Categories R&S

OSPF – Implement and troubleshoot filtering – Distribute-list

Following our path through the CCIEv5 topics, let’s move on to the OSPF Implement and troubleshoot filtering series.   We will start with distribute-list.   Theory: With an inbound distribute-list, we can affect the local routing table to prevent routes to be inside a routing table.   Requirements : Make sure R5 loopbacks 10,11,12 are […]

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Categories R&S

OSPF – Implement and troubleshoot route summarization – External summarization

Let’s now have a look at external summarization.   Theory: This is specific to external routes redistributed in OSPF. We need to implement this on the router that is doing the redistribution.   Requirements: Create three new loopbacks on R5 (Lo 10,11,12) and R6 (Lo 10,11,12). Make sure those new IP addresses are summarize in […]

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Categories R&S

OSPF – Implement and troubleshoot route summarization – Internal summarization

Let’s move to route summarization. First internal summarization.   Theory: OSPF can summarize LSA type 3 on an ABR.   Requirements: Use internal summarization so that R3 prefer to go through R1 when trying to reach R6 ip 172.10.1.17   Diagram:   Configuration and verification: For testing purpose we will create some new loopback interfaces […]

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Categories R&S

OSPF – Implement and troubleshoot authentication – SHA authentication

Let’s finish this authentication series by having a look at the strongest one.   Theory: HMAC-SHA algorithms for cryptographic authentication with OSPFv2 is defined in RFC 5709. Note that as per Cisco config guide, this features was release in IOS version 15.4(1)T.   Requirements: Configure OSPF HMAC-SHA based authentication in area 0.   Diagram:   […]

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Categories R&S

OSPF – Implement and troubleshoot authentication – MD5 authentication

Let’s continue our CCIE R&Sv5 study with more OSPF authentication.   Requirements:   Configure OSPF authentication in area 2 using MD5 and key CISCO.   Diagram:   Configuration and verification: Let’s start by R4. Because R4 has all his interfaces in area 2, we will enable the authentication at the OSPF process level. Still we […]

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Categories R&S

OSPF – Implement and troubleshoot authentication – Clear text authentication

Let’s move on to OSPF authentication. First, basic clear text authentication.   Theory: OSPFv2 supports three types of authentication: Type 0= null authentication (no authentication) Type 1= clear text authentication Type 2= MD5 authentication or HMAC-SHA authentication.   Requirements: Configure OSPF clear text authentication between R6 and R7.   Diagram:   Configuration and verification:   […]

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Categories R&S

OSPF – Implement and troubleshoot path preference – Non backbone transit areas

Theory: From the Cisco website: « The OSPF Area Transit Capability feature is enabled by default. RFC 2328 defines OSPF area transit capability as the ability of the area to carry data traffic that neither originates nor terminates in the area itself. This capability enables the OSPF ABR to discover shorter paths through the transit area […]

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