Tuesday, May 11, 2010

[Cisco] How can find traffic flow across load-balance


ตัวอย่างต้องการทราบ traffic ที่ flow ผ่านทาง load-balance link ซึ่งโดย default CEF จะ loadbalance by src-dst ip
โดยมีข้อมูลดังนี้
source address: 192.168.100.1
destination address: 192.168.200.1

C6509#sh ip route 192.168.200.0
Routing entry for 192.168.200.0/24
Known via "ospf 100", distance 110, metric 20
Tag 65001, type extern 1
Last update from 10.0.0.71 on Port-channel2, 03:51:18 ago
Routing Descriptor Blocks:
10.0.0.90, from 10.0.254.98, 03:51:18 ago, via Port-channel2
Route metric is 20, traffic share count is 1
Route tag 65001
* 10.0.0.71, from 10.0.254.20, 03:51:18 ago, via Port-channel2
Route metric is 20, traffic share count is 1
Route tag 65001

C6509#sh ip cef exact-route 192.168.100.1 192.168.200.1
192.168.100.1 -> 192.168.200.1 => IP adj out of Port-channel2, addr 10.0.0.90

C6509#sh mls cef exact-route 192.168.100.1 192.168.200.1

Interface: Po2, Next Hop: 10.0.0.90, Vlan: 1014, Destination Mac: 0012.0111.bbbb

C6509#sh etherchannel load-balance
EtherChannel Load-Balancing Configuration:
src-dst-ip
mpls label-ip

EtherChannel Load-Balancing Addresses Used Per-Protocol:
Non-IP: Source XOR Destination MAC address
IPv4: Source XOR Destination IP address
IPv6: Source XOR Destination IP address
MPLS: Label or IP

C6509#sh etherchannel load-balance hash-result int po2 ip 192.168.100.1 192.168.200.1
Computed RBH: 0x1
Would select Te4/2 of Po2


สรุปได้ว่ามี flow ของ 192.168.100.1 ----> 192.168.200.1 จะมี next-hop ไปที่ 10.0.0.90 แต่จะส่งออกทาง interface Te4/2 ซึ่งเป็นสมาชิกของ port-channel2

** อ้างอิง
Cisco IOS Software, s72033_rp Software (s72033_rp-ADVENTERPRISEK9_WAN-M), Version 12.2(33)SXI2a