CCNP Equal Cost Multi Path (ECMP)

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(→‎Polarization)
 
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=CEF with EtherChannel=
 
=CEF with EtherChannel=
 
From: [http://www.cisco.com/c/en/us/support/docs/lan-switching/etherchannel/12023-4.html#catalyst Understanding EtherChannel Load Balancing and Redundancy on Catalyst Switches] paragraph [http://www.cisco.com/c/en/us/support/docs/lan-switching/etherchannel/12023-4.html#catalyst Catalyst 3560]
 
From: [http://www.cisco.com/c/en/us/support/docs/lan-switching/etherchannel/12023-4.html#catalyst Understanding EtherChannel Load Balancing and Redundancy on Catalyst Switches] paragraph [http://www.cisco.com/c/en/us/support/docs/lan-switching/etherchannel/12023-4.html#catalyst Catalyst 3560]
−
You can find out which interface is used in the EtherChannel to forward traffic based on the load balancing method. The command for this determination is  
+
 
 +
You can find out which interface is used in the EtherChannel to forward traffic based on <br>
 +
the load balancing method. The command for this determination is  
 
  test etherchannel load-balance interface port-channel number {ip | mac} [source_ip_add | source_mac_add] [dest_ip_add | dest_mac_add]
 
  test etherchannel load-balance interface port-channel number {ip | mac} [source_ip_add | source_mac_add] [dest_ip_add | dest_mac_add]
  
 
Example:
 
Example:
−
 
+
  6509-sp#'''test etherchannel load-balance interface port-channel 1 mac 00d0.c0d7.2dd4 0002.fc26.2494'''
 +
  Would select Gi6/1 of Po1
 +
  6509-sp#
  
 
----------------
 
----------------
Line 187: Line 191:
 
### END ###
 
### END ###
 
</pre>
 
</pre>
 +
On 6500--PFC-3C system with src-dst-ip enhanced algorithm:
 +
 +
    PFC-3C#show etherchannel load-balance hash-result interface port-channel
 +
    1 ip 10.1.1.1 vlan 10 10.2.2.2
 +
 +
    Computed RBH: 0x1
 +
    Would select Gig3/2 of Po1
 +
 +
 +
In the end let me just share with you command to verify transmitters of Catalyst 4500 and 2k/3k respectively:
 +
 +
“show platform software etherchannel port-channel 5 map ip 1.1.1.1 1.1.1.2”
 +
“test etherchannel load-balance interface port-channel 1 ip 1.1.1.1 1.1.1.2”
 +
From: [http://packetpushers.net/understand-etherchannel-load-balancing-catalyst-switches/ packetpushers.net]
  
 
=dCEF=
 
=dCEF=
Line 200: Line 218:
 
[http://www.gossamer-threads.com/lists/cisco/nsp/140211 http://www.gossamer-threads.com/lists/cisco/nsp/140211]
 
[http://www.gossamer-threads.com/lists/cisco/nsp/140211 http://www.gossamer-threads.com/lists/cisco/nsp/140211]
  
−
=NEXT2=
+
=First Try on 7609 to 6504, 10 GBE=
−
bbb
+
<pre>
−
=NEXT3=
+
Leaf3-7609#
 +
Leaf3-7609#show ip cef exact 10.33.33.33 10.11.11.11 detail
 +
10.33.33.33    -> 10.11.11.11    : TenGigabitEthernet8/1 (next hop 10.1.1.1)
 +
Leaf3-7609#
 +
Leaf3-7609#show ip cef exact 10.33.33.33 10.11.11.11
 +
10.33.33.33    -> 10.11.11.11    : TenGigabitEthernet8/1 (next hop 10.1.1.1)
 +
Leaf3-7609#
 +
 
 +
Leaf3-7609#show running | beg ospf
 +
router ospf 1
 +
log-adjacency-changes
 +
network 10.0.0.0 0.255.255.255 area 0
 +
!
 +
 
 +
!
 +
interface TenGigabitEthernet8/1
 +
ip address 10.1.1.3 255.255.255.0
 +
end
 +
 
 +
 
 +
 
 +
Leaf3-7609#
 +
Leaf3-7609#show ip cef state
 +
                        ^
 +
% Invalid input detected at '^' marker.
 +
 
 +
Leaf3-7609#show ip cef ?
 +
  A.B.C.D            prefix of entries to show
 +
  Async              Async interface
 +
  CTunnel            CTunnel interface
 +
  Dialer              Dialer interface
 +
  GigabitEthernet    GigabitEthernet IEEE 802.3z
 +
  Group-Async        Async Group interface
 +
  Loopback            Loopback interface
 +
  MFR                Multilink Frame Relay bundle interface
 +
  Multilink          Multilink-group interface
 +
  Null                Null interface
 +
  Port-channel        Ethernet Channel of interfaces
 +
  Pos-channel        POS Channel of interfaces
 +
  TenGigabitEthernet  Ten Gigabit Ethernet
 +
  Tunnel              Tunnel interface
 +
  Vif                PGM Multicast Host interface
 +
  Virtual-Template    Virtual Template interface
 +
  Virtual-TokenRing  Virtual TokenRing
 +
  Vlan                Catalyst Vlans
 +
  XTagATM            Extended Tag ATM interface
 +
  adjacency          Display all prefixes resolving through adjacency
 +
  detail              Display full information
 +
  epoch              Display epoch information
 +
  events              Show CEF table events
 +
  exact-route        Display exact route for a session
 +
  fcpa                Fiber Channel
 +
  inconsistency      Show table inconsistency information
 +
  non-recursive      Display non-recursive routes only
 +
  summary            CEF table summary
 +
  traffic            Display traffic statistics
 +
  unresolved          Display unresolved routes only
 +
  vrf                Show VPN Routing/Forwarding instance CEF table
 +
  |                  Output modifiers
 +
  <cr>
 +
 
 +
Leaf3-7609#show ip cef 10.33.33.33 ?
 +
  A.B.C.D  prefix mask
 +
  detail  Display full information
 +
  |        Output modifiers
 +
  <cr>
 +
 
 +
Leaf3-7609#
 +
 
 +
Leaf3-7609#show fabric switching-mode
 +
Global switching mode is Compact
 +
dCEF mode is not enforced for system to operate
 +
Fabric module is not  required for system to operate
 +
Modules are allowed to operate in bus mode
 +
Truncated mode is allowed, due to presence of DFC, CEF720, Standby supervisor module
 +
 
 +
Module Slot    Switching Mode
 +
    2                Crossbar
 +
    3                Crossbar
 +
    4                Crossbar
 +
    5                    dCEF
 +
    6                Crossbar
 +
    8                    dCEF
 +
Leaf3-7609#
 +
Leaf3-7609#
 +
 
 +
Leaf1-6504#
 +
 
 +
    1                dCEF
 +
    2                Crossbar
 +
    3                Crossbar
 +
    '''4                Crossbar'''
 +
 
 +
Interface Ten sitter i bladplats 4
 +
</pre>
 +
[http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipswitch_cef/configuration/15-sy/isw-cef-15-sy-book/isw-cef-enhancements.html#GUID-F4F9F79F-354A-4EA8-B48E-4CE651E8BDED http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipswitch_cef/configuration/15-sy/isw-cef-15-sy-book/isw-cef-enhancements.html#GUID-F4F9F79F-354A-4EA8-B48E-4CE651E8BDED]
 +
 
 +
=Polarization=
 +
[https://bethepacketsite.wordpress.com/2016/12/13/reviewperspective-cef-concepts/ Be The Packets – CCIE Study Blog]
 +
 
 +
 
 +
[https://bethepacketsite.wordpress.com/2016/12/13/reviewperspective-cef-concepts/ Review/Perspective: CEF Concepts]
  
−
hej.
+
*1.1.b Identify Cisco express forwarding concepts
 +
**    1.1.b [i] RIB, FIB, LFIB, Adjacency table
 +
**    1.1.b [ii] Load balancing Hash
 +
**    1.1.b [iii] Polarization concept and avoidance

Latest revision as of 10:21, 19 December 2016

Intro

Contents

[edit] Routing - Verifying CEF's 15 hash-buckets

Verification of Configuration 

Leaf-1#show ip route
Gateway of last resort is not set


      10.0.0.0/8 is variably subnetted, 10 subnets, 2 masks
C        10.1.1.0/24 is directly connected, gig0/1
L        10.1.1.1/32 is directly connected, gig0/1
C        10.2.2.0/24 is directly connected, gig0/2
L        10.2.2.1/32 is directly connected, gig0/2
C        10.3.3.0/24 is directly connected, gig0/3
L        10.3.3.1/32 is directly connected, gig0/3

Note above that we have one subnet for each spine switch 


O        10.2.0.0/16  [110/2] via 10.1.1.3, 1d19h, gig0/1   ← Assuming we add summary
                      [110/2] via 10.2.2.3, 1d19h, gig0/2
                      [110/2] via 10.3.3.3, 1d19h, gig0/3
O        10.3.0.0/16  [110/2] via 10.1.1.3, 1d19h, gig0/1   ← Assuming we add summary
                      [110/2] via 10.2.2.3, 1d19h, gig0/2
                      [110/2] via 10.3.3.3, 1d19h, gig0/3
O        10.4.0.0/16  [110/2] via 10.1.1.3, 1d19h, gig0/1   ← Assuming we add summary
                      [110/2] via 10.2.2.3, 1d19h, gig0/2
                      [110/2] via 10.3.3.3, 1d19h, gig0/3

Note above that we have three equal cost paths to servers on other leafs, the same amount of parallel paths as we have spines. 


C        10.1.10.0/30 is directly connected, gig0/10
L        10.1.10.1/32 is directly connected, gig0/10
C        10.1.11.0/30 is directly connected, gig0/11
L        10.1.11.1/32 is directly connected, gig0/11
C        10.1.12.0/30 is directly connected, gig0/12
L        10.1.12.1/32 is directly connected, gig0/12

Note above that every server is in its own LAN, with 10.$leaf.$down_port.1 as default-gateway. ($y ??)


Now we check the hash-buckets for load balancing over spines/between leafs. 

Leaf-4#show ip cef 10.5.0.0 internal
10.5.0.0/16, epoch 3, RIB[I], refcount 6, per-destination sharing
  sources: RIB
  feature space:
   Broker: linked, distributed at 4th priority
  ifnums:
   FastEthernet0/1(469): 10.1.1.5
   FastEthernet0/2(470): 10.2.2.5
   FastEthernet0/2(470): 10.3.3.5
  path 0625780C, path list 053A00B0, share 1/1, type attached nexthop, for IPv4
  nexthop 10.1.1.5 gig0/1, adjacency IP adj out of gig0/1, addr 10.1.1.5 058EF420
  path 0625787C, path list 053A00B0, share 1/1, type attached nexthop, for IPv4
  nexthop 10.2.2.5 gig0/2, adjacency IP adj out of gig0/2, addr 10.2.2.5 058EF280
  path 0625787C, path list 053A00B0, share 1/1, type attached nexthop, for IPv4
  nexthop 10.3.3.5 gig0/2, adjacency IP adj out of gig0/2, addr 10.2.2.5 05EFAKE0
 

  output chain:
    loadinfo 0588EE68, per-session, 2 choices, flags 0003, 6 locks
    flags: Per-session, for-rx-IPv4
    16 hash buckets
     < 0 > IP adj out of FastEthernet0/1, addr 10.1.1.3 058EF420
     < 1 > IP adj out of FastEthernet0/2, addr 10.2.2.3 058EF280
     < 2 > IP adj out of FastEthernet0/3, addr 10.1.1.3 058FAKE0
     < 3 > IP adj out of FastEthernet0/1, addr 10.2.2.3 058EF420
     < 4 > IP adj out of FastEthernet0/2, addr 10.1.1.3 058EF280
     < 5 > IP adj out of FastEthernet0/3, addr 10.2.2.3 058FAKE0
     < 6 > IP adj out of FastEthernet0/1, addr 10.1.1.3 058EF420
     < 7 > IP adj out of FastEthernet0/2, addr 10.2.2.3 058EF280
     < 8 > IP adj out of FastEthernet0/3, addr 10.1.1.3 058FAKE0
     < 9 > IP adj out of FastEthernet0/1, addr 10.2.2.3 058EF420
     <10 > IP adj out of FastEthernet0/2, addr 10.1.1.3 058EF280
     <11 > IP adj out of FastEthernet0/3, addr 10.2.2.3 058FAKE0
     <12 > IP adj out of FastEthernet0/1, addr 10.1.1.3 058EF420
     <13 > IP adj out of FastEthernet0/2, addr 10.2.2.3 058EF280
     <14 > IP adj out of FastEthernet0/3, addr 10.1.1.3 058FAKE0
     <15 >  -- not used /Robert
   Subblocks:
    None
Leaf-4#

Sometimes you need to tweak the load balancing scheme with the command 

 ip cef load-sharing algorithm include-ports source destination

Done! 

Congratulations.

[edit] Routing - Verifying path in CEF

This has not been verified for L3 Etherchannels 

show ip cef exact-route source-ip-address destination-ip-address

Example from http://packetlife.net/blog/2011/may/27/show-ip-cef/ 

Router# show ip cef exact-route 10.0.9.5 192.168.0.1
10.0.9.5        -> 192.168.0.1    : FastEthernet0/1 (next hop 10.0.9.18)
Router# show ip cef exact-route 10.0.9.6 192.168.0.1
10.0.9.6        -> 192.168.0.1    : FastEthernet0/0 (next hop 10.0.9.14)

Source: http://www.netcraftsmen.com/load-balancing-and-cisco-express-forwarding-cef-with-parallel-paths/

[edit] CEF with EtherChannel

From: Understanding EtherChannel Load Balancing and Redundancy on Catalyst Switches paragraph Catalyst 3560

You can find out which interface is used in the EtherChannel to forward traffic based on
the load balancing method. The command for this determination is 

test etherchannel load-balance interface port-channel number {ip | mac} [source_ip_add | source_mac_add] [dest_ip_add | dest_mac_add]

Example: 

 6509-sp#test etherchannel load-balance interface port-channel 1 mac 00d0.c0d7.2dd4 0002.fc26.2494 
 Would select Gi6/1 of Po1
 6509-sp#

switch#show ip cef exact-route 172.16.79.186 192.168.42.183
172.16.79.186 -> 192.168.42.183 => IP adj out of Vlan100, addr 10.10.1.245 

switch#show vlan id 100
VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
100 uplink1 active Po4



switch#test etherchannel load-balance interface po4 ip 172.16.79.186 192.168.42.183
Would select Gi0/51 of Po4

switch#show controller util | inc (^Port|Gi0/51)
Port Receive Utilization Transmit Utilization
Gi0/51 1 0

Example 2: 

switch#show control util
Port Receive Utilization Transmit Utilization
Gi0/49 1 55
Gi0/50 6 0
Gi0/51 1 0
Gi0/52 12 57

[edit] Debugging according to Cisco

Regular Interface (No Subinterfaces) 

Step 1
View the Address Resolution Protocol (ARP).
RP/0/RSP0/CPU0:router# show arp 

Step 2
Verify that the lag table is programmed properly in the hardware.
RP/0/RSP0/CPU0:router# show interface bundle-ether bundle-id 

Step 3
View the running configuration information.
RP/0/RSP0/CPU0:router# show running-config 

Step 4
View information about packets forwarded by CEF.
RP/0/RSP0/CPU0:router# show cef 

Step 5
RP/0/RSP0/CPU0:router# show cef hardware ingress location node-id

Step 6
RP/0/RSP0/CPU0:router# show cef hardware egress location node-id 

'''Subinterface''' 

Step 1
Troubleshoot Layer 3 IPv4 traffic.
Step 2
Ensure that VLAN traffic coming in matches that on the incoming interface.

Ping Failed over Bundle
Step 1
View the ARP.
RP/0/RSP0/CPU0:router# show arp 
Step 2
View the ARP information on the particular LC or RSP.
RP/0/RSP0/CPU0:router# show arp location node-id
Step 3
RP/0/RSP0/CPU0:router# show cef hardware detail location node-id ingress 
Step 4
RP/0/RSP0/CPU0:router# show interface 
Step 5
Use the hash calculator to determine which bundle member (interface) to test.
Step 6
Remove the interface from the bundle.
Step 7
Assign an IP address to the interface.
Step 8
Ping the interface.
Step 9
Ensure that the ARP is resolved between the router and the node being pinged.
### END ###

On 6500--PFC-3C system with src-dst-ip enhanced algorithm: 

   PFC-3C#show etherchannel load-balance hash-result interface port-channel 
   1 ip 10.1.1.1 vlan 10 10.2.2.2

   Computed RBH: 0x1
   Would select Gig3/2 of Po1


In the end let me just share with you command to verify transmitters of Catalyst 4500 and 2k/3k respectively: 

“show platform software etherchannel port-channel 5 map ip 1.1.1.1 1.1.1.2”
“test etherchannel load-balance interface port-channel 1 ip 1.1.1.1 1.1.1.2”

From: packetpushers.net

[edit] dCEF

Brandon, Just as a side note, "show ip cef exact-route" will show you the software CEF hash. It's not useful on hardware platforms to determine path selection as hardware will not necessarily make the same decision. "show mls cef exact-route" is what you want to use on these platforms. For distributed forwarding(DFC) platforms it may need to be checked by attaching to the ingress LC.

-Ben http://www.gossamer-threads.com/lists/cisco/nsp/140211

[edit] First Try on 7609 to 6504, 10 GBE

Leaf3-7609#
Leaf3-7609#show ip cef exact 10.33.33.33 10.11.11.11 detail
10.33.33.33     -> 10.11.11.11    : TenGigabitEthernet8/1 (next hop 10.1.1.1)
Leaf3-7609#
Leaf3-7609#show ip cef exact 10.33.33.33 10.11.11.11
10.33.33.33     -> 10.11.11.11    : TenGigabitEthernet8/1 (next hop 10.1.1.1)
Leaf3-7609#

Leaf3-7609#show running | beg ospf
router ospf 1
 log-adjacency-changes
 network 10.0.0.0 0.255.255.255 area 0
!

!
interface TenGigabitEthernet8/1
 ip address 10.1.1.3 255.255.255.0
end



Leaf3-7609#
Leaf3-7609#show ip cef state
                        ^
% Invalid input detected at '^' marker.

Leaf3-7609#show ip cef ?
  A.B.C.D             prefix of entries to show
  Async               Async interface
  CTunnel             CTunnel interface
  Dialer              Dialer interface
  GigabitEthernet     GigabitEthernet IEEE 802.3z
  Group-Async         Async Group interface
  Loopback            Loopback interface
  MFR                 Multilink Frame Relay bundle interface
  Multilink           Multilink-group interface
  Null                Null interface
  Port-channel        Ethernet Channel of interfaces
  Pos-channel         POS Channel of interfaces
  TenGigabitEthernet  Ten Gigabit Ethernet
  Tunnel              Tunnel interface
  Vif                 PGM Multicast Host interface
  Virtual-Template    Virtual Template interface
  Virtual-TokenRing   Virtual TokenRing
  Vlan                Catalyst Vlans
  XTagATM             Extended Tag ATM interface
  adjacency           Display all prefixes resolving through adjacency
  detail              Display full information
  epoch               Display epoch information
  events              Show CEF table events
  exact-route         Display exact route for a session
  fcpa                Fiber Channel
  inconsistency       Show table inconsistency information
  non-recursive       Display non-recursive routes only
  summary             CEF table summary
  traffic             Display traffic statistics
  unresolved          Display unresolved routes only
  vrf                 Show VPN Routing/Forwarding instance CEF table
  |                   Output modifiers
  <cr>

Leaf3-7609#show ip cef 10.33.33.33 ?
  A.B.C.D  prefix mask
  detail   Display full information
  |        Output modifiers
  <cr>

Leaf3-7609#

Leaf3-7609#show fabric switching-mode
Global switching mode is Compact
dCEF mode is not enforced for system to operate
Fabric module is not  required for system to operate
Modules are allowed to operate in bus mode
Truncated mode is allowed, due to presence of DFC, CEF720, Standby supervisor module

Module Slot     Switching Mode
    2                 Crossbar
    3                 Crossbar
    4                 Crossbar
    5                     dCEF
    6                 Crossbar
    8                     dCEF
Leaf3-7609#
Leaf3-7609#

Leaf1-6504#

    1                 dCEF
    2                 Crossbar
    3                 Crossbar
    '''4                 Crossbar'''

Interface Ten sitter i bladplats 4

http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipswitch_cef/configuration/15-sy/isw-cef-15-sy-book/isw-cef-enhancements.html#GUID-F4F9F79F-354A-4EA8-B48E-4CE651E8BDED

[edit] Polarization

Be The Packets – CCIE Study Blog


Review/Perspective: CEF Concepts

  • 1.1.b Identify Cisco express forwarding concepts
    • 1.1.b [i] RIB, FIB, LFIB, Adjacency table
    • 1.1.b [ii] Load balancing Hash
    • 1.1.b [iii] Polarization concept and avoidance
Retrieved from "http://catch-up.cnap.hv.se/wiki/index.php?title=CCNP_Equal_Cost_Multi_Path_(ECMP)&oldid=3035"
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