ditrapanij
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Prefix list BGP 0.0.0.0/0 and 0.0.0.0/ le 32
7 votes

ip prefix-list out seq 10 permit 0.0.0.0/0 will match only a default route (0.0.0.0/0) whereas ip prefix-list out seq 10 permit 0.0.0.0/0 le 32 will match anything thats within 0.0.0.0/0 with a prefix ...

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Is it possible to specify a route for a packet to take?
7 votes

Routing is done on an end to end basis. This means, each router along the path needs to make its own individual routing decision based on which path that Router thinks is the best. Fortunately, ...

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BGP prefix filtering mismatch between peers
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6 votes

BGP prefix lists evaluate an exact match when not using le or ge statements on the end. For example, when your prefix list includes only ip prefix-list PREFIX-FROM-A seq 15 permit 192.168.0.0/24, your ...

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How to block advertisement of a prefixes recieved from 1 BGP neighbor to another
Accepted answer
6 votes

As mentioned by Ron, you can use no-export (Don't advertise to any eBGP peers) or no-advertise (Don't advertise to iBGP or eBGP peers) to achieve this. However, this may strain scalability issues if ...

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BGP running on VLAN interface or loopback0?
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5 votes

It is always recommended in BGP best practices to peer with loopback addresses for iBGP peers as we no longer have to rely on a single physical interface (or in your case a VLAN SVI) to be up/up. As ...

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How can a server from US connect to a tier 1 ISP?
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5 votes

Is there fibers over the ocean ? They're more under the Ocean but absolutely, you can see a somewhat accurate map of them here. These undersea cables are how continents are interconnected and will ...

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If I’m an ISP, would I be assigning customer addresses from PI or PA space?
Accepted answer
4 votes

Firstly, it's important to understand who allocates each address space. PI (Provider Independent) are assigned by a local RIR (RIPE, APNIC, AFRINIC, ARIN, etc) to a Provider/Business/Entity. Whereas ...

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Finding the right BFD timers between Juniper QFX5110 and Cisco ASR1000
4 votes

I strongly recommend you look at upgrading your IOS to something a lot more recent as IOS XE 3.16 is no longer in support for Security Vulnerabilities as of August 2016. For your reference, I have an ...

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Understanding BGP communities
3 votes

Communities are usually applied to prefixes via route-maps. In your example, RouterA may have something like this: route-map to-router-b permit 10 description Tag Prefixes with Community match ip ...

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What's the BGP route `active received accepted damped` status meaning?
Accepted answer
3 votes

The Juniper documentation here actually words this well. In summary, that is a multipurpose field used to display information about BGP peer sessions. The field’s contents depend upon whether a ...

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eBGP failover without packet drops
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3 votes

Modify your Local Preference inbound on the eBGP relationship to the ISP on Core2 to be greater than 100. You will also need to add a route-map to AS-PATH prepend your prefix to the eBGP neighbour on ...

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Are the submarine cables used only for internet?
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3 votes

It depends what you define as the "Internet", If by the "Internet" you mean the large mesh of publically routable IP space then no. These cables can also be used to provide direct private optical ...

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TCP sequence numbers in Actual Transmission vs. in Wireshark Capture
Accepted answer
3 votes

This is known as a TCP sequence prediction attack. There is a RFC defined to defend against it, RFC6528 In a nutshell, some vendors are responding to the threat by introducing random sequence number ...

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Wireshark captures TCP packet with no flag
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3 votes

A TCP flag is used in a packet to identify a connection state or provide further information to the receiving party, common examples include SYN, ACK, RST, FIN + more. In your instance, you've come ...

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Interface VLAN IP address not on exclude list?
3 votes

No, the router is smart enough to not hand out is own IP address.

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Routing IPs through another ASN
2 votes

Yes this can be done however, you will need to engage your ISP regardless as this is completely dependant on your ISPs network design and capabilities. For example, with permission your ISP may allow ...

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nexus n3k %ACLQOS-SLOT1-4-ACLQOS_OVER_THRESHOLD alert
2 votes

As per Cisco Documentation, this warning is informing you that you are maxing the TCAM resource allocation for a specific feature. You should be able to see your utilisation/allocation per feature via:...

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Extract upstream/downstream ASNs from BGP table path
2 votes

You need to remember that an AS path is relative to the network you're sourcing from. In your above example, just because AS24218 is to the left of Vocus (AS4826), doesn't necessarily mean they're an ...

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Get ASN Upstreams/Downstreams/Peers
2 votes

Comparing this RIPE RIS data with data I can verify, It seems that their data counts left as Upstreams/Transit providers and right as customers. It seems that uncertain may also be Bilateral peers on ...

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Internet Scale Routing Table Size
Accepted answer
2 votes

I want to know that it is a must for ISP routers to cache all these million IPv4 entries? No. However, ISP's & CDN's wanting to run within a DFZ (Default Free Zone) will usually hold all of these ...

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JunOS, access mode interface asks for a vlan
2 votes

set interfaces xe-0/0/24 unit 0 family ethernet-switching interface-mode access Since you're setting the port to be an access port, the switch requires you to set the access VLAN of the port using ...

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how do hackers get public ip off packet sniffing
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2 votes

your computer send the packet to your router, which gonna change the destination ip for the server of the app Layer 3 information (source IP & destination IP) are end-to-end and do not change ...

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BGP Cisco best practices to filter client asn and prefixes
1 votes

Given the customer of yours is a single ASN with a /24 prefix, it would be in your best interest to simply apply a prefix-list (Always better to assign the prefix-list within a route-map to allow ...

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Policy Based Routing by Interface and IP
1 votes

PBR in Juniper land is called Filter Based Forwarding. FBF uses ingress firewall filters to match and move traffic into a forwarding routing instance. What you could do here assuming you're on a MX or ...

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Arista Automation Script 7050S
1 votes

Firstly, without knowing too much about your environment I feel like you're going about this the wrong way, this is the exact reason (well, one of many) why dynamic protocols exist (e.g. STP, BGP or ...

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Do subnets need a router between them to communicate or can multiple subnets communicate from within the same router?
Accepted answer
1 votes

As per Network fundamentals, a Layer 3 gateway is required to exit a broadcast domain. This can be in the form of a subinterface, SVI or even just two raw interfaces. For example: interface Gig0/0/1 ...

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What is ethernet length/type 0x9104
Accepted answer
1 votes

Based on the Wireshark source here, this is a broadcast packet sent by the EERO: 0x9104 /* EERO: broadcast packets sent by EERO MESH AP's (not officially registered) */

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IP Helper in Multiple Access Switches
1 votes

IP Helpers are used to translate a DHCP Broadcast into a Unicast message to be forwarded outside of a Broadcast domain. As a result, this helper needs to be configured on the edge of the Broadcast ...

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PVC not Accepted by CISCO 878
1 votes

You can show the maximum supported PVC's for a device by checking the output of show atm interface ATM0. I suspect you will be limited to 4 VC's with a maxiumum of 1024 VCI's per VPI. If this is the ...

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Getting network traffic of a remote IP?
Accepted answer
1 votes

To answer your question bluntly, no. To "sniff" traffic to/from a destination you must be on the sending end, receiving end or somewhere along the path. If you were wanting to find out the IP's of ...

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