Saturday, July 21, 2018

Cisco and Huawei Command references

Route XP
Cisco and Huawei Command references

This is one of the interesting topic where a network using both of the devices in a enterprise shell and want the skills of both routers so that admin can execute the commands for Cisco and Huawei routers. It's a new world where the best of the devices are mixed in the network to get the best practices in the network design.

Although the network is more now moving to the cloud or automation but the concept of the CLI is the major in today's network as many of the devices are still on the CLI based commands which is executed manually in the devices.

You can also share the information like the command lines for Cisco-Juniper, Cisco-Alcatel, Hauwei-Juniper, Huawei-Alcatel and Alcatel-Juniper commands lines with us as well.

Today i am discussing about the CLI commands of these devices as Cisco and Huawei and how they are differ from each other in the commands. Lets have a look on this. If you guys have more commands information between Cisco and Huawei please share with us, so that same can be share with the people around the world.

Fig 1.1- Cisco and Huawei Commands

Above is the some of the commands of Cisco and Huawei that how they differ from each other when used in the Cisco and in Huawei.

Please let me know if i am wrong somewhere so that we can edit and also please share if you have any other information regarding the comparison of the commands between them.

BGP Route Aggregation

Route XP
BGP Route Aggregation

Today, i am going to have the discussion on the topic called as " BGP Route Aggregation". There are many instances in the network where you really want this BGP route aggregation should be there. May be you want to have the aggregated routes not the specified routes from the other networks.

So now question is Why we required " BGP Route Aggregation" in the Network ?
Well there are lot of reason for it, some says you have lot of routes specific from the same network and needs to avoid the same, so they want route aggregation in the network. Some says it is way to shorten the multiple routes in the routing tables. It also saves the CPU utilisation on the device itself.

Where these kinds of Scenario used ?
Like if we have the cases where service provider have so many routes on the PE router and you knew you have so many customers connected to your one PE route and you limit the routes ( may be 50 ) from the customer network and customer is asking for more than 50 routes may be there are lot of routes which are specific routes then you can limit them by using the long IP prefix routes or called as aggregated routes which can accommodate all the specific routes in a one route.

Below is an sample topology showing the route aggregation on Router R2
Fig 1.1- Sample Topology BGP Route Aggregation

Well all the points which is discussed above it right, For example, for the aggregate destination, routes to and are contributing routes, but routes to and are not.

Route aggregation helps to minimizing the number of routing tables in an enterprise IP network which means, it consolidates selected multiple routes into a single route advertisement in which every routing table contains a unique entry for each route.

On the router which does the aggregation, this technique does not help in reducing the size of the routing-table. Whereas when you configure an export policy which only advertises the aggregate but not the contributing routes anymore, you would have the aggregation effect on the routers which receive updates.

A route can contribute only to a single aggregate route. However, an active aggregate route can recursively contribute to a less specific matching aggregate route. For example, an aggregate route to the destination can contribute to an aggregate route to
When an aggregate route becomes active, it is installed in the routing table with the following information:

  • Reject next hop—If a more-specific packet does not match a more-specific route, the packet is rejected and an ICMP unreachable message is sent to the packet’s originator.
  • Metric value as configured with the aggregate statement. 
  • Preference value that results from the policy filter on the primary contributor, if a filter is specified.
  • AS path as configured in the aggregate statement, if any. Otherwise, the path is computed by aggregating the paths of all contributing routes. 
  • Community as configured in the aggregate statement, if any is specified.
So let us suppose we have one AS 400. we have neighbor BGP addresses are connected to AS 500, while neighbour is connected to AS 600, Neighbour connected to AS 700 and we got 3 routes named and received from AS 800. For the routes coming from AS 800 we need aggregated routes then we need populate the in the BGP configuration as below.

router bgp 400
neighbor remote-as 500
neighbor remote-as 600
neighbor remote-as 700
aggregate-address summary-only


Let's check the configuration now.

Router# show ip bgp 
BGP table version is 6, local router ID is X.X.X.X
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network          Next Hop            Metric LocPrf Weight Path
*>                            32768 i      <-----Aggregated Route
s>                  0             0 200 i   <-----Specific Route
s>                  0             0 100 I   
<-----Specific Route

Hope the above example will clear your concept on " BGP Route Aggregation concept". Now you know which routes can be aggregated and how these routes can be done as route-aggregated routes.

Tuesday, July 3, 2018

Cisco Datacenter: vPC ( Single and Double Sided vPC)

Route XP
Cisco Datacenter: vPC ( Single and Double Sided vPC)

Lets talk about the two different scenarios in Cisco Datacenter environment. The two different concept of vPC called single-sided vPC and Dual sided vPC.

We have two different deployment scenarios for vPC in the datacenter as
  • In the single datacenter environment we can use Single-sided vPC (access layer or aggregation layer) or we can go with the scenario Double-sided vPC, also called multilayer vPC (access layer using vPC interconnected to aggregation layer using vPC)
  • In the multi datacenter environment we can have Multilayer vPC for Aggregation and DCI or we can have and Dual Layer 2 /Layer 3 Pod Interconnect.
Let's start discussion on every deployment methods

Single-Sided vPC: In single-sided vPC, access devices are directly dual-attached to pair of Cisco Nexus 7000 Series Switches forming the vPC domain
The access device can be anything like L2 switches, rack mount or blade servers , Load balancers, firewalls or any storage devices. The end device which is an access device will have to support the port-channel connection between them. The Bundling can be LACP mode active, LACP mode passive and static bundling- mode on. There are some recommendations using LACP protocol connecting to the vPC domains.
  • vPC with Cisco Nexus M1 Series module line-card: 16 active member ports (8 on peer device 1 and 8 on peer device 2)
  • vPC with Cisco Nexus F1/F2 Series module line card: 32 active member ports (16 on peer device 1 and 16 on peer device 2)
Fig 1.1- vPC -Single and Double Sided vPCs

Double-Sided vPC: In Dual sided vPC where you have the two different vPC domain from distribution to Access layer parent switch and other vPC domain from parent access switch to the FEX devices you can say. vPC domain at the bottom is used for active/active connectivity from endpoint devices to network access layer. vPC domain at the top is used for active/active FHRP in the L2/L3 boundary aggregation layer

Benefits of double-sided vPC over single-sided vPC topology are listed below:
  • Enables a larger Layer 2 domain.
  • Provides a higher resilient architecture. In double-sided vPC, two access switches are connected to two aggregation switches whereas in single-sided vPC, one access switch is connected to two aggregation switches.
  • Provides more bandwidth from the access to aggregation layer. Using a Cisco Nexus F1 or F2 Series modules line card for vPC and Cisco Nexus 5000 Series Switches
we can further discuss on Multilayer vPC for Aggregation and DCI in another post. Keep connected and supported. Check out the other story on vPC as well
vPC Story

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