CCIE Routing & Switching Advanced Technologies Class - IPv6 Routing Overview, IPv6 Static Routing

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 34m
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 59m

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

0:00:13	So next, we're going to talk about the different IPv6
0:00:16	routing protocols.
0:00:19	We'll see that IPv6 does support routing basically
0:00:22	through all the different variations in the current
0:00:25	IOS versions so we could do static routing, RIPng
0:00:29	is the equivalent of RIPv2, EIGRPv6 is the equivalent of
0:00:33	regular EIGRP
0:00:34	OSPFv3 is the equivalent of OSPFv2
0:00:38	IS-to-IS and multiprotocol BGP
0:00:41	use the same protocol for both the IPv4 and the IPv6
0:00:47	address family.
0:00:50	So in the case of IS-to-IS, it's simply a type length value
0:00:53	extension in order to do IPv6 routing.
0:00:58	For multiprotocol BGP, it's simply a new AFI
0:01:02	and SAFI, the Address Family Identifier and the Sub Address Family Identifier
0:01:09	where in the case of IPv4 unicast routing, we use
0:01:12	AFI 1 and SAFI 1
0:01:15	IPv6 unicast routing is AFI 2
0:01:19	and sub address family identifier 1
0:01:21	so 11 for IPv4 unicast 21 for IPv6 unicast
0:01:30	then we also have policy routing basically the same logic as we have for
0:01:33	IPv4 where we can match a criteria based on an access list
0:01:39	in a route map
0:01:41	and then set either the outgoing interface or the connected next hop
0:01:45	that we want to route traffic to as the packets
0:01:48	come in on that particular link.
0:01:53	So we're not going to get into a lot of detail with the
0:01:55	static routing and the policy routing, it's the same logic as
0:01:58	we already talked about in regular IPv4 routing.
0:02:01	For the dynamic protocols I am going to show examples
0:02:04	of all of these today though.
0:02:08	Now one of the important points to note about the dynamic
0:02:11	protocols with IPv6 is that the routing information
0:02:15	as it is learned inbound
0:02:19	recurses to the remote link local address
0:02:22	of the neighbor
0:02:24	as opposed to their global unicast address.
0:02:28	Now again, the link local address is only locally significant
0:02:31	between any of the neighbors on that particular segment.
0:02:36	So in the case of an Ethernet LAN whoever is in that VLAN
0:02:40	is going to have significance for those particular link local addresses.
0:02:44	For a point-to-point link like PPP or HDLC
0:02:47	it's just going to be significant between the two neighbors on the segment.
0:02:55	For any point-to-point or broadcast configuration
0:02:59	so again, either Ethernet or PPP, HDLC
0:03:03	we really don't care about the link local addressing
0:03:06	because either ICMP neighbor discovery is going to
0:03:08	take care of the resolution for us or with point-to-point we don't
0:03:12	need the resolution. The exception is going to be when we run this
0:03:16	over multipoint non-broadcast not only will we need a resolution
0:03:21	for the remote global unicast address, but also for the remote
0:03:26	link local address.
0:03:34	Now the reason that the IOS does this is that with
0:03:37	IPv6, you can have designs where you don't use
0:03:41	global unicast addresses on the transit links
0:03:44	and you only assign the global addresses down to your actual
0:03:48	end hosts.
0:03:51	Now the main reason to do this is for security of the network
0:03:54	because from the service provider's point of view
0:03:57	there should be no reason that people are sending traffic
0:04:00	actually to the frame relay link itself
0:04:03	or sending traffic to the point-to-point link between
0:04:06	Router 1 and Router 3
0:04:09	so when IPv6 traffic goes into the network, usually
0:04:12	it should be coming from a host on the LAN
0:04:15	going to a host on the LAN
0:04:18	so this means that we would have a global unicast address on
0:04:21	Switch 3's VLAN 9 interface, a global unicast address
0:04:25	on Router 5's Fast Ethernet 0/1 interface
0:04:30	but then the transit links between them we really only
0:04:33	care about the locally significant communication between the two
0:04:37	routers that are on that particular segment.
0:04:40	So if Switch 3 and Switch 1 are running RIPng
0:04:45	the only people that really care about that are Switch 1 and
0:04:48	Switch 3 on that particular segment.
0:04:53	So when you're configuring this on the routers, you technically
0:04:56	do not have to use global unicast addresses at all
0:04:59	you could route the entire network on just link local addresses
0:05:04	but then the potential problem you have with that is it makes
0:05:07	management a little bit more difficult to the router
0:05:10	like you wouldn't be able to telnet to the router
0:05:13	because none of the link local addresses can be routed
0:05:16	between the interfaces.
0:05:19	So in a lot of designs, what people do is have a loopback
0:05:24	that's on the router that either is a global unicast address that's
0:05:28	globally routable or something that's just a unique local address
0:05:33	this would be used for in-band management
0:05:36	like SSHing to the router or doing SNMP polling
0:05:43	but then any of the routing communication over the LAN
0:05:46	or over the point-to-point segments, that would just use the link
0:05:49	local addresses.
0:05:53	So first let's take a look at static routing with IPv6
0:05:57	where mainly there are three variations of this
0:05:59	just like there were in IPv4
0:06:02	where we can use a static route that points to a next
0:06:06	hop value or that points to an interface.
0:06:11	Now the difference between them depends on whether
0:06:13	the interface is multipoint or point-to-point.
0:06:16	If we're routing to a point-to-point interface, then we don't really
0:06:20	care because there's no Layer 3 to Layer 2 resolution
0:06:23	that's required.
0:06:26	Any time we are routing to a multipoint interface
0:06:30	if the static route points directly to the link
0:06:33	it means that we would need to resolve the Layer 2
0:06:35	address of the final destination, not the intermediary next hop
0:06:42	so in the case of IPv6, it almost never makes sense to
0:06:45	point a static route towards a multipoint interface.
0:06:48	We'll see one of the issues that is inherent to this
0:06:52	is the lack of proxy neighbor discovery or proxy inverse
0:06:57	neighbor discovery that is replacing the proxy ARP feature of
0:07:01	IPv4
0:07:06	Now technically there is an RFC that specifies how
0:07:09	proxy neighbor discovery is supposed to work
0:07:11	but as far as I know, Cisco IOS does not implement that.
0:07:15	It's kind of a security issue most of the time in the real world
0:07:18	you should disable regular proxy ARP for IPv4
0:07:22	the same would be true for IPv6
0:07:29	Now any time we are routing to a next hop value
0:07:33	regardless of whether this is on a multipoint non-broadcast
0:07:37	interface or a multipoint broadcast interface, it
0:07:40	means that we're going to do the Layer 2 resolution for the next hop value
0:07:43	itself, not for the final destination
0:07:47	which is typically what we would want to do if we were pointing a
0:07:50	static route at a multipoint interface
0:07:52	we would want to route to the next hop, not directly
0:07:55	to the interface itself.
0:08:07	So let's take a look at this in our particular topology
0:08:10	I'm going to add some additional addresses here
0:08:12	where we will enable IPv6 on Router 6
0:08:17	on the LAN segment between Switch 1 and Router 6
0:08:22	we already have it configured on the link between Router 1
0:08:25	and Router 5, then we'll also put it on Router 5's
0:08:30	Ethernet segment.
0:08:32	Now for some of the switch platforms, you'll see that
0:08:36	by default the memory is not allocated
0:08:40	to store any buffer space for the IPv6 routing table.
0:08:45	So in the case of the 3560 if I go to global config and
0:08:48	say IPv6 unicast routing
0:08:51	it looks like the platform doesn't support this command
0:08:54	when in reality what I need to do first is change the
0:08:57	buffer allocation of the switch database manager
0:09:01	or the SDM template.
0:09:08	To do this I'm going to say sdm prefer
0:09:11	and I want to run both IPv4 and IPv6 unicast routing.
0:09:15	So sdm prefer dual ipv6
0:09:18	dual ipv4 ipv6 routing
0:09:20	the problem with this now though is that I need to
0:09:23	save and reload.
0:09:25	So within the scope of the lab exam if you know that
0:09:27	you need to run IPv6 on that particular device
0:09:30	you may want to just change the template, reload and then
0:09:33	move on to something else and come back later.
0:09:39	So I'm going to do this on Switch 1 and Switch 2
0:09:45	so on Switch 2 I'll change the SDM template and then
0:09:49	save and reload.
0:09:59	In the meantime while we're waiting for this to come back, let's go to
0:10:01	Router 6
0:10:04	we'll turn IPv6 unicast routing on.
0:10:11	Router 6 is going to be in the same subnet that Router 1 is
0:10:19	this is on Fast Ethernet 0/0.146
0:10:24	so its address is going to end in a 6
0:10:27	On the link to Switch 1
0:10:31	this will be 2001:155:28:67::6
0:10:45	then I'll also add a loopback interface on Router 6, so
0:10:48	interface loopback 0
0:10:51	ipv6 address I'll make this a 128 that would be a host
0:10:54	route, let's say 155:28:6::6/128
0:11:03	so 128 here this is equivalent of the /32 host route
0:11:07	in IP version 4
0:11:18	so next let's take a look at Router 1
0:11:21	and look at the different variations of configuring the static routes
0:11:24	whether we're pointing towards the interface pointing towards the
0:11:28	next hop and then when we're pointing at the interface with the
0:11:31	differences between the point-to-point and the
0:11:33	multipoint config.
0:11:38	And before I do this, on Router 5 I need to add
0:11:41	that additional segment, so let's say on Fast Ethernet 0/1
0:11:52	this will have the ipv6 address
0:11:55	2001:155:28:5::5/64
0:12:07	so on Router 1 we'll look at a couple different variations of the static routes.
0:12:12	The first one is simply going to be routing towards the next
0:12:15	hop value.
0:12:17	So if Router 1 were to say to get to the destination
0:12:21	that is Router 6's loopback
0:12:24	so that exact host route
0:12:29	I'm going to route towards the next hop of Router 6
0:12:35	What this essentially means is that when Router 1
0:12:38	sends traffic to the final destination,
0:12:41	it's going to look for the Layer 2 address
0:12:44	of the next hop.
0:12:54	Now since the next hop is directly connected on the LAN
0:12:57	it means that if Router 1 looks at the show ipv6 neighbors
0:13:01	which is the equivalent of the show arp
0:13:04	Router 1 should already know what is the Mac address
0:13:06	that is associated with Router 6
0:13:09	So based on the fact that we know the Mac address of the
0:13:12	next hop, we're going to infer that that is the Layer 2 address
0:13:16	we should use to reach the loopback of Router 6
0:13:26	Now if we were to change this route and point it
0:13:29	directly out the interface
0:13:32	the problem that we're going to run into is that the router
0:13:35	does not run proxy neighbor discovery.
0:13:38	So if I were now to ping
0:13:44	ping 2001:155:28:6::6
0:13:48	I have the debug ipv6 packet on
0:13:52	we should see that Router 1 is going to try to send the
0:13:56	resolution request
0:13:58	for this particular neighbor
0:14:02	but it doesn't know what the Mac address is.
0:14:06	It says encapsulation failed, resolving the next hop
0:14:10	on the interface, so the key is that this message here means
0:14:13	that we're trying to do a Layer 3 to Layer 2 resolution
0:14:16	not for the intermediary next hop value, but for the final
0:14:21	destination.
0:14:28	Now for IP version 4, this is usually not a problem
0:14:32	because if the router receives an arp request for something it
0:14:35	already has a route for in the routing table
0:14:39	it will reply with its own Mac address in proxy
0:14:43	and that's what proxy arp does for IPv4
0:14:46	so if I were to go to Router 6
0:14:49	and say that I had the IPv4 address 6.6.6.6/32
0:14:58	then on Router 1 I said to get to the address 6.6.6.6/32
0:15:06	I'm going to go directly out Fast Ethernet 0/0
0:15:11	basically what this means is that Router 1 is going to send an
0:15:14	arp request and Router 6 is going to reply with its own
0:15:18	Mac address in proxy.
0:15:26	However, with IP version 6, this is not supported in the IOS
0:15:29	so Router 1 does not know what is the Mac address that should
0:15:33	be associated with this final destination.
0:15:42	So essentially there's two solutions to this problem
0:15:45	the first and easiest one would just be not to point the route
0:15:48	out the interface.
0:15:50	If the route pointed to the next hop, then it's going to
0:15:52	solve the problem to begin with.
0:15:55	But if we did not want to change the static route here
0:15:58	if on Router 1 we said show run include route
0:16:05	what kind of workaround could do we do in order for Router 1
0:16:08	to get connectivity
0:16:10	to this address?
0:16:22	We could basically do the equivalent of a static arp entry
0:16:27	so if we told Router 1 what is the Mac address
0:16:30	of that particular IPv6 destination
0:16:34	if we say the IPv6 neighbor
0:16:37	with this IPv6 address
0:16:39	is out Fast Ethernet 0/0
0:16:43	and it has this Mac address
0:16:48	this is essentially a static ICMP neighbor discovery mapping
0:16:53	so now Router 1 should be able to reach that destination
0:16:59	so the key point here is that it's not really a routing problem per se
0:17:03	it's a problem with the Layer 3 to Layer 2 resolution
0:17:07	that ultimately controls the encapsulation.
0:17:10	So if the Router doesn't know what Mac address to use or what DLCI
0:17:14	to use on the frame relay, it's not going to be able to build the
0:17:16	Layer 2 frame.
0:17:25	Now the same would be true over the frame relay network.
0:17:28	On Router 1 if I were to say to get to
0:17:30	2001:155:28:5:5
0:17:37	I would want to use the next hop value of Router 5
0:17:45	so we'll say /64
0:17:50	Now if I send packets to this particular destination
0:17:54	since I already have a resolution for the next hop
0:17:58	I'm able to reach that.
0:18:01	Now additionally, Router 1 has a point-to-point sub interface here
0:18:08	that is configured for the frame relay
0:18:10	this means that I could change the route so that it points directly
0:18:15	at the point-to-point interface and it's not going to negatively
0:18:20	affect the connectivity because Router 1 already knows what is the
0:18:25	DLCI number that is supposed to be used for that link.
0:18:38	Now on the way back from Router 5's perspective, it's going to
0:18:41	be different because Router 5 is using the multipoint frame relay
0:18:46	interface, if we show run interface serial 0/0/0
0:18:53	since this is a multipoint NBMA interface, Router 5 had to do
0:18:56	the static Layer 3 to Layer 2 resolution.
0:19:00	If I were now to say to get to the destination 2001:155:28:146/64
0:19:14	so this is the segment between routers 1, 4 and 6
0:19:19	I want to use the next hop of Router 1
0:19:24	then this should be fine because we already know that that
0:19:29	next hop value is reachable via circuit number 501
0:19:40	Now the problem would come in here if I were to change the route
0:19:44	and say that instead of routing towards the next hop value
0:19:50	we're going to route directly to the interface.
0:19:52	We're routing directly at serial 0/0/0
0:19:56	If we look at the debug frame relay packets
0:20:04	then we ping
0:20:10	the address of Router 1
0:20:21	we see that Router 5 says encapsulation is failing
0:20:24	because it doesn't have a mapping for that particular destination.
0:20:34	So again, just like on Router 1 we basically have two solutions here.
0:20:38	We could either fix the route which would be really the easiest
0:20:42	way to do this is just to change the route so that it points
0:20:45	at the next hop value and not the interface
0:20:50	or we could do what as a workaround?
0:20:59	So what is the problem that Router 5 is having in the first place?
0:21:05	It knows the route to the destination, but it doesn't know what?
0:21:15	It knows what interface to use, but it doesn't know what
0:21:18	DLCI to use, so if we were to go to the frame relay interface
0:21:22	and say to get to the final destination, if we said
0:21:26	frame relay map ipv6
0:21:28	then put the address that we're actually trying to send the traffic to
0:21:35	and tell it that this is reachable out circuit 501
0:21:41	we're basically manually binding what particular Layer 2 address
0:21:46	is supposed to go inside of that packet.
0:21:50	The problem then would be if we were to try to send traffic to
0:21:52	any other destination on that LAN, Router 5 is not going to
0:21:57	know how to resolve that.
0:22:05	So it's kind of like a stupid router trick, you could get it to do this
0:22:09	but there's really no design reason that you would want to.
0:22:12	So instead, the static route for a multipoint interface
0:22:16	it should always point at the next hop value.
0:22:19	If the interface is point-to-point like a point-to-point GRE tunnel
0:22:23	or an IPv6 IP tunnel, an automatic 6 to 4 tunnel
0:22:27	that's fine with pointing the route at the interface
0:22:31	but any time it's multipoint so an Ethernet or a multipoint
0:22:34	frame relay interface, the route should always point at the next
0:22:37	hop value.
0:22:47	Now there's a question here, "What about the link local address?"
0:22:51	Technically they could also point at the remote link local address.
0:22:56	When we do that, we would need to tell the router what
0:22:58	interface to recurse to
0:23:00	because by default, it doesn't know where the link local address
0:23:04	is reachable because we could have the same address let's say
0:23:08	FE80::1 we could have that same address assigned to multiple
0:23:13	links on the same local router.
0:23:21	So let's see on Router -- Switch 1
0:23:24	if it came back and we're running
0:23:27	let's look at the show sdm prefer
0:23:42	so it says now we're running the desktop IPv4 and IPv6
0:23:45	routing template which basically means that we have buffer space that's
0:23:49	allocated both for IPv6 routes and IPv4 routes.
0:23:55	So next let's enable IPv6 between Router 6 and Switch 1
0:23:59	but I'm not going to do this with a global address.
0:24:03	I'm simply going to go to the interface VLAN 67
0:24:07	and say ipv6 enable
0:24:12	what this command does is to turn the protocol on the interface
0:24:16	but not to assign a global unicast address.
0:24:20	This is telling the router just to generate the link local address.
0:24:27	Now if we were to look at the show ipv6 neighbors
0:24:33	from Switch 1 we would basically need to know what is the link
0:24:36	local address of Router 6
0:24:40	Now I could just go to Router 6 and say show ipv6 neighbors and
0:24:45	look at what the Mac address is. I might also be able to
0:24:48	get this if we send packets to FF02::1 which is the all hosts
0:24:56	multicast
0:24:58	this is the equivalent of the all 255 address in IPv4
0:25:08	so basically what this is telling me here if we look at the show ipv6 neighbors
0:25:13	this should now be the link local address of Router 6
0:25:20	On Router 6 if we look at the show ipv6 route local
0:25:26	this tells me what are the local addresses that I have
0:25:29	assigned on my interfaces, we see the loopback 0 is
0:25:33	2001:155:28::6/128
0:25:41	Now on Switch 1 let's turn routing on, so ipv6 unicast routing
0:25:48	then I'll say to get to this particular destination
0:25:53	I'm going to simply use the link local destination.
0:25:59	The problem is now the router also needs to know what is the outgoing interface
0:26:04	because that link local address it could be on
0:26:06	multiple possible links.
0:26:09	So this needs to be on VLAN 67
0:26:13	Now if I were to send traffic to this destination
0:26:20	we can see I can reach that address even though I don't
0:26:22	have a global unicast address assigned to my local interface.
0:26:35	If I were to telnet to that address on Router 6
0:26:38	let's say on Router 6 line console or line vty 0 4
0:26:44	no login
0:26:48	Switch 1 should be able to
0:26:56	telnet to that, I may need to source this from
0:27:02	a global unicast source.
0:27:06	So the key here is that in the normal design if you're
0:27:09	using only link local, it means you're using that segment
0:27:12	just as transit, so if there's an end host here and an end host
0:27:18	here, we could use global unicast addresses on those
0:27:22	end segments, but then use just link local addresses on the
0:27:26	transit links because no one is actually going to
0:27:30	send traffic to the VLAN 67 itself
0:27:33	or the VLAN 79
0:27:35	again, assuming that those are just transit interfaces
0:27:38	that they're not where any of the actual end hosts reside.
0:27:44	So again, the IPv6 static routing is the same exact
0:27:47	logic as IP version 4
0:27:49	you can either route to the next hop or you can route to the
0:27:51	interface, but the problem is if you route at a multipoint
0:27:54	interface, you're going to have Layer 3 to Layer 2 resolution problems.
0:27:58	So it's a general rule just only point the static route
0:28:01	to an interface if it's point-to-point to begin with
0:28:04	like a GRE tunnel or a PPP interface.

Now Viewing

CCIE Routing & Switching Advanced Technologies Class
Title:	CCIE Routing & Switching Advanced Technologies Class
Duration:	81h 59m
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.
Get instant access to our entire library!
$159/month	Add to Cart
Download this Course
$299.00	Add to Cart

IPv6 Routing Overview, IPv6 Static Routing

Create Bookmark