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وب سایت شخصی مهندس رامین ملک قاسمی

مقالات شبکه و کامپیوتر

بايگاني براي اکتبر, 2017

SuperNet چیست

https://network.itpro.ir/articles/27462/supernetting-%DA%86%DB%8C%D8%B3%D8%AA%D8%9F

نوشته شده به وسيله ramin_malek در BGP ، دیدگاه‌ها برای SuperNet چیست بسته هستند

BGP Aggregates تجمیع کننده Prefix

https://wiki.mikrotik.com/wiki/Manual:BGP_Case_Studies

 

 

هر چی prefix خرد باشد الویت Route بالاتر باشد

هر چه Subnet

more specific تر باشد داره الویت بیشتری است

نوشته شده به وسيله ramin_malek در BGP ، دیدگاه‌ها برای BGP Aggregates تجمیع کننده Prefix بسته هستند

weight in bgp

The first attribute is weight. It is a Cisco proprietary attribute that is locally significant. It is an ultimate tool for route control on a Cisco BGP router. It is evaluated before any other attribute, and a higher value wins. So, if you want to make sure that prefixes learned from certain neighbors always have preference, you can just assign a weight to those neighbors and be sure that paths via those neighbors will be preferred over the others.

نوشته شده به وسيله ramin_malek در BGP ، دیدگاه‌ها برای weight in bgp بسته هستند

Local preference

The second attribute is a local preference. This is a standard, well-known transitive attribute. “Transitive” means that it is one of the attributes that travel with the route to the neighbors. And the word “local” in its name means that it only travels within its own AS and doesn’t get propagated outside of it. The default value for local preference is 100. But what happens to the prefixes that are being learned via EBGP neighbors? As I said before, local preference attribute is not passed across the AS boundary. So, a prefix received from EBGP neighbor won’t have any local preference attached to it

نوشته شده به وسيله ramin_malek در BGP ، دیدگاه‌ها برای Local preference بسته هستند

Show ip bgp neighbers

https://supportforums.cisco.com/t5/wan-routing-and-switching/question-show-ip-bgp-neig-and-advertised-routes/td-p/1353266

نوشته شده به وسيله ramin_malek در BGP ، دیدگاه‌ها برای Show ip bgp neighbers بسته هستند

Bgp preprend

What is BGP As-path prepending ? 

BGP As-path prepending is used to influence inbound traffic to the company. Outbound traffic is usually done via BGP local preference attribute or BGP hot-potato routing.

BGP As-path prepending is used in active-standby link scenarios. When there are two BGP neighborship which prefix will be advertised, one link for set of prefixes or maybe all the prefixes can be used as backup. In this case, one way to achieve this setup is using BGP AS-path prepending

با این صفت می شود مسیر  ترافیک ورودی به شبکه رو کنترل کنیم

inbound Traffic

 

 

Example

 

No preprend

AS path: xxx47 xxx02 Your -AS

 

Set Preprend 5

xxx47 xxx02 YOUr-AS YOUr-AS YOUr-AS YOUr-AS YOUr-AS

در حالتی که 5 گذاشنه شود 5 بار شماره

AS به مسیر As-path اضافه میشود پس چون در bgp کوتاهترین مسیر انتخاب می شود مسیر بدون preprend یا با preprend کمتر برای ترافیک ورودی به شبکه ما انتخاب می شود

 

 

نوشته شده به وسيله ramin_malek در BGP ، دیدگاه‌ها برای Bgp preprend بسته هستند

portfast and portfast trunk in cisco

First of all PortFast is Cisco proprietary.
PortFast can negatively effect DHCP services.

PortFast is used to more quickly prevent and eliminate bridging loops.
You can use PortFast to connect a single end station or a switch port to a switch port. If you enable PortFast on a port that is connected to another Layer 2 device, such as a switch, you might create network loops.

And Spanning-tree portfast trunk should never be used on switch interconnects because with switch interconnects you want STP to make sure there is no loop before forwarding.
You can configure This command is really designed for servers which are running 802.1q on their NICs and which can transition to forwarding immediately.

نوشته شده به وسيله ramin_malek در Cisco ، دیدگاه‌ها برای portfast and portfast trunk in cisco بسته هستند

Set Time and date in centos

https://www.garron.me/en/linux/set-time-date-timezone-ntp-linux-shell-gnome-command-line.html

نوشته شده به وسيله ramin_malek در Linux ، دیدگاه‌ها برای Set Time and date in centos بسته هستند

Cisco bgp explain

http://docwiki.cisco.com/wiki/Border_Gateway_Protocol

نوشته شده به وسيله ramin_malek در BGP ، دیدگاه‌ها برای Cisco bgp explain بسته هستند

CDN toplogy

Different CDN technologies: DNS Vs Anycast Routing

نوشته شده به وسيله ramin_malek در هاستینگ ، دیدگاه‌ها برای CDN toplogy بسته هستند

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