Author Archives: cyruslab

Small office requirement Set up PaloAlto1 and 2 to be active passive HA. Set up SW5 and SW6 as HSRP routers, vlan 100 towards the external and vlan 10 towards the internal. HSRP for vlan 10 and vlan 100. SW4 … Continue reading

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BGP attributes: Weight

Facts about BGP weight attribute Cisco proprietary. Only available for Cisco routers, this attribute is not included in BGP update message. Because it is not included in update message, this attribute is only locally significant to one router. Because it … Continue reading

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Is full meshed iBGP necessary?

Revisit the configuration of the iBGP routers R2#sh run | s r b router bgp 2 bgp log-neighbor-changes neighbor 3.3.3.3 remote-as 2 neighbor 3.3.3.3 update-source Loopback2 neighbor 3.3.3.3 next-hop-self neighbor 4.4.4.4 remote-as 2 neighbor 4.4.4.4 update-source Loopback2 neighbor 4.4.4.4 next-hop-self … Continue reading

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IP routing with BGP

Problem 1: Did not receive prefix advertised by BGP peer. R2#sh ip bgp summary BGP router identifier 2.2.2.2, local AS number 2 BGP table version is 1, main routing table version 1 Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ … Continue reading

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Solving routing loop problem due to poorly configured redistribution

The diagram Routing loop when vIOS2 (R2) is trying to reach 1.1.1.1 in vIOS1 (R1) R2#traceroute 1.1.1.1 numeric Type escape sequence to abort. Tracing the route to 1.1.1.1 VRF info: (vrf in name/id, vrf out name/id) 1 192.168.23.3 4 msec 4 … Continue reading

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Administrative distance

Administrative distance (AD) influences the decision on which routing protocol the router should trust: AD can be modified. AD is only locally significant to the router, other router’s AD of routing protocol might be modified. Router will use the routing … Continue reading

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Classless routing vs classful routing

Router routes traffic based on the longest prefix, and cannot find any match traffic will be dropped. Classless routing The routing that we normally understand is classless routing. Let’s explore the routing tables of R1 and R2. R1 pings to … Continue reading

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