CCIE Pursuit Blog

August 17, 2008

Lab Tip: IPv6 EUI-64 Unexpected (For Me) Behavior

I ran across an unexpected behavior with IPv6 EUI-64 addressing today.  I had configured an interface with EUI-64 addressing.  Knowing that I would need to run OSPFv3 over this Frame Relay interface, I followed my normal procedure of creating a simplified link-local address.  To my surprise, this link-local address changed my EUI-64 address:

interface Serial0/0
 ipv6 address 2001:CC1E:1:1515::/64 eui-64
 ipv6 address FE80::1 link-local

r1(config-if)#do sh ipv int br | sec l0/0
Serial0/0                  [up/up]
    FE80::1
    2001:CC1E:1:1515::1

For some reason the EUI-64 part of the IPv6 address was replaced with the host address of the link-local address.

Let’s recreate the scenario by stripping off the IPv6 addressing:

r1(config-if)#int s0/0
r1(config-if)#no ipv6 address 2001:CC1E:1:1515::/64 eui-64
r1(config-if)#no ipv6 address FE80::1 link-local

r1(config-if)#do sh run int s0/0 | i l0/0|ipv
interface Serial0/0

r1(config-if)#do sh ipv int br | sec l0/0
Serial0/0                  [up/up]
    unassigned

Now configure the EUI-64 address:

r1(config-if)#int s0/0
r1(config-if)#ipv6 address 2001:CC1E:1:1515::/64 eui-64

r1(config-if)#do sh ipv int br | sec l0/0
Serial0/0                  [up/up]
    FE80::211:93FF:FEB0:7640
    2001:CC1E:1:1515:211:93FF:FEB0:7640

Now create add a link-local address:

r1(config-if)#int s0/0
r1(config-if)#ipv add FE80::1 link-local

r1(config-if)#do sh ipv int br | sec l0/0
Serial0/0                  [up/up]
    FE80::1
    2001:CC1E:1:1515::1

It’s good to know about this behavior in case you get a task that asks you to use an EUI-64 address.  Depending on the grading method, you could lose points for this.

August 13, 2008

Internetwork Expert Volume II: Lab 12 – Section 7

Section 7 – IPv6 – 16 Points

7.1 IPv6 Addressing

Very basic IPv6 addressing task.  The only confusing bit:

“Use the address 2001:CC1E:X:3::Y/64 for r3′s Ethernet interface.”

Ummm…r3 has TWO Ethernet interfaces?  Which one do they mean?  It turns out that they only mean e0/0 (VLAN3).

7.2 IPv6 over Frame Relay

This is a basic IPv6 Frame Relay hub-and-spoke task.  They even go so far as to tell you what to use for the link-local addresses.  I always read ahead in the IPv6 section to see if we will be running an IPv6 IGP over the Frame Relay network.  In this case task 7.4 will require exactly that.  SO….if there are no requirements against it, I hardset the link-local addresses to Fe80::Y (where Y is the router number) AND I go ahead and create frame maps for the link-local addresses.  It’s not required in this task, but we might as well do it now.

R1 (spoke) before:

Rack16R1(config-if)#do sh run int s0/0 | i face|add|rame
interface Serial0/0
 ip address 129.16.124.1 255.255.255.0
 encapsulation frame-relay
 frame-relay map ip 129.16.124.2 104
 frame-relay map ip 129.16.124.4 104 broadcast
 no frame-relay inverse-arp

R1 after:

Rack16R1(config-if)#do sh run int s0/0 | i face|add|rame
interface Serial0/0
 ip address 129.16.124.1 255.255.255.0
 encapsulation frame-relay
 ipv6 address 2001:CC1E:16:124::1/64
 ipv6 address FE80::1 link-local
 frame-relay map ipv6 FE80::2 104
 frame-relay map ipv6 FE80::4 104
 frame-relay map ipv6 2001:CC1E:16:124::2 104
 frame-relay map ipv6 2001:CC1E:16:124::4 104 broadcast
 frame-relay map ip 129.16.124.2 104
 frame-relay map ip 129.16.124.4 104 broadcast
 no frame-relay inverse-arp

7.3 RIPng

This is a simple RIPng task.

“Configure r2 so that RIPng routes learned from BB2 with a mask longer than /64 will not be passed on to r3.”

Here are the RIPng routes that we’re receiving from BB2:

Rack16R2#sh ipv6 route rip
IPv6 Routing Table – 12 entries
Codes: C – Connected, L – Local, S – Static, R – RIP, B – BGP
       U – Per-user Static route
       I1 – ISIS L1, I2 – ISIS L2, IA – ISIS interarea, IS – ISIS summary
       O – OSPF intra, OI – OSPF inter, OE1 – OSPF ext 1, OE2 – OSPF ext 2
       ON1 – OSPF NSSA ext 1, ON2 – OSPF NSSA ext 2
R   2001:205:90:31::/64 [120/2]
     via FE80::200:CFF:FE4A:689C, FastEthernet0/0
R   2001:220:20:3::/64 [120/2]
     via FE80::200:CFF:FE4A:689C, FastEthernet0/0
R   2001:222:22:2::/64 [120/2]
     via FE80::200:CFF:FE4A:689C, FastEthernet0/0

R   2001:CC1E:16:3::/64 [120/2]
     via FE80::206:D7FF:FEBD:1741, Serial0/1

We need to filter some routes.  Our old filtering friends from RIPv1/2 are still available although the offset-list has been moved to the interface level and renamed:

Rack16R2(config)#ipv6 router rip RIPng
Rack16R2(config-rtr)#?
  distance         Administrative distance
  distribute-list  Filter networks in routing updates

Rack16R2(config-if)#ipv6 rip RIPng ?
  metric-offset        Adjust default metric increment

Well…the metric-offset is not quite as flexible as the old skool offset-list because you can’t specify the routes to offset.  It’s an “all or nothing” solution:

Rack16R2(config-if)#ipv rip RIPng metric-offset 16 ?
  <cr>

ipv6 rip metric-offset

Let’s use a distribute list instead:

distribute-list prefix-list (IPv6 RIP)

The first thing that we need to do is write an IPv6 prefix-list to match any IPv6 routes that are /64 or less:

Rack16R2(config)#ipv6 prefix-list TASK_7_2 perm 0::0/0 le 64

Then apply the distribute-list under the RIPng process:

Rack16R2(config)#ipv6 router rip RIPng
Rack16R2(config-rtr)#distribute-list prefix-list TASK_7_2 out s0/1

Since we don’t have any routes greater than /64 coming from BB2, there is really no good way to validate this.  BUT make sure that the this doesn’t break your IPv6 routing by making sure that the RIPng routes from BB2 are getting to r3:

Rack16R3#sh ipv route rip
IPv6 Routing Table – 10 entries
Codes: C – Connected, L – Local, S – Static, R – RIP, B – BGP
       U – Per-user Static route
       I1 – ISIS L1, I2 – ISIS L2, IA – ISIS interarea, IS – ISIS summary
       O – OSPF intra, OI – OSPF inter, OE1 – OSPF ext 1, OE2 – OSPF ext 2
       ON1 – OSPF NSSA ext 1, ON2 – OSPF NSSA ext 2
R   2001:192:10:16::/64 [120/2]
     via FE80::211:92FF:FE17:C860, Serial1/3
R   2001:205:90:31::/64 [120/3]
     via FE80::211:92FF:FE17:C860, Serial1/3
R   2001:220:20:3::/64 [120/3]
     via FE80::211:92FF:FE17:C860, Serial1/3
R   2001:222:22:2::/64 [120/3]
     via FE80::211:92FF:FE17:C860, Serial1/3

7.4 OSPFv3

OSPFv3 is enabled under the interface as well:

Rack16R2(config)#int s0/0
Rack16R2(config-if)#ipv os 666 area 0

If you did not create frame maps for the link-local addresses then you will need to do this now (IPv6 IGPs use the link-local address for next-hop processing).

We need to get our neighbor adjacencies up, but we’re not allowed to change the default OSPF type.  This means we need neighbor statements on the hub (and priority 0 statements on the spokes).  The only deviation form the OSPFv2 process is that this is done under the interface:

Rack16R4(config-rtr)#int s0/0.124
Rack16R4(config-subif)#ipv6 ospf ?
  <1-65535>            Process ID
  authentication       Enable authentication
  cost                 Interface cost
  database-filter      Filter OSPF LSA during synchronization and flooding
  dead-interval        Interval after which a neighbor is declared dead
  demand-circuit       OSPF demand circuit
  flood-reduction      OSPF Flood Reduction
  hello-interval       Time between HELLO packets
  mtu-ignore           Ignores the MTU in DBD packets
  neighbor             OSPF neighbor
  network              Network type
  priority             Router priority
  retransmit-interval  Time between retransmitting lost link state
                       advertisements
  transmit-delay       Link state transmit delay

Rack16R4(config-subif)#ipv6 ospf neigh 2001:CC1E:16:124::2
OSPFv3: Neighbor address needs to be a link-local address

Doh!

Rack16R4(config-subif)#ipv6 ospf neigh FE80::2
Rack16R4(config-subif)#ipv6 ospf neigh FE80::1

Rack16R4#sh ipv os neigh

Neighbor ID     Pri   State           Dead Time   Interface ID    Interface
150.16.1.1        0   FULL/DROTHER    00:01:42    5               Serial0/0.124
150.16.2.2        0   FULL/DROTHER    00:01:32    5               Serial0/0.124

7.5 OSPv3

Create two new OSPFv3 areas and:

“r6 should see only one router for both the Frame Relay segment and VLAN 17 of r1.”

Here’s what we see on r6 right now:

Rack16R6#sh ipv route os
IPv6 Routing Table – 6 entries
Codes: C – Connected, L – Local, S – Static, R – RIP, B – BGP
       U – Per-user Static route
       I1 – ISIS L1, I2 – ISIS L2, IA – ISIS interarea, IS – ISIS summary
       O – OSPF intra, OI – OSPF inter, OE1 – OSPF ext 1, OE2 – OSPF ext 2
       ON1 – OSPF NSSA ext 1, ON2 – OSPF NSSA ext 2
OI  2001:CC1E:16:1::/64 [110/66]
     via FE80::207:EFF:FE9C:F4C2, FastEthernet0/0
OI  2001:CC1E:16:124::/64 [110/65]
     via FE80::207:EFF:FE9C:F4C2, FastEthernet0/0

So…is the task asking us to summarize these two routes or is it asking for a single default route?  I would ask the proctor on this one.

Since making this a totally-stubby area is the easier solution, that’s the one I chose.  :-)  IE also went this route.

Rack16R4(config-if)#ipv6 router ospf 666
Rack16R4(config-rtr)#area 2 stub no-summ

Rack16R6(config)#ipv6 router ospf 666
Rack16R6(config-rtr)#area 2 stub

Rack16R6#sh ipv route os
IPv6 Routing Table – 5 entries
Codes: C – Connected, L – Local, S – Static, R – RIP, B – BGP
       U – Per-user Static route
       I1 – ISIS L1, I2 – ISIS L2, IA – ISIS interarea, IS – ISIS summary
       O – OSPF intra, OI – OSPF inter, OE1 – OSPF ext 1, OE2 – OSPF ext 2
       ON1 – OSPF NSSA ext 1, ON2 – OSPF NSSA ext 2
OI  ::/0 [110/2]
     via FE80::207:EFF:FE9C:F4C2, FastEthernet0/0

7.6 IPv6 Redistribution

Oh fun.  :-)  At least there are only two IPv6 protocols and one point of redistribution (r2).

I tried to build a TCL script and quickly found out that there is no ‘show ipv6 alias” command.  :-(  I just did a “show ipv6 int brief” and copied the addresses:

foreach x {
2001:CC1E:16:1::1
2001:CC1E:16:124::1
2001:CC1E:16:3::3
2001:CC1E:16:23::3
2001:192:10:16::2
2001:CC1E:16:124::2
2001:CC1E:16:23::2
2001:CC1E:16:124::4
2001:CC1E:16:46::4
2001:CC1E:16:46::6
2001:222:22:2::1} {ping $x re 2}

The redistribution is pretty straight-forward except I couldn’t decide if I needed “include-connected” as well.  I voted “no” – which ended up being a mistake.   I need to review IPv6 redistribution to find out why.

Rack16R2(config-rtr)#ipv6 router ospf 666
Rack16R2(config-rtr)#redistribute rip RIPng include-conn

Rack16R2(config-rtr)#ipv6 router rip RIPng
Rack16R2(config-rtr)#redist ospf 666 metric 1 include-conn

Rack16R1#sh ipv route os
IPv6 Routing Table – 13 entries
Codes: C – Connected, L – Local, S – Static, R – RIP, B – BGP
       U – Per-user Static route
       I1 – ISIS L1, I2 – ISIS L2, IA – ISIS interarea, IS – ISIS summary
       O – OSPF intra, OI – OSPF inter, OE1 – OSPF ext 1, OE2 – OSPF ext 2
       ON1 – OSPF NSSA ext 1, ON2 – OSPF NSSA ext 2
OE2  2001:192:10:16::/64 [110/20]
     via FE80::2, Serial0/0
OE2  2001:205:90:31::/64 [110/20]
     via FE80::2, Serial0/0
OE2  2001:220:20:3::/64 [110/20]
     via FE80::2, Serial0/0
OE2  2001:222:22:2::/64 [110/20]
     via FE80::2, Serial0/0
OE2  2001:CC1E:16:3::/64 [110/20]
     via FE80::2, Serial0/0
OE2  2001:CC1E:16:23::/64 [110/20]
     via FE80::2, Serial0/0

OI  2001:CC1E:16:46::/64 [110/74]
     via FE80::4, Serial0/0

April 29, 2008

Internetwork Expert Volume II: Lab 5 – Section 6

IPv6 – 12 Points

6.1 IPv6 Addressing

Very basic IPv6 addressing task.

6.2 IPv6 over Frame Relay

Easy IPv6 over Frame Relay task. 

The IE solution configured a link-local address on r1 and r3.  I did not.  This is a point-to-point connection so I saw no need for a link-local address.

Task 6.2

I did configure the link-local addresses on r2, r3, and r4 (along with frame maps) but it looks like those addresses and maps were not needed (actually, they used them later in the BGP IPv6 sections).

6.3 IPv6 BGP Advertisements

6.4 IPv6 BGP Summarization

6.5 IPV6 BGP

Since IPv6 BGP is not on the exam I simply read the solution guide for task 6.3 – 5 and configured my routers to match.

April 17, 2008

OSPFv3 Router-ID Uses IPv4 Address

Filed under: Cisco,Cisco Certification,IOS,IPv6,OSPF — cciepursuit @ 8:37 am
Tags: , , , , ,

Ivan Pepelnjak over at Cisco IOS Hint and Tricks (an absolute must-read site) has a nice post about the use of IPv4 addresses as the router ID in OSPFv3.  I touched on this in this Question of the Day.

This part of the post made me laugh out loud:

One of the obscure facts of IPv6 OSPF (OSPFv3) is that it uses a 32-bit router ID like OSPFv2. It’s a reasonable choice, I haven’t seen an OSPF network with more than a billion routers yet.

I love the “yet” qualifier.  :-)

—Read The Rest Here—

April 8, 2008

Question Of The Day: 08 April, 2008

Topic: IPv6

Router r1 is running OSPFv3:

r1#show ip interface brief | e ass
Interface                  IP-Address      OK? Method Status                Protocol
Serial1/0.12               10.1.12.1       YES NVRAM  up                    up     
Serial1/0.13               10.1.13.1       YES NVRAM  up                    up     
Loopback0                  1.1.1.1         YES NVRAM  up                    up     
Loopback1                  11.11.11.11     YES NVRAM  up                    up     
Loopback2                  12.12.12.12     YES NVRAM  up                    up     
Loopback3                  13.13.13.13     YES NVRAM  up                    up   

r1#show ip interface brief
Serial1/0                  [up/up]
Serial1/0.12               [up/up]
    FE80::CE00:20FF:FE78:0
    2001:10:1:12:CE00:20FF:FE78:0
Serial1/0.13               [up/up]
    FE80::CE00:20FF:FE78:0
    2001:10:1:13:CE00:20FF:FE78:0
Loopback0                  [up/up]
    FE80::CE00:20FF:FE78:0
    2001:1:1:1::1
Loopback1                  [up/up]
    FE80::CE00:20FF:FE78:0
    2001:11:11:11::11
Loopback2                  [up/up]
    FE80::CE00:20FF:FE78:0
    2001:12:12:12::12
Loopback3                  [up/up]
    FE80::CE00:20FF:FE78:0
    2001:13:13:13::13

r1#show ip protocols summary
Index Process Name
0     connected
1     static

r1#show ipv6 protocols summary
Index Process Name
0      connected
1      static
2      ospf 100

r1#show ipv6 ospf interface
Serial1/0.12 is up, line protocol is up
  Link Local Address FE80::CE00:20FF:FE78:0, Interface ID 15
  Area 0, Process ID 100, Instance ID 0, Router ID ????
  Network Type POINT_TO_POINT, Cost: 64
  Transmit Delay is 1 sec, State POINT_TO_POINT,
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 00:00:00
  Index 1/1/1, flood queue length 0
  Next 0×0(0)/0×0(0)/0×0(0)
  Last flood scan length is 0, maximum is 0
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 0, Adjacent neighbor count is 0
  Suppress hello for 0 neighbor(s)

r1#show run | sec ipv6 ospf|router-id
 ipv6 ospf 100 area 0

What is the OSPFv3 router-id of r1?

Click Here For Answers


Yesterday’s Question

Question Of The Day: 07 April, 2008 

Topic: IP Prefix Lists

Write an IP prefix list called “NO_DEFAULT” that allows all routes except the default route.

Answer:
 ip prefix-list NO_DEFAULT sequence 10 deny 0.0.0.0/0
 ip prefix-list NO_DEFAULT sequence 20 permit 0.0.0.0/0 le 32

IP prefix lists are something that you’ll need to know well for the CCIE lab.  This example uses two of the most important prefix-lists to know: the ‘all prefixes list’ and the ‘default route prefix list’.

ip prefix-list

April 5, 2008

Internetwork Expert Volume II: Lab 6 – Section 6

IPv6 – 7 Points

6.1 IPv6 Addressing

Easy task, but I’m not sure why the IE solution uses eui-64 addressing for fa0/0 on r3?

Task 6.1 – IPv6

6.2 RIPng

Configure RIPng on all interfaces running IPv6.  Have r3 originate a default route to r2.  r2 should not see any of the specific subnets learned from BB2, but don’t use a prefix-list to accomplish this.

NOTE: Don’t forget to disable split-horizon on r1 (FR hub).

I’d love to give you a link to the DOCCD for some of these commands, but Cisco has completely fucked up the IPv6 documentation.

r3(config-if)#int s0/3:0
r3(config-if)#ipv rip RIPng en
r3(config-if)#ipv rip RIPng ?
  default-information  Configure handling of default route

r3(config-if)#ipv rip RIPng default-information ?
  only       Advertise only the default route
  originate  Originate the default route

r3(config-if)#ipv rip RIPng default-information only

r2#sh ipv route rip
IPv6 Routing Table – 8 entries
Codes: C – Connected, L – Local, S – Static, R – RIP, B – BGP
       U – Per-user Static route, M – MIPv6
       I1 – ISIS L1, I2 – ISIS L2, IA – ISIS interarea, IS – ISIS summary
       O – OSPF intra, OI – OSPF inter, OE1 – OSPF ext 1, OE2 – OSPF ext 2
       ON1 – OSPF NSSA ext 1, ON2 – OSPF NSSA ext 2
       D – EIGRP, EX – EIGRP external
R   ::/0 [120/2]
     via FE80::211:93FF:FEB0:9DA0, Serial0/1/0

R   2001:192:10:1::/64 [120/2]
     via FE80::211:93FF:FEB0:9DA0, Serial0/1/0
R   2001:CC1E:1:5::/64 [120/3]
     via FE80::1, Serial0/0/0

6.3 RIPng Summarization

Configrue r3 to advertise a single /48 summary of all of the IPv6 addresses.

r3(config)#int fa0/0
r3(config-if)#ipv6 rip RIPng summary-address 2001:CC1E:1::/48

r3#debug ipv6 rip fa0/0
RIP Routing Protocol debugging is on for interface FastEthernet0/0
*Mar  1 22:31:38: RIPng: Sending multicast update on FastEthernet0/0 for RIPng
*Mar  1 22:31:38:        src=FE80::211:93FF:FEB0:9DA0
*Mar  1 22:31:38:        dst=FF02::9 (FastEthernet0/0)
*Mar  1 22:31:38:        sport=521, dport=521, length=52
*Mar  1 22:31:38:        command=2, version=1, mbz=0, #rte=2
*Mar  1 22:31:38:        tag=0, metric=1, prefix=2001:192:10:1::/64
*Mar  1 22:31:38:       tag=0, metric=1, prefix=2001:CC1E:1::/48 

 

April 4, 2008

Internetwork Expert Volume II: Lab 3 – Section 7

IPv6 – 4 Points

7.1 IPv6 Addressing

Easy.

“The host portion of the IPv6 addresses should be based partly off of their interfaces’ respective MAC addresses.”

That’s your clue to use eui-64:

r4(config-if)#ipv6 add 2001:CC1E:1:404::/64 ?
  anycast  Configure as an anycast
  eui-64   Use eui-64 interface identifier
  <cr>

r4(config-if)#ipv6 add 2001:CC1E:1:404::/64 eui-64

r4(config-if)#do sh int fa0/0 | i bia
  Hardware is MV96340 Ethernet, address is 0017.0ee7.9058 (bia 0017.0ee7.9058)

r4(config-if)#do sh ipv6 int fa0/0
FastEthernet0/0 is up, line protocol is up
  IPv6 is enabled, link-local address is FE80::217:EFF:FEE7:9058
  Global unicast address(es):
    2001:CC1E:1:404:217:EFF:FEE7:9058, subnet is 2001:CC1E:1:404::/64 [EUI]

This is the second time that this has happened to me in this lab:

“The network administrator has requested that VLAN 29 and VLAN 4 be configured to support IPv6.”

VLAN 4 is only configured (at L3) on r4′s fa0/0 interface.  VLAN 29 (at L3) is configured between r2′s fa0/0 and sw3′s vlan29 (SVI) interface.  Why doesn’t the solution include sw3?

7.2  IPv6 Tunneling

Create a GRE tunnel between VLAN 29 and VLAN 4.  Use any site-local address for the IPv6 addressing within the tunnel.  Configure an IPv6 static route to obtain reachability.

r4#sh run | sec Tunnel|ipv6 route
interface Tunnel0
 no ip address
 ipv6 address FEC0::4/64
 tunnel source 150.1.4.4
 tunnel destination 150.1.2.2
!
ipv6 route 2001:CC1E:1:202::/64 Tunnel0

r2#sh run | sec Tunnel|ipv6 route
interface Tunnel0
 no ip address
 ipv6 address FEC0::2/64
 tunnel source 150.1.2.2
 tunnel destination 150.1.4.4
!
ipv6 route 2001:CC1E:1:404::/64 Tunnel0

r2#p 2001:CC1E:1:404:217:EFF:FEE7:9058

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:CC1E:1:404:217:EFF:FEE7:9058, timeout is
2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 136/138/140 ms

r4#p 2001:CC1E:1:202:217:EFF:FEE7:9940

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:CC1E:1:202:217:EFF:FEE7:9940, timeout is
2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 136/137/140 ms

April 1, 2008

Question Of The Day: 01 April, 2008

Topic: IPv6

FastEthernet0/0 is up, line protocol is up
  Hardware is AmdFE, address is cc01.17b4.0000 (bia cc01.17b4.0000)
  Internet address is 100.100.100.100/8

r2(config)#ipv6 unicast-routing
r2(config)#int fa0/0
r2(config-if)#ipv6 enable

What will be the IPv6 address of interface fa0/0?

Click Here For Answer


Yesterday’s Question

Question Of The Day: 31 March, 2008 

Topic: IPv6

FastEthernet0/0 is up, line protocol is up
  Hardware is AmdFE, address is cc00.17b4.0000 (bia cc00.17b4.0000)
  Internet address is 100.1.1.1/24

r1(config)#ipv6 unicast-routing
r1(config)#int fa0/0
r1(config-if)#ipv6 address 2001:B00B:1E5:1::/64 eui-64

What will r1’s fao/o IPv6 address be after this configuration is applied?

Answer: 2001:B00B:1E5:1:CE00:17FF:FEB4:0

The (modified) IPv6 eui-address is derived from the interface’s MAC Address with the following method:

Step 1 – Invert the seventh most significant bit of the MAC address.

This requires us to do some quick and dirty hexadecimal to binary conversion.  Luckily each hex character represents 4 bits, so we only need to convert the first two hex characters of the MAC address to include the seventh most significant bit:

cc = 1100 1100

Now let’s flip that seventh bit

1100 1110

Finally let’s convert this back to hex:

1100 1110 = ce

Step 2 – Split the MAC address in half and insert ‘fffe’

ce00.17 | b4.0000
ce0017fffeb40000
ce00:17ff:feb4:0000

Voila!  Now our 48-bit MAC address has been converted to 64-bits.  We just need to combine it with the IPv6 network portion and we will have our eui-64 IPv6 address:

2001:B00B:1E5:1:CE00:17FF:FEB4:0000
2001:B00B:1E5:1:CE00:17FF:FEB4:0

r1#sh ipv6 int br | sec net0/0
FastEthernet0/0            [up/up]
    FE80::CE00:17FF:FEB4:0
    2001:B00B:1E5:1:CE00:17FF:FEB4:0

March 31, 2008

Question Of The Day: 31 March, 2008

Topic: IPv6

FastEthernet0/0 is up, line protocol is up
  Hardware is AmdFE, address is cc00.17b4.0000 (bia cc00.17b4.0000)
  Internet address is 100.1.1.1/24

r1(config)#ipv6 unicast-routing
r1(config)#int fa0/0
r1(config-if)#ipv6 address 2001:B00B:1E5:1::/64 eui-64

What will r1′s fao/o IPv6 address be after this configuration is applied?

Click Here For Answer


Yesterday’s Question

 Question Of The Day: 28 March, 2008 

Topic: Route Summarization

You have the following subnets in your network:

132.16.32.0/24
132.16.121.0/24
132.16.34.0/24
132.16.33.0/24
132.16.5.0/24
132.16.181.0/24
132.16.27.0/24
132.16.2.0/24

Write a single summary route that will encompass all of these routes while being as specific as possible.

Answer: 132.16.0.0/16

Since the first two octets (132.16) are the same we need to look at the third octet.  Since we’re writing a single line we can just use the lowest (2) and highest (181) values:

132.16.2.0     10000100 00010000 00000010 00000000
132.16.181.0 10000100 00010000 10110101 00000000

I this case we can see that the first bits that are different the first bits of the 3rd octet.  We can stop right there.  Everything before those bits will be our network address (132.16.0.0) and the rest will be our mask (255.255.0.0)  Our summary will be 132.16.0.0/16.

Route Summarization

February 15, 2008

Crack Cocaine, Human Livers, and IPv4 Addresses?

Filed under: IPv6,OT: Humor — cciepursuit @ 5:54 pm
Tags:

Network World recently interviewed David Conrad, general manager of the Internet Assigned Numbers Authority (IANA) about the possibility of a black (or white) market for IPv4 addresses developing as those addresses run out.

Do you think there would be a market for IPv4 addresses after the free pool is handed out?

Yes. I can’t actually imagine there not being a market. The market will either be black or white. If black, it will have a negative impact on the ability of ARIN to maintain accurate databases, such as, Whois. If white, ARIN (and the other Regional Internet Registries) will undoubtedly get dragged into politics related to fairness, particularly with respect to the developing world.

Do you foresee organizations with excess IPv4 address space (universities, government agencies) making a profit by selling it?

Yes.

Would allowing IPv4 address space transfers slow down the transition to IPv6?

I would imagine it would accelerate the transition as the cost of obtaining IPv4 address space will become unpredictable and this will encourage organizations to obtain IPv6 space which will have predictable costs.

—Read The Rest Here—

 

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