Skip to main content

CCIE LAB TIP 3550/3560

During my practice to the lab exam, i am facing with some new stuff and some memory refreshers. for me as I was explaining before I have been handling mostly voice in the past ~7 years, I would like to give you a tip hopefully it is only a memory refresher When you face with a setup of a new Catalyst 3550/3560 you will face the lab with some layer 3 When you take the Catalyst fresh configuration and you are trying to put under x interface an IP Address you could be facing with this error Bad mask /xx for address x.x.x.x and why!? due to the fact that Cisco do not use the first subnet after subneting the network unless you tell it to. also called subnet zero so under global config simply put ! (config)#ip subnet-zero ! and like magic no more Bad mask message.
Post a Comment

Popular posts from this blog

Step By Step MPLS – Basic MPLS Setup

Initial configuration , very basic with no MPLS, connectivity only to directly connected interfaces.R1R2R3R4!
!
!
interface Loopback0
ip address 1.1.1.1 255.255.255.255
!
interface FastEthernet0/0
ip address 10.0.31.1 255.255.255.0
duplex auto
speed auto
!
!
!
interface Loopback0
ip address 2.2.2.2 255.255.255.255
!
interface FastEthernet0/0
ip address 10.0.42.2 255.255.255.0
duplex auto
speed auto
!
!
!
interface Loopback0
ip address 3.3.3.3 255.255.255.255
no clns route-cache
!
interface FastEthernet0/0
ip address 10.0.31.3 255.255.255.0
duplex auto
speed auto
  no clns route-cache
!
interface Serial1/0
ip address 10.0.43.3 255.255.255.0
  serial restart-delay 0
no clns route-cache
!
!
!
interface Loopback0
ip address 4.4.4.4 255.255.255.255
no clns route-cache
!
interface FastEthernet0/0
ip address 10.0.42.4 255.255.255.0
duplex auto
speed auto
!
interface Serial1/0
ip address 10.0.43.4 255.255.255.0
  serial restart-delay 0
no clns route-cache
!
adding to the following configuration MPLS labels we will start wi…

VRF Maximum Routes

Maximum routes under customer vrf, if the service provider had unlimited resources he would not have needed that!
however normally resources are limited and expensive, and Service provider would like to make money from his available resources. maximum routes configured under VRF provide a mean of controlling PE local resource and abuse avoidance from the CE side.I have vrf called DC_EXTRANET, you can see that I have 16 routes, I have configured 10 maximum routes under that vrf however I did not want to be aggressive so I have set the warning only option. See that immediately I get a notice that I have more routes then the maximum, however no action is taken other then alerting and sending a syslog. ! PE_ashdod_otherisp.n(config-vrf)# maximum routes 10 warning-only % The current number of routes in the routing table is equal to, or exceeds the configured warning limit PE_ashdod_otherisp.n(config-vrf)# *Nov 26 20:39:41.175: %IPRT-3-ROUTELIMITWARNING: IP routing table limit warning - DC_…

ISIS Database Reading

ISIS is simple to operate normally while everything is working, most common deployments are flat network based on L2, however when there is a problem and we need to start troubleshooting then people start to get lost.So I would like to provide some tools on how to read ISIS database.notice to the “*” sign, that mean LSP was generated on the router you did the show command, you can see that host name from the show command match also host name on the LSPID,LSPID identified by hostname.xx-yy,  xx is normally 00 unless that LSP is pseudo node LSP generated by DIS , yy is representing the number of fragments for that LSP 00 – FF (max 255 fragments, plenty), most cases all the important information will be in 00 unless there are many fragments.LSP Holdtime is the amount of time an LSP will stay in database without any refresh.ATT/P/OL - 0/0/0, ATT bit or attached bit is used on L1/L2 connected to L1 node, if set to 1 L1 node will generate default route to the best L1/L2 node (best metric)AT…