Latest posts
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BGP – Path Selection Criteria
Below is the BGP path selection criteria. 1. Highest Weight 2. Highest local preference 3. Locally generated routes 4. Shortest AS Path 5. Origin Code 6. Lowest MED 7. eBGP over iBGP 8. Lowest IGP metric to the BGP next hop. 9. Oldest Route in case of ebgp 10. BGP router with the lowest…
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IPsec configuration example
PC1:- PC1> show ip NAME : PC1[1] IP/MASK : 10.1.1.10/24 GATEWAY : 10.1.1.1 DNS : MAC : 00:50:79:66:68:00 LPORT : 10005 RHOST:PORT : 127.0.0.1:10004 MTU: : 1500 R1:- interface FastEthernet0/0 description *** Connected to R2 *** ip address 12.12.12.1 255.255.255.0 no shut interface FastEthernet2/0 description *** Connected to PC1 *** ip address 10.1.1.1 255.255.255.0 no…
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Link termination requirement
Below are the requirement to terminate a link. Router model Router Rack details Power and rack availability Dual or single power supply devices constraints WAN link media type WAN link Bandwidth details Routing protocol on WAN link WAN and LAN port details LAN port media type Patching details Transciever availability WAN and LAN subnet details.…
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VPC between nexus 5510 and 5548?
VPC between 5510/5520 and 55xx is not supported whereas VPC between other 55xx models are supported. In other words 5510/5520 cannot be peer with any Nexus 5k series. Both have below different ASICs and have different CFS messages which are not compatible. 5010/5020 – gatos asic 5548/5596 – carmel asic
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Weight attribute – BGP
Below are the characteristics of weight:- 1. Manipulate Outgoing traffic 2. Cisco Proprietary 3. Only applicable when two exit points are on single router. 4. Never advertise out from router and will remain local to router. 5. Higher is preferred 6. Range is 0 – 65535. 7. When using Route-map to manipulate weight then it…
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BGP Attribute – MED
In the below topology, Traffic is asymmetric as outgoing taffic from R1 is going via R2 -> R5 ->R6 whereas Incoming traffic is coming from R6-> R4 ->R3->R1 To remove asymmetric routing, we need to manipulate the incoming traffic. MED is used on R3 so that R6 will always prefer the path from R5 R1:-…
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BGP Attribute – AS Prepend
In the below topology, Traffic is asymmetric as outgoing taffic from R1 is going via R2 -> R5 ->R6 whereas Incoming traffic is coming from R6-> R4 ->R3->R1 To remove asymmetric routing, we need to manipulate the incoming traffic. AS-Prepend to be done on R3 so that R6 will always prefer the path from R5.…
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BGP Attribute :- Local Preference
R1:- interface Loopback0 ip address 1.1.1.1 255.255.255.255 interface FastEthernet0/0 description ” Connected to R2″ ip address 12.12.12.1 255.255.255.0 no shut interface FastEthernet0/1 description ” Connected to R3″ ip address 13.13.13.1 255.255.255.0 no shut interface FastEthernet2/0 description ” Connected to PC1″ ip address 10.1.1.1 255.255.255.0 no shut router bgp 1 no synchronization bgp log-neighbor-changes network 10.1.1.0…
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iBGP Multipath
R1 interface Loopback0 ip address 1.1.1.1 255.255.255.255 interface FastEthernet0/0 description ” Connected to R2″ ip address 12.12.12.1 255.255.255.0 no shut interface FastEthernet0/1 description ” Connected to R3″ ip address 13.13.13.1 255.255.255.0 no shut interface FastEthernet2/0 description ” Connected to PC1″ ip address 10.1.1.1 255.255.255.0 no shut router bgp 1 no synchronization bgp log-neighbor-changes network 10.1.1.0…
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BGP attributes – Well known vs Optional
Well Known :- All BGP implementations must understand and support it. It cannot be ignored. Mandatory:- Must be present in all update and all will support it Discretionary:- It can or cannot be present in update(optional) but all implementations must support it. Optional:- It is not mandatory to include and support it. Transitive:- Can travel…