Jeff Wheeler
  • Member for 1 year, 10 months
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Does UDP do anything at all?
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61 votes

Interesting perspective and question! Yes, most of what UDP does is supply a standard means for multiple applications to co-exist using the same IP address, by defining the concept of UDP ports. The ...

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What is this device used by a networking technology company?
17 votes

They're a fiber splicing crew. The white plastic trays are used to organize fiber connections. A waterproof enclosure will protect the whole assembly from debris when their job is finished, and the ...

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How to setup self hosting with redundant Internet connections?
13 votes

In your question, you're broadly describing the concepts implemented by Border Gateway Protocol (BGP), a signaling protocol "big" Internet routers use to coordinate the Internet routing ...

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Difference between Reverse Proxy and Port Forwarding
6 votes

Port forwarding describes a layer-4 mechanism, operating on TCP connections or UDP packets without necessarily understanding the application data. Reverse proxy suggests a higher-layer (this is where ...

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Why does Ethernet use EtherType field to determine what type of packet is in a frame instead of just looking at the packet header?
6 votes

This is a fun question with a lot of history. Originally, the EtherType field indicated the length of the frame; not the type of payload. The relevant Wikipedia article contains a good explanation ...

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What layer 2 encryption can I run over a leased line with the underlay (MP-BGP with MPLS on top if it)?
5 votes

MACsec is an option if your vendor is supplying layer-2 transport and your switches support enough MACsec configuration flexibility to be compatible with your transport provider's network. Normally, ...

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Is it possible to move a persistent TCP connection?
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5 votes

Yes, it is possible, but requires support from the operating system. You've also got to ensure packets for the affected TCP connection are directed to the right host post-connection-migration. This ...

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Why eBGP don't need config local-address?
5 votes

In almost all situations, iBGP sessions should be between loopback addresses. To achieve this, you must configure a local-address. In almost all situations, eBGP sessions should be between interface ...

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Capturing LACP PDUs in an aggregated link on Juniper MX
5 votes

show lacp interfaces <aeX> displays detailed state information for each member-link in a LAG. For example: user@router> show lacp interfaces ae0 extensive LACP state: Role Exp Def ...

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Is it possible to filter directly connected networks redistribute with BGP based on a peer basis?
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5 votes

Yes, absolutely; there are a variety of ways to accomplish this. I'll suggest two just to give you some inspiration. Match Protocol option On your route-map toward the BGP neighbors, you can match ...

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What is the difference between Targeted LDP and Directed LDP in MPLS?
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5 votes

Directed LDP is not a term that appears in the LDP specification (RFC 5036.) Perhaps you're trying to understand the difference between Basic Discovery which uses LDP Link Hellos and Extended ...

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What could go wrong if I use public IP range for intranet?
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5 votes

They'll accidentally allow public IP traffic through ACLs and reduce the effectiveness of their perimeter security design. They'll also make parts of the real Internet inaccessible to themselves. The ...

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Is TCP's MSL value equivalent to IP's TTL value?
5 votes

TCP MSL isn't a field carried in packets/segments. It's a time interval used by the TCP state-machine. The values and their uses are very different. IP TTL is mainly needed for loop prevention, ...

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Cisco ACL Entries
4 votes

That's correct -- the ACL doesn't consume additional TCAM space as you apply it to more interfaces.

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CB fabric links require upgrade/training after adding New FPC in Juniper MX480
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4 votes

When upgrading a fabric e.g. from SCB to SCBE, there is a process to train the fabric links so they operate at higher speed. The require upgrade/training alarm is documented in the related upgrade ...

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Many ways of configuring MPLS pseudowires, and choosing only one
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4 votes

vlan 50 method of configuration consolidates all related statements onto the PE-CE logical interface. This is the easiest to understand if you are configuring manually or doing any kind of ...

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BGP (RIB-Failure - Higher admin distance)
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4 votes

The rib-failure is telling you the learned BGP route isn't best because there is another route -- in this case, directly connected routes -- with a better Admin Distance (AD). On R1 & R3 there is ...

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What's the meaning of `unit 0` and `family ethernet-switching`?
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4 votes

It helps to look at a different kind of Junos interface configuration and compare. The reason for unit <n> is to allow multiple, logical subinterfaces (IFLs) to exist within a given physical ...

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Juniper keeps a received BGP prefix in hidden state when the BGP next-hop is overwritten to a static route
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4 votes

The problem is lack of accept-remote-nexthop configuration on the BGP neighbor. Junos is applying your ingress policy-statement, then doing a validation check. This probably isn't how it should work ...

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What are the differences between injecting the default route to IGP using a static route or using a generated route?
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4 votes

Static route This route will be installed as long as its next-hop is reachable. The default route Preference is 5. Static routes are simpler and are appropriate when there's no routing protocol ...

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If you have multiple domains pointing to the same IP address, can you see which domain a packet was sent to?
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4 votes

Application-layer protocols such as HTTP generally have this capability. At the network layer, no, you can't tell.

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Will IPv6 make private IP addresses become obsolete?
4 votes

Yes, IPv6 NAT is possible. Juniper Junos, for example, supports generally similar features for IPv6 as it has for IPv4. You may wish to read about IPv6 Unique Local Addresses. Many will argue that 6-...

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Inconsistent address and mask error
4 votes

The error message is indicating the host bits of the address are not all-zero. For a /24 network (netmask 255.255.255.0) the last byte should be zero when configuring a routing table entry. For ...

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Why is accurate time important with networking?
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4 votes

The specific failures you're talking about were likely caused by SSL/TLS certificates which had notBefore or notAfter dates. These determine the time-span during which the cert is valid. If your ...

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How to judge whether a Juniper device is a PPC platform device?
Accepted answer
3 votes

I'm not aware of an official way using the CLI/API, unless you want to populate a table of routing-engine part numbers and map those to CPU architecture. Another method likely to work is run uname -a ...

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Why does STP choose the lowest bridge ID as the root bridge?
3 votes

The bridge priority (and other xSTP priority parameters) is user-configurable.

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Cisco N3K-C3064 RACL question
3 votes

No, you don't have enough room for 270 more Ingress Router ACL entries (216 free). Here is a Cisco document explaining the different ACL types on Nexus 3000. It looks like you're trying to reproduce ...

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How does RIRs actually ensure IP ranges ownership
3 votes

RIPE publishes a database indicating who is authorized to use address space. Other RIRs have similar databases. Outside entities also operate IRR databases for routing information. These systems ...

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What is difference between Route object and AS-SET object in RIRs?
3 votes

A route: object should include an origin: AS<x> attribute associating the route with its BGP origin AS. You can create multiple route objects to announce the same prefix from multiple ASNs. An ...

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

Customer address pools & re-assignments come from PA space. You can use PI for your own network/business but it's not intended to be delegated to customers.

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