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44 Cards in this Set
- Front
- Back
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What are the 3 most notable features of IPv6?
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Larger 128-bit address, a simplified packet header optimized for 32 & 64 bit processors which can be processed more efficiently, provides a flexible extension headers mechanism for support of other features, mobile IP and security at L3 (IPSec).
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What are the 3 apparent changes in IPv6 headers over IPv4 headers?
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The checksum is removed since can be handled by upper layer protocols and caused more processing due to TTL, Fragmentation has been moved to extension headers and now the source node fragments packets, and Flow label added which allows similar traffic to be switched quickly along a path instead of being examined by using tags.
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Name and describe 5 types of extension headers
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Hop-by-hop=options for routers, Destination options=options for end node, Routing=Specify routers that route must include, Fragment=To divide packets too large for MTU of a link, and Authentication and Encapsulation Security Payload (ESP)=Used by IPSec to provide packet authentication, integrity and confidentiality.
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How is an IPv6 address made up and how can it be shortened?
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Eight 16 bit fields separated by colons. Each Hex digit maps to 4 bits (each 16-bit field is 4 digits long), and between colons it is 16 bits. It can be shortened by: 1.Omitting the leading 0s in each 16 bit field, 2.Once and only once, sequential 0s can be replaced with a pair of colons. Only 1 pair of colons can be used within an IPv6.
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What are the 3 types of IPv6 addresses?
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Unicast (global or link-local), Multicast or anycast. An interface can have several addresses including a link-local address, any global unicast or anycast assigned, a loopback address (::1 /128), the all-nodes multicast, solicited nodes multicast and any other multicast address to which the node is assigned.
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What is a link-local unicast address?
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It allows devices on the same local network to communicate without requiring to have global unicast addresses. They are used by routing and discovery protocols and autoconfigure using the FE80::/10 prefix and the EUI-64 format interface ID.
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What is an anycast address?
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Their is no reserved address space for anycast, is created by assigning a global unicast address to 2 or more devices. It Identifies a set of interfaces on different devices, and a packet sent to it goes only to the nearest interface as determined by the metric of the routing protocol in use. Therefore, all nodes with the same anycast address should provide the same service. This technique automatically load-balances traffic toward the closest exit and provides redundancy incase an exit router goes down.
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What is a solicited nodes multicast?
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They are sent on the local link by a device that wants to determine the data link layer address of another device on the same local link (similar to ARP). Is formed by starting with the prefix FF02::1:FF00:/104, appending the last 24 bits of the corresponding unicast or anycast address of the device.
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What is the subnet-router anycast address?
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All routers must support the subnet-router anycast address for the subnets on which they have interfaces. It is the unicast address of the subnet with the interface ID set to zero. So is like a network address.
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What are IPv6 Interface Identifiers (IDs), sometimes referred too as Host portion?
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They identity a unique interface on a link, are 64 bits long, can be dynamically created and are based on the data-link layer. The specific data link layer type of the interface determines how they are dynamically created and how address resolution works.
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How is an IPv6 address made up?
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The first 48 bits are used for global routing at the ISP level, and the next 16 are the subnet ID, allowing an enterprise to subdivide the network. The final 64 bits are the interface ID, typically in EUI-64 format. The far left bits indicate the routing prefix and may be summarized.
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How is the Interface ID made for Ethernet?
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It is based on the MAC of the interface in a format called Extended Universal Identifier 64 (EUI-64) format. It is derived from the 48-bit MAC by inserting the HEX number FFFE between the OUU (upper 3 bytes) and the vender code (lower 3 bytes) of the MAC. The 7th bit of the resulting interface ID (corresponding to the universal/ Local (U/L)) is set to 1 since IDs derived from universally unique MACs are assumed to be globally unique. The 8th bit is the individual/ group (I/G) bit for managing multicast groups, and isn't changed.
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What are the IPv6 address ranges?
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Assigned Global Unicast and anycast address=2001::/3, Link-local unicast address=FE80::/10 (1111 1111 1000 0000), Loopback address=::1/128 IPv4-mapped-IPv6 address=0::FFFF:0:0/96 (replace 0:0 for IPv4 address), multicast=FF00::/8 (1111 1111), All-nodes multicast address=FF01:: & FF02::1, All-routers multicast address=FF01::2, FF02::2 & FF05::2
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How is a IPv6 Multicast address made up?
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They all start with an 8 bit prefix of FF00/8. The next 4 bits are flags, and the 4 bits after the flags are the scope which determines how far the multicast packet can travel. Similar to TTL in IPv4 but not as limited.
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What multicast addresses should an interface be able to recognize?
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Each interface should recognize several multicast addresses, including the all-nodes mulitcast address, the solicited nodes multicast and other multicast group addresses to which the node belongs. Also the all-routers multicast address.
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What is stateless Auto configuration?
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Each router advertises its network info (either periodically or upon request from a host), including the 64 prefix on each of its links. End systems add this prefix and there EUI-64 format interface ID together. Is called stateless auto configuration because no device tracks the state of a particular address. The process can also be used to renumber a network. Duplicate Address Detection (DAD) detects and avoids loops.
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How does IPv6 Mobility work?
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An IPv6 mobile node has a home address on its home network and a care-of-address on its current network. A node communicating with a mobile node is called a corresponding node. It either routes packets directly to the care-of-address of the mobile node, or routes packets to the home node which are then tunneled to the mobile node.
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What routing protocols can be used with IPv6?
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Ripng (uses multicast FF02::9) , EIGRP for IPv6 (available in IOS 12.4(6) T and later), IS-IS for IPv6 (Create new protocol Identifier & 2 new TLVs), MP-BGP for IPv6 (new extensions to carry reachability info for other protocols), OSPFv3 (Uses Multicast FF02::5 for all OSPF routers & FF02::6 for all DRs & BDRs)
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What are some of the differences between OSPFv2 and OSPFv3?
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OSPFv3 uses links rather than subnets using link-local address as src, has smaller 16 bit header by doing way with authentication (IPv6 ext headers deal with it), supports multiple instance so multiple routing domains can communicate over same link. However it still uses a 32 bit RID, area ID and link-state id.
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What's the difference in the LSAs between OSPFv2 and OSPFv3?
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LSA types 1 & 2 no longer contain route prefixes, instead they contain 32-bit IDs advertising RID from a router or DR respectively. Types 3 & 4 are the same but renamed, and types 8 & 9 are new LSAs in v3. Type 3 and 9 carry all IPv6 info, as apposed to 1 & 2 in v2.
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What are the 2 main differences in configuring and troubleshooting OSPFv2 and OSPFv3?
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1.The inclusion of the "ipv6" keyword in OSPFv3 cmds. 2.Interfaces are enabled in the interface config mode instead of in global config using the "network" keyword.
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What is Dual-stack and how is it enabled?
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It is the approach used to run IPv6 and IPv4 on a router concurrently with no communication between the two. It works so long as the infrastructure supports both protocols. To implement it simply enable IPv6, and then configure Ipv4 and v6 addresses.
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What is tunneling?
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It simply encapsulates the v6 traffic inside v4 packets, and when the dst receives the IPv4 packet it decapsulates it. A downside to it is that it decreases the MTU because of the 20 bytes consumed by the IPv4 header on the intermediate links. There are 4 types, manual tunnels, IPv6-to-IPv4 (6-to-4) tunnels, Teredo (Can traverse NAT devices and firewalls) and ISATAP (allows IPv4 private network to implement IPv6 without upgrading network).
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How do you configure a Manual Tunnel?
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First use "interface tunnel [num]" to enter the tunnel and then assign it an IP. Define the tunnel src with "tunnel src "ip add" and tunnel dst with "tunnel dst". Finally use "tunnel mode ipv6" to specify that the manual tunnel has IPv6 as the passenger protocol and IPv4 as both the encapsulation and transport protocols.
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How do 6-to-4 tunnels work?
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They are the similar to manual tunnels except that the tunnel is setup automatically. They use IPv6 addresses that concategate 2002::/16 with the 32-bit IPv4 address of the edge router, creating a 48-bit prefix. So a router would extract the IPv4 address from the IPv6 address, encapsulate the v6 packet with the v4 address, and then route the packet normally.
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How does IPv6 translation work?
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Stateless IP/ICMP (SIIT) translates the IP headers, and NAT Protocol Translation (NAT-PT) maps IPv6 addresses to IPv4 addresses. It has the capability to interpret application traffic and understand when IP info is included in the application traffic so it can change it. For example, DNS. Application Level Gateways (ALG or proxies), can also translate between protocols.
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What are Bump-in-the API (BIA) and Bump-in-the-stack (BIS)?
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They are NAT-PT implementations within a host, allowing a server to be converted to IPv6 without rewriting applications.
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To enable IPv6, it must be done before configuring any routing protocol
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router(config)# ipv6 unicast-routing
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To enable CEFv6. This needs to be done after enabling IPv6. It is an advanced L3 IP-switching technology for forwarding IPv6 packets.
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router(config)# ipv6 cef
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To configure interfaces with an IPv6 unicast address. The "EUI-64" keyword causes the router to complete the lower 64 bits using an EUI-64 format interface ID.
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router(config-if)# ipv6 address [IPv6-add/prefix length] [eui-64]
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The cmd to configure a IPv6 static route. Default routes are represented by ::/0
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router(config)# ipv6 route [ipv6-prefix/prefix-length] [[next hop ipv6-add] | [type] [mod/num]] [administrative-distance]
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To create an OSPF v3 process
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router(config)# ipv6 router ospf [process-id]
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To assign a 32 bit RID which must be in IPv4 dotted decimal format. Priority works in same way, default is 1, higher priority means better chance of being elected DR or BDR, and 0 means cant be elected as either.
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router(config-rtr)# router id [32-bit RID]
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To summarize the area into another area
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router(config-rtr)# area [area-id] range [summary-range/prefix-length] [advertise \ not-advertise] [cost [cost]]
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To assign an interface to an OSPFv3 area. Two instance need same instance-id to communicate with each other since they have separate neighbor tables, linkstate databases and shortest path trees for each instance.
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router(config-if)# ipv6 ospf [process-id] area [area-id] [instance [instance-id]]
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To change the OSPF priority from its default value of 1.
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router(config-if)# ipv6 ospf priority [priority]
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To change the default cost value. Like in v2 it is by default inversely proportional to the b/w of the interface.
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router(config-if)# ipv6 ospf cost [interface-cost]
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To see the IPv6 routing table. Is a good place to start troubleshooting OSPFv3 since you can verify routes are being advertised.
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router# show ipv6 route
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To trigger a SPF recalculation and repopulation of the routing table. The "process" keyword causes both, while "force-spf" performs just an SPF recalculation
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router# clear ipv6 [process-id] [process | force-spf ]
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To display IPv6 info about an interface. This includes the IPv6 addresses and the interfaces status. Using the "brief" keyword shows a mini table of the info.
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router# show ipv6 interface [brief] [[type] [mod/num]] [prefix]
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To display interface specific OSPFv3 info. You can check if OSPFv3 is enabled on the interface, and if so the settings and timer values for it. You also get stats about retransmission times, up times, etc
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router# show ipv6 ospf interface [[type] [mod/num]] [prefix]
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To verify the OSPFv3 RID, timers, and area details, as well as other general routing protocol settings.
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router# show ipv6 ospf
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To display OSPFv3 neighbor information so you can verify that neighbor relationships have been established with directly connected routers.
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router# show ipv6 ospf neighbor [detail]
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To display the OSPFv3 Database, and details of LSAs that may be helpful in recognizing how routes are propagated. Adding "database-summary" keyword simply provides the totals for the various types of LSAs.
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router# show ipv6 ospf database [database-summary]
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