Pavel Stefanov’s Blog

I’ve got a simple OSPF topology – two routers in area 0 on the ethernet interfaces and in area 1 on the unnumbered serial interfaces, which use the loopback interfaces’ addresses.

What is interesting in this setting is that in the router LSAs the MIB-II interface index of the serial interfaces is put in the Link Data field of the LSA and not the loopback ip address. Then if you try to bring up a virtual-link across area 1 to the other router, the MIB-II index will be used as the destination ip address of the OSPF hello packet used to negotiate a virtual-link and 0.0.0.0 is put in the source address field of the ip packet.

R1′s Config:

interface Loopback0
ip address 1.1.1.1 255.0.0.0
ip ospf 1 area 1
!
interface FastEthernet0/0
ip address 12.0.0.1 255.0.0.0
ip ospf 1 area 0
duplex auto
speed auto
!
interface Serial1/0
ip unnumbered Loopback0
ip ospf 1 area 1
serial restart-delay 0
!
router ospf 1
router-id 1.1.1.1
log-adjacency-changes
area 1 virtual-link 2.2.2.2


R2′s Config:

interface Loopback0
ip address 2.2.2.2 255.0.0.0
ip ospf 1 area 1
!
interface FastEthernet0/0
ip address 12.0.0.2 255.0.0.0
ip ospf 1 area 0
duplex auto
speed auto
!
interface Serial1/0
ip unnumbered Loopback0
ip ospf 1 area 1
serial restart-delay 0
!
router ospf 1
router-id 2.2.2.2
log-adjacency-changes
area 1 virtual-link 1.1.1.1

OSPF Area 1 Database:

R1#show ip ospf database router
! omitted output
Router Link States (Area 1)

LS age: 569
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 1.1.1.1
Advertising Router: 1.1.1.1
LS Seq Number: 80000003
Checksum: 0x9D2B
Length: 48
Area Border Router
Number of Links: 2

Link connected to: a Stub Network
(Link ID) Network/subnet number: 1.1.1.1
(Link Data) Network Mask: 255.255.255.255
Number of TOS metrics: 0
TOS 0 Metrics: 1

Link connected to: another Router (point-to-point)
(Link ID) Neighboring Router ID: 2.2.2.2
(Link Data) Router Interface address: 0.0.0.4
Number of TOS metrics: 0
TOS 0 Metrics: 64

Routing Bit Set on this LSA
LS age: 227
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 2.2.2.2
Advertising Router: 2.2.2.2
LS Seq Number: 80000004
Checksum: 0x1FA0
Length: 48
Area Border Router
Number of Links: 2

Link connected to: a Stub Network
(Link ID) Network/subnet number: 2.2.2.2
(Link Data) Network Mask: 255.255.255.255
Number of TOS metrics: 0
TOS 0 Metrics: 1

Link connected to: another Router (point-to-point)
(Link ID) Neighboring Router ID: 1.1.1.1
(Link Data) Router Interface address: 0.0.0.4
Number of TOS metrics: 0
TOS 0 Metrics: 64

R1#debug ip packet
IP packet debugging is on
*Mar 1 00:43:29.339: IP: s=0.0.0.0 (local), d=0.0.0.4, len 76, unroutable


ifIndex of S1/0:

R1#sh snmp mib ifmib ifindex s1/0
Interface = Serial1/0, Ifindex = 3


Conclusion: Remember when you are trying to configure a virtual-link between two routers, make sure the virtual-link’s best path is not through an unnumbered interface or otherwise the adjacency would not be formed!

Just a day after Liverpool’s Official Website posted the sad news about a young fellow red dying from cancer, Liverpool fans are ready with their flags for Liam. A couple from Wales responded to the prompt of Liverpool Football Club to make flags and banners for the young lad and Hollyhead Reds are preparing another one, so when they lift them on Tuesday’s match, Liam could luckily see the flags and feel happy one more time.

Here’s the full story: Story. Take the time to read it.

Доста стара реклама, но е една от любимите ми.

Today I read one of the most touching stories ever – http://www.liverpoolfc.tv/news/drilldown/N159620080418-2139.htm . It’s about a 17-year old boy named Liam who is dying from cancer in the stomach. He is in a very bad condition and last Friday he was told he had to weeks more to live and was released from hospital to die at home. His only wish was to spend his last days in a Liverpool shirt, and when news spread to Melwood, a shirt signed by all Liverpool players was dispacted to him. He also wants his dad to bury him with this shirt because he has only lived for Liverpool Football Club.

Liverpool fans are doing their best to be able to lift a transparent with the boy’s name during Tuesday’s match against Chelsea at Anfield. We just hope he can make it to the match. This is a great gesture by the lads.

You will be remembered, Liam!

YWNA

Cafe del Mar. Едно от най-известните заведения на остров Ибиса. Видеото е от 1993-та, парчето е едно най-великите някога създавани, парче, което разтърси целия музикален свят и даде тласък на много нови идеи. Преди около година за първи път видях това видео, беше пролет, на крачка от лятото, и бях като обезумял от звуците на това парче, не бях чувал подобно нещо. Оттогава го търсех (първоначално в youtube го гледах, след като го свалиха (по незнайни прични) и го търсех отчаяно, но днес го намерих в last.fm (по-точно в youtube).

Не крия, че много често си мечтая за различни неща и едно от тях е да отида в Ибиса през лятото и да гледам залеза под звуците на chill out, лежеейки на плажа. Това е най-красивият залез..

Поредната “фалафелска” история на Сиско… IOS 12.4(15)T1. Конфигвам си аз PBR за locally originated traffic и става следното нещо:

1. Дефинирам си route-map

route-map LOCAL_POLICY

match ip address LOCAL_TRAFFIC

set interface loopback 0

2. Apply-вам route-map-а

ip local policy route-map LOCAL_POLICY

Е, добре, ама не бачка. Познайте защо! Фалафелите пак са си оставили ръцете, като са писали IOS-а – първо трябва да се specify-не non-existing route-map с предната команда, след което чак тогава да се дефинират стейтмънтите в нея. Ето за тази простотия си троших главата 1 час.

Цял ден се сблъсквам с подобни глупости благодарение на едни индийци, които цял ден пишат с краката си, и се съмнявам скоро да ги оправят.

Another Cisco IOS dung beetle… Series: Cisco IOS Indian Soap Opera Episode: 12.4T(15)T1. Today I had to configure policy-based routing for locally originated traffic and here’s what happened:

1. Defined a route-map

route-map LOCAL_POLICYmatch ip address LOCAL_TRAFFIC

set interface loopback 0

2. Applied the route-map as a local policy

ip local policy route-map LOCAL_POLICY

Well, you’d say that would work, but it doesn’t, and guess why – you must apply a non-existing route-map with the aforementioned command and THEN you must define the route-map entries in order for PBR to work properly. If you do it in any other order (configure the route-map first, and then apply it), you will end up spending hours troubleshooting what seems a perfectly configured feature.

Wohoooo, току-що получих потвърждение от UEFA, че съм спечелил 2 билета за финала на Лигата в Москва на 21-ви май. Решил съм твърдо да ходя, ако се класират Ливърпул, иначе ще ги шитна на някой. 310 евро са двата с administrative charges, категория 2, което е много добре – мисля, че местата ще са добри.

We won it five times, Istanbul, we won it five times!!! Let’s make it 6 now!!!