path
0:05:46	we're mainly just gonna be
0:05:50	Now, the actual calculation itself,
0:05:53	to understand this first, we need to know
0:05:57	when it's referring to the different
0:06:01	where dual is the diffusing
0:06:04	that's what we're using the
0:06:07	and then, ultimately make the calculation
0:06:10	to figure out what is the end-to-end
0:06:16	Now, as I mentioned, the successor, this is
0:06:20	So, this is the route itself that we
0:06:25	The feasible distance is the
0:06:30	So, it's the metric of the successor.
0:06:33	A feasible successor is a valid
0:06:39	that we have pre-computed to be
0:06:45	Now, what we see when we look at
0:06:51	the main reason that EIGRP can
0:06:56	is that we have these pre-calculated
0:07:02	So, if the router basically says, "I have my primary
0:07:07	but then, I have this backup
0:07:10	If the link with the metric of 10 goes down,
0:07:15	without having to rerun the dual algorithm."
0:07:19	Whereas with something like OSPF or IS-IS,
0:07:22	once the primary path fails,
0:07:24	we need to flood the new LSAs
0:07:29	or at least say a partial routing calculation
0:07:32	in order to figure out what the
0:07:35	Next, we have the advertised distance.
0:07:38	This is gonna be the composite
0:07:42	So, from the upstream neighbor's perspective,
0:07:45	this is their feasible distance of their successor.
0:07:49	From my perspective downstream of them,
0:07:52	this is the value that they are advertising to me.
0:07:56	So essentially, if we were to have...
0:08:00	router 1...
0:08:01	advertising some destination to a LAN segment
0:08:05	connecting to router 2, who then connects to...
0:08:09	router 3,
0:08:13	from router 1's perspective,
0:08:16	this LAN interface, let's say that it has a...
0:08:19	a cost of 10.
0:08:22	The feasible distance...
0:08:25	would be 10 from router 1's perspective.
0:08:28	If the link between router 1 and 2 has a...
0:08:32	cost of 20,
0:08:34	from 2's perspective,
0:08:36	the advertised distance that router 1 is sending is 10,
0:08:42	where router 2's feasible distance would then be 30.
0:08:45	So, just the addition of the two of them.
0:08:47	Then, likewise, from router 3's perspective,
0:08:50	the advertised distance that 2 is sending is 30,
0:08:54	where my feasible distance is gonna be 30
0:09:01	So, it's the same type of logic as
0:09:05	It's just thay EIGRP uses these
0:09:09	Beyond the advertised distance,
0:09:12	which is our composite metric to
0:09:17	In this example, the local distance would be the
0:09:22	and the 5 on the link between router 2 and 3.
0:09:25	So, it's whatever my cost is to reach them,
0:09:27	I'm gonna add that to whatever
0:09:31	That end-to-end cost would then
0:09:34	Then, lastly, the feasibility condition,
0:09:37	this is the logic that we're
0:09:40	do we have alternate backup paths
0:09:47	to install in the topology?
0:09:50	Now, we saw previously when we looked
0:09:54	versus the Show IP EIGRP
0:09:59	the All Links options will show us all of
0:10:03	even ones that are not meeting
0:10:08	So, by default, when we look
0:10:12	that's gonna show us our successor,
0:10:15	which is simply the best path.
0:10:18	It will show us the feasible distance,
0:10:22	Then, it's gonna show us any feasible
0:10:27	because they are passing
0:10:31	Now, the feasibility condition...
0:10:33	and the normal path selection,
0:10:37	The problem is that a lot of
0:10:41	overly complicated the way that it is explained.
0:10:45	So, like I mentioned before, everytime we
0:10:49	that's gonna include the advertised distance.
0:10:52	So, it's just the upstream neighbor's
0:10:57	Since I already know what my
0:11:02	I'll add those two values together,
0:11:04	that's gonna be my potential metric
0:11:08	So, I'll look at all the possible paths
0:11:11	the lowest metric based on all of them.
0:11:15	So, the best path called the successor
0:11:18	will then have a feasible distance
0:11:22	plus the upstream neighbor's
0:11:26	Like again, from router 2's perspective,
0:11:28	they're saying that...
0:11:31	"Router 1's advertised distance is 10.
0:11:33	My local distance is 20.
0:11:36	So then, it means that my
0:11:39	Now, the feasibility condition that is
0:11:45	uses a basic logic that says that
0:11:50	is higher than my end-to-end metric,
0:11:54	there could be a possibility that you are actually
0:12:03	Based on this logic, the feasibility condition says...
0:12:06	that I will only use alternate paths for which
0:12:14	is lower than my feasible distance.
0:12:18	So, let's look at it from
0:12:22	Okay again, we have router 1
0:12:25	2 connecting to 3, and then
0:12:30	2 connecting to router 4,
0:12:37	So, the cost between router 1
0:12:40	Router 1's feasible distance is 10.
0:12:48	is 10.
0:12:51	Router 2's feasible distance then...
0:12:58	is 30, because it's the local distance
0:13:05	Then, we said, the link between
0:13:09	So, router 2 out both of these links
0:13:12	it is advertising 30.
0:13:18	Let's then say from router 4's perspective,
0:13:22	it has a...
0:13:25	cost of 10 on this link.
0:13:28	Okay, so it means that router 4's
0:13:32	Router 3's feasible distance is 35.
0:13:39	Then, there's gonna be some
0:13:42	router 3 and router 4, let's
0:13:46	Okay, so router 4 is then advertising...
0:13:49	to router 3.
0:13:52	My distance is 40.
0:13:55	Router 3 is advertising to router 4.
0:13:58	My advertised distance is 35.
0:14:02	The routers are then gonna take...
0:14:05	the result of their own feasible distance
0:14:13	Now, we know that regardless
0:14:18	if 4 routes through 3 or 3 routes through 4,
0:14:21	eventually, we should end up in a loop-free path.
0:14:24	As long as we're not both routing out
0:14:28	So, we don't want router 3 to send packets this
0:14:33	But based on the feasibility condition,
0:14:38	that "You are advertising to me a cost of 40.
0:14:43	Since this is higher than my current metric,
0:14:46	I don't have any way of knowing that you're
0:14:54	So, maybe, there's some alternate link of
0:14:59	The reason why router 3 doesn't know that
0:15:01	is that because EIGRP does not
0:15:06	Since it is still a distance vector protocol,
0:15:09	it only knows what its directly
0:15:14	If this were OSPF or IS-IS,
0:15:18	because they know about every node
0:15:22	and all the states of the link
0:15:26	So, essentially, OSPF and IS-IS, they
0:15:31	But with EIGRP, we only know what the
0:15:35	So, router 3 in this case would say that
0:15:41	the feasibility condition fails."
0:15:44	Because router 4's advertised distance of 40...
0:15:47	is higher than my feasible distance of 35,
0:15:51	so, I cannot guarantee
0:15:55	From router 4's perspective however,
0:15:58	router 4 says, "My feasible distance is 40,
0:16:02	and router 3 is advertising 35 to me.
0:16:06	So, it means that router 3 is further
0:16:13	Because if router 3 was
0:16:17	3's metric would have to
0:16:20	It would be at least 40 plus 1.
0:16:25	But since 3's end-to-end
0:16:28	it means router 4 could
0:16:35	So, what we would see as the
0:16:40	that router...
0:16:42	3 says its feasible distance is 35,
0:16:45	router 4 saying its feasible distance is 40.
0:16:48	From router 3's perspective,
0:16:51	the route to 2 is the successor.
0:16:54	Same thing from router 4.
0:16:57	From router 2's perspective
0:16:59	the route to 1 is the successor.
0:17:02	Then, from router 4's perspective,
0:17:04	the route to 3 is a feasible successor.
0:17:10	So it means that if the link between...
0:17:13	2 and 4 goes down,
0:17:15	router 4 can immediately start routing traffic
0:17:21	Now, if you are gonna use EIGRP
0:17:24	this is the main key design that you
0:17:28	This is how EIGRP can be scalable
0:17:34	only if you have feasible successors
0:17:39	So, you would want a design the
0:17:43	that I have primary routes
0:17:47	but also alternate backup path that
0:17:52	so that I don't need to send a query
0:17:57	when I want to reconverge for
0:18:01	Now, we'll also see...
0:18:03	that these paths that pass
0:18:06	which are considered the
0:18:09	these are the only routes that are
0:18:18	So, we'll see, once we use
0:18:21	and try to use multiple links at the same time
0:18:27	only the valid backup paths,
0:18:31	only those can be used for the
0:18:35	So, regardless what we configure
0:18:39	we an set it to the highest value.
0:18:42	but still, only the feasible successors are gonna
0:18:49	Now, as I mentioned for the actual
0:18:54	the bandwidth is gonna be
0:18:57	So, this means that on a per-route basis,
0:19:00	we would have to take this into account if we
0:19:05	If we're trying to modify the path selection.
0:19:08	So, in the vast majority of designs,
0:19:10	it's much easier to change the delay value
0:19:13	to modify an EIGRP path selection
0:19:18	Whereas for OSPF, since the cost is
0:19:25	changing the bandwidth is essentially the
0:19:28	But with EIGRP, if I change the bandwidth
0:19:34	it doesn't necessarily mean that it's
0:19:38	I'd have to look at on a per-route basis
0:19:40	what is the bandwidth
0:19:44	and then, lower my metric according to that
0:19:51	But with the delay, since it's cumulative
0:19:56	we can change it anywhere in the network,
0:19:58	and see if it's going to affect all paths
0:20:03	So, let's take a look at this...
0:20:05	in our case now, and we'll look at it
0:20:10	So, router 2 has two different paths...
0:20:14	out to the rest of the network.
0:20:18	and we have the link that
0:20:22	Since router 5 disabled Split Horizon,
0:20:25	there shoud be no issue with it receiving updates
0:20:31	and then, advetising these
0:20:35	It doesn't necessarily mean router 2
0:20:39	It's gonna depend on what the
0:20:44	So first, we'll look at what is the lowest
0:20:51	Then, we will look at
0:20:52	what are the alternate paths
0:20:56	and is router 5 or router 3 advertising a
0:21:05	So, let's say for example, we're gonna
0:21:09	that we're using to get
0:21:13	So, there's basically two possible paths.
0:21:17	or route it out to 5.
0:21:20	Then, they're gonna go
0:21:25	Now, just looking at the topology here,
0:21:28	it's probably more likely that router 3
0:21:34	to get to router 6.
0:21:37	Simply based on the number of hops
0:21:41	Because when we look
0:21:44	these serial interfaces for the frame-relay,
0:21:48	these are gonna have the
0:21:52	1544 kilobits per second.
0:21:55	So, this is gonna be the
0:21:58	If we compare this to the Fast Ethernet
0:22:04	the Ethernet's bandwidth is not even gonna be
0:22:09	If we were to raise the
0:22:14	that woud affect the EIGRP path selection.
0:22:17	But then, we need to take into account,
0:22:23	So, this means, if router 2
0:22:26	from 1544 to a 100,000,
0:22:32	but if router 5 is routing out this
0:22:37	it would still mean the lowest
0:22:42	So technically, we can
0:22:45	but a lot of the times, it's
0:22:49	So, when we change the
0:22:51	we're gonna be using the delay
0:22:55	So first, let's look at what router 2's
0:23:00	to these destinations.
0:23:02	First, let's make sure, are we
0:23:04	So, let's say Show IP EIGRP Neighbors.
0:23:09	and Show IP Route EIGRP.
0:23:14	So, we see, we have the adjacencies
0:23:18	We have a mix of routes
0:23:21	Some of them are going to router 5,
0:23:25	So, I wanna know, how am I
0:23:29	We could see it says,
0:23:33	on the point-to-point serial link.
0:23:36	It says, "The total composite
0:23:41	Then administrative distance of
0:23:48	So now, let's look at what are the
0:23:52	of this path to router 6.
0:23:54	And why are we choosing this route
0:23:57	over the potential alternate path
0:24:02	So, we'll say Show IP EIGRP Topology.
0:24:05	For the exact prefix, 150.10.6.0/24.
0:24:15	It says, "For this path,
0:24:17	there are..."
0:24:18	"Or for this prefix, there are two possible paths.
0:24:21	One of them is being learned from router 3, one
0:24:27	There is one successor, which means that only one
0:24:34	The actual metric of the successor,
0:24:42	Now, if we look at what router 5
0:24:48	router 3 is saying that its cost
0:24:52	is a 156,000.
0:24:55	Where router 5's cost to
0:25:00	We then take whatever our
0:25:05	add those together, and we're gonna get...
0:25:09	the total...
0:25:11	composite metric.
0:25:13	So, now, we're looking at a value
0:25:18	So, the top one is lower, that's what
0:25:23	Which means that this route is the successor.
0:25:26	Now, the actual values that
0:25:29	are based on a minimum bandwidth
0:25:32	of 1,544 kilobits per second.
0:25:37	And a total delay of 25,110 microseconds
0:25:48	But remember, with the actual calculation,
0:25:50	it doesn't use these values directly.
0:25:53	Okay, it takes the...
0:25:57	the inverse lowest bandwidth along the path.
0:26:01	Multiplies it by 10 to the 7 times 256.
0:26:07	Then it takes the delay in tens
0:26:16	So, if we were to take these values
0:26:22	and put them into this formula,
0:26:23	we'll see it matches up with the
0:26:28	The problem is just by looking
0:26:31	it's not really obvious as to
0:26:36	So, the next thing I'm gonna do here,
0:26:37	is change the metric weightings
0:26:41	to remove the bandwidth,
0:26:45	the load or the reliability from
0:26:51	Now, as I mentioned before,
0:26:54	the defaults for these are k1 is 1,
0:27:04	Which essentially means that default
0:27:09	If I were to weight k5, then it would
0:27:16	was also part of the calculation.
0:27:20	If I were to weight k2, it means that
0:27:27	would also be part of the calculation.
0:27:31	Most of the time, thses values
0:27:34	Because athey change based on
0:27:39	So, when we look at the output here
0:27:42	we'll see that the load value and the
0:27:47	Depending on what are the
0:27:50	So, how much traffic is actually
0:27:55	And what is the packet loss
0:28:01	So, this means that if we were
0:28:05	EIGRP is constantly gonna
0:28:09	because these are effectively real time
0:28:16	So, we looked at before the load
0:28:20	That's what's determining what
0:28:25	So, if I were to go to router
0:28:30	and say the load interval is 30 seconds,
0:28:35	then on router 3, i'll send a bunch
0:28:51	Which goes that way? Why would
0:28:56	Show IP EIGRP Neighbors.
0:29:03	We'll,let's do this. Let's send traffic to just
0:29:10	So, i'll set a high repeat count.
0:29:13	A timeout of 0 and a size of 15,000 bytes.
0:29:18	So, router 3's gonna be sending
0:29:21	If we look at router 2 now, and say
0:29:28	if we look at these load values,
0:29:33	so, let's say Show Interface Include the Load,
0:29:42	So, they're now a 30 second average of how much
0:29:48	This means that if EIGRP was
0:29:52	it's gonna have to recalculate
0:29:57	So, the original logic behind it, was that EIGRP
0:30:03	that would tell the nodes about
0:30:07	The problem is it's not very scaleable.
0:30:10	So, by default, the load and the reliability,
0:30:15	So, what I'm gonna do now is to tell
0:30:20	So, this is gonna remove the
0:30:23	It will make a little bit easy for us to see why are
0:30:28	So, under the routing
0:30:32	we'll say the Metric Weights
0:30:38	k1 would be the bandwidth.
0:30:41	k2 would be the load value.
0:30:47	So, k2 times the bandwidth
0:30:51	k3 is gonna be the delay.
0:30:56	And then k4 and 5 will be the
0:31:02	Now, you don't need to memorize
0:31:05	What you do need to know though is where can
0:31:10	So, under EIGRP command reference,
0:31:15	This is where it shows us
0:31:21	And we can see the defaults
0:31:25	Now, once I change this, we can
0:31:28	It says that the neighbors are down
0:31:32	So, if I change it on one
0:31:34	I effectively need to change it everywhere.
0:31:38	So, I'll take these values I used on router 2,
0:31:46	So, under router EIGRP 1, the metric
0:31:52	k1 and 2 are 0, k3 is 1, which is the delay.
0:31:57	And then k4 and 5 are all 0.
0:32:05	So, once we change this, we'll see
0:32:10	If we look at now the topology,
0:32:14	for that particular route,
0:32:19	the route to router 6,
0:32:24	And it looks like router 3
0:32:28	Not because it's doing the pings.
0:32:31	Okay, so, under EIGRP 1,
0:32:43	Okay, now the adjacencies are up.
0:32:44	So, now, from router 2's perspective,
0:32:48	we should still see these two routes.
0:32:53	One of them is from router 3,
0:32:57	But we could see from the metric
0:33:02	So, it says now, the total
0:33:07	Which is the metric being
0:33:12	Okay, actually, the metric learned
0:33:15	The total metric is 642.
0:33:19	Whereas we compare this to the total
0:33:25	And what router 5 is advertising
0:33:31	Now, if we compare what
0:33:37	versus what router 3 is the total metric,
0:33:42	notice that the advertised
0:33:48	is less than our feasible distance.
0:33:54	So, what just this now mean
0:33:59	It means that this is a feasible successor.
0:34:04	So, if I were to shutdown the link
0:34:09	and do some pings from router 2 to router 6,
0:34:13	we should see that even with
0:34:17	the convergence is gonna be very fast.
0:34:20	So, on router 2, if I ping, 150.10.6.6
0:34:26	and let's say the timeout is 1 second.
0:34:31	Then I go to router 3 and on serial 0/1,
0:34:36	Actually, it's serial 1/3.
0:34:50	Now, depending on what router 6's
0:34:58	you can see that there were 3 dots, 1 2 3.
0:35:02	So, it means it takes about 3
0:35:06	Which is pretty good considering that we
0:35:11	So, as long as the feasibility condition is met,
0:35:14	then the convergence should
0:35:22	Okay, so let's bring this interface back up.
0:35:25	Okay, next thing we're gonna look at is what
0:35:29	So, I know which way I'm routing now.
0:35:31	I'm routing through router 3 to get to 6.
0:35:37	But let's say that I don't want to do that.
0:35:40	I wanna change the path selection
0:35:43	so that 2 goes to 5, 5 goes to 4,
0:35:52	In order to do this, I'm gonna have to
0:35:56	Because if router 4 is not using
0:36:02	it means that it's not gonna
0:36:08	So remember, in EIGRP, you can only
0:36:14	But if it's not installed in the routing
0:36:19	So, let's look at rotuer 4.
0:36:22	On router 4, we'll say,
0:36:25	How do we get to 150.10.6.0/24?
0:36:33	It says, "The feasible distance is a 130,000"
0:36:41	Simply based on the fact that the delay
0:36:46	than the total delay on the
0:36:50	Okay, so router 4 is routing
0:36:53	If I trace...
0:36:56	150.10.6.6, we're going
0:37:02	Okay, now, I'm gonna see
0:37:04	So, if we Show IP EIGRP Topology,
0:37:07	150.10.6.0/24...
0:37:14	Router 5 says, "The feasible
0:37:22	which is equally coming
0:37:29	But not 2 or 3.
0:37:35	So, I am routing through both
0:37:43	Which is not what I want.
0:37:44	I wanna route to that point-to-point
0:37:48	And let's make sure that the
0:37:50	Let's Show IP EIGRP Neighbors.
0:37:55	And it's not. I think I may have
0:38:00	So, let's bring this back up.
0:38:10	So, let's check the topology again.
0:38:19	And now, we actually have
0:38:23	to get there.
0:38:26	Form router 1, from router 4, twice.
0:38:31	On the frame-relay and on
0:38:34	So, if we look at the result on
0:38:38	and we Show IP Route 150.10.6.6,
0:38:42	we see that there's actually
0:38:46	So, depending now on what are
0:38:51	so whether we do a Fast Swtiching or
0:38:54	that's gonna control how do we actually
0:39:00	But in my case, that's
0:39:02	I wann use only this top link.
0:39:06	So, essentially, I have two options now.
0:39:08	I can either lower the delay of the
0:39:14	Or I can raise the delay
0:39:17	Both of them are essentially
0:39:21	In either case, if I look at the
0:39:29	it says, "The delay value is
0:39:36	This means that the actual command that
0:39:41	is a delay of 2000 tens of microseconds.
0:39:48	So, that's the default on
0:39:51	But let's say this is gonna be higher.
0:39:55	40,000 microseconds,
0:39:58	which is 4000 tens of microseconds.
0:40:02	If I now clear the EIGRP neighbors,
0:40:06	this is gonna cost us to
0:40:10	based on the new delay value.
0:40:13	If I know look at the routing table,
0:40:17	now, I'm only routing through the
0:40:23	Based on the fact when we
0:40:28	now, the total cost to go through either
0:40:36	is higher than the
0:40:44	So, changing the delay here is essentially just
0:40:51	Because the delay is cummulative
0:40:54	If I were to change the minimum bandwidth,
0:40:58	that's a little more complicated because
0:41:02	that every single link that
0:41:08	So, now, let's see how did this affect to
0:41:12	Let's do another trace.
0:41:15	Okay, we still didn't change our path selection.
0:41:17	So, now, let's look at the Show IP
0:41:27	it says, "I have still have two paths."
0:41:30	The one from router 5 has 11.5 or
0:41:36	1.1 million.
0:41:38	Where the path from
0:41:44	We can see the reason why that they're different
0:41:52	So, now, If I were to go to the
0:41:58	And set the delay much higher,
0:42:04	when we clear IP EIGRP Neighbors,
0:42:18	we see that now, the total
0:42:22	is higher than it is through router 5.
0:42:30	So, it's essentailly just like changing the OSPF cost
0:42:35	But the issue you need to take into account
0:42:38	is that to begin with, you only
0:42:43	So, if I'm trying to change my path
0:42:47	it means I would need to look
0:42:51	to make sure they are routing
0:42:54	Because if rotuer 5 is routing
0:43:01	then there's no way a change in router 2
0:43:06	There's a question here, "If we have
0:43:09	or router 1 frame-relay link from
0:43:13	since there's only one single interface
0:43:16	how do we change the cost?"
0:43:18	There's actually no way we can do that.
0:43:22	So, the issue was here.
0:43:24	Let's say we want the traffic to go...
0:43:30	from 2 to 5, to 5 to 1
0:43:37	To 1 to 6.
0:43:39	The issue is that when router 5 looks
0:43:46	the delay and the minimum bandwidth
0:43:48	whether we're going to routers 1 or 4.
0:43:56	So, there's no change on router 5
0:44:01	Now, I could get that to work
0:44:04	but what would I have to change
0:44:10	So, let's see currently, what is
0:44:14	We should see that it goes
0:44:18	Which it does.
0:44:21	If I now want to change it that it
0:44:28	what do I need to make
0:44:31	From router 5's perspective,
0:44:39	is gonna be the same regardless of
0:44:46	So, what I would need to change then
0:44:52	that they are sending to 5.
0:44:55	If router 4's advertised
0:45:00	then router 5 should prefer
0:45:03	versus the path through router 4.
0:45:09	The way we could do this
0:45:12	and set the delay on this
0:45:16	On Fast Ethernet 0/1.
0:45:18	So, let's go to router 4 and
0:45:24	our link to router 6, which
0:45:29	the delay is some high value.
0:45:33	If we clear IP EIGRP Neighbors,
0:45:38	it's gonna cost everyone to recalculate.
0:45:40	If we now look at router 5, and look at
0:45:51	it says, "Now, I have the
0:45:55	And I have the path through router 3."
0:45:58	The one through router 1 is lower.
0:46:02	So, 11545 versus 11548.
0:46:09	Once we're totally converged here,
0:46:15	it says the feasible distance is
0:46:20	I need to either...
0:46:24	Let's say Clear IP Route on router 5.
0:46:30	Or I need to clear the neighbors.
0:46:32	Let's say Clear IP EIGRP Neighbors.
0:46:45	So, now, it has the new value installed.
0:46:49	Now, notice that I don't even have
0:46:55	What this implies is that router 4
0:47:00	is going this way to reach the path.
0:47:04	So, router 4 cannot advertise
0:47:09	which is via Fast Ethernet 0/1 to router 5
0:47:12	because it's not the one being
0:47:17	If we look at the final result to this
0:47:21	now, the trace should go
0:47:25	Which it does.

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CCIE R&S Advanced Technologies Class v4.5
Title:	CCIE R&S Advanced Technologies Class v4.5
Duration:	81h 42m
The CCIE Routing & Switching Advanced Technologies Class is the first step in understanding CCIE level technologies and is a companion to the Advanced Technologies Lab Workbook. Each technology you need to know for the CCIE Routing & Switching lab will be described in detail using an instructor led hands on demonstration. The class consists of over 80 hours of in depth explanations and examples.
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