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CH16 Exam PrepDesign Review
Design Goal Possible Implementation Choices Covered in This Chapter
An IPv6 design suggests that all client hosts should
dynamically learn their IPv6 addresses. Which tools can be
used? (2)
Stateful DHCP and Stateless autoconfiguration
A plan shows the use of stateless Autoconfiguration. What
functions should we expect the IPv6 DHCP server to
perform?
DNSv6 Server Addresses
Notable Questions from This Chapter to Consider During an Implementation Plan Peer Review
Question Answers
An implementation plan states that router IPv6 address
should be assigned as obvious values, using the lowest
numbers in the range per each assigned prefix. What
configuration methods could be used to configure these
low address values?
Static Ipv6 configuration, or Static EUI-64 configuration
and configuring the router interface MAC to be a simple
low address.
A plan calls for the use of stateless autoconfig for client
hosts. What must be configured on the routers to support
this process?
Ipv6 unicast routingand an ipv6 unicast address
configuring on the interface attached to the LAN where
the hosts reside.
Implementation Plan Configuration Memory Drill
Feature Configuration Commands / Notes
Configure the full global unicast address on an interface. Ipv6 address interface-id/length
Configure the unicast IPv6 prefix on an interface, and let
the router add the interface ID.
Ipv6 addressprefix/length eui-64
Configure an interface to find its unicast IPv6 address usingstateless autoconfig.
Ipv6 address autoconfig
Configure an interface to enable IPv6 and use another
interfaces IPv6 address as needed.
Ipv6 address unnumbered interface
Enable IPv6 on an interface and do not configure a unicast
IPv6 address.
Ipv6 enable
Configure the link local address of an interface. Ipv6 address interface-id/length link-local
Verification Plan Memory Drill
Information Needed Commands
All IPv6 routes Show ipv6 route
A single line per IPv6 address Show ipv6 int brief
Detailed information about IPv6 on an interface, including
multicast addresses
Show ipv6 int interface
The MAC address used by an interface Show int interface
The MAC addresses of neighboring IPv6 hosts Show ipv6 neighbors
The information learned from another router in an RA
message
Show ipv6 router
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Review all the Key TopicsKey Topics for CH16
Key Topic
Element
Description Page
Number
Figure 16-1 Conceptual view of IPv6 global routes 535
List Rules for abbreviating IPv6 addresses 536
List Rules about how to write IPv6 prefixes 538
Figure 16-3 IPv6 public prefix assignment concepts 540List IPv6 subnetting process 541
Figure 16-5 IPv6 subnetting concepts 542
List Three steps used by the stateless autoconfig feature 545
Figure 16-8 IPv6 address format when using EUI-64 548
Table 16-7 Comparisons of Stateful and Stateless DHCP 549
List IPv6 address types (unicast, multicast, and anycast) 550
Figure 16-10 Link local address format 552
Table 16-9 Address types and prefixes 552
Figure 16-11 NDP concepts 555
CH16 Memory TablesExample IPv6 Prefixes and Their Meanings
Term Assignment Example from Chapter 16
Registry prefix IANA to RIR 2000::/12
ISP prefix RIR to ISP 2000:1111::/32
Site prefix or global routing prefix ISP to Site 2000:1111:AAAA::48
Subnet prefix Site Engineer subnets 2000:1111:AAAA:1::/64
Although an RIR can assign a prefix to an ISP, an RIR may also assign a prefix to other internet registries, which might
subdivide and assign additional prefixes, until eventually an ISP and then their customers are assigned some unique
prefix.
Summary of IPv6 Address Assignment for Global Unicast Addresses
Method Dynamic or Static Prefix and length
learned from
Host learned
from
Default router
learned from
DNS addresses
learned from
Stateful DHCP Dynamic Stateful DHCPv6
Server
Stateful DHCPv6
Server
NDP Stateful DHCP
Stateless
autoconfig
Dynamic NDP EUI-64 NDP Stateless DHCP
static
configuration
Static Configuration Configuration NDP Sttateless DHCP
Static config with
EUI-64
Static Configuration EUI-64 NDP Stateless DHCP
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Details of the RS/RA Process
Message RS RA
Multicast destination FF02::2 FF02::1
Meaning of Multicast address All Routers on the local-link All Nodes on the local-link
Comparing Stateless and Stateful DHCPv6 ServicesFeature Stateful DHCP Stateless DHCP
Remembers IPv6 address (state
information) of clients that make
requests
Yes No
Assigns IPv6 address to client Yes No
Supplies useful information, such as
DNS server IP addresses
Yes Yes
Most useful in conjunction with
stateless autoconfiguration
No Yes
Common Link-Local Multicast Addresses
Type of Address Purpose Prefix Easily Seen Hex Prefix(es)
Global unicast Unicast packets sent
through the public Internet
2000::/3 2 or 3`
Unique local Unicast packets inside one
organization
FD00::/8 FD
Link local Packets sent in the local
subnet
FE80::/10 FE8, FE9, FEA, FEB
Site local Deprecated; originally
meant to be used like
private IPv4 addresses
FEC0::/10 FEC, FED, FEE, FEF
Unspecified An address used when a
host has no usable IPv6
address
::/128 N/A
Loopback Used for software testing,
like IPv4s 127.0.0.1
::1/128 N/A
IPv6 RFCs define the FE80::/10 prefix, which technically means that the first three hex digits could be FE8, FE9, FEA, or
FEB. However, bit positions 11-64 of link local addresses should be 0, so in practice, link local addresses should always
begin with FE80.
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Common Multicast Addresses
Purpose IPv6 Address IPv4 Equivalent
All IPv6 nodes on the link FF02::1 Broadcast
All IPv6 routers on the link FF02::2 N/A
OSPF messages FF02::5, FF02::6 224.0.0.5, 224.0.0.6
RIP-2 messages FF02::9 224.0.0.9
EIGRP messages FF02::A 224.0.0.10
DHCP relay agents (routers that
forward to the DHCP server)
FF02:1:2 N/A
DHCP servers (site scope) FF05::1:3 N/A
All NTP servers (site scope) FF05::101 N/A
Router IOS IPv6 Configuration Command Reference
Command Description
ipv6 address address/length Assign static ipv6 address
ipv6 addressprefix/length eui-64 Assign prefix/length and let router dervie the interface-id
using the link address (of the lowest numbered LANinterface if configuring a serial interface.)
ipv6 address autoconfig Configure a router interface for stateless
autoconfiguration
ipv6 address dhcp Configure a router interface to use stateful DHCP
ipv6 unnumbered interface-type number Configure a router interface to use the ipv6 address of the
interface stated in the configuration
ipv6 enable Enable ipv6 on a router interface, thereby telling the
router to create a link-local address
ipv6 address address link-local Statically configuring the link-local address on a router
interface.
ipv6 address address/length anycast Assinging an ipv6 address as anycast
Define Key TermsTerm Definition
Global Unicast Address Globally routable ipv6 address
Link Local Address FE80::/10, local link address used for link local communication, derived by EUI-64
Unique Local Address Ipv6 private addressing FD00::/8
Stateful DHCP Stateful DHCP is the same thing as Ipv4 DHCPkeeps track of all state information while
providing prefix/length/interfaceid/and DNS. NDP still provides default routers though.
Stateless DHCP Only provides DNSv6 server addressesStateless Autoconfig Dynamic address assignment, interface or host finds the prefix/length and default router
using NDP, while the interface-id is derived using EUI-64
Neighbor Discovery
Protocol (NDP)
NDP is the protocol responsible for DAD, RS, RA, NS, NA
Neighbor Solicitation (NS) Used like ARP
Neighbor Advertisement
(NA)
Used like ARP response
Router Solicitation (RS) Used to obtain prefix/length and default router information
Router Advertisement
(RA)
Used to respond to an RS with prefix/length and default router information
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Solicited Node Multicast
Address
FF02::1:FF00:0/104the last 24 bits are derived from the last 24 bits of every unicast
address assigned to the host or interface. For each unicast address this group is joined.
Duplicate Address
Detection (DAD)
Host or interface sends a NS to its solicited node multicast address. If it gets a response
then the unicast address is a duplicate.
Inverse Neighbor
Discovery
Used like InARP
CH17 Exam PrepNotable Questions from This Chapter to Consider During an Implementation Plan Peer Review
Question Answers
A RIPng implementation plan lists two neighbor routers
with unicast IPv6 addresses 2000::1/64 and 2001::2/64,
respectively. Will this cause a neighborship issue?
RIPng doest have any concept of neighbors, but the
routers will exchange routes just fine.
Same issues as in the previous row, but the plan uses
EIGRP for IPv6.
EIGRP neighbors do not have to share a common
prefix/length to become neighbors or exchange routes
A plan shows a planned config for a new router, with no
IPv4 addresses, IPv6 addresses on all interfaces, and EIGRP
for IPv6 configuration. What potential issues should you
look for in the configuration? (3)
Router ID
EIGRP process shutdown
Interface configuration`
Same scenario as the previous row, but with OSPFv3. Router ID
Interface configuration
OSPF starts up already, so no need to issue a no shut
The plan shows an EIGRP for IPv6 and OSPFv3 domain with
mutual redistribution. The configuration shows a
redistribute eigrp 1 command under the OSPF process.
What kinds of routes should be redistributed? Which
kinds will not?
All routes in the routing table will be redistributed that
have been leared via EIGRP. The following routes will not
be redistributed:
LC
C
Link Local
Implementation Plan Configuration Memory Drill
Feature Configuration Commands / Notes
Assuming IPv6 routing and IPv6 addresses have already
been configured, configure RIPng.
Ipv6 router ripprocess-name
Interface interface
Ipv6 ripprocess-name
Assuming IPv6 routing and IPv6 addresses have already
been configured and no IPv4 addresses exist on the router,
configure EIGRP for IPv6.
Ipv6 router eigrpasnEigrp router-idx.x.x.x
no shut
Interface interface
Ipv6 eigrp asn
Assuming IPv6 routing and IPv6 addresses have already
been configured and no IPv4 addresses exist on the router,
configure OSPFv3.
Ipv6 router ospf Process-id
Router-idx.x.x.x
Interface interface
Ipv6 ospfprocess-id area area
Configure RIPng to redistribute routes from OSPF process 1
including subnets, and connected interfaces.
Redistribute OSPF 1 include-connected
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Verification Plan Memory Drill
Information Needed Commands
All IPv6 routes show ipv6 route
Details about a given IPv6 prefix show ipv6 route address/prefix
All routes within a given IPv6 prefix Show ipv6 routeprefix/length longer-prefixes
All RIP-learned IPv6 routes Show ipv6 route rip
All next-hop IPv6 addresses used by RIP routes Show ipv6 rip next-hops
The interfaces on which RIP is enabled Show ipv6 protocols
All EIGRP-learned IPv6 routes Show ipv6 route eigrp
All EIGRP neighbors Show ipv6 eigrp neighbors
Summary of the EIGRP topology table Show ipv6 eigrp topology
OSPF router ID and SPF statistics Show ipv6 ospf
List of OSPF neighbors Show ipv6 ospf neighbor
All OSPF-learned IPv6 routes Show ipv6 route ospf
Interfaces enabled for OSPF and their assigned areas Show ipv6 ospf int brief
Show ipv6 protocols
OSPF costs per interface Show ipv6 ospf int brief
Show ipv6 ospf int interface
Summary of the OSPF database Show ipv6 ospf database
Review all the Key TopicsKey Topics for CH17
Key Topic
Element
Description Page
Number
Table 17-3 Comparisons between RIP-2 and RIPng 574
List Configuration steps for RIPng 575
Table 17-5 Comparisons between EIGRP for IPv4 and EIGRP for IPv6 581
List Configuration steps for EIGRP for IPv6 582
List Decision process for choosing an EIGRP for IPv6 router ID 583
Table 17-7 Comparisons between EIGRP for IPv4 and EIGRP for IPv6 588
List Additional explanations of key differences between OSPFv3 and OSPFv2 589
List Configuration steps for OSPFv3 590
List Similarities and differences with IPv4 and IPv6 redistribution 595
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CH17 Memory TablesComparing RIP-2 to RIPng
Feature RIP-2 RIPng
Advertises routes for Ipv4 Ipv6
RIP messages use these Layer 3 / 4 protocols Ipv4 / UDP Ipv6 / UDP
UDP Port 520 521Use Distance Vector Yes Yes
Default Administrative distance 120 120
Supports VLSM Yes Yes
Can perform automatic summarization Yes No
Uses Split Horizon Yes Yes
Uses Poison Reverse Yes Yes
30 second periodic full updates Yes Yes
Uses triggered updates Yes Yes
Uses Hop Count metric Yes Yes
Metric meaning infinity 16 16
Supports route tags Yes Yes
Multicast Update destination 224.0.0.9 FF02::9
Authentication RIP specific Ipv6 AH/ESP
Comparing Verification Commands: show ip and show ipv6
Function IPv4 IPv6
All routes show ip route Show ipv6 route
All RIP learned routes Show ip route rip Show ipv6 route rip
Details on the routes for a specific prefix Show ip route
prefix/length
Show ipv6 route
prefix/lengthInterfaces on which RIP is enabled Show ip protocols Show ipv6 protocols
List of routing information sources Show ip protocols Show ipv6 rip next-
hops
Debug that displays sent and received Updates Debug ip rip Debug ipv6 rip
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Comparing EIGRP for IPv4 and IPv6
Feature EIGRP for IPv4 EIGRP for IPv6
Advertises routes for Ipv4 Ipv6
Layer 3 protocol for EIGRP messages Ipv4 Ipv6
Layer 3 header protocol type 88 88
UDP Port N/A N/A
Uses Successor, Feasible Successor logic Yes Yes
Uses Dual Yes Yes
Supports VLSM Yes Yes
Can perform automatic summarization Yes N/A
Uses triggered updates Yes Yes
Uses composite metric, default using bandwidth and delay Yes Yes
Metric meaning infinity 2^32-1 2^32-1
Supports route tags Yes Yes
Multicast Update destination 224.0.0.10 FF02::A
Authentication EIGRP specific Ipv6 AH/EST
Comparing EIGRP Verification Commands: show ip and show ipv6Function show ip show ipv6
All routes Show ip route Show ipv6 route
All EIGRP learned routes Show ip route eigrp Show ipv6 route eigrp
Details on the routes for a specific prefix Show ip routeprefix/length Show ipv6 routeprefix-length
Interfaces on which EIGRP is enabled, plus
metric weights, variance, redistribution, max-
paths, admin distance
Show ip protocols Show ipv6 protocols
List of routing information sources Show ip protocols
Show ip eigrp neighbors
Show ipv6 eigrp neighbors
Hello interval Show ip eigrp interfaces detail Show ipv6 eigrp interfaces detail
EIGRP database Show ip eigrp topology [all-links]
Show ipv6 eigrp topology [all-links
Debug that displays sent and received Updates Debug ip eigrp notifications Debug ipv6 eigrp notifications
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Comparing OSPFv2 and OSPFv3
Feature OSPFv2 OSPFv3
Advertises routes for Ipv4 Ipv6
OSPF messages use this Layer 3 protocol Ipv4 Ipv6
IP Protocol Type 89 89
Uses Link State logic Yes Yes
Supports VLSM Yes Yes
Process to choose RID, compared to OSPFv2 Same Same
LSA flooding and aging compared to OSPFv2 Same Same
Area structure compared to OSPFv2 Same Same
Packet types and uses compared to OSPFv3 (Table 6-4) Same Same
LSA flooding and aging compared to OSPFv2 Same Same
RID based on highest up/up loopback IPv4 address, or highest other IPv4
interface address?
Same Same
32-bit LSID Yes Yes
Uses interface cost metric, derived from interface bandwidth Yes Yes
Metric meaning infinity 2^16-1 2^16-1
Supports route tags Yes Yes
Elects DR based on highest priority, then highest RID Yes Yes
Periodic reflooding every 30 minutes 30 minutes
MulticastAll SPF routers 224.0.0.5 FF02::5
MulticastAll designated routers 224.0.0.6 FF02::6
Authentication OSPF specific Ipv6 AH/ESP
Neighbor checks compared to OSPFv2 (table 5-5) Same Same except no
same subnet
check
Multiple instances per interface No Yes
Comparing OSPF Verification Commands: show ip and show ipv6
Function show ipv4 show ipv6
All OSPFlearned routes Show ip route ospf Show ipv6 route ospf
Router ID, Timers, ABR, SPF statistics Show ip ospf Show ipv6 ospf
List of routing information sources Show ip protocols
Show ip ospf neighbor
Show ipv6 ospf neighbor
Interfaces assigned to each area Show ip protocols
Show ip ospf int brief
Show ipv6 protocols
Show ipv6 ospf int brief
OSPF interfacescosts, state, area, number of
neighbors
Show ip ospf int brief Show ipv6 ospf int brief
Detailed information about OSPF interfaces Show ip ospf int interface Show ipv6 ospf int interface
Displays summary of OSPF database Show ip ospf database Show ipv6 ospf databaseDefine Key TermsTerm Definition
RIP Next Generation RIP for ipv6
OSPF Version 3 OSPF for ipv6
EIGRP for IPv6 EIGRP for ipv6
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CH18 Exam PrepDesign Review
Design Goal Possible Implementation Choices Covered in This Chapter
The design states that an Enterprise needs IPv6 support for
most LANs, with a regular high-volume of IPv6 traffic.
Would native IPv6, point-to-point tunnels, or multipoint
tunnels seem most appropriate?
Native ipv6
The design states that an Enterprise needs IPv6 support for
a set small subset of LANs but that their traffic will be
regular. Would native IPv6, point-to-point tunnels, or
multipoint tunnels seem most appropriate?
Point-to-point tunnels
The design states that an Enterprise needs IPv6 support for
a set small subset of LANs but that their traffic will be
irregular and occasional. Would native IPv6, point-to-point
tunnels, or multipoint tunnels seem most appropriate?
Multipoint tunnels
The plan calls for IPv6 tunneling so that new routers, when
added to the tunnel, do not require additional
configuration on existing routers. What type tunnel would
you choose, and what IPv6 address ranges?
6to4 tunneling using the range 2002::/16
Notable Questions from This Chapter to Consider During an Implementation Plan Peer Review
Question Answers
The plan calls for the use of OSPFv3 along with the
implementation of IPv6 tunnels. What tunnel types do you
expect to find the sample configurations? (2)
MCT
GRE
The planning diagrams show multipoint tunnels, with IPv6
addresses that embed an IPv4 address in the last two quartets.
What type of tunneling do you expect to see in the sample
configurations?
ISATAP
The plan lists a sample configuration with the command tunnel
mode ipv6ip under a tunnel interface. What type of tunneling is
used in this case?
MCT
Same question as the previous row, but the command listed as
tunnel mode ipv6ip isatap.
ISATAP
Same question as the previous row, but the command listed is
tunnel mode gre ip.
GRE
Same question as the previous row, but the command listed is
tunnel mode ipv6ip 6to4
6to4
A plan shows the use of a manually configured tunnel and an
ISATAP tunnel. What tunnel subcommand would you expect tosee for the point-to-point tunnel, but not the multipoint tunnel?
tunnel destination for the point-to-point MCT, but
not the multipoint tunnel.
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Implementation Plan Configuration Memory Drill
Feature Configuration Commands / Notes
Configure an IPv6 manually configured tunnel using a
loopback IPv4 address. Ignore IPv6 addressing and routing
configuration.
Int l1
Ip address x.x.x.x
Int tunnel0
Ipv6 address
Tunnel mode ipv6ip
Tunnel source l1
Tunnel destination y.y.y.yAdd IPv6 addressing and routing configuration to the
previous rows list. Assume EIGRP for IPv6 ASN 1 is
preconfigured.
Ipv6 unicast-routing
Int tunnel0
Ipv6 address
Ipv6 eigrp 1
Configure an IPv6 GRE tunnel using a loopback IPv4
address. Ignore IPv6 addressing and routing configuration.
Int l1
Ip address x.x.x.x
Int tunnel0
Tunnel mode gre ip
Tunnel source l1
Tunnel destination y.y.y.y
Configure an IPv6 automatic 6to4 tunnel using a loopbackIPv4 address. Include only IPv6 configuration required for
the tunnel to pass IPv6 traffic. Assume all hosts use
addresses in the 2002::/16 range.
Ipv6 unicast-routingInt l1
Ip address x.x.x.x
Int tunnel0
Ipv6 address z.z.z.z
Tunnel mode ipv6ip 6to4
Tunnel source l1
Ipv6 route 2002::/16 tunnel0
List steps to migrate from the automatic 6to4 tunnel from
the previous row to a comparable ISATAP tunnel
Interface tunnel0
Ipv6 address prefix/64 eui-64
Tunel mode ipv6ip isatap
No ipv6 route 2002::/16 tunnel0
Ipv6 route prefix/length tunnel0 next-hop
Verification Plan Memory Drill
Information Needed Commands
Tunnel interface status for IPv6. Show ipv6 interface brief
Show ipv6 interface tunnel0
Show interfaces tunnel0
Tunnel interfaces IPv6 address(es). Show ipv6 interface brief
Show ipv6 interface tunnelConnected routes related to the tunnel. show ipv6 route
The tunnel source and destination IPv4 addresses. Show interface tunnel
Test the tunnel to see if it can pass traffic. Ping
traceroute
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Review all the Key TopicsKey Topics for CH18
Key Topic
Element
Description Page
Number
Figure 18-3 Point-to-point IPv6 tunnel concept 614
Figure 18-4 Multipoint IPv6 tunnel concept 616
Table 18-2 Comparisons of four IPv6 tunnel types 617
Figure 18-5 NAT-PT concepts 618List Manually configured tunnel configuration checklist 620
List Configuration differences between GRE and manually configured IPv6 tunnels 625
Table 18-3 Comparisons of manually configured tunnels and GRE tunnels 626
Figure 18-8 Address planning for automatic 6to4 tunnels 628
List Configuration checklist for automatic 6to4 tunnels 629
List Comparisons of automatic 6to4 and ISATAP tunnels 634
Figure 18-10 ISATAP tunnel logic 635
List Modified EUI-64 rules for forming ISATAP IPv6 addresses 636
List ISATAP tunnel configuration checklist 636
Table 18-4 Comparisons of Automatic 6to4 and ISATAP tunnels 640
CH18 Memory TablesComparing Manual and GRE IPv6-over-IP Tunnels
Manual Tunnels GRE
RFC 4213 2784
Tunnel mode command Tunnel mode ipv6ip Tunnel mode gre ip
Passenger MTU default 1480 1476
Supports IPv6 IGPs? Yes Yes
Forwards IPv6 multicasts? Yes Yes
Uses static configuration of tunnel
destination?
Yes Yes
Supports multiple passenger
protocols?
No Yes
Link local based on FE80::/96, plus 32 bits from tunnel
source Ipv4 address
Ipv6 EUI-64, using lowest numbered
interfaces MAC address
Comparing IPv6 Multipoint Tunnels
Automatic 6to4 ISATAP
Defined by RFC or Cisco? 3056 4214
Uses a reserved IPv6 address prefix. Yes 2002::/16 No
Supports the use of global unicast addresses? Yes Yes
Quartets holding the IPv4 destination address. 2 and 3 7 and 8
End-user host addresses embed the IPv4 destination? Sometimes No
Tunnel endpoints IPv6 addresses encode IPv4 destination. Sometimes Yes
Uses modified EUI-64 to form tunnel IPv6 addresses? No Yes
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Define Key TermsTerm Definition
Dual stacks
Network Address
TranslationProtocol
Translation (NAT-PT)
tunneling
tunneltunnel interface
point-to-point tunnel
multipoint tunnel
ISATAP tunnel
ISATAP
automatic 6to4 tunnel
manually configured
tunnel
GRE tunnel
Modified EUI-64
Top Related