Figure 146 FTP packets TCP ports 20 and 21 are being forwarded to Lucy whereas Telnet packets TCP port 23 with the same source and destination addresses are forwarded to Pigpen Echo Reply packets ICMP type 0 which do not find a match in the policy route a
&chreeder«<jet)uq ip packet <m t .■> l j 10 ]P packet ik-tjuyyiiKj is en uit:'. iiii<:iJ.i for a^tn ii^t iu
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&chreeder«<jet)uq ip packet <m t .■> l j 10 ]P packet ik-tjuyyiiKj is en uit:'. iiii<:iJ.i for a^tn ii^t iu
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|
IP: |
s 16. ! |
2 |
(Etherneta), |
d ITS |
16.6. |
1 (Serial«!, |
g-172.16.2.1 |
len |
i&y/, forward |
|
|
TCP ti-c = 3e |
ris! 10.17, sin |
37027701365, |
.irk 59124&297, ¿.in 1.133s |
AjCK F^II |
||||||
|
IP: |
s 172.16,1.2 |
(Etherneta), |
d -rd |
1 ti. JJ . |
1 (Serial«), |
5=172,16,2.1 |
6*. |
r 'j rwa rcl |
||
|
TCP $r-c = 31 |
rift! ftin |
3&G21OT31 , |
■v.k 591205663, H33? |
AC* PSH |
||||||
|
IP: |
;; 1 72 . :■>. 1 |
2 |
(Etheroeta), |
d 172 |
16.6. |
1 (Serial«), |
g=172.1^.2.1 |
len |
H76, forward |
|
|
(i-e=2e |
rift! 1017, ft*n 3702771885, |
,l:!k 59124S297, 1.1« 14335 |
At-K Pill |
|||||||
|
1P: |
K 1 72 . 1 |
2 |
(Etherneta), |
<! 1/2 |
■(i.-i. |
1 (Seriall!, |
8=172.16.3.1 |
len |
-ID. |
r 'j i T.ii rd |
|
TCP |i-e = 33 |
rift! lain, sin |
373*385279, |
■v.k 5fl1?77S73. -J.in 14332 |
|||||||
|
IP: |
s 1 72 .1:>. i .2 |
(Ethemeta), |
d 172 |
16,6, |
1 (Serial! |, |
5=172,16,3.1 |
len |
S2, |
forward |
|
|
T£P (r-e=33 |
rift! lain, sin |
J73-I^fi5?7y, |
■ink 5S127707J, v:in T.133S |
ACK PKII |
||||||
|
IP: |
K 1 72. 16. ! |
2 |
(Etherneta}, |
(1 172 |
'ii.ii. |
1 (Serial!!, |
g*172.16.3.1 |
len |
-10. |
forward |
|
TCP (i"e = 33 |
rift! loin, sin |
3734395291 , |
,1-k 5S1277876, j.in 14332 |
|||||||
|
IP: |
£ 1 72. • ■},. 1 |
2 |
(Etherneta), |
d 172 |
16,6, |
i (Serial«!, |
9=172.16.2.1 |
len |
iiB. |
forward |
|
tcni" typi = |
f:i.rli' 5 |
|||||||||
|
IP: |
1 72. ■■>. 1 |
2 |
(Ether-neta), |
(1 -72 |
■ii.-i. |
1 (Serial!!, |
g=172.16.3.1 |
len |
iiD. |
forward |
|
COSfl ft |
||||||||||
|
IP: |
ii 1 72. !■>. 1 |
2 |
(Etheroeta), |
<1 W2 |
16,6, |
i (Serial«!, |
g=172.16.2.1 |
len |
forward |
|
|
rcNi> tjfpe- |
t. |
C048 p |
||||||||
|
]P: |
!i • 72. ■■>. 1 |
2 |
(Ether-neta), |
(I W2 |
■ii.ii. |
l (Serial!!, |
g=172,16,3.1 |
len |
6«, |
forward |
|
ICNP typt- |
ii>r1i: LI |
|||||||||
The purpose of segregating bulk and interactive traffic, as demonstrated in the last example, is so that the small packets characteristic of interactive traffic do not become delayed by the large packets characteristic of bulk traffic. The problem with the approach in this example is that if many types of traffic must be segregated, the access lists identifying the traffic by destination port may become prohibitively large.
If the objective is to segregate small packets from large packets, the length of the packet can be matched:
interface EthernetO
ip address 172.16.1.4 255.255.255.0 ip policy route-map Woodstock
route-map Woodstock permit 20 match length 1000 1600 set ip next-hop 172.16.2.1
route-map Woodstock permit 30 match length 0 400 set ip next-hop 172.16.3.1
Here the match length statement specifies a minimum and a maximum packet size. Statement 20 of the route map causes all packets between 1000 and 1600 octets in length to be routed across the serial link to Lucy. Statement 30 causes all packets up to 400 octets in length to be routed across the serial link to Pigpen. Packets between 400 and 1000 octets are routed normally.
Figure 14.7 shows the results of the new route map. Again there are FTP, Telnet, and Echo Reply packets from 172.16.1.2 to 172.16.6.1, but now the packets are routed according to their size instead of their addresses and ports.
Continue reading here: Case Study Policy Routing and Quality of Service Routing
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